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  • 1
    Electronic Resource
    Electronic Resource
    Statistical validation of GCM-simulated climates for the U.S. Great Lakes and the C.I.S. Emba and Ural River basins (1992)
    Springer
    Stochastic environmental research and risk assessment 6 (1992), S. 69-80 
    Details
    ISSN: 1436-3259
    Keywords: Hydrology ; global circulation models ; statistics ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Many researchers use outputs from large-scale global circulation models of the atmosphere to assess hydrological and other impacts associated with climate change. However, these models cannot capture all climate variations since the physical processes are imperfectly understood and are poorly represented at smaller regional scales. This paper statistically compares model outputs from the global circulation model of the Geophysical Fluid Dynamics Laboratory to historical data for the United States' Laurentian Great Lakes and for the Emba and Ural River basins in the Commonwealth of Independent States (C.I.S.). We use maximum entropy spectral analysis to compare model and data time series, allowing us to both assess statistical predictabilities and to describe the time series in both time and frequency domains. This comparison initiates assessments of the model's representation of the real world and suggests areas of model improvement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01581676
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  • 2
    Electronic Resource
    Electronic Resource
    Inference of ground surface temperature history from subsurface temperature data: Interpreting ensembles of borehole logs (1996)
    Springer
    Pure and applied geophysics 147 (1996), S. 537-550 
    Details
    ISSN: 1420-9136
    Keywords: Borehole temperature ; climate change ; inversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Ground surface temperature histories (GSTHs) inferred from borehole temperaturedepth (T-z) data are often degraded, to a various extent, by random or systematic noise in theT-z data and in the measurements of thermophysical properties of the earth. To minimize the effects of noise, and hence improve the fidelity of the inferred GSTH, a plausible approach is to perform a simultaneous inversion, of theT-z logs in a region, or alternatively, to invert the individualT-z logs and then average the resulting GSTHs. Averaging and simultaneous inversion are conceptually different: whereas an averaging can always be peformed, a simultaneous inversion is predicated on the assumption of a common transient component of the GSTH in all theT-z logs. In this work we examine and compare the two approaches, using a time domain inverse formulation based on the method of least squares. We consider a set of scenarios: (a) multipleT-z logs from a single borehole, (b) multiple boreholes from a single site, (c) multiple boreholes in similar climatological settings, and (d) multiple boreholes in different climatological settings. We show that for (a), (b) and (c), averaging and simultaneous inversion yield nearly identical results. For boreholes in different settings, the assumption of a common transient GSTH may be invalid and averaging and simultaneous inversion give divergent results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00878843
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  • 3
    Electronic Resource
    Electronic Resource
    Diatom responses to late Quaternary vegetation and climate change, and to deposition of two tephras in an alpine and a sub-alpine lake in Yoho National Park, British Columbia (1994)
    Springer
    Journal of paleolimnology 11 (1994), S. 173-188 
    Details
    ISSN: 1573-0417
    Keywords: Late Quaternary ; diatoms ; pollen ; climate change ; tephra ; shallow alpine and sub-alpine Iakes ; British Columbia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The late Quaternary diatom records from alpine Opabin Lake (altitude 2285 m a.s.l.) and sub-alpine Mary Lake (altitude 2054 m a.s.l.), located in Yoho National Park, British Columbia (lat. 51 ° 21′N; long. 116 ° 20′), have been analyzed, and changes in these records have been used to reconstruct lake histories. The results have also been related to independently inferred vegetation and climate changes. Following deglaciation, when both lakes were receiving high inputs of clastic materials, benthic diatom taxa dominate the records of these two shallow lakes with small species ofFragilaria being particularly prominent. During the early to mid-Holocene period, when treeline was at a higher elevation than today, the diatom flora of both lakes became more diverse with previously minor species becoming more prominent.Cyclotella radiosa occurs in cores from both Mary Lake, and much deeper, neighbouring Lake O'Hara during the warm early Holocene, and may reflect this warmer climate, a longer ice-free season than presently, and perhaps less turbid water, or its presence may reflect a subtly higher nutrient status of the lake water during this period. The Neoglacial is marked by increased amounts of sediments originating from glacial sources in Opabin Lake, which undoubtedly led to very turbid water, and by the presence ofEllerbeckia arenaria f.teres andCampylodiscus noricus v.hibernica in Opabin Lake; however, these species are absent from Mary Lake which has not been influenced by either glacial activity since the recession of the glaciers prior toc. 10 000 years BP or water originating from Opabin Lake. The impact of the two tephras during the Holocene was dramatic in terms of increased diatom production, as exemplified by the increases in diatom numbers, but there was little effect upon species composition. The diatom records and changes in the diatom:cyst ratio suggest that the chemical status of these two small, shallow lakes has changed little during the Holocene, other than after deposition of the two tephras. These results provide evidence that shallow alpine and high sub-alpine lakes are sensitive recorders of past environmental changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00686864
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  • 4
    Electronic Resource
    Electronic Resource
    Holocene pollen record from a peatland in the West Caucasus, Abkhasia, Black Sea region (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 65-74 
    Details
    ISSN: 1573-0417
    Keywords: forest dynamics ; peatland development ; mountain environments ; Castanea ; Sphagnum ; Quaternary ; pollen analysis ; human impact ; climate change ; USSR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A pollen sequence spanning over 4000 years was recovered from a small (0.1 ha)Sphagnum-dominated peatland in the mountains near Sukhumi, Abkhasia, West Georgia. The peatland lies atc. 1650 m a.s.l. in denseFagus-Abies forest. The pollen record reveals totally forested surroundings throughout since at least 4000 years BP (90–95% AP). It begins with a complex forest dominated byFagus with large proportions ofCastanea, Acer andUlmus. ThenCastanea became dominant whileFagus was still prominent. This might indicate a warmer climate. Later development shows a dramatic decline ofCastanea. Its pollen drops down to 3–5%. RecentlyAbies has been experiencing an exponential growth. Now it comprises over 50% of the forest composition around the peatland. These changes have possibly been caused by human influence together with climatic change. The basin started as aPotamogeton-dominated shallow lake with ferns andAlisma along the margins. Later it developed into a sedge fen and finally aSphagnum andMenyanthes poor fen with scatteredCarex limosa. The record indicates a progression towards oligotrophy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678087
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  • 5
    Electronic Resource
    Electronic Resource
    Rates of peat accumulation over the past 200 years in fiveSphagnum-dominated peatlands in the United States (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 35-47 
    Details
    ISSN: 1573-0417
    Keywords: carbon cycling ; climate change ; organic matter ; peat ; peatland ; Sphagnum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Using210Pb-dating of peat cores, corroborated by pollen and acid-insoluble ash approaches, rates of vertical height growth, dry mass accumulation, and organic matter accumulation were determined for fiveSphagnum-dominated peatland sites (one in Minnesota, one in Pennsylvania, one on the Maryland/West Virginia border, two in West Virginia), spanning a mean annual temperature range of 4.5 °C and differing in total annual precipitation by a factor of almost 2. Site differences in rates of vertical height growth and dry mass accumulation were documented, but both within-core and between-site differences in bulk density and ash concentrations of peat confound efforts to relate vertical height growth and dry mass accumulation to net organic matter accumulation. Taking bulk densities and ash concentrations into account, rates of net organic matter accumulation over the past 150–200 years were strikingly similar at four of the five sites, an unexpected result given the general trend that with decreasing latitude, peat deposits become older, thinner, and more highly decomposed. More comprehensive studies are needed in which net organic matter accumulation is determined at several locations within a single peatland, at several peatlands within a particular geographic/climatic region, and at peatland sites in different geographic/climatic regions. If additional studies confirm that recent (past 200 years) net organic matter accumulation is relatively insensitive to broad-scale regional climatic differences, boreal and subarctic peatlands may continue to function as a net sink for atmospheric CO2 and a net source of atmospheric CH4 with no change in rates of net organic matter accumulation, even under predicted scenarios of global climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00677988
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  • 6
    Electronic Resource
    Electronic Resource
    Acidity of twelve northern New England (U.S.A.) lakes in recent centuries (1994)
    Springer
    Journal of paleolimnology 12 (1994), S. 103-154 
    Details
    ISSN: 1573-0417
    Keywords: acidification ; alkalization ; pH ; alkalinity ; diatoms ; sediment chemistry ; New England ; catchment effects ; land use ; logging ; acidic deposition ; air pollutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Studies of sediment cores from 12 acidic lakes in granitic, forested and uninhabited catchments in northern New England, U.S.A. produced diatom-inferred pH (IpH) 5.2 to 5.8 and alkalinity (Ialk) −12 to 31 µeq l−1, with slowly declining values at some lakes, for one to four centuries prior to logging. Increases of IpH (Δ0.05 to 0.60) and Ialk (Δ5 to 40 µeq l−1) correlate with logging in the catchments in the early-1800s to early-1900s. Recovery to pre-logging IpH and Ialk correlates with forest succession toward conifers, and is completed in the late-1800s to mid-1900s. Beginning at 1915–1920 (4 lakes), 1930–1950 (4 lakes) and 1965–1970 (4 lakes), IpH and Ialk start decreasing below pre-logging values due to atmospheric acidic deposition, leading to respective total decreases of 0.10 to 0.45 (X=0.25) and 5 to 25 µeq l−1 (X=15). Inputs of anthropogenic Pb, Zn, V, polycyclic aromatic hydrocarbons, and soot from the atmosphere are first detectable in early- to late-1800s sediment, and Cu in late-1800s sediment, increase rapidly in the late-1800s to mid-1900s, and level off or decrease since the 1960s — partly due to emission controls. Decreasing Ca, Mn, and possibly Zn relative to other metals and normalized to organic content, and increasing flux of Fe to the lakes, indicate soil and water acidification after 1900.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678090
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  • 7
    Electronic Resource
    Electronic Resource
    Paleolimnological analysis of Ullswater using testate amoebae (1995)
    Springer
    Journal of paleolimnology 13 (1995), S. 51-63 
    Details
    ISSN: 1573-0417
    Keywords: acidification ; England ; Holocene ; Lake District ; paleolimnology ; testate amoebae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Tests of testate amoebae extracted from samples of bottom sediments from 33 tarns in the English Lake District reveal a relationship between their distribution and physical-chemical parameters of the tarn waters.Nebela and several species ofDifflugia appear to prefer more acidic conditions, i.e., pH less than 6.2, while others such asCentropyxis, Lesquereusia and some species ofCyclopyxis andDifflugia are more common in lakes with pH's above that value. Using these data, and inferring rates of sedimentation from the densities of tests found in a 6-m core, a paleolimnological history for the past 11 000 years is presented for Ullswater (English Lake District). The record of testate amoebae, beginning shortly after deglaciation, depicts an uneven increase in acidity and a history of episodes of rapid and slow deposition that correlate reasonably well with paleoclimatological changes and anthropogenic alterations in the catchment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678110
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  • 8
    Electronic Resource
    Electronic Resource
    The representation of diatom communities by fossil assemblages in a small acid lake (1995)
    Springer
    Journal of paleolimnology 14 (1995), S. 185-223 
    Details
    ISSN: 1573-0417
    Keywords: taphonomy ; representativity ; diatoms ; acidification ; liming ; sediment traps
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The representative quality of fossil diatom assemblages in the recent sediment of a lake is compared with its contemporary diatom flora. In April 1986 experimental liming of the catchment of a small acidified lake, Loch Fleet (Galloway, U.K.), produced immediate changes in water quality. Lakewater pH rose from a mean of approximately 4.5 to 6.5, and in the two year period following liming a consistently higher pH was maintained. The marked response of diatom species to changing water quality provided a means of tracing events from living communities to the fossil assemblages. Diatom periphyton and plankton were sampled during a 20 month period and archived material was used to characterise earlier diatom communities. A comparison is made between living diatom communities and diatom assemblages collected by sediment traps and from sediment cores taken during the same period. Following liming, the diatom communities were found to respond within days or weeks to the changes in water quality. There is an initial change from acidobiontic communities, dominated byTabellaria quadriseptata, to dominance by the acidophilous speciesEunotia incisa andPeronia fibula. However, in the epipsammic community the acidobiontic speciesTabellaria binalis fo.elliptica remains abundant after liming. Approximately one year after liming the abundances of species such asAchnanthes minutissima andBrachysira vitrea increase in the epilithon, epiphyton and epibryon, whilst in the epipsammonT. binalis fo.elliptica is replaced by smallEunotia spp. andAchnanthes altaica. During the latter part of 1987 and in 1988, despite a stable pH, fluctuating patterns of species abundances are seen in the epilithon, epiphyton and epibryon whilst the species composition of the epipsammon remains relatively stable. Spring blooms of the planktonic speciesSynedra acus andAsterionella formosa occur during 1988 and 1989 respectively. Sediment trapping, which began in April 1987, records shifts in species composition corresponding with those seen in the epilithon, epiphyton and epibryon and with the blooms of planktonic species. The signal from the smaller, and probably less easily transportable, epipsammic community is not so clearly discernible. Although the fundamental record of the sediment traps is one from living diatom communities, the appearance of taxa ‘extinct’ during the post-liming period reflects a low, but significant level of sediment resuspension. In contrast to the rapid response of living communities and their record in sediment traps, sediment cores do not begin to reflect changes in diatom composition until about 14 months after the initial liming. The first appearance of circumneutral taxa in significant abundance occurs only approximately 17 months after liming. The delayed reaction of sediment assemblages cannot be attributed principally to a slow rate of transport from the littoral to the profundal zone. Time-averaging processes within the sediment appear to be the main cause of the lag in core response. In contrast, blooms of planktonic species are quickly reflected in the stratigraphy of cores, but indicate that a considerable degree of downward mixing occurs. Comparison of the time trajectories of whole species assemblages in living communities, sediment traps and core surface sediments shows that the direction of change is similar in all three, but that the magnitude of change is attenuated in sediment assemblages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00735481
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  • 9
    Electronic Resource
    Electronic Resource
    A preliminary investigation of siliceous microfossil succession in late Quaternary sediments from Lake Baikal, Siberia (1997)
    Springer
    Journal of paleolimnology 18 (1997), S. 189-206 
    Details
    ISSN: 1573-0417
    Keywords: Lake Baikal ; Russia ; paleolimnology ; diatoms ; chrysophyte cysts ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Siliceous microfossil assemblage succession was analyzed in a 100 m sediment core from Lake Baikal, Siberia. The core was recovered from the lake's central basin at a water depth of 365 m. Microfossil abundance varied greatly within the intervals sampled, ranging from samples devoid of siliceous microfossils to samples with up to 3.49 × 1011 microfossils g-1 sediment. Fluctuations in abundance appear to reflect trends in the marine δ18O record, with peak microfossil levels generally representing climate optima. Microfossil taxa present in sampled intervals changed considerably with core depth. Within each sample a small number of endemic diatom species dominated the assemblage. Changes in dominant endemic taxa between sampled intervals ranged from extirpation of some taxa, to shifts in quantitative abundance. Differences in microfossil composition and the association of variations in abundance with climate fluctuations suggest rapid speciation in response to major climatic excursions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007924310688
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  • 10
    Electronic Resource
    Electronic Resource
    A weighted-averaging regression and calibration model for inferring lakewater salinity from fossil diatom assemblages in saline lakes of the Vestfold Hills: a new tool for interpreting Holocene lake histories in Antarctica (1998)
    Springer
    Journal of paleolimnology 19 (1998), S. 99-113 
    Details
    ISSN: 1573-0417
    Keywords: Antarctica ; saline lakes ; weightedaveraging ; transfer function ; diatom analysis ; palaeolimnology ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationship between surface sediment diatom assemblages and measured limnological variables in thirty-three coastal Antarctic lakes from the Vestfold Hills was examined by constructing a diatom-water chemistry dataset. Previous analysis of this dataset by canonical correspondence analysis revealed that salinity accounted for a significant amount of the variation in the distribution of the diatom assemblages. Weighted-averaging regression and calibration of this diatom-salinity relationship was used to establish a transfer function for the reconstruction of past lakewater salinity from fossil diatom assemblages. Weighted-averaging regression and calibration with classical deshrinking provided the best model for salinity reconstructions and this was applied to the fossil diatom assemblages from one of the saline lakes in the Vestfold Hills in order to assess its potential for palaeosalinity and palaeoclimate reconstruction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007947402927
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  • 11
    Electronic Resource
    Electronic Resource
    Late Quaternary diatom response to vegetation and climate change in a subalpine lake in Banff National Park, Alberta (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 253-265 
    Details
    ISSN: 1573-0417
    Keywords: Late Quaternary ; diatoms ; climate change ; vegetation change ; shallow ; subalpine ; Crowfoot Lake ; Alberta ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The late Quaternary diatom record from subalpine Crowfoot Lake, Banff National Park, Alberta (lat. 51° 61′N; long. 116° 31′W) has been analyzed. Results are related to independently inferred vegetation and climate changes. No diatoms were found in the basal diamict that predates 11330 14C yr BP. Very few occur until ca. 10 10014 C yr BP probably due to the short time between de-glaciation and an advance of the Crowfoot Glacier during the ‘Younger Dryas Chron’. Initial pioneering species were characteristic of alkaline water and calcareous organic sediments. They appeared as sediments became organic and laminated suggesting increasing water clarity, and as the Pinus-dominated forest expanded and the climate warmed. After ca. 9060 14C yr BP diatom numbers increased rapidly, reaching a maximum prior to the Mazama tephra; they remained high until ca. 3500 14C yr BP. The period between ca. 9060 and 3500 14C yr saw timberline elevation increase and the dominance of xerophytic taxa. These are consistent with early to mid-Holocene warmth and aridity. Diatom productivity reflects the warm climate and presumably longer ice-free season, a stable catchment and transparent water. Decreases in diatom productivity coincide with a vegetation change with reduction of xerophytic taxa and the appearance of a closed Picea-Abies forest, hence a cooler, wetter climate at ca. 4100 to 3500 14C yr BP. The diatom numbers during the Neoglacial were of the same magnitude as prior to ca. 9060 14C yr BP. Small species of Fragilaria (overwhelmingly Fragilaria construens v. venter) became extremely dominant during the period of high diatom productivity, and remained so thereafter. Recovery of the lake appears to have been rapid after deposition of the Mazama tephra. Maximum occurrence of Cyclotella radiosa occurred ca. 8000 14C yr BP during the warm early Holocene and may reflect this warmer climate, a longer ice-free season than presently, perhaps less turbid water, or it may reflect a subtly higher nutrient status of the lake water. The diatom record of Crowfoot Lake has responded with sensitivity, particularly in terms of productivity, to the Holocene vegetation and climate changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007978730349
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  • 12
    Electronic Resource
    Electronic Resource
    Paleolimnological evidence for the recent acidification of Llyn Hir, Dyfed, Wales (1989)
    Springer
    Journal of paleolimnology 2 (1989), S. 245-262 
    Details
    ISSN: 1573-0417
    Keywords: acidification ; diatoms ; sediment chemistry ; magnetic stratigraphy ; soot ; paleolimnology ; Wales
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A variety of paleolimnological techniques, coupled with historical data on land-use and fisheries, are used to evaluate the magnitude, timing, and causes of acidification of Llyn Hir, a moorland lake in central Wales. pH reconstruction based on diatom analysis suggests a gradual decline in lakewater pH beginning ca. 1870 and intensifying in the mid-1930's, with a total decline of 1.1 pH units between 1870 and 1984. This pH decline correlates with increased sedimentary concentrations of carbonaceous particles, trace metals, and magnetic minerals, which indicate the local deposition of atmospherically transported products of fossil-fuel combustion. Pollen data and the historical record show no significant alterations in land-use or catchment vegetation, indicating that acidification of Llyn Hir is a result of the increased deposition of atmospheric pollutants, not of land-use and vegetation change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195475
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  • 13
    Electronic Resource
    Electronic Resource
    Chrysophycean cysts in Sierra Nevada (California) lake sediments: paleoecological potential (1992)
    Springer
    Journal of paleolimnology 7 (1992), S. 73-94 
    Details
    ISSN: 1573-0417
    Keywords: acidification ; Chrysophyceae ; cyst ; paleolimnology ; Sierra Nevada ; statospore ; stomatocyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Thirty-three lakes in the Sierra Nevada range of California were investigated as part of a paleoecological study of the potential effects of acid deposition on sensitive lake/watershed ecosystems. Chrysophyte cysts from surface sediment samples were analyzed and compared with data on pH and alkalinity. This paper identifies the twenty-five dominant chrysophyte cyst taxa and provides information on their morphology, abundance, distribution and ecology. Chrysophycean cysts were generally abundant and well-preserved in lake sediments of our study sites. Twelve taxa occurred in more than twenty of the thirty-three lakes; these taxa were often quite abundant. In contrast, only nine taxa occurred in ten or fewer lakes. Abundance Weighted Mean (AWM) pH varied from 6.45 to 8.34 and AWM alkalinity varied from 46 to 588 μeq/L. We delineated pH preference categories, based on AWM pH values and frequency diagrams of cyst abundance vs. lake-water pH. We classified five taxa as acidophilous, nine as circumneutrals, six as alkaliphilous and five as indifferent. Given that the cyst types differ greatly in their abundance relative to pH and alkalinity, it is clear that they have potential for paleolimnological studies of Sierra lakes biogeochemistry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197032
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  • 14
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    Acidification and metal contamination in Whitepine Lake (Sudbury, Canada): a paleolimnological perspective (1993)
    Springer
    Journal of paleolimnology 9 (1993), S. 141-146 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; chrysophytes ; acidification ; Al ; Ni ; Sudbury ; recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatom and chrysophyte assemblages from a sediment core from Whitepine Lake were examined to infer changes in lakewater pH, nickel and aluminum concentrations since pre-industrial times, and to help determine the cause of the virtual extirpation of the lake trout population from the lake during the 1960s and 1970s. Our study indicates that acidification started in the 1920s, and that the maximum inferred pH decline (from 6.2 to 5.8) occurred between 1960 and 1970, coincident with the peak in metal mining and smelting activity in the Sudbury basin. Lakewater [Al] and [Ni], as inferred from our diatom transfer functions, increased. It appears that in addition to the pH decline, elevated [Al] may have played an important role in the decline of lake trout from Whitepine Lake in the 1960s and 1970s. Diatom-inferred lakewater pH and [Ni] have recovered slightly in the recent sediments, which coincides with reductions in emissions that have occurred since the mid-1970s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00677515
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  • 15
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    A paleolimnological assessment of lake acidification in five Connecticut lakes (1993)
    Springer
    Journal of paleolimnology 9 (1993), S. 209-221 
    Details
    ISSN: 1573-0417
    Keywords: acidification ; scaled chrysophytes ; Connecticut ; inference models ; weighted averaging ; fossils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract New England has received significant amounts of precipitation with a pH between 4.2 and 4.6. Paleolimnological studies based on siliceous microalgal remains support the hypothesis that some lakes in northern New England have acidified as a result of the acidic deposition. However, paleolimnological analyses from five software lakes in southern New England suggest that these lakes have not acidified in recent years. In all of the study lakes the inferred pH has remained relatively stable, and in two lakes the pH has actually increased slightly in recent years. Despite the relatively stable inferred pH reconstructions, significant shifts in species assemblages were observed in each lake, many of which are believed to correlate with land use changes. It is possible that effects of land use changes (e.g. increased urbanization) have masked potential effects of acid deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00677214
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  • 16
    Electronic Resource
    Electronic Resource
    Stable isotopic compositions of sulfur in PIRLA sediment cores (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 23-29 
    Details
    ISSN: 1573-0417
    Keywords: sulfur ; stable isotopes ; cores ; lakes ; δ34S ; acidification ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Stable isotopic compositions of total sedimentary sulfur were determined for cores from eight of the PIRLA study lakes. Preindustrial sulfur deposited prior to 1800 had roughly constant isotopic compositions within a 1–2‰ range in each core. In more recent sediments, large 5–10‰ decreases in 34S content occurred and likely resulted from the addition of anthropogenic sulfur. These isotopic changes began at the same time that lead concentrations increased in sediments, suggesting a close linkage between lead and sulfur deposition in the mid and late 1800s.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208296
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  • 17
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    Sedimentary chrysophycean cyst assemblages as paleoindicators in acid sensitive lakes (1991)
    Springer
    Journal of paleolimnology 5 (1991), S. 19-72 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; lakes ; resting cysts ; algae ; Chrysophyceae taxonomy ; stratigraphy ; acidification ; ecology ; stomatocyst ; statospore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Relationships between surface sediment cyst assemblages and lakewater characteristics were studies in 50 lakes located in central Ontario. The main purposes of the study were to identify the environmental factors most strongly controlling the distribution of chrysophycean cysts and to develop indices and equations to infer lake water pH from cyst assemblages. Principal components analysis indicates that alkalinity and associated TDS as well as elements related to trophic status are the factors most strongly correlated with the distribution of chrysophycean cysts. There are significant differences in the relative importance of these factors among the lakes. The transfer functions developed provide good prediction of pH values. This report also provides a descriptive analysis of the ‘fossil’ chrysophycean cyst flora of Ontario lakes. The descriptions include representative SEM micrographs and detailed characterization of each morphotype in consideration of the morphological variation observed among specimens of the same morphotype. Special attention has been paid to the anatomy of the collar complex and to the nature of the cyst surface ornamentation. One hundred and thirty seven morphotypes are described.
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    URL: http://dx.doi.org/10.1007/BF00226557
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    Timing of the last highstand of Lake Lahontan (1991)
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    Journal of paleolimnology 5 (1991), S. 115-126 
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    ISSN: 1573-0417
    Keywords: Lake Lahontan ; lake-level change ; climate change ; paleolimnology ; paleohydrology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Radiocarbon and uranium-series ages of a variety of materials from the Lahontan basin indicate that the last highstand lake occurred between 14 500 and 13 000 yr B.P. Although few in number, existing radiocarbon and uranium-series age data also indicate that lakes in the western Lahontan subbasins were small or moderate in size between 30 000 and 25 000 yr B.P. Existing data do not support the conclusions of Bradbury et al. (1989) who did not find evidence of a 14 000±yr B.P. highstand lake in the sediments of the Walker Lake subbasin. These data also do not support the existence of a highstand lake in the Walker Lake subbasin between 30 000 and 25 000 yr B.P.
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    URL: http://dx.doi.org/10.1007/BF00176873
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    Paleoindication of acidification in Kleiner Arbersee (Federal Republic of Germany, Bavarian Forest) by chydorids, chrysophytes, and diatoms (1988)
    Springer
    Journal of paleolimnology 1 (1988), S. 149-157 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; acidification ; diatoms ; chydorids ; scaled chrysophytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract In a sediment core of Lake Kleiner Arbersee, located in the Bavarian Forest on gneiss bedrock and with spodosolic soils in the catchment, acidification was reconstructed using assemblages of chydorids, scaled chrysophytes, and diatoms as paleoindicators. All paleoindicators demonstrated acidification of Kleiner Arbersee. There were marked differences, however, in the extent of the indicated acidification: In lower layers, where scaled chrysophytes and chydorids clearly indicate beginning acidification, pH-decline inferred by diatoms lies within the standard deviation, and is statistically not significant until the 7 cm layer. We conclude that mallomonadaceans reflect the acidification of the water body and strongly respond to the lowest seasonal pH, as their indicated rate of acidification is higher than that of diatoms, which appear to more closely indicate the pH of the sediment/water interface, especially when the pH of the water column has dropped below ca. 5.5. Chydorids may additionally be influenced by proton release of dense Sphagnum-stands, which cover the littoral of Kleiner Arbersee completely.
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    URL: http://dx.doi.org/10.1007/BF00196071
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    Late Quaternary paleolimnology of Walker Lake, Nevada (1988)
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    Journal of paleolimnology 1 (1988), S. 249-267 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; river diversion ; climate change ; pollen ; diatoms ; ostracodes ; brine shrimp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatoms, crustaceans, and pollen from sediment cores, in conjunction with dated shoreline tufas provide evidence for lake level and environmental fluctuations of Walker Lake in the late Quaternary. Large and rapid changes of lake chemistry and level apparently resulted from variations in the course and discharge of the Walker River. Paleolimnological evidence suggests that the basin contained a relatively deep and slightly saline to freshwater lake before ca. 30 000 years B.P. During the subsequent drawdown, the Walker River apparently shifted its course and flowed northward into the Carson Sink. As a result, Walker Lake shallowed and became saline. During the full glacial, cooler climates with more effective moisture supported a shallow brine lake in the basin even without the Walker River. As glacial climates waned after 15 000 years ago, Walker Lake became a playa. The Walker River returned to its basin 4700 years ago, filling it with fresh water in a few decades. Thereafter, salinity and depth increased as evaporation concentrated inflowing water, until by 3000 years ago Walker Lake was nearly 90 m deep, according to dated shoreline tufas. Lake levels fluctuated throughout this interval in response to variations in Sierra Nevada precipitation and local evaporation. A drought in the Sierras between 2400 and 2000 years ago reduced Walker Lake to a shallow, brine lake. Climate-controlled refilling of the lake beginning 2000 years ago required about one millennium to bring Walker lake near its historic level. Through time, lake basins in the complex Lake Lahontan system, fill and desiccate in response to climatic, tectonic and geomorphic events. Detailed, multidisciplinary paleolimnologic records from related subbasins are required to separate these processes before lake level history can be reliably used to interpret paleoclimatology.
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    URL: http://dx.doi.org/10.1007/BF00184000
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    The detection of Rhizosolenia (Bacillariophyceae) in sediment of Ontario lakes and implications for paleoecology (1988)
    Springer
    Journal of paleolimnology 1 (1988), S. 61-69 
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    ISSN: 1573-0417
    Keywords: Rhizosolenia ; paleoecology ; diatoms ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The detection of the freshwater genus Rhizosolenia (Bacillariophyceae) remains in sediments is affected by the oxidants used in the digestion procedures. The Rhizosolenia counts decrease from 30% H2O2〉50% HNO3〉50% chromic acid〉100% HNO3〉100% H2SO4. Rhizosolenia is mostly found in Ontario lakes with summer average pH ranging from 5.6 to 8.3, Gran alkalinity from 0.2 to 120 mg L−1 as CaCO3 and water colour from 4 to 105 Hazen units. Large Rhizosolenia populations are generally found in clear lakes, neutral pH and low alkalinity.
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    URL: http://dx.doi.org/10.1007/BF00202194
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    A synthesis of post-glacial diatom records from Lake Baikal (1994)
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    Journal of paleolimnology 10 (1994), S. 213-252 
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    ISSN: 1573-0417
    Keywords: diatoms ; paleolimnology ; palynology ; Holocene ; climate change ; Lake Baikal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The biostratigraphy of fossil diatoms contributes important chronologic, paleolimnologic, and paleoclimatic information from Lake Baikal in southeastern Siberia. Diatoms are the dominant and best preserved microfossils in the sediments, and distinctive assemblages and species provide inter-core correlations throughout the basin at millennial to centennial scales, in both high and low sedimentation-rate environments. Distributions of unique species, once dated by radiocarbon, allow diatoms to be used as dating tools for the Holocene history of the lake. Diatom, pollen, and organic geochemical records from site 305, at the foot of the Selenga Delta, provide a history of paleolimnologic and paleoclimatic changes from the late glacial (15 ka) through the Holocene. Before 14 ka diatoms were very rare, probably because excessive turbidity from glacial meltwater entering the lake impeded productivity. Between 14 and 12 ka, lake productivity increased, perhaps as strong winds promoted deep mixing and nutrient regeneration. Pollen evidence suggests a cold shrub — steppe landscape dominated the central Baikal depression at this time. As summer insolation increased, conifers replaced steppe taxa, but diatom productivity declined between 11 and 9 ka perhaps as a result of increased summer turbidity resulting from violent storm runoff entering the lake via short, steep drainages. After 8 ka, drier, but more continental climates prevailed, and the modern diatom flora of Lake Baikal came to prominence. On Academician Ridge, a site of slow sedimentation rates, Holocene diatom assemblages at the top of 10-m cores reappear at deeper levels suggesting that such cores record at least two previous interglacial (or interstadial?) periods. Nevertheless, distinctive species that developed prior to the last glacial period indicate that the dynamics of nutrient cycling in Baikal and the responsible regional climatic environments were not entirely analogous to Holocene conditions. During glacial periods, the deep basin sediments of Lake Baikal are dominated by rapidly deposited clastics entering from large rivers with possibly glaciated headwaters. On the sublacustrine Academician Ridge (depth = 300 m), however, detailed analysis of the diatom biostratigraphy indicates that diastems (hiatuses of minor duration) and (or) highly variable rates of accumulation complicate paleolimnologic and paleoclimatic reconstructions from these records.
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    Radiometric dating of lake sediments from Signy Island (maritime Antarctic): evidence of recent climatic change (1995)
    Springer
    Journal of paleolimnology 13 (1995), S. 179-191 
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    ISSN: 1573-0417
    Keywords: maritime Antarctic ; Signy Island ; lakes ; sediments ; Pb-210 ; Cs-137 ; radionuclide fluxes ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sediment cores from three lakes (Moss, Sombre and Heywood) in the maritime Antarctic (Signy Island, South Orkney Islands) have been successfully dated radiometrically by210Pb and137Cs. The core inventories of both fallout radionuclides are an order of magnitude higher than that which can be supported by the direct atmospheric flux at this latitude. The elevated values may be explained by fallout onto the catchment during the winter being delivered directly to the lakes during the annual thaw. Two of the lakes (Sombre and Heywood) show marked increases in sediment accumulation afterc. 1950. This appears to be associated with a documented rise in temperature in the South Orkney Islands, which has caused extensive deglaciation at Signy Island.
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    Recent diatom assemblage changes in subarctic Lake Saanajärvi, NW Finnish Lapland, and their paleoenvironmental implications (1998)
    Springer
    Journal of paleolimnology 20 (1998), S. 205-215 
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    ISSN: 1573-0417
    Keywords: subarctic lakes ; diatoms ; paleolimnology ; climate change ; Cyclotella ; Finnish Lapland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Diatoms were analysed from a 30-cm long sediment core obtained from remote subarctic Lake Saanaärvi (69°03′N, 20°52′E) in order to trace possible changes in the lake. Diatom assemblages were relatively constant throughout the core, except in the top 4–5 cm (approx 1850 A.D.) where relative frequencies of Aulacoseira italica subsp. subarctica, A. lirata var. biseriata, Cyclotella comensis and C. glomerata increased markedly. No significant trends were observed in the weighted averaging (WA) reconstructed pH values. Several hypotheses, including (i) airborne pollution, (ii) climatic change, and (iii) catchment disturbances have been put forth to explain the recent changes in diatom assemblages. The diatom change coincides with a marked increase in mean annual temperature that has been documented in the area since the termination of the Little Ice Age. Our evidence favours climate change as the main causative mechanism for the observed diatom compositional changes, although other explanations cannot be ruled out.
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    URL: http://dx.doi.org/10.1023/A:1007953515620
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    Paleolimnological investigation of the effects of post-1970 reductions of acidic deposition on an acidified Adirondack lake (1999)
    Springer
    Journal of paleolimnology 21 (1999), S. 207-213 
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    ISSN: 1573-0417
    Keywords: acidification ; chrysophytes ; Adirondack Park ; Big Moose Lake ; New York ; acidic deposition ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A 40-cm sediment core from Big Moose Lake (Adirondack Mountains, New York, U.S.A.) was analyzed for recent changes in chrysophyte composition of chrysophyte species to assess if legislated reductions of sulphur emissions have resulted in changes in biological composition and inferred lakewater pH in this lake. This core, taken in September 1994, had a record of stratigraphic changes in chrysophyte assemblages remarkably similar to those in 210Pb-dated sediment cores taken in 1983 and 1988. Abrupt changes in chrysophyte stratigraphy were used to date the newest sediment core by stratigraphic correlation. We observed relatively constant composition of chrysophyte species and inferred-pH values in post-1970 sediments, which suggests that there has been little change in lakewater pH values despite the reductions in sulfate deposition since 1970 in the Adirondacks. These results are consistent with recent monitoring measurements in the Adirondacks. Further research is necessary to ascertain the applicability of these findings to other lakes in the Adirondacks and to determine the reasons for the lack of recovery.
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    Temporal and spatial trends of lake acidity in northern Sweden (1999)
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    Journal of paleolimnology 22 (1999), S. 1-15 
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    ISSN: 1573-0417
    Keywords: diatoms ; lake sediments ; acidification ; pH ; alkalinity ; colour ; regional estimates ; northern Sweden
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Changes in lake-water pH, alkalinity and colour were inferred from diatoms in surface sediment samples and sediment samples from pre-industrial times from 118 northern Swedish lakes. This palaeolimnological study does not support the hypothesis that there is a large-scale modern acidification in the two northernmost counties of Sweden; pH had decreased significantly in eight lakes, while five had a significant increase. Partial least-squares regression of changes in water chemistry in relation to catchment characteristics was performed to evaluate the causes of the acidity status. Furthermore, temporal trends were assessed from long sediment cores from five acidic lakes. The results suggest that the presently acid lakes have faced a long-term acidification trend over several thousand years due to soil-forming processes and vegetation development. However, due to the acid sensitivity of the region, future acidification trends in northern Swedish lakes should be carefully observed and assessed.
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    Mineral magnetic and geochemical records of late Glacial climatic change from two northwest European carbonate lakes (1999)
    Springer
    Journal of paleolimnology 22 (1999), S. 97-107 
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    ISSN: 1573-0417
    Keywords: environmental magnetism ; lacustrine marl ; late Glacial ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We present the results of mineral magnetic measurements and geochemical analyses of late Glacial sediments from two marl-precipitating lakes in the Northwest of England. Mineral magnetic assemblages dominated by detrital and/or authigenic ferrimagnetic minerals, and enhanced delivery of metal elements, characterise a lower (Oldest Dryas) and an upper (Younger Dryas) phase of catchment instability, with detrital clay and silt sedimentation. Magnetic mineral assemblages with lower concentrations of finer ferrimagnetic grains characterise the authigenic carbonate sediments (marls). The marls indicate both enhanced lake productivity and catchment stability in response to prevailing warm conditions during the Bølling - Allerød Interstadial. The Bølling - Allerød marl phase contains two short-term, low amplitude shifts characterised by changes in the concentration and the size of ferrimagnetic grains. These shifts may represent the Older Dryas and the Amphi-Atlantic Oscillation, short-lived Northern hemisphere climatic deteriorations. Overall, the results suggest that marl lakes are sensitive indicators of Lateglacial climatic change, and that these changes are readily identifiable through the use of mineral magnetic measurements.
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    Late-glacial and early-Holocene Trichoptera (Insecta) from Kråkenes Lake, western Norway (2000)
    Springer
    Journal of paleolimnology 23 (2000), S. 49-56 
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    ISSN: 1573-0417
    Keywords: Trichoptera ; caddisflies ; late glacial ; Allerød ; Younger Dryas ; early Holocene ; Kråkenes ; palaeolimnology ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Fossil Trichoptera (caddisfly) remains have been identified and quantitatively recorded in the late-glacial and early-Holocene sediments from Kråkenes Lake, western Norway. The sediment sequence was deposited between 12,300 and 8850 14C BP, covering the Allerød, Younger Dryas, and early-Holocene periods. The first Trichoptera were recorded at 12,000 14C BP, and during the Allerod a diverse assemblage of Limnephilidae taxa developed in the lake. By about 11,400 14C BP the relatively thermophilous Polycentropus flavomaculatus and Limnephilus rhombicus were present, suggesting that the summer water temperature was at least 17 °C. This temperature fell by 5-8 °C at the start of the Younger Dryas, and the thermophilous taxa were replaced within 20-40 14C yrs by Apatania spp., including the arctic-alpine A. zonella, suggesting a maximum summer water temperature of 10-12 °C. The Trichoptera assemblage was impoverished in numbers and in diversity over the next 200 yrs as the severe conditions of the Younger Dryas developed. As soon as temperatures rose and glacial meltwater and silt input ended about 700 14C yrs later, the resident Apatania assemblage expanded immediately, within 10 yrs. About 130 yrs later, thermophilous taxa replaced Apatania, and a much more diverse assemblage than in the Allerod occupied the varied habitats made available by the development of the Holocene lake ecosystem. The 130 yr delay may have been caused by a gradual temperature increase crossing a critical threshold, or by the time taken for thermophilous taxa to migrate from their Younger Dryas refugia.
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    Paleolimnological investigation of recent acidity changes in Sawanoike Pond, Kyoto, Japan (2000)
    Springer
    Journal of paleolimnology 23 (2000), S. 285-304 
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    ISSN: 1573-0417
    Keywords: paleolimnology ; acidification ; sediment chemistry ; diatoms ; metals ; spheroidal carbonaceous particles ; pollen ; radionuclides ; Japan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Sawanoike Pond, an artificial reservoir constructed ca. 150 yrs. ago, lies in an area geologically sensitive to acidification and contains water that is presently weakly acidic (pH 5.5; alkalinity 15 μeq 1-1). Sediments from a core obtained from the northern part and a core from the central part of the pond were analyzed for organic matter, total organic carbon, total nitrogen, natural and artificial radionuclides, pollen, diatoms, metals and spheroidal carbonaceous particles. A peaty silt layer at the bottom of the central core was replaced by a silt layer initially rich in humic substances, but became more mineral-rich near the surface. Although most of the dominant diatoms throughout the cores were acidophilous taxa, some acidobiontic species increased moderately in abundance after the middle 1960's. Diatom-inferred pH values for the northern core are relatively low before about 1930, then increase, reaching a maximum level between the 1930's and the late 1940's. They then decrease to the surface and reach minimum level during the middle 1980's. Diatom-inferred pH declined by 0.4-0.5 units in the northern core and 0.2-0.3 units in the central core since ca. 1910, when vegetation around the shore changed to a community similar to that of recent years. An increase in labile Pb, Zn, Cd and spheroidal carbonaceous particles, indicative of atmospheric deposition of fossil fuel combustion by-products, preceded the decline in inferred pH. The inferred pH decline of the pond could be an acidification due to acidic precipitation caused by fossil fuel combustion.
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    Evidence for mid-Eemian cooling in continental climatic record from Lake Baikal (2000)
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    Journal of paleolimnology 23 (2000), S. 365-371 
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    ISSN: 1573-0417
    Keywords: Lake Baikal ; diatoms ; biogenic silica ; Eemian ; climate change ; Siberia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The discussion on climatic instability observed in Greenland ice cores during the Eemian period (substage 5e) resulted in discovery of a pronounced mid-Eemian cooling event. We report that the mid-Eemian cooling is found for the first time in the biogenic silica climatic record and microfossil abundance record of Lake Baikal. Timing of this event in Lake Baikal correlates well with timing of the European pollen records and marine sedimentary records. The presence of the mid-Eemian cooling signal in the Lake Baikal record suggests a much closer link between Asian climate influenced by strong pressure fields over the vast land masses and the climate-controlling processes in the North Atlantic during interglacial periods, than what was generally believed. Furthermore, the Lake Baikal record suggests that after the mid-Eemian cooling, the climatic conditions returned close to the warmth of the 5e optimum and thus argues that the warm conditions of the last interglacial persisted in Siberia throughout 5e, and did not end with the mid-Eemian cooling as suggested by several published marine records.
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    Holocene lake sediment records of Arctic hydrology (2000)
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    Journal of paleolimnology 24 (2000), S. 1-13 
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    ISSN: 1573-0417
    Keywords: Arctic ; Holocene ; paleohydrology ; paleolimnology ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Although paleoclimatic research in the Arctic has most often focused on variations in temperature, the Arctic has also experienced changes in hydrologic balance. Changes in Arctic precipitation and evaporation rates affects soils, permafrost, lakes, wetlands, rivers, ice and vegetation. Changes in Arctic soils, permafrost, runoff, and vegetation can influence global climate by changing atmospheric methane and carbon dioxide concentrations, thermohaline circulation, and high latitude albedo. Documenting past variations in Arctic hydrological conditions is important for understanding Arctic climate and the potential response and role of the Arctic in regards to future climate change. Methods for reconstructing past changes in Arctic hydrology from the stratigraphic, isotopic, geochemical and fossil records of lake sediments are being developed, refined and applied in a number of regions. These records suggest that hydrological variations in the Arctic have been regionally asynchronous, reflecting the impacts of different forcing factors including orbitally controlled insolation changes, changes in geography related to coastal emergence, ocean currents, sea ice extent, and atmospheric circulation. Despite considerable progress, much work remains to be done on the development of paleohydrological proxies and their application to the Arctic.
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    Diatom transfer-functions for quantifying past air temperature, pH and total organic carbon concentration from lakes in northern Sweden (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 109-123 
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    ISSN: 1573-0417
    Keywords: diatoms ; climate change ; temperature ; pH ; transfer functions ; lake sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2 jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2 jack = 0.61, RMSEP = 0.30) and TOC (R2 jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.
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    Variability of sediment diatom assemblages in an upland, wind-stressed lake (Loch Fleet, Galloway, S.W. Scotland) (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 43-59 
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    ISSN: 1573-0417
    Keywords: diatoms ; concentrations ; accumulation rates ; variability ; acidification ; correspondence analysis ; cluster analysis ; surface sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The variability of diatom distribution in an acidified, upland wind-stressed lake (Loch Fleet, Galloway, S. W. Scotland) was assessed by analysis of 28 surface sediment samples and 11 cores. Correspondence analysis (CA) and cluster analysis were used to illustrate the variability of the surface sediment and core samples. There was reasonable uniformity of taxa in most of the surface sediment samples, although 7 samples, as indicated by both CA and cluster analyses were atypical. Most cores recorded clearly the acidification of the lake, although percentages of individual taxa varied up to 20% between cores. Two cores had old, preacidification diatom assemblages (of indeterminate age) close to the sediment surface. These old sediments were probably the source of the re-worked diatoms found in the atypical surface sediment assemblages. Diatom trends, as CA ordinations and pH profiles, were less variable than the surface sediment assemblages. It is argued that non-uniform sediment accumulation rates and diatom deposition cause variability in surface sediment diatom samples. This variability may be reduced in core profiles by homogenization during further resuspension/deposition cycles and burial. Cores, and the associated time component they offer, may be useful in assessing the variability of surface sediment assemblages.
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    Diatom-derived palaeoconductivity estimates for Lake Awassa, Ethiopia: evidence for pulsed inflows of saline groundwater (1999)
    Springer
    Journal of paleolimnology 21 (1999), S. 409-422 
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    ISSN: 1573-0417
    Keywords: Africa ; climate change ; conductivity ; diatoms ; Ethiopia ; Holocene ; lake levels ; palaeolimnology ; Rift Valley
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A 6,500-year diatom stratigraphy has been used to infer hydrochemical changes in Lake Awassa, a topographically closed oligosaline lake in the Ethiopian Rift Valley. Conductivity was high from ~6400-6200 BP, and from 5200-4000 BP, with two brief episodes of lower conductivity during the latter period. Although the timing of the conductivity changes is similar to the timing of lake-level change in the nearby Zwai-Shalla basin, their directions are the reverse of that expected from a climatic cause. Dissolution of the tephras which precede both phases of high conductivity cannot explain the increases in salinity, because rhyolitic tephras are only sparingly soluble. Instead, the pulsed input of groundwater made saline by the reaction of silicate minerals and volcanic glass with carbonic acid, formed from the solution of carbon dioxide degassed from magma under the Awassa Caldera, is suggested as a plausible mechanism for the observed change in lake chemistry. Diatom-inferred hydrochemistry cannot therefore be used to reconstruct climate change in Lake Awassa.
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    URL: http://dx.doi.org/10.1023/A:1008092823410
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    Fossil midge associations and the historical status of fish in acidified lakes (1990)
    Springer
    Journal of paleolimnology 3 (1990), S. 113-127 
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    ISSN: 1573-0417
    Keywords: paleoecology ; Chaoboridae ; Chironomidae ; fish ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Chaoborid and chironomid (Diptera) fossils were examined in sediment cores form nine Ontario Precambrian Shield lakes that were fishless in 1979. An abundance of Chaoborus americamus (intolerant of predation by fish) throughout cores from four lakes indicated that they were fishless historically. Occurrence of Chaoborus punctipennis and C. flavicans and absence of C. americanus in cores, except near the surface in two cases, indicated that four other lakes were inhabited by fish historically. One of these was probably periodically fishless as suggested by fluctuations among these Chaoborus species. The ninth lake was not suitable for Chaoborus; only one specimen of C. trivittatus was found in this core. Chironomid fossil associations were substantially different in historically fishless and inhabited lakes. Fishless lakes had chironomids typical of eutrophic conditions indicating that seasonal oxygen depletion likely was inimical to fish. Chironomid associations of oligotrophic waters occurred in lakes historically inhabited by fish. Both good water quality and accessibility were required for long-term habitation by fish. Partial recovery of alkalinity and rise in pH were accompanied by substantial re-invasion by fish in two lakes which had been inhabited historically by fish. Diptera associations provide valuable information on the historical suitability of lakes for fish and the presence/absence of fish in regions where acidification of surface waters has occurred.
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    URL: http://dx.doi.org/10.1007/BF00414066
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    Estimation of pH optima and tolerances of diatoms in lake sediments by the methods of weighted averaging, least squares and maximum likelihood, and their use for the prediction of lake acidity (1988)
    Springer
    Journal of paleolimnology 1 (1988), S. 39-49 
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    ISSN: 1573-0417
    Keywords: weighted averaging ; least squares ; maximum likelihood ; diatoms ; acidification ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Ecological optima and tolerances with respect to autumn pH were estimated for 63 diatom taxa in 47 Finnish lakes. The methods used were weighted averaging (WA), least squares (LS) and maximum likelihood (ML), the two latter methods assuming the Gaussian response model. WA produces optimum estimates which are necessarily within the observed lake pH range, whereas there is no such restriction in ML and LS. When the most extreme estimates of ML and LS were excluded, a reasonably close agreement among the results of different estimation methods was observed. When the species with unrealistic optima were excluded, the tolerance estimates were also rather similar, although the ML estimates were systematically greater. The parameter estimates were used to predict the autumn pH of 34 other lakes by weighted averaging. The ML and LS estimates including the extreme optima produced inferior predictions. A good prediction was obtained, however, when prediction with these estimates was additionally scaled with inverse squared tolerances, or when the extreme values were removed (censored). Tolerance downweighting was perhaps more efficient, and when it was used, no additional improvement was gained by censoring. The WA estimates produced good predictions without any manipulations, but these predictions tended to be biased towards the centroid of the observed range of pH values. At best, the average bias in prediction, as measured by mean difference between predicted and observed pH, was 0.082 pH units and the standard deviation of the differences, measuring the average random prediction error, was 0.256 pH units.
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    The relationship between sedimentary diatom assemblages and lakewater pH in 35 Quebec lakes, Canada (1988)
    Springer
    Journal of paleolimnology 1 (1988), S. 23-38 
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    ISSN: 1573-0417
    Keywords: diatoms ; paleolimnology ; diatom-inferred pH ; acidification ; Quebec
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Surface sediment diatoms from 35 soft-water lakes in southern Quebec were studied to examine the relationship with lakewater pH. The lakes ranged in pH from 5.25 to 7.66. The species composition and the relative abundance of diatoms in the study lakes was found to be closely related to pH and/or factors closely associated with pH. Predictive models were developed to infer lakewater pH using simple linear regression equations of index alpha, index B, and multiple regressions using pH preference categories. Among the predictive models examined here, the multiple regression technique provided the highest correlation coefficient (r2=0.88) and the lowest standard error (±0.26 of a pH unit) in computing diatom-inferred pH. This model appears to be the most appropriate to reconstruct lake pH histories in Quebec region.
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    High-frequency climatic oscillations during the last deglaciation as revealed by oxygen-isotope records of benthic organisms (Ammersee, southern Germany) (1994)
    Springer
    Journal of paleolimnology 11 (1994), S. 349-357 
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    ISSN: 1573-0417
    Keywords: stable isotopes ; ostracods ; climate change ; late glacial ; holocene ; seasonal effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract High-resolution oxygen-isotope records of benthic ostracods and molluscs from Ammersee, southern Germany, show high-frequency climatic changes during the last deglaciation and parallel in great detail published faunal and floral variations reconstructed from Norwegian Sea sediments and isotope variations in Greenland ice cores. The marine and the terrestrial records give evidence of a synchronous late glacial climatic development in Greenland, NW- and Mid-Europe. However,14C-ages of the supraregional climatic events and of two tephra layers in the marine sediments of the northeastern Atlantic Ocean are significantly older than the14C-ages of the corresponding horizons on land. These differences strongly suggest that major short-term events have affected the exchangeable carbon on earth during the dramatic environmental changes related to the deglaciation and in particular have affected the CO2-distribution within the ocean and between ocean and atmosphere. Dating methods independent of climatic variations and of the global carbon budget should be given priority to refine the timescales of the marine and atmospheric processes during the last deglaciation.
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    URL: http://dx.doi.org/10.1007/BF00677994
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    Siliceous microfossil succession in the recent history of two basins in Lake Baikal, Siberia (1995)
    Springer
    Journal of paleolimnology 14 (1995), S. 165-184 
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    ISSN: 1573-0417
    Keywords: Lake Baikal ; Russia ; paleolimnology ; diatoms ; chrysophyte cysts ; Little Ice Age ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract As part of the international cooperative Baikal Drilling Project, siliceous microfossil assemblage succession was analyzed in two short (∼ 30-cm) sediment cores from Lake Baikal. One core was recovered from the north basin (Core 324, 55°15′N, 109°30′E), a second from between the central and southern basins (Core 316, 52°28′N, 106°5′E). The northern core had higher amounts of biogenic silica (40 g SiO2 per 100 g dry weight sediment) compared to the southern core, and increased deposition in the more recent sediments. Weight percent biogenic silica was lower in the southern core, ranging from approximately 20–30 g SiO2 per 100 g dry weight sediment throughout the entire core. Trends in absolute microfossil abundance mirror those of biogenic silica, with generally greater abundance in the northern core (86–275×106 microfossils g−1 dry sediment) compared to the southern core (94–163×106 microfossils g−1 dry sediment). Cluster analyses using relative abundance of the dominant diatom and chrysophyte taxa revealed four zones of microfossil succession in each core. Microfossil assemblage succession in the north basin may be reflecting shifts in nutrient supply and cycling driven by climatic changes. The most recent sediments in the northern basin (Zone 1,c. 1890's–1991 A.D.) were characterized by an increased abundance ofAulacoseira baicalensis andAulacoseira ‘spore’. Zone 3 (c. 1630's–1830's A.D.) was dominated by the endemicCyclotella spp. and reduced abundance of theAulacoseira spp. Zone 3 corresponds approximately to the Little Ice Age, a cooler climatic period. The microfossil assemblages between Zones 1 and 3 (Zone 2,c. 1830's–1890's A.D.) and below Zone 3 (Zone 4,c. 830's–1430's A.D.) are similar to one another suggesting they represent transitional intervals between warm and cold periods. Southern basin sediments record similar changes in the endemic taxa. However, the increased abundance of non-endemic planktonic taxa (e.g.Stephanodiscus binderanus, Synedra acus, Cyclostephanos dubius) during two periods in recent history (post World War II and late 1700's) suggests evidence for anthropogenic induced changes in southern Lake Baikal.
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    Late Holocene climate change and human disturbance on Andros Island, Bahamas (1996)
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    Journal of paleolimnology 15 (1996), S. 133-145 
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    ISSN: 1573-0417
    Keywords: Bahamas ; Holocene ; fire history ; climate change ; human disturbance ; charcoal stratigraphy ; pollen analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A 2 m sediment core from Church's Blue Hole on Andros Island, Bahamas provides the first paleoecological record from the Bahama Archipelago. The timing of events in the lower portion of the core is uncertain due to inconsistencies in the radiocarbon chronology, but there is evidence that a late Holocene dry period altered the limnology of Church's Blue Hole and supported only dry shrubland around the site. The dry period on Andros may correlate with a widespread dry period in the Caribbean from 3200 to 1500 yr BP. After the dry period ended, a more mesic climate supported tropical hardwood thicket around Church's Blue Hole. At c. 740 radiocarbon yr BP there is a sudden rise in charcoal concentration and a rapid transition to pinewoods vegetation, while at c. 430 radiocarbon yr BP charcoal concentration drops, but is higher again near the top of the core. Although climatic shifts could have caused these changes in vegetation and charcoal concentration, the changes post-date human colonization of the Bahamas and may reflect human arrival, followed by the removal of humans c. 1530 AD and the recolonization of Andros Island c. 200 years later.
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    The environmental history of a mountain lake (Lago Paione Superiore, Central Alps, Italy) for the last c. 100 years: a multidisciplinary, palaeolimnological study (1996)
    Springer
    Journal of paleolimnology 15 (1996), S. 245-264 
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    ISSN: 1573-0417
    Keywords: palaeolimnology ; acidification ; diatoms ; chrysophytes ; pigments ; chironomids ; temperature ; Alps ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A palaeoecological study of an oligotrophic alpine lake, Paione Superiore (Italy), provided a record of historical changes in water quality. Historical trends in lake acidification were reconstructed by means of calibration and regression equations from diatoms, chrysophycean scales and pigment ratios. The historical pH was inferred by using two different diatom calibration data sets, one specific to the alpine region. These pH trends, together with the record of sedimentary carbonaceous particles and chironomid remains, indicate a recent acidification of this low alkalinity lake. Concentration of total organic matter, organic carbon, nitrogen, biogenic silica (BSiO2), chlorophyll derivatives (CD), fucoxanthin, diatom cell concentration and number of chironomid head capsules increased during the last 2–3 decades. When expressed as accumulation rates, most of these parameters tended to decrease from the past century to c. 1950, then all except P increased to the present day. A marked increase in sedimentary nitrogen may be related to atmospheric pollution and to the general increases in output of N in Europe. High C/N ratios indicate a prevailing allochthonous source of organic matter. Finally, the increase in measured air temperature from the mid-1800's appeared to be related to lake water pH before industrialization: cold periods generally led to lower pH and vice-versa. The more recent phenomenon of anthropogenic acidification has apparently decoupled this climatic-water chemistry relationship.
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    Recent environmental changes in a naturally acidic rocky lake in southern Finland, as reflected in its sediment geochemistry and biostratigraphy (1997)
    Springer
    Journal of paleolimnology 17 (1997), S. 191-213 
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    ISSN: 1573-0417
    Keywords: acidification ; geochemistry ; atmospheric loading ; diatoms ; in situ alkalinity ; forest fires
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Paleolimnological methods are combined with statistical multivariate analyses (PCA and CCA) to study the effects of local environmental disturbances and changes in loading of atmospheric origin on water acidity and the physiochemical properties of the sediment in a small, naturally acidic rocky lake in southern Finland. The pH of the lake as calculated from the diatom flora increased by 0.9 pH units as a consequence of a forest fire in the catchment area at the turn of the last century, and the changes in the diatom assemblages point to an increase in dys(eu)trophy and turbulence. In terms of element influx (in µg cm-2 yr-1), the effects of the fire are seen in a slight increase in the accumulation of lithophilous elements. Diatom-inferred pH values decline upwards in the sediment, but do not regain the level recorded before the fire. This is attributed to reactions between Fe3+ and S, which has partly accumulated from the air as SO2-, producing internal alkalinity. Accumulation rates of many elements increase markedly after the 1960s, an effect for Al, Mg, Na, P and Zn may be connected mainly with the enhanced accumulation of dry matter, whereas the accumulation of K, Ni, Pb, Ti and V in surface sediment are obviously related to atmospheric loading. Measured accumulation rates of Cd and Cu are lower than the calculated values especially in the surface sediment, possibly because of diagenetic changes. Accumulation of Ca and Mn decreases towards the surface on account of acidification of anthropogenic origin.
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    Relationships between sedimentary diatom assemblages and lakewater pH values in the Experimental Lakes Area (1992)
    Springer
    Journal of paleolimnology 7 (1992), S. 145-156 
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    ISSN: 1573-0417
    Keywords: Experimental Lake Area (ELA) ; paleolimnology ; inferred pH ; diatoms ; acidification ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Relationships between sedimentary diatom assemblages and lakewater pH values from 36 lakes and experimentally acidified Lake 223, in the Experimental Lakes Area, were analyzed. The relationships were used to assign diatoms in the 36 lakes into pH preference groupings. Based on their regional distribution Cyclotella stelligera and Tabellaria flocculosa strain IIIp were categorized as pH indifferent, in comparison to other areas were they have been categorized as acidophilic. Two models were then applied to calculate transfer coefficients which were used to calculate diatom-inferred pH values for Lake 223. Index B and a multiple linear regression of the pH groupings yielded similar correlations (r2 0.82 and 0.84 respectively, p=0.0001). The multiple linear regression inferred a pH of 5.36 for acidified Lake 223 compared to a measured pH of 5.46.
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    A first estimate of organic carbon storage in Holocene lake sediments in Alberta, Canada (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 395-400 
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    ISSN: 1573-0417
    Keywords: carbon storage ; lake sediment ; Holocene ; Canada ; climate change ; organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract This paper reports a first estimate of the Holocene lake sediment carbon pool in Alberta, Canada. The organic matter content of lake sediment does not appear to depend strongly on lake size or other limnological parameters, allowing a simple first estimate in which we assume all Alberta lake sediment to have the same organic matter content. Alberta lake sediments sequester about 15 g C m-2 yr-1, for a provincial total of 0.23 Tg C yr-1, or 2.3 Pg C over the Holocene. Alberta lakes may represent as much as 1/1700 of total global, annual permanent carbon sequestration.
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    A palaeoecological test of the land-use hypothesis for recent lake acidification in South-West Norway using hill-top lakes (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 69-85 
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    ISSN: 1573-0417
    Keywords: diatoms ; pollen ; chrysophytes ; heavy metals ; acidification ; land-use ; Norway ; pH changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Lakes perched on hill-tops have very small catchments. Their water chemistry is largely influenced by the chemical composition of precipitation and by the underlying bedrock geology. They are ideal sites for testing the hypothesis that land-use and associated soil changes are a major cause of recent lake acidification. On this hypothesis, hill-top lakes in SW Norway are predicted not to show any recent lake acidification because, by their very nature, the chemistry of such lakes is little influenced by land-use or soil changes. Palaeolimnological analyses of diatoms and chrysophytes show that prior to ca. 1914 the two hill-top lakes investigated were naturally acid with reconstructed lake-pH values of at least 4.8–5.1. Since ca. 1914 lake pH values declined to ca. 4.5–4.7. These results contradict the land-use hypothesis. All the available palaeolimnological evidence (diatoms, chrysophytes, pollen, sediment geochemistry, carbonaceous particles) is consistent with the acid-deposition hypothesis. In the absence of any evidence to support the land-use hypothesis as a primary cause of recent lake acidification and in the light of several independent refutations, it is perhaps time to put the land-use hypothesis for recent lake acidification to rest.
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    Chaoborus (Diptera: Chaoboridae) mandibles—paleolimnological indicators of the historical status of fish populations in acid-sensitive lakes (1990)
    Springer
    Journal of paleolimnology 4 (1990), S. 139-151 
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    ISSN: 1573-0417
    Keywords: Chaoborus ; Chaoboridae ; Diptera ; fish ; acidification ; paleolimnology ; Adirondacks ; Bosmina
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Paleolimnological analyses of Chaoborus mandibles were used to assess the status of fish populations over the previous 150 to 300 years in five lakes from the Adirondack region of New York State. Windfall Pond (pH 6.5) has not acidified and currently has viable fish populations. Big Moose Lake (pH 5.0) has acidified in recent years, and the number of fish populations declined from 14 in the 1930's to seven in the early 1980's. The occurrence of only migratory Chaoborus (subgenus Sayomyia) in the cores indicated the long term presence of fish populations in Windfall Pond and Big Moose Lake. Brooktrout Lake (pH 5.0), Deep Lake (pH 4.7) and Upper Wallface Pond (pH 4.8) have all acidified in recent years, and all three are currently fishless. Chaoborus (Sayomyia) was present throughout the Brooktrout Lake core, but the entirely limnetic species, C. americanus, appeared in the topmost interval in the core. The appearance of C. americanus in the top of the core indicated a recent elimination of fish from Brooktrout Lake, probably during the 1970's. Elimination of fish by the 1940's was inferred for Deep Lake because C. americanus appeared above the 1930 level and replaced C. trivittatus as the dominant. Dominance of C. americanus throughout the Upper Wallface Pond core indicated that planktivorous fish were never present. These results strongly suggest that stratigraphic analyses of Chaoborus mandibles provide a useful assessment of the general status of historical fish populations in Adirondack lakes. The technique should be useful in other regions, as well as for applications other than those concerning lake acidification.
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    Variability in diatom and chrysophyte assemblages and inferred pH: paleolimnological studies of Big Moose Lake, New York, USA (1991)
    Springer
    Journal of paleolimnology 5 (1991), S. 267-284 
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    ISSN: 1573-0417
    Keywords: variability ; diatoms ; chrysophytes ; acidification ; paleolimnology ; Adirondacks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We measured variability in the composition of diatom and chrysophyte assemblages, and the pH inferred from these assemblages, in sediment samples from Big Moose Lake, in the Adirondack Mountains of New York. Replicate samples were analyzed from (1) a single sediment core interval, (2) 12 different intervals from each of 3 separate cores, and (3) 10 widely spaced surface sediment samples (0–1 cm). The variability associated with sample preparation (subsampling, processing, and counting) was relatively small compared to between-core and within-lake variability. The relative abundances of the dominant diatom taxa varied to a greater extent than those of the chrysophyte scale assemblages. Standard deviations of pH inferences for multiple counts from the same sediment interval from diatom, chrysophyte, and diatom plus chrysophyte inference equations were 0.04 (n=8), 0.06 (n=32), and 0.06 (n=8) of a pH unit, respectively. Stratigraphic analysis of diatoms and chrysophytes from three widely spaced pelagic sediment cores provided a similar record of lake acidification trends, although with slight differences in temporal rates of change. Average standard deviations of pH inferences from diatom, chrysophyte and diatom plus chrysophyte inference equations for eight sediment intervals representing similar time periods but in different cores were 0.10, 0.20, and 0.09 pH unit, respectively. Our data support the assumption that a single sediment core can provide an accurate representation of historical change in a lake. The major sources of diatom variability in the surface sediments (i.e., top 1.0 cm) were (1) differences in diatom assemblage contributions from benthic and littoral sources, and (2) the rapid change in assemblage composition with sediment depth, which is characteristic of recently acidified lakes. Because scaled chrysophytes are exclusively planktonic, their spatial distribution in lake sediments is less variable than the diatom assemblages. Standard deviations of pH inferences for 10 widely spaced surface sediment samples from diatom, chrysophyte and diatom plus chrysophyte inference equations were 0.21, 0.09, and 0.16 of a pH unit, respectively.
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    Automatic equipment to monitor groundwater radon (1993)
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    Pure and applied geophysics 141 (1993), S. 125-137 
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    ISSN: 1420-9136
    Keywords: Automatic equipment ; groundwater radon ; environment ; earthquake precursors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Prototype instrumentation, able to automatically measure groundwater radon content variations, is presented. The equipment is made of stainless steel and has spherical valves with automatic and pneumatic control. The deemanation of the gases from the water is obtained by evacuating a suitable expansion chamber. The instrumentation can make discrete sampling ranging from 1 per hour to 1 per 99 hours. The equipment was tested in the laboratory: the efficiency was measured by means of a266Ra solution. A mean value of (0.65±0.07) count/s/Bq was obtained. A calibration test was carried out by comparing countings from the automatic equipment with those obtained by the standard laboratory cell. Results of an operational check over a period of approximately one year indicate that variations in radon at the calibration site are attributable more to meteorological than to tectonic causes.
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    Environmental applications of magnetometry profiling (1996)
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    Environmental geology 27 (1996), S. 178-183 
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    ISSN: 1432-0495
    Keywords: Magnetometry profiling ; Ireland ; faults ; environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Environmental impact assessment is currently a standard procedure for assessing the possible consequences of any particular activity that may cause degradation of the environment. Magnetometry profiling, which involves accurate measurements of the Earth's magnetic field at closely spaced stations is a technique that has a large number of environmental applications that can greatly improve this assessment. The technique has been applied successfully for waste disposal site evaluation, toxic waste detection, assessment of the quality of roadstone before excavations and can provide information that allows subsurface water movement models to be refined. Magnetometry profiling is inexpensive, nondestructive, and a very costeffective method of acquiring useful information about the environment.
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    Environmental applications of magnetometry profiling (1996)
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    Environmental geology 27 (1996), S. 178-183 
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    ISSN: 1432-0495
    Keywords: Key words: Magnetometry profiling ; Ireland ; faults ; environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Environmental impact assessment is currently a standard procedure for assessing the possible consequences of any particular activity that may cause degradation of the environment. Magnetometry profiling, which involves accurate measurements of the Earth's magnetic field at closely spaced stations is a technique that has a large number of environmental applications that can greatly improve this assessment. The technique has been applied successfully for waste disposal site evaluation, toxic waste detection, assessment of the quality of roadstone before excavations and can provide information that allows subsurface water movement models to be refined. Magnetometry profiling is inexpensive, nondestructive, and a very cost-effective method of acquiring useful information about the environment.
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    Gas Production from an Ombrotrophic Bog-Effect of Climate Change on Microbial Ecology (1998)
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    Climatic change 40 (1998), S. 277-284 
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    ISSN: 1573-1480
    Keywords: ombrotrophic bogs ; microbial ecology ; methane ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Gases are produced from wetlands when plant biomass is degraded by microbial consortia, producing carbon dioxide aerobically and methane when oxygen is lacking. In anaerobic waterlogged situations, such as the catotelm of ombrotrophic bogs, this methane forms minute gas bubbles that severely reduce the hydraulic conductivity and hence the degradation of biomass due to the lack of nutrients. The bogs thus become carbon sinks, formed from the partially degraded biomass that accumulates as peat. The results of an investigation of an ombrotrophic bog, Mer Bleue, Ontario, Canada are summarized here, and the effects that climate change may have on such bogs are discussed. Any change of the water table in wetlands will have a substantial effect upon their ecology. If the water table should fall allowing bogs to become aerobic, most of the accumulated biomass carbon could be returned to the atmosphere by degradation to carbon dioxide, and as well, methane entrapped within the matrix would be released directly to the atmosphere. If on the other hand, the bogs are flooded, then the entrapped bubbles will coalesce allowing the gas to escape to the atmosphere, while at the same time the degradation of the peat will be enhanced.
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    URL: http://dx.doi.org/10.1023/A:1005421004276
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    Material use, economic growth, and the environment (1996)
    Springer
    Natural resources research 5 (1996), S. 197-210 
    Details
    ISSN: 1573-8981
    Keywords: Sustainable development ; material use ; economic growth ; environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The three broad categories of commodity inputs to the economy are food, fuel, and material, defined as everything else not used for the first two purposes. Material provides physical structure, houses, cars, and packaging; is an important constitutent of modern agriculture in the form of fertilizer and insecticides; and supports the service sector through telecommunications and equipment and paper for our copying machines. The efficient flow of this material is an important factor in the U.S. economy.
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    URL: http://dx.doi.org/10.1007/BF02257435
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    Long-Term Variations of Potential Temperature and Dissolved Oxygen of the Japan Sea Proper Water (1999)
    Springer
    Journal of oceanography 55 (1999), S. 197-205 
    Details
    ISSN: 1573-868X
    Keywords: Japan Sea ; Japan Sea Proper Water ; climate change ; long-term variation ; one-dimensional model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Observed potential temperatures and concentrations of dissolved oxygen are analyzed to elucidate their variations during the period from 1958 to 1996 at Stn. P (37°43′ N, 134°43′ E) and from 1965 to 1996 at Stn. H (40°30′ N, 137°40′ E) in the Japan Sea. At Stn. P, increases of the potential temperature for the period are found below 800 m depth with the largest value of 0.16 ± 0.09°C per century at 800 m depth. At Stn. H, the potential temperature increased below 500 m depth. The increase rate has the largest value of 0.50 ± 0.18°C per century at 500 m depth and it is 0.30 ± 0.09°C per century at 800 m depth. The concentrations of dissolved oxygen increased around 800 m depth at Stn. P. At Stn. H, they increased above 800 m depth. On the other hand, they decreased below 1200 m depth at both stations. The layer of the dissolved oxygen minimum has deepened in these decades. These features appearing in the distributions of temperature and dissolved oxygen are successively simulated by a vertical one-dimensional advection-diffusion model including consumption of dissolved oxygen and termination of the deep water supply. These results suggest that the supply of the Japan Sea Proper Water into the deep layer, which is cold and rich in dissolved oxygen, has been decreasing for the last four decades.
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    URL: http://dx.doi.org/10.1023/A:1007889929187
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    The globalization of N deposition: ecosystem consequences in tropical environments (1999)
    Springer
    Biogeochemistry 46 (1999), S. 67-83 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; anthropogenic nitrogen ; cations ; nitrate leaching ; nitric oxide ; nitrous oxide ; nutrient limitation ; phosphorus ; productivity ; tropical ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Human activities have more than doubled the inputs of nitrogen (N) into terrestrial systems globally. The sources and distribution of anthropogenic N, including N fertilization and N fixed during fossil fuel combustion, are rapidly shifting from the temperate zone to a more global distribution. The consequences of anthropogenic N deposition for ecosystem processes and N losses have been studied primarily in N-limited ecosystems in the temperate zone; there is reason to expect that tropical ecosystems, where plant growth is most often limited by some other resource, will respond differently to increasing deposition. In this paper, we assess the likely direct and indirect effects of increasing anthropogenic N inputs on tropical ecosytem processes. We conclude that anthropogenic inputs of N into tropical forests are unlikely to increase productivity and may even decrease it due to indirect effects on acidity and the availability of phosphorus and cations. We also suggest that the direct effects of anthropogenic N deposition on N cycling processes will lead to increased fluxes at the soilwater and soil-air interfaces, with little or no lag in response time. Finally, we discuss the uncertainties inherent in this analysis, and outline future research that is needed to address those uncertainties.
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    URL: http://dx.doi.org/10.1007/BF01007574
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    Mycorrhizal weathering: A true case of mineral plant nutrition? (2000)
    Springer
    Biogeochemistry 49 (2000), S. 53-67 
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    ISSN: 1573-515X
    Keywords: acidification ; Al3+ toxicity ; coniferous trees ; ectomycorrhiza ; microbiological weathering ; podzolization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Weatherable minerals in all podzol surface soils andshallow granitic rock under European coniferousforests studied hitherto are criss-crossed bynumerous open, tubular pores, 3–10 µm in width. Wehypothesize that these pores were formed bycomplex-forming, low-molecular weight organic acidsexuded by or formed in association with mycorrhizalfungi. It is well known that ectomycorrhizal myceliumrepresents a greatly extended, and better distributed,surface area for the absorption of nutrients. However, there have been few investigations of how thewhereabouts of individual hypha affect nutrientuptake. The results presented here provide directevidence that the mycelium is able to penetrate, andmost probably create, microsites which areinaccessible to plant roots and isolated from bulksoil solution phenomena. Dissolved products could betranslocated to the host plant roots, bypassing thesoil solution with often toxic concentration ofAl3+ from acid rain, and bypassing competitionfor nutrient uptake by other organisms. Furthermore,there is strong evidence that ``rock-eating''mycorrhizal fungi play a role in the formation ofpodzol E horizons. The partly speculativeinterpretations presented here challenge conventionalideas about (1) the importance of nutrient uptakefrom the bulk soil solution (2) criteria for criticalloads of acid atmospheric deposition for forests, and(3) the process of podzolization.
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    URL: http://dx.doi.org/10.1023/A:1006256231670
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    Forest soil solutions: Acid/base chemistry and response to calcite treatment (1996)
    Springer
    Biogeochemistry 32 (1996), S. 195-220 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; acid neutralizing capacity ; aluminum ; calcite ; calcium ; liming ; nitrogen cycling ; soil chemistry ; soil solutions ; spodosols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Soil solution chemistry was investigated at a forested watershed draining into Woods Lake. N.Y. as part of the Experimental Watershed Liming Study (EWLS). The objective of this study was to assess the response of soil water to watershed treatment of calcite (CaCO3). This material was applied in an effort to mitigate the effects of acidic atmospheric deposition. Soil solutions draining Oa and Bs horizons in reference subcatchments were characterized by low pH and acid neutralizing capacity (ANC) due to elevated concentrations of SO 4 2− , NO 3 − and organic anions relative to the sum of base cation (CB Ca2+, Mg2+, Na+, K+) concentrations. Seasonal and spatial variation of pH andANC in soil solutions appeared to belargely controlled by variations in the concentrations of dissolved organic acids which, in turn, were regulated by reactions of Al with soil organic matter. Nitrate was positively correlated and SO2+ was negatively correlated with Ca2+ and Al concentrations in reference soil solutions, indicating that changes in NO 3 − influences spatial and seasonal variations in Ca2+ and Al concentrations. On this basis, NO 3 − appears to be important in soil acidification and the dynamics of drainage water acidity. Comparison of our results with historical data for the site showed declines in concentrations of SO 4 2− , which are consistent with decreases in emissions of SO4, in the eastern U.S. and atmospheric deposition of SO 4 2− , to the Adirondack region. Mineral soil solutions have shown large increases in concentrations of NO 3 − . Declines in concentrations of CB and increases in concentrations of Al have occurred over the last ten years, suggesting depletion of soil pools of exchangeable basic cations and increased sensitivity to acidic deposition. Calcite (CaCO3) treatment of 6.89 Mg/ha resulted in a significant increase of Ca2+, ANC and pH in both Oa and Bs horizon soil solutions. Soil water response to CaCO3 addition was most evident during the first year after treatment, apparently due to macropore transport of particulate and dissolved CaCO3 However, increases in ANC and pH in the mineral soil waters were not sustained and appeared insufficient to result in substantial improvement in surface water quality over the 43 month study period.
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    URL: http://dx.doi.org/10.1007/BF02187139
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    The significance of storms for the concentration and export of dissolved organic carbon from two Precambrian Shield catchments (1997)
    Springer
    Biogeochemistry 36 (1997), S. 67-88 
    Details
    ISSN: 1573-515X
    Keywords: climate change ; dissolved organic carbon (DOC) ; forested catchments ; nutrient export ; Precambrian Shield streams ; storm runoff
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Dissolved organic carbon (DOC) concentrations and DOC export arestudied during storms to examine the relationship between DOCconcentration and stream discharge and to assess the importance of stormson DOC export. Storms were monitored in seven subcatchments within twosmall watersheds (Harp 4--21 and Harp 3A) on the Precambrian Shield inCentral Ontario, Canada. Stream DOC concentrations increase during stormsby as much as 100% and 410% in Harp3A and Harp 4--21 respectively. The seasonal regression between DOC andstream discharge is significant in subcatchments without wetlands(r2 〉 0.7) but is not significant in thetwo subcatchments with small wetland areas (r2 〈0.06). On average, regressions based on weekly data yield accurate estimatesof DOC export but the variation in regressions among individual storms andthe small number of high DOC samples result in uncertainties of more than30% in DOC export. The period-weighted calculation ofDOC export from weekly data underestimates export by 14%and 22% in Harp 3A and Harp 4--21 respectively. Stormswere responsible for 57% to 68% of theDOC export in the autumn and 29% to 40%of the DOC export in the spring. A single large storm accounted for31% of the autumn DOC export in Harp 3A. The importanceof individual storms for DOC export and the variation in the relationshipbetween DOC and stream discharge among storms make it difficult to predictthe effects of climate change on DOC export and DOC concentrations.
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    URL: http://dx.doi.org/10.1023/A:1005779711821
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    A field study on the fate of 15N-ammonium to demonstrate nitrification of atmospheric ammonium in an acid forest soil (1991)
    Springer
    Biogeochemistry 13 (1991), S. 241-255 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; air pollution ; ammonium sulfate ; forest soil ; nitrate formation ; nitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract To demonstrate the contribution of atmospheric ammonium to soil acidification in acid forest soils, a field study with13N-ammonium as tracer was performed in an oak-birch forest soil. Monitoring and analysis of soil solutions from various depths on the13N-ammonium and15N-nitrate contents, showed that about 54% of the applied15N-ammonium was oxidized to nitrate in the forest floor. Over a period of one year about 20% of the15N remained as organic nitrogen in this layer. The percentage15N enrichment in ammonium and nitrate were in the same range in all the forest floor percolates, indicating that even in extremely acid forest soils (pH 〈 4) nitrate formation from ammonium can occur. Clearly, atmospheric ammonium can contribute to soil acidification even at low soil pH.
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    URL: http://dx.doi.org/10.1007/BF00002943
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    Effects of air pollutant-temperature interactions on mineral-N dynamics and cation leaching in reciplicate forest soil transplantation experiments (1997)
    Springer
    Biogeochemistry 39 (1997), S. 295-326 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; aluminium ; Arrhenius’ law ; calcium ; cation leaching ; climate ; ion equilibrium ; forest soil ; N-cycle ; N-deposition ; nitrification ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increased emissions of nitrogen compounds have led to atmosphericdeposition to forest soils exceeding critical loads of N overlarge parts of Europe. To determine whether the chemistry offorest soils responds to changes in throughfall chemistry, intactsoil columns were reciprocally transplanted between sites, withdifferent physical conditions, across a gradient of N and Sdeposition in Europe. The transfer of a single soil to the various sites affected itsnet nitrification. This was not simply due to the nitrificationof different levels of N deposition but was explained bydifferences in physical climates which influenced mineralizationrates. Variation in the amount of net nitrification between soiltypes at a specific site were explained largely by soil pH. Within a site all soil types showed similar trends in netnitrification over time. Seasonal changes in net nitrificationcorresponds to oscillations in temperature but variable time lagshad to be introduced to explain the relationships. WithArrhenius‘ law it was possible to approximate gross nitrificationas a function of temperature. Gross nitrification equalled netnitrification after adaptation of the microbial community oftransplanted soils to the new conditions. Time lags, andunderestimates of gross nitrification in autumn, were assumed tobe the result of increased NH 4 + availability due either tochanges in the relative rates of gross and net N transformationsor to altered soil fauna-microbial interactions combined withimproved moisture conditions. Losses of NO 3 - were associated with Ca2+and Mg2+ in non-acidified soil types and with losses ofAl3+ in the acidified soils. For single soils the ionequilibrium equation of Gaines-Thomas provided a useful approximationof Al3+ concentrations in the soil solution as a functionof the concentration of Ca2+. The between site deviationsfrom this predicted equilibrium, which existed for single soils, couldbe explained by differences in throughfall chemistry which affectedthe total ionic strength of the soil solution. The approach of reciprocally transferring soil columnshighlighted the importance of throughfall chemistry, interactingwith the effect of changes in physical climate on forest soilacidification through internal proton production, in determiningsoil solution chemistry. A framework outlining the etiology offorest die-back induced by nitrogen saturation is proposed.
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    URL: http://dx.doi.org/10.1023/A:1005814929879
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    The globalization of N deposition: ecosystem consequences in tropical environments (1999)
    Springer
    Biogeochemistry 46 (1999), S. 67-83 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; anthropogenic nitrogen ; cations ; nitrate leaching ; nitric oxide ; nitrous oxide ; nutrient limitation ; phosphorus ; productivity ; tropical ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Human activities have more than doubled the inputs of nitrogen (N) into terrestrial systems globally. The sources and distribution of anthropogenic N, including N fertilization and N fixed during fossil fuel combustion, are rapidly shifting from the temperate zone to a more global distribution. The consequences of anthropogenic N deposition for ecosystem processes and N losses have been studied primarily in N-limited ecosystems in the temperate zone; there is reason to expect that tropical ecosystems, where plant growth is most often limited by some other resource, will respond differently to increasing deposition. In this paper, we assess the likely direct and indirect effects of increasing anthropogenic N inputs on tropical ecosytem processes. We conclude that anthropogenic inputs of N into tropical forests are unlikely to increase productivity and may even decrease it due to indirect effects on acidity and the availability of phosphorus and cations. We also suggest that the direct effects of anthropogenic N deposition on N cycling processes will lead to increased fluxes at the soil-water and soil-air interfaces, with little or no lag in response time. Finally, we discuss the uncertainties inherent in this analysis, and outline future research that is needed to address those uncertainties.
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    URL: http://dx.doi.org/10.1023/A:1006152112852
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    Potential Effects of Global Warming on Waterfowl Populations Breeding in the Northern Great Plains (1998)
    Springer
    Climatic change 40 (1998), S. 343-369 
    Details
    ISSN: 1573-1480
    Keywords: effects of global warming ; drought ; climate change ; Prairie Pothole Region ; waterfowl ; waterfowl breeding ecology ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Prairie Pothole Region (PPR) of the Northern Great Plains is the most important breeding area for waterfowl in North America. Historically, the size of breeding duck populations in the PPR has been highly correlated with spring wetland conditions. We show that one indicator of climate conditions, the Palmer Drought Severity Index (PDSI), is strongly correlated with annual counts (from 1955 to 1996) of both May ponds (R2 = 0.72, p 〈 0.0001) and breeding duck populations (R2 = 0.69, p 〈 0.0001) in the Northcentral U.S., suggesting the utility of PDSI as an index for climatic factors important to wetlands and ducks. We then use this relationship to project future pond and duck numbers based on PDSI values generated from sensitivity analyses and two general circulation model (GCM) scenarios. We investigate the sensitivity of PDSI to fixed changes in temperature of 0°C, +1.5°C, +2.5°C, and +4.0°C in combination with fixed changes in precipitation of -10%, +0%, +7%, and +15%, changes spanning the range of typically-projected values for this region from human-induced climatic change. Most (11 of 12) increased temperature scenarios tested result in increased drought (due to greater evapotranspiration under warmer temperatures) and declining numbers of both wetlands and ducks. Assuming a doubling of CO2 by 2060, both the equilibrium and transient GCM scenarios we use suggest a major increase in drought conditions. Under these scenarios, Northcentral U.S. breeding duck populations would fluctuate around means of 2.1 or 2.7 million ducks based on the two GCMs, respectively, instead of the present long-term mean of 5.0 million. May pond numbers would fluctuate around means of 0.6 or 0.8 million ponds instead of the present mean of 1.3 million. The results suggest that the ecologically and economically important PPR could be significantly damaged by climate changes typically projected. We make several recommendations for policy and research to help mitigate potential effects.
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    URL: http://dx.doi.org/10.1023/A:1005441608819
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    Potential Impacts of Climate Change on Fire Regimes in the Tropics Based on Magicc and a GISS GCM-Derived Lightning Model (1998)
    Springer
    Climatic change 39 (1998), S. 273-296 
    Details
    ISSN: 1573-1480
    Keywords: Fire regime ; fire scenarios ; climate change ; tropical vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Investigations of the ecological, atmospheric chemical, and climatic impacts of contemporary fires in tropical vegetation have received increasing attention during the last 10 years. Little is known, however, about the impacts of climate changes on tropical vegetation and wildland fires. This paper summarizes the main known interactions of fire, vegetation, and atmosphere. Examples of predictive models on the impacts of climate change on the boreal and temperate zones are given in order to highlight the possible impacts on the tropical forest and savanna biomes and to demonstrate parameters that need to be involved in this process. Response of tropical vegetation to fire is characterized by degradation towards xerophytic and pyrophytic plant communities dominated by grasses and fire-tolerant tree and bush invaders. The potential impacts of climate change on tropical fire regimes are investigated using a GISS GCM-based lightning and fire model and the Model for the Assessment of Greenhouse Gas-Induced Climate Change (MAGICC).
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    URL: http://dx.doi.org/10.1023/A:1005371923658
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    The effects of below-cloud aerosol on the acidification process of rain (1993)
    Springer
    Journal of atmospheric chemistry 17 (1993), S. 157-178 
    Details
    ISSN: 1573-0662
    Keywords: Aerosol ; pollution gases ; acidification ; alkalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Using a model of the acidification process of rain, we calculate and analyze the effects and contributions of a below-cloud aerosol in its different concentrations and acidities on the pH and ion components of rain (SO 4 2− , H+, NO 3 − , NH 4 + , etc.) under the conditions of different concentrations of pollution gases. The results show that the aerosol has an acidification or alkalization effect on the rain which changes the pHs of rain and aerosol. As acidifying pollution gas concentrations (SO2, HNO3) are low, the acid aerosol has important effects on the pH and H+ of rain, but as the gas concentrations are high, the acid aerosol has very little effect. The alkalizing aerosol makes the pH of rain increase by between 0.3 and 0.5 and neutralizes about 60% of H+ in the rain. As alkalizing pollution gas NH3 exists, the acid aerosol has important effects on the pH and H+ of rain. But the alkalizing aerosol has very little effect, especially as the NH3 concentration is high. The percentage contribution of the aerosol to SO 4 2− in rain is generally 7–15%, the contribution of the aerosol to NO 3 − is nearly the same as that of HNO3=1 ppb, and the contribution of the aerosol to NH 4 + is nearly the same as that of NH3, from 5 to 7 ppb, and is an important source of NH 4 + in rain. Finally, according to the actual conditions of typical regions in the south and north of China (Chongqing and Beijing), we analyze the effects of aerosol and pollution gases on the ion components of rain.
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    Lunar Influences On Climate (1999)
    Springer
    Earth, moon and planets 85-86 (1999), S. 99-113 
    Details
    ISSN: 1573-0794
    Keywords: Astronomic influence ; climate change ; Moon ; solar cycles ; weather
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Popular beliefs on the effects of the Moon on the weather probably go back to when ancient civilisations followed a lunar calendar, and the Moon went from being a purely temporal reference to becoming a causal reference. The incoming heat flow on the Earth may vary slightly after solar activity. to and generate considerable effects. The light reflected from the Moon has also been hypothesised as a cause, but the associated energy is too small. The anomalistic period of the Moon (i.e., 27.5 days) coincides substantially with that of the sunspots found on the 17–18th parallel of the heliocentric latitude. Climatic modulation which lasts for around 27.5 days should be related to solar activity, which supplies energy with an amount of two orders of magnitude greater than the lunar-reflected energy. Another mechanism responsible for climatic variations is the redistribution of heat on the Earth. The Moon with the tides induces movement of the water masses of the oceans and with this there is a transport of heat. Semidiurnal lunar tides have been identified, although with modest impact, in the atmospheric pressure, the wind field and the precipitation. On a monthly time scale, variation of daily precipitation data shows that gravitational tides do indeed affect heavy rainfalls more than mean precipitation values. On the longer time scale, several authors have identified the 18.6-yr nutation cycle, which is clearly visible in several data analyses, but often it cannot be easily distinguished from the 19.9 Saturn–Jupiter cycle and the quasi-regular 22-yr double sunspot cycle which at times may be dominant. In the time scale of centuries, covering a number of periods with minimum solar activity, an analysis of meteorological data has demonstrated that only the Spörer Minimum (A.D. 1416–1534) was characterised by climatic anomalies., whereas the other periods had no singularities, or else the weak climate forcing was covered or masked by other factors, leaving the question still open. In practice, lunar and solar influences can be found and have been demonstrated with more or less the same level of confidence. Both have the same order of magnitude, and are generally weak, interacting, and being often masked by local effects.
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    Climate Change, Extreme Events and the Canadian Insurance Industry (1997)
    Springer
    Natural hazards 16 (1997), S. 135-163 
    Details
    ISSN: 1573-0840
    Keywords: climate change ; extreme events ; insurance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract At the same time that a scientific consensus has arisen that the world will most likely experience a changing climate in the near future, with more frequent extreme events of some weather hazards, the insurance industry, worldwide, has been hit with rapidly escalating costs from weather-related disasters. This conjunction of scientific belief and economic impact has raised the questions as to (1) whether more frequent extreme events have contributed to the rising insurance costs and (2) how will future climate change affect the industry? Based upon historical data, it is difficult to support the hypothesis that the recent run of disasters both world-wide and in Canada are caused by climate change; more likely other factors such as increased wealth, urbanization, and population migration to vulnerable areas are of significance. It seems likely, though, that in the future some extreme events such as convective storms (causing heavy downpours, hail and tornadoes), drought and heat waves will result in increased costs to the industry, should the climate change as anticipated.
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    Single Particle Analysis of Aerosols, Observed in the Marine Boundary Layer during the Monterey Area Ship Tracks Experiment (MAST), with Respect to Cloud Droplet Formation (2000)
    Springer
    Journal of atmospheric chemistry 37 (2000), S. 299-329 
    Details
    ISSN: 1573-0662
    Keywords: aerosols ; cloud formation ; microanalysis ; ship tracks ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The chemical composition of individual particles 〉0.2 μm sampled duringthe MAST-experiment wereanalysed by SEM-EDX, in combination with multivariatetechniques. The objective of this experiment was toidentify the mechanisms responsible for themodification of marine stratocumulus clouds byemissions from ships and in a wider sense to provideinformation on the global processes involved inatmospheric modification of cloud albedo. Aerosolswere examined under different MBL pollution levels(clean, intermediately polluted and moderatelypolluted) in five different reservoirs: backgroundbelow-cloud and above-cloud aerosol; background clouddroplet residual particles; below-cloud ship plumeaerosol and ship track cloud droplet residualparticles.In this study a relation was provided between theaerosol emitted from the ship's stack to an effect incloud. Additionally, a large fraction of the ambientaerosol was found to be composed of organic materialor other compounds, consisting of low Z-elements,associated with chlorine. Their number fraction waslargest in clean marine boundary layers, and decreasedwith increasing pollution levels. The fraction of`transformed sea salt' (Na, Cl, S), on the other hand,increased with the pollution level in the MBL. Only20% of the particles fell within the detectable rangeof the analysis.
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    Long-term measurements of surface ozone in the German Democratic Republic (1987)
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    Journal of atmospheric chemistry 5 (1987), S. 1-21 
    Details
    ISSN: 1573-0662
    Keywords: Ozone near the ground ; ozone trends ; wet chemical method ; anthropogenic effects ; influence on biosphere ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The ozone concentration near the earth's surface has been measured at some stations in the GDR for more than 30 yr using the wet chemical method. Even at rural stations the ozone data show a significant linear increase by about 1–3% yr−1. The ozone increase being stronger in summer than in winter is assumed to be due to photochemical ozone production from increasing anthropogenic emissions of trace gases that are transported over long distances. A weaker ozone increase by only about 0.2% per year was observed in the free troposphere (5.5 km) from balloon-soundings at Lindenberg within the period 1975–1984. If the ozone trends continue, the ozone concentration near the surface and its seasonal amplitude will have doubled around the turn of the century as compared to the mid-fifties.
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    URL: http://dx.doi.org/10.1007/BF00192500
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    The effect of nitrogen fertilization on the COS and CS2 emissions from temperature forest soils (1989)
    Springer
    Journal of atmospheric chemistry 9 (1989), S. 411-417 
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    ISSN: 1573-0662
    Keywords: Trace gases ; carbonyl sulfide ; carbon disulfide ; acid rain ; nitrogen fertilization ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The net fluxes of carbonyl sulfide (COS) and carbon disulfide (CS2) to the atmosphere from nitrogen amended and unamended deciduous and coniferous forest soils were measured during the spring of 1986. We found that emissions of these gases from acidic forest soils were substantially increased after nitrogen fertilization. The total (COS+CS2) emissions were increased by nearly a factor of three in the hardwood stand and were more than doubled in the pine stand. Furthermore, vegetation type appeared to have an influence on which was the dominant sulfur gas released from the forest soils. The added nitrogen caused a dramatic increase in COS emissions from the hardwood stand (a factor of three increase), while CS2 emissions from this site were not affected. We observed the opposite response in the pine stand; that is, the nitrogen fertilization had no affect on COS emissions, but did stimulate CS2 emissions (a factor of more than nine increase).
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    URL: http://dx.doi.org/10.1007/BF00114753
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    What can we learn from aerosol measurements at baseline stations? (1985)
    Springer
    Journal of atmospheric chemistry 3 (1985), S. 153-169 
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    ISSN: 1573-0662
    Keywords: Aerosol: Antarctic/Arctic/atmospheric/baseline/marine ; atmospheric monitoring ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract In this paper the results of existing baseline aerosol monitoring programs are reviewed. For this purpose, aerosol data from five baseline stations in both hemispheres are analysed. Their information content is compared to that which can be derived when utilizing experiences of recent field experiments and the present state of aerosol sciences in general. Recommendations for extensions and reductions of baseline aerosol measurements are given.
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    URL: http://dx.doi.org/10.1007/BF00049374
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    Interpretation of Mauna Loa atmospheric transmission relative to aerosols, using photometric precipitable water amouts (1985)
    Springer
    Journal of atmospheric chemistry 3 (1985), S. 53-68 
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    ISSN: 1573-0662
    Keywords: Water vapor ; atmospheric transmission ; aerosol optical depth ; precipitable water pyrheliometer ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Precipitable water measurements made coincident in time and space with direct broadband solar irradiance measurements are used in conjunction with an atmospheric transmission model to derive a parameter whose major dependence is on total aerosol extinction. Irradiance measurements are used to calculate an atmospheric transmission factor (ATF) that is independent of the instrument calibration and the extraterrestrial solar constant. The dependency of the ATF on precipitable water is determined using LOWTRAN5, an atmospheric transmission model with high spectral resolution. Precipitable water measurements are then used to adjust the measured ATF to correspond to an ATF value obtained for a constant precipitable water amount. The remaining variability in the adjusted ATF is due mostly to aerosol extinction. The technique is applied to a 6-year period (1978–1983) for clear-sky mornings at Mauna Loa, Hawaii (MLO). MLO ATF aerosol residuals are compared with independently measured monochromatic aerosol optical depth. Results show that the ATF aerosol residual is nearly equal to the 500 nm aerosol optical depth prior to the eruption of E1 Chichon, at which time a nonlinear time-dependent relationship between the two quantities is evident. ATF aerosol residuals reflect the spectrally integrated aerosol influence on transmission and, therefore, could indicate better than monochromatic optical depth the radiation balance perturbations due to aerosols. The 6-year precipitable water record for MLO, determined from a dual-channel sunphotometer, has a mean value of 0.3 cm. An annual cycle in precipitable water is evident, as is a 4-month 5-standard-deviation “drought” from December 1982 through March 1983.
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    URL: http://dx.doi.org/10.1007/BF00049368
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    Acid-base chemistry and aluminum transport in an acidic watershed and pond in New Hampshire (1995)
    Springer
    Biogeochemistry 28 (1995), S. 69-91 
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    ISSN: 1573-515X
    Keywords: Acid neutralizing capacity ; acidification ; aluminum ; dissolved organic carbon ; lake ; watershed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Cone Pond is one of the few acidic, clear-water ponds in the White Mountains of New Hampshire, a region dominated by high inputs of strong acids from atmospheric deposition and low base content of bedrock. Monitoring was conducted for 13 months to compare and contrast the acid-base chemistry of the terrestrial and aquatic portions of the watershed. Variations in Al concentration and speciation in drainage waters were correlated with changes in the supply of naturally occurring organic ligands. During the study period, the pond retained 28% of Al inputs, including nearly half of the inputs of organically complexed Al. Chemical equilibrium calculations indicated that the entire water-column was oversaturated with respect to the solubility of synthetic gibbsite during summer, as was the hypolimnion during winter. Retention of Al resulted from an increase in pH in the hypolimnion concomitant with SO4 2− reduction, and from loss of organic anions in epilimnetic waters. Acid neutralizing capacity (ANC) generated in the pond primarily through SO4 2− reduction and base cation (C B ) release was balanced by ANC consumed as a result of Al retention.
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    Methane emissions from floodplain swamps of the Ogeechee River: long-term patterns and effects of climate change (1992)
    Springer
    Biogeochemistry 15 (1992), S. 151-174 
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    ISSN: 1573-515X
    Keywords: climate change ; floodplains ; greenhouse warming ; methane ; simulation models ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Patterns and rates of wetland methane emissions and their sensitivity to potential climate change are critical components of the global methane cycle. In this study, we use empirical simulation models to investigate these processes in floodplain swamps of the Ogeechee River in Georgia, U.S.A. We developed statistical models that relate methane emissions to monthly climate and river flow based on field observations of methane emissions from this system made during 1987–1989. Models were then applied to observed climate and hydrograph for 1937–1989 and to simulated altered climates. Altered climates were generated from the present-day climate by changing monthly temperatures by a constant amount and/or changing monthly precipitation by a constant proportion, thus altering long-term averages and preserving year-to-year variation. Under the present-day climate regime, simulated methane emissions were variable between years and responded very strongly to changes in river discharge. The long-term average was 27 g C m-2 yr-1, with no significant linear trend over the model period. In the altered climate simulations, methane emissions were very sensitive to changes in precipitation amounts, with a 20% decrease in rainfall resulting in 30–43% declines in methane emissions. Predicted effects of temperature changes on methane emissions were less consistent, and were strongly dependent on assumptions made about the response of evapotranspiration to elevated temperatures. In general, hydrologic impacts of changes in evapotranspiration rates (such as may occur in response to temperature shifts) were more important than direct temperature effects on methane production.
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    URL: http://dx.doi.org/10.1007/BF00002934
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    The effects of acidification on metal budgets of lakes and catchments (1988)
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    Biogeochemistry 5 (1988), S. 201-220 
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    ISSN: 1573-515X
    Keywords: metals ; mass balances ; acidification ; lakes ; catchment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Metal (Cu, Ni, Zn, Fe, Mn and Al) budgets were measured for 5 lakes and their catchments near Sudbury, Ontario, an area severely affected by the emission and deposition of strong acids (H2SO4/SO2) and metals. Three of the lakes were circum-neutral (pH 6.3–7.1) during the study period, while one lake had a pH of ∼ 4.8 and a fifth had very low pH (∼ 4.4). The lakes' catchments were all sources of Al, Mn and Ni, but were sinks for Cu and Zn. The Fe results were inconsistent; two lakes' catchments were sources while three were sinks. The acidic lakes were conservative (i.e. net retention of zero) with respect to Cu and Ni, while the circum-neutral lakes were effective sinks for these 2 metals. All of the lakes were sinks for Zn and Al, but the acidic lakes were less effective. All lakes were also Fe sinks. While there was no pattern relative to the lakes' pH's, there was a trend towards increasing Fe retention with increasing water replenishment time. The most acidic lake was actually a source of Mn, while the others were sinks.
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    Comparison of brook trout reproductive success and recruitment in an acidic adirondack lake following whole lake liming and watershed liming (1996)
    Springer
    Biogeochemistry 32 (1996), S. 323-337 
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    ISSN: 1573-515X
    Keywords: liming ; acidification ; brook trout ; spawning ; reproduction ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Limestone applications to the catchment of one tributary to Woods Lake were highly effective in reducing stream acidity and stabilizing seasonal fluctuations in pH. The resulting improvement in stream water quality also led to a dramatic shift in reproductive strategy of the Woods Lake brook trout population. Prior to catchment liming, brook trout in Woods Lake were restricted to spawning on poor quality near shore substrate with limited ground water seepage. Reproductive success was limited by high mortality of eggs and larvae and recruitment from in lake spawning was not successful. Spawning brook trout did not utilize the tributary for spawning prior to watershed liming. Mitigation of acidity in the tributary, by catchment liming, effectively extended the spawning habitat available to the Woods Lake brook trout population and one year following treatment brook trout spawned successfully in the tributary for the first time in 6 years of observation. Significant recruitment of young trout into the lake population occurred from 1991 through 1993, although the absolute number of fish captured was relatively small. In the fall of 1993, four year classes of naturally spawned brook trout were present in the lake. Although reproductive success was enhanced by improving tributary spawning habitat in the Woods Lake basin, self maintenance of the population may be limited by low recruitment rates of young trout, due to high levels of summer mortality resulting from predation. Mitigation of this constraint would require substantially higher levels of fry production than were observed in Woods Lake and/or enhanced refugia for young trout. The results of this experiment suggest that re-establishment of tributary spawning populations of brook trout may be possible, with future reductions in acidic deposition, in acidic Adirondack lakes with limited in-lake spawning habitat.
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    URL: http://dx.doi.org/10.1007/BF02187144
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    Streamflow-induced variations in nitrate flux in tributaries to the Atlantic Coastal Zone (1996)
    Springer
    Biogeochemistry 33 (1996), S. 149-177 
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    ISSN: 1573-515X
    Keywords: Atlantic estuaries ; climate change ; climatic variability ; coastal management ; nitrate flux ; seasonal variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Streamflow-related variability in nutrient flux represents an important source of uncertainty in managing nutrient inputs to coastal ecosystems. Quantification of flux variability is of particular interest to coastal resource managers in adopting effective nutrient-reduction goals and monitoring progress towards these goals. We used historical records of streamflow and water-quality measurements for 104 river monitoring stations in an analysis of variability in annual and seasonal flux of nitrate to the Atlantic coastal zone. We present two measures of temporal flux variability: the coefficient of variation (CV) and the exceedence probability (EP) of 1.5 times the median flux. The magnitude of flux variations spans a very wide range and depends importantly upon the season of year and the climatic and land-use characteristics of the tributary watersheds. Year-to-year variations (CV) in annual mean flux range over two orders of magnitude, from 3–200% of the long-term mean flux, although variations more typically range from 20–40% of the long-term mean. The annual probability of exceeding the long-term median flux by more than 50% (EP) is less than 0.10 in most rivers, but is between 0.10 and 0.35 in 40% of the rivers. Year-to-year variability in seasonal mean flux commonly exceeds that in annual flux by a factor of 1.5 to 4. In western Gulf of Mexico coastal rivers, the year-to-year variablity in the seasonal mean flux is larger than in other regions, and is of a similar magnitude in all seasons. By contrast, in Atlantic coastal rivers, the winter and spring seasons, which account for about 70% of the annual flux, display the smallest relative variability in seasonal mean flux. We quantify the elasticity of nutrient flux to hypothetical changes in Streamflow (i.e., the percent increase in flux per percentage increase in mean discharge) to allow the approximation of flux variability from streamflow records and the estimation of the effects of future climatically-induced changes in Streamflow on nutrient flux. Flux elasticities are less than unity (median = 0.93%) at most stations, but vary widely from 0.05% to 1.59%. Elasticities above unity occur most frequently in the largest rivers and in rivers draining the arid portions of the western Gulf of Mexico Basin. Historical flux variability and elasticity generally increase with the extent of arid conditions and the quantity of nonurban land use in the watershed. We extend the analysis of flux variability to examine several case studies of highly unusual meteorological events capable of significantly elevating nitrate flux and degrading estuarine ecology.
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    URL: http://dx.doi.org/10.1007/BF02181070
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    Carbon storage in forest soil of Finland. 1. Effect of thermoclimate (1997)
    Springer
    Biogeochemistry 36 (1997), S. 239-260 
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    ISSN: 1573-515X
    Keywords: boreal forests ; carbon balance ; climate change ; climatic warming ; podzols ; soil carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A total of 30 coniferous forest sites representing two productivityclasses, forest types, were investigated on a temperature gradient(effective temperature sum using +5°C threshold 800–1300degree-days and annual mean temperature –0.6–+3.9°C) inFinland for studying the effect of thermoclimate on the soil C storage.Other soil forming factors were standardized within the forest types sothat the variation in the soil C density could be related to temperature.According to the applied regression model, the C density of the 0–1 mmineral soil layer increased 0.266 kg m–2 for every 100 degree-dayincrease in the temperature sum, and the layer contained 57% and28% more C under the warmest conditions of the gradient comparedto the coolest in the less and more productive forest type, respectively.Accordingly, this soil layer was estimated to contain 23 more C ina new equilibrium with a 4°C higher annual meantemperature in Finland. The C density of the organic layer was notassociated with temperature. Both soil layers contained more C at thesites of the more productive forest type, and the forest type explained36% and 70% of the variation in the C density of the organic and 0–1m layers, respectively. Within the forest types, the temperature sumaccounted for 33–41% of the variation in the 0–1 m layer. Theseresults suggest that site productivity is a cause for the large variation inthe soil C density within the boreal zone, and relating the soil C densityto site productivity and temperature would help to estimate the soil Creserves more accurately in the boreal zone.
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    URL: http://dx.doi.org/10.1023/A:1005711024022
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    Experimental investigation of drought induced acidification in a rich fen soil (1997)
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    Biogeochemistry 37 (1997), S. 15-32 
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    ISSN: 1573-515X
    Keywords: acidification ; drought ; peat soil ; rich fen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Intact rich fen soil cores with controlled water levels near thesurface were installed in an open greenhouse. To simulate short termsummer drought, water levels were lowered (20 cm) after two weeks inhalf of the cores (experimental cores) and remained near the surface inthe other half (blanks). After two more weeks, the water levels werebrought back to the surface in the experimental cores and remainedthere for another two weeks. In the blanks, reduction and alkalinizationof the top peat layer occurred. In the experimental soil cores oxidationand acidification started within one week after drawdown. An indicationfor a drought induced rise in soluble reactive phosphorus has beenfound. The velocity of the acidification process illustrates the dynamicnature of the hydrochemical conditions in fen soils during drought. Theprocesses controlling the acid/base status of rich fen, the effect ofdrought induced acidification on P availability and the significance forthe vegetation are discussed.
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    Enhanced CH4 emission from a wetland soil exposed to Elevated CO2 (1997)
    Springer
    Biogeochemistry 37 (1997), S. 77-88 
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    ISSN: 1573-515X
    Keywords: climate change ; elevated carbon dioxide ; hydrology ; methane ; transpiration ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Methane emissions from wetland soils are generally a positive function ofplant size and primary productivity, and may be expected to increase dueto enhanced rates of plant growth in a future atmosphere of elevatedCO2. We performed two experiments with Orontium aquaticum, acommon emergent aquatic macrophyte in temperate and sub-tropical wetlands, todetermine if enhanced rates of photosynthesis in elevated CO2atmospheres would increase CH4 emissions from wetland soils.O. aquaticum was grown from seed in soil cores under ambient and elevated(ca. 2-times ambient) concentrations of CO2 in an initialglasshouse study lasting 3 months and then a growth chamber study lasting 6months. Photosynthetic rates were 54 to 71% higher underelevated CO2 than ambient CO2, but plantbiomass was not significantly different at the end of the experiment. Ineach case, CH4 emissions were higher under elevated thanambient CO2 levels after 2 to 4 months of treatment, suggestinga close coupling between photosynthesis and methanogenesis in our plant-soilsystem. Methane emissions in the growth chamber study increased by 136%. We observed a significant decrease in transpirationrates under elevated CO2 in the growth chamber study, andspeculate that elevated CO2 may also stimulate CH4 emissions by increasing the extent and duration offlooding in some wetland ecosystems. Elevated CO2 maydramatically increase CH4 emissions from wetlands, a sourcethat currently accounts for 40% of global emissions.
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    Modelling the ecosystem effects of nitrogen deposition: Simulation of nitrogen saturation in a Sitka spruce forest, Aber, Wales, UK (1997)
    Springer
    Biogeochemistry 38 (1997), S. 129-148 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; forest ecosystems ; models ; Sitka spruce
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A new model for simulating nitrogen leaching fromforested ecosystems has been applied to data from anexperimentally manipulated 30-year-old Sitka sprucestand. The manipulation experiment (at Aber, in north-western Wales, UK) was part of the European NITREXproject and involved five years of additions ofinorganic nitrogen to the spruce stand. The model(MERLIN) is a catchment-scale, mass-balance model thatsimulates both biotic and abiotic processes affectingnitrogen in ecosystems. The structure of MERLIN includes representationsof the inorganic soil, one plant compartment and twosoil organic compartments. Fluxes in and out of thesimulated ecosystem and transfers between compartmentsare regulated by atmospheric deposition, hydrologicaldischarge and biological processes such as plantuptake, litter production, immobilization,mineralization, nitrification and denitrification.Rates of nitrogen uptake, cycling and release amongpools are regulated by carbon productivity, inorganicnitrogen availability and the C:N ratios of theorganic pools. Inputs to the model are temporalsequences of carbon fluxes and pools, hydrologicaldischarge and external sources of nitrogen. The NITREX experiment at Aber began in 1990 withweekly additions of ammonium nitrate(NH4NO3) at a rate of 35 kg N ha-1 yr-1.Data were collected from both control andtreatment plots within the stand. The site-intensivedata from the control plots at Aber were augmented bydata taken from a chronosequence of 20 Sitka sprucestands and data from a survey of 5 moorland catchmentsin the same region to providecalibration data for the model. The data were used toestablish current conditions at the Aber site and toreconstruct historical sequences of carbon fluxes andpools from 1900 to the present day with which to drivethe model. The reconstructed sequences included anincrease in nitrogen deposition and a vegetationchange from moorland to plantation forest in 1960. Thecalibrated model was then used to predict the effectsof the experimental nitrogen additions begun in 1990. MERLIN successfully reproduced the observedincrease in NO3 leaching from aging spruce standsthat results from forest maturation and increasednitrogen deposition (as inferred from thechronosequence and forest survey data in the region).MERLIN also correctly predicted the increases insoilwater NO3 concentrations, the changes innitrogen content of tree and soil organic matterpools, and the changes in nitrogen fluxes that occurin spruce stands in response to increased nitrogeninputs (as observed in the nitrogen additionexperiment).
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    Response of tundra CH4 and CO2 flux tomanipulation of temperature and vegetation (1998)
    Springer
    Biogeochemistry 41 (1998), S. 215-235 
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    ISSN: 1573-515X
    Keywords: arctic ; carbon dioxide ; climate change ; methane ; plant transport ; species composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We conducted plant species removals, air temperaturemanipulations, and vegetation and soil transplants inAlaskan wet-meadow and tussock tundra communities todetermine the relative importance of vegetation typeand environmental variables in controlling ecosystemmethane (CH4) and carbon dioxide (CO2) flux. Plastic greenhouses placed over wet-meadow tundraincreased air temperature, soil temperature, and soilmoisture, but did not affect CH4 or CO2 flux(measured in the dark). By contrast, removal ofsedges in the wet meadow significantly decreased fluxof CH4, while moss removal tended to increaseCH4 emissions. At 15 cm depth, pore-waterCH4 concentrations were higher in sedge-removalthan in control plots, suggesting that sedgescontribute to CH4 emissions by transportingCH4 from anaerobic soil to the atmosphere, ratherthan by promoting methanogenesis. Inreciprocal-ecosystem transplants between thewet-meadow and tussock tundra communities, CH4and CO2 emissions were higher overall in thewet-meadow site, but were unrelated to transplantorigin. Methane flux was correlated with localvariation in soil temperature, thaw depth, andwater-table depth, but the relative importance ofthese factors varied through the season. Our resultssuggest that future changes in CH4 and CO2flux in response to climatic change will be morestrongly mediated by large-scale changes in vegetationand soil parameters than by direct temperature effects.
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    Disruption of sulfur cycling and acid neutralization in lakes at low pH (1995)
    Springer
    Biogeochemistry 28 (1995), S. 115-130 
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    ISSN: 1573-515X
    Keywords: acidification ; alkalinity generation ; metaphyton ; sulfur ; sulfate reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Experimental acidification of a softwater lake to below pH 5 fundamentally changed the sulfur cycle and lowered internal alkalinity generation (IAG). Prior to reaching pH 4.5, the balance of sulfur reduction and oxidation reactions within the lake was in favour of reduction, and the lake was a net sink for sulfate. In the four years at pH 4.5 the balance of reduction and oxidation reactions was in favour of oxidation, and there was a net production of sulfate (SO4 2−) within the lake. Evidence indicating a decrease in net SO4 2− reduction at pH 4.5 was also obtained in an anthropogenically acidified lake that had been acidified for many decades. In both lakes, the decrease in net SO4 2− reduction appeared to be linked not to a simple inhibition of SO4 2− reduction but rather to changes in benthic ecosystem structure, especially the development of metaphytic filamentous green algae, which altered the balance between SO4 2− reduction and sulfur oxidation. At pH's above 4.5, net SO4 2− reduction was the major contributor to IAG in the experimental lake, as it is in many previously studied lakes at pH 5 and above. At pH 4.5, the change in net annual SO4 2− reduction (a decrease of 110%) resulted in a 38% decrease in total IAG. Because of the important role of net SO4 2− reduction in acid neutralization in softwater lakes, models for predicting acidification and recovery of lakes may need to be modified for lakes acidified to pH 〈5.
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    In situ toxicity tests of fishes in acid waters (1987)
    Springer
    Biogeochemistry 3 (1987), S. 181-208 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; Adirondacks ; aluminum ; aquatic toxicology ; In Situ toxicity tests ; water quality ; brook trout ; lake trout ; creek club ; blacknose dace
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Toxicity of waters within the North Branch of the Moose River to various life stages of lake trout (Salvelinus namaycush), brook trout (Salvelinus fontinalis), creek chub (Semotilus atromaculatus), and blacknose dace (Rhinichthys atratulus) were examined in situ. Study sites were selected that were expected to range from toxic to favourable water quality. For example, pH varied from 4.25 to 7.17, inorganic monomeric Al ranged from ND (〈 0.01 mg/l) to 0.40 mg/l, and Ca, from 0.41 to 4.27 mg/l. Toxicity tests were conducted at times when the life stages would naturally occur in these waters and were continued until a range of mortality was observed at the various sites. These experiments suggested that the extent of the drainage system that is toxic to fish increases during snowmelt and major runoff events. Summer base flow water quality was generally the least toxic. Critical life stages were upon hatching and as early feeding fry. In general, young of the year fish were the most tolerant life stage tested. Yearling and adult fish, however, were very sensitive. Blacknose dace were the most sensitive fish of the four species tested, and brook trout were the most tolerant. Hydrogen ion (H+) concentration was the most toxic variable in the majority of tests. Inorganic monomeric Al was the most toxic in several, and the combination of H+ and Al seemed to cause increased toxicity in many instances. A three-variable model employing hours of exposure, H+ concentration, and inorganic monomeric Al predicted mortality quite well. A simple two-variable model using H+ and color was nearly as good (R2 from 0.49 to 0.94). Documented differences in toxicity among sites and species agreed with observed patterns of fish distribution. These in situ results indicated that laboratory estimates of safe levels of pH and concentrations of Al can result in mortality of fishes in surface waters subject to acidification.
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    Processes regulating temporal and longitudinal variations in the chemistry of a low-order woodland stream in the Adirondack region of New York (1987)
    Springer
    Biogeochemistry 3 (1987), S. 225-241 
    Details
    ISSN: 1573-515X
    Keywords: acid neutralizing capacity ; acidification ; beaver impoundment ; episodic events ; sulfate reduction ; watershed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Watershed processes influence the acid neutralizing capacity of surface waters by mediating changes in concentration of ionic solutes. Acidification of surface waters by atmospheric deposition of mineral acids and the extent to which ecosystem transformations neutralize this acidity are of particular concern. Seasonal variations in flow paths of water through soil and biological processes result in short-term changes in chemistry that may be critical to surface water ecology. In this study, we assessed longitudinal and temporal variations in the chemistry of a low-order stream, Pancake-Hall Creek, located in the west-central Adirondack region of New York. By quantifying changes in ionic solute concentration (e.g. Ca2+, Ala+, SO 4 2− , NO 3 − ) we were able to evaluate processes responsible for short-term fluctuations in acid/base chemistry. In the headwater sites, stream water was acidic; changes in pH, acid neutralizing capacity (ANC) and Al were primarily due to seasonal variations in basic cation and NO 3 − concentrations. At the downstream sites, water migrated through a large beaver impoundment and thick till resulting in higher pH, acid neutralizing capacity and basic cation concentrations, and lower concentrations of Al. Neutralization of acidity was particularly evident during the low flow summer period and coincided with retention of SO 4 2− in the beaver impoundment. During the high flow non-summer (October to June) period, depressed pH and ANC, and elevated Al concentrations were observed in the downstream sites. Acidic conditions during the non-summer period were not due to the oxidation of reduced sulfur deposits (e.g. SO 4 2− events) but rather the resumption of conservative SO 4 2− transport through the beaver impoundment (e.g. minimal SO 4 2− retention) coupled with increases in NO 3 − .
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    URL: http://dx.doi.org/10.1007/BF02185194
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    Methane consumption by montane soils: implications for positive and negative feedback with climatic change (1996)
    Springer
    Biogeochemistry 32 (1996), S. 53-67 
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    ISSN: 1573-515X
    Keywords: climate change ; feedback ; greenhouse gas ; methane oxidation ; montane meadow ; sagebrush
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract We report here three years of field observations of methane uptake, averaging 1.2 mg CH4 m−2 d−1 in montane meadow soils. Surface soil moisture influenced diffusion of substrate while in deeper soil, where methane oxidation was maximum, moisture influenced both diffusion and microbial activity. Microbial oxidation of methane was maximum at an intermediate level of soil moisture, at this site at about 25% moisture by weight (50% water holding capacity). Laboratory incubations also showed inhibition below 20% moisture. These results provide in situ characterization of moisture limitation of methanotroph activity and evidence that soil drying may diminish the methane sink strength. The microbial limitation to methane consumption at low soil moisture provides a mechanism for positive feedback between methane flux and climate warming, as suggested by ice core data (Blunier et al. 1993; Chappellaz et al. 1990; Stauffer et al. 1985).
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    URL: http://dx.doi.org/10.1007/BF00001532
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    The experimental watershed liming study: Comparison of lake and watershed neutralization strategies (1996)
    Springer
    Biogeochemistry 32 (1996), S. 143-174 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; acid neutralizing capacity ; calcite ; lake chemistry ; liming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The Experimental Watershed Liming Study (EWLS) was initiated to evaluate the application of CaCO3 to a forested watershed in an effort to mitigate the acidification of surface water. The objective of the EWLS was to assess the response of the Woods Lake watershed to an experimental addition of CaCO3. During October 1989, 6.89 Mg CaCO3/ha was applied by helicopter to two subcatchments comprising about 50% (102.5 ha) of the watershed area. The EWLS involved individual investigations of the response of soil and soil water chemistry, forest and wetland vegetation, soil microbial processes, wetland, stream and lake chemistry, and phytoplankton and fish to the CaCO3 treatment. In addition, the Integrated Lake/Watershed Acidification (ILWAS) model was applied to the site to evaluate model performance and duration of the treatment. The results of these studies are detailed in this volume. The purposes of this introduction and synthesis paper are to: 1) present the overall design of the EWLS, 2) discuss the linkages between the individual studies that comprise the EWLS, and 3) summarize the response of the lakewater chemistry to watershed addition of CaCO3 and compare these results to previous studies of direct lake addition. An analysis of lake chemistry revealed the watershed treatment resulted in a gradual change in pH, acid neutralizing capacity (ANC) and Ca2+ in the water column. This pattern was in contrast to direct lake additions of CaCO3 which were characterized by abrupt changes following base addition and subsequent rapid reacidification. Over the three-year study period, the supply of ANC to drainage waters was largely derived from dissolution of CaCO3 in wetlands. Relatively little dissolution of CaCO3 occurred in freely draining upland soils. The watershed treatment had only minor effects on forest vegetation. The watershed treatment eliminated the episodic acidification of streamwater and the near-shore region of the lake during snowmelt, a phenomenon that occurred during direct lake treatments. Positive ANC water in the near-shore area may improve chemical conditions for fish reproduction, and allow for the development of a viable fish population. The watershed CaCO3 treatment also decreased the transport of Al from the watershed to the lake, and increased the concentrations of dissolved organic carbon (DOC) and dissolved silica (H4SiO4) in stream and lakewater. The watershed treatment appeared to enhance soil nitrification, increasing concentrations of NO3 − in soilwater and surface waters. However, the acidity associated with this NO3 − release was small compared to the increase in ANC due to CaCO3 addition and did not alter the acid-base status of Woods Lake. Acid neutralizing capacity (ANC) budgets for 12-month periods before and after the watershed treatment showed that the lake shifted from a large source of ANC to a minor source due to retention of SO4 2−, NO3 −, Al and the elevated inputs of Ca2+ associated with the watershed CaCO3 application. In contrast to the direct lake treatments, Ca2+ inputs from the watershed application were largely transported from the lake.
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    URL: http://dx.doi.org/10.1007/BF02187137
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    TOC fluctuations in a humic lake as related to catchment acidification, season and climate (1997)
    Springer
    Biogeochemistry 36 (1997), S. 139-151 
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    ISSN: 1573-515X
    Keywords: humic lake ; TOC ; acidification ; climate ; carbon budget
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Studies of fluctuations in total organic carbon (TOC) were performedin both the reference basin and the acidified basin of experimental LakeSkjervatjern, in order to separate effects of various catchment and in-lakeprocesses. Nearly five years of catchment acidification did not inducesignificant changes in TOC. TOC concentrations was not related clearly toprecipitation or runoff. In both basins, there was a regular, seasonal patternwith a gradual increase in TOC concentrations from spring to late autumn.Minima in concentrations occurred during periods with frozen ground inwinter, irrespective of discharge patterns. The decrease from ∼10 mg C l-1 in autumn to 1--2 mg C l-1 in latewinter, was only seen in surface layers. Runoff was the major loss routefor surface TOC in the lake. Photo-oxidation, bacterial oxidation, andsedimentation combined yielded maximum loss rates of 3%of surface TOC d-1. Below a depth of 1 m 0.5%d-1 was lost to these same processes. The surface microlayerhad 5--10 times more TOC than the bulk water on average, and could haveeffects on gas exchange and sub-surface light. Despite the oxidation ofTOC, the short residence time of the lake and rapid replacement of TOCfrom the catchment was the major determinant of lake water TOC.
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    URL: http://dx.doi.org/10.1023/A:1005740030477
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    Nitrous oxide emissions from a gully mire in mid-Wales, UK, under simulated summer drought (1999)
    Springer
    Biogeochemistry 44 (1999), S. 151-162 
    Details
    ISSN: 1573-515X
    Keywords: ammonium ; climate change ; drought ; groundwater table ; nitrate ; nitrous oxide ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Certain general circulation models predict that a doubling of atmospheric carbon dioxide concentrations will increase the frequency of summer drought in northern wetlands due to hotter, drier summers. There is currently much uncertainty as to how drought will affect emissions of the greenhouse gas, nitrous oxide, from wetlands. We have demonstrated that an eight centimetre drawdown of the water table in a gully mire does not significantly affect nitrous oxide emissions from this site. However, under a more extreme drought scenario carried out on peat monoliths, nitrous oxide emissions increased exponentially with a linear decrease in water table height. Drought caused a significant increase in nitrous oxide production below the water table but most of the total increase could be attributed to increased emissions above the water table. Results from an acetylene block experiment suggested that increased emissions were caused by increased nitrous oxide production from denitrification, rather than by increased production from nitrification. In the laboratory study, drought severity had no effect on peatwater nitrate concentrations below the water table, however, increasing drought severity decreased ammonium concentrations.
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    URL: http://dx.doi.org/10.1023/A:1006031731037
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    Nitrous oxide emissions from a gully mire in mid-Wales, UK, under simulated summer drought (1999)
    Springer
    Biogeochemistry 44 (1999), S. 151-162 
    Details
    ISSN: 1573-515X
    Keywords: ammonium ; climate change ; drought ; groundwater table ; nitrate ; nitrous oxide ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Certain general circulation models predict that a doubling of atmospheric carbon dioxide concentrations will increase the frequency of summer drought in northern wetlands due to hotter, drier summers. There is currently much uncertainty as to how drought will affect emissions of the greenhouse gas, nitrous oxide, from wetlands. We have demonstrated that an eight centimetre drawdown of the water table in a gully mire does not significantly affect nitrous oxide emissions from this site. However, under a more extreme drought scenario carried out on peat monoliths, nitrous oxide emissions increased exponentially with a linear decrease in water table height. Drought caused a significant increase in nitrous oxide productionbelow the water table but most of the total increase could be attributed to increased emissionsabove the water table. Results from an acetylene block experiment suggested that increased emissions were caused by increased nitrous oxide production from denitrification, rather than by increased production from nitrification. In the laboratory study, drought severity had no effect on peatwater nitrate concentrations below the water table, however, increasing drought severity decreased ammonium concentrations.
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    URL: http://dx.doi.org/10.1007/BF00992976
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    Temporal changes in the fluoride levels of jaws of European deer in industrial regions of Western Pomerania, Poland (1995)
    Springer
    Environmental geochemistry and health 17 (1995), S. 155-158 
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    ISSN: 1573-2983
    Keywords: Deer ; bone ; fluoride ; mineral composition ; environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract The factories processing natural phosphates and apatites in Poland release into the atmosphere considerable amounts of fluorine compounds. Fluoride is known to accumulate in the hard tissues of animals and humans. This paper describes the determination of fluoride in mandibles of deer in the years 1982 and 1990. In recent years, the establishments have restricted their output and modernized the technology of phosphate fertilizer production. The fluoride content in jaws has decreased, particularly in those animals having their habitat in the vicinity of the two factories.
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    URL: http://dx.doi.org/10.1007/BF00661327
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    Urban geochemistry: A study of element distributions in the soils of tallinn (Estonia) (2000)
    Springer
    Environmental geochemistry and health 22 (2000), S. 173-193 
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    ISSN: 1573-2983
    Keywords: chemical elements ; contamination ; environment ; geochemistry ; soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract First results are presented from the ‘Urban geochemistry of Tallinn’, a project supported by the Scientific and Environmental Affairs Division of NATO. The distribution of chemical elements in 532 samples of the topsoils from the territory of the biggest industrial centre of Estonia (pop. 500,000) is interpreted. Statistical analysis and mapping of major and trace elements at the territory of the Tallinn region and of the city were performed and background values and local anomalies of chemical elements on the territory were determined. The investigation focussed on the determination of zones with anomalously high concentrations of elements and the relationships of soil contamination with different pollution sources. The increase of the element concentrations has natural as well as anthropogenic origins. A detailed comparative analysis of the element distributions and the results of a factor analysis showed that the distribution of the major chemical elements depended mainly on the composition of the underlying sedimentary rocks. The territory of Tallinn is characterised by relatively high and widespread concentrations of Ba, Cr, Ga, Ni, Ti and Zn. Especially intensive local concentrations were determined for As, Cr, Mn, Ni, Pb, S, V and Zn, which are typical for the local pollution of the soils by industrial sources. The levels of As, Cr, Mn and V are more than three times. Pb and Zn are more than five times higher in the geochemical anomalies than for background levels. For the Tallinn region two major associations of elements connected with industrial pollutions of the soil are typical: the first association includes Ba, Cr, Mn, Ni and partly Fe and the second one includes As, Pb and Zn. For the city of Tallinn an increase of Ag, Ba, Be, La, Pb, Sn and Zn concentration in the soil was detected. Ba, Cr, Mn and Ni occur in high concentrations in the soils around Maardu. Different types of contamination sources can be identified in Tallinn and its suburbs.
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    URL: http://dx.doi.org/10.1023/A:1006754326260
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    Geochemistry and acidity of sulphide-bearing postglacial sediments of western Finland (1997)
    Springer
    Environmental geochemistry and health 19 (1997), S. 155-164 
    Details
    ISSN: 1573-2983
    Keywords: geochemistry ; metals ; sulphide sediment ; oxidation ; acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract The geochemistry, mineralogy, acidity and electric conductivity of sulphide-bearing postglacial sediments located on the coastal plains of western Finland were studied. Grain size and mineralogical analysis (eight samples studied) indicated that the sediments are silts dominated by primary minerals (quartz, feldspars), and that the clay fraction (〈2µm), which made up less than one-third of the bulk samples, is enriched in phyllosilicates but depleted in quartz and feldspars, relative to bulk samples. As compared to the metal contents of the fine-fraction of glacial till (data of the Geological Survey of Finland), the fine sediments appear to be enriched in sulphur (median = 0.54%) and trace metals such as Ni (31 µg g−1), Zn (90 µg g−1), Co (13 µg g−1), Cr (48 µg g−1) and V (50 µg g−1). Statistical analysis indicated that aluminosilicates are the principal carrier phases of trace metals, and that sulphides and organic matter only partially control the distribution of elements other than S and C. A 3-g portion of 232 samples was oxidised in the laboratory by atmospheric oxygen for a period of 1 year. After this period of oxidation, 15 ml of water was added, after which pH and electric conductivity of the suspensions (sediment:water, 1:5) were measured. The quantities of elements mobilised by the oxidation was calculated from the dissolved concentrations found in 3 g of oxidised sediment suspended in 30 ml of deionised water (eight samples studied). The results of the experiment showed that the impact of sulphide oxidation on the pH and conductivity of the sediments is large, and that a high proportion (〉13%) of the aqua-regia extractable contents of several elements (Co, Mn, Ca, Ni, Zn, Sr, Na and B) are mobilised at oxidation. Because of the high quantities of acidity and metals liberated at oxidation, it is argued that stream-water quality, which is poor in the study area, will not improve unless artificial draining is restricted in areas of sulphide sediments.
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    URL: http://dx.doi.org/10.1023/A:1018462824486
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    Urban Geochemistry: Investigations in the Berlin Metropolitan Area (2000)
    Springer
    Environmental geochemistry and health 22 (2000), S. 233-248 
    Details
    ISSN: 1573-2983
    Keywords: Berlin agglomeration ; environment ; environmental geochemistry ; geochemical background ; soil contamination ; trace elements ; urban geochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract The distribution of 41 trace and 11 major elements in 4000 samples of topsoils (0–20 cm) from the Berlin Megacity is interpreted. The detailed comparative analysis of the element distributions and the results of factor analysis showed that the distributions of the elements Al, K, Na, Rb, Zr, Nb and Ti are mainly natural origin, i.e. related to the composition of the parent material. Industrial and commercial areas often display considerably elevated values for Mo, Ni, As, Ag, Cr, Sb, Fe, Mn, Mg, P, TOC and especially Pb, Hg and electrical conductivity relative to the geogenic background of the area surrounding Berlin. Industrial areas tend to be characterised by contamination of the subsoil with Cu, Cd, Zn, Hg, Pb and Sn. In the area around Berlin, extensive, strong anamalies of Cd, Zn, Pb, Cu and Hg occur near iron and steel industries and construction materials industries, as well as in the vicinity of sewage farms.
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    URL: http://dx.doi.org/10.1023/A:1026554308673
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    Climate Change in the Urals, Russia, Inferred from Borehole Temperature Data (1997)
    Springer
    Studia geophysica et geodaetica 41 (1997), S. 225-246 
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    ISSN: 1573-1626
    Keywords: climate change ; borehole temperature ; ground and air temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract Borehole temperatures in the central and south Urals were analysed for the past ground surface temperature (GST) signal. 31 highquality temperature logs were selected for this purpose and inverted with algorithms based on the generalised least squares theory. The signal to noise ratio was improved by averaging the results of individual borehole inversions. No distinct regional trends were found in the studied region except for some indications of more pronounced warming in the south. The mean GST history (GSTH) was characterised by cooling down to −0.6 °C in the 18th century and subsequent warming to 0.5 °C above the longterm mean at the beginning of this century, and to 1 – 1.5 °C by 1980. The stability of the mean GSTH was tested in dependence on the number of holes used for the averaging. It showed that any subset of 15 holes yielded a GSTH similar to that obtained from the whole set. A surface air temperature (SAT) time series comprising the period 1832 – 1989 was combined from 17 meteorological records. Its least squares warming rate of 1.1 °C per 100 years is somewhat higher than that of the GST (0.7 – 0.8°C/100 years) in the same period.
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    URL: http://dx.doi.org/10.1023/A:1023394732365
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    Climate Change Projections Based on GCM-Simulated Daily Data (1999)
    Springer
    Studia geophysica et geodaetica 43 (1999), S. 201-222 
    Details
    ISSN: 1573-1626
    Keywords: climate change ; GCM-based scenarios ; daily series of extreme and mean temperatures ; global radiation ; precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract Three-dimensional general circulation models (GCMs) are 'state-of-the-art' tools for projecting possible changes in climate. Scenarios constructed for the Czech Republic are based on daily outputs of the ECHAM-GCM in the central European region. Essential findings, derived from validating, procedures are summarized and changes in variables between the control and perturbed experiments are examined. The resulting findings have been used in selecting the most proper methods of generating climate change projections for assessing possible hydrological and agricultural impacts of climate change in selected exposure units. The following weather variables have been studied: Daily extreme temperatures, daily mean temperature, daily sum of global solar radiation, and daily precipitation amounts. Due to some discrepancies revealed, the temperature series for changed climate conditions (2×CO 2 ) have been created with the help of temperature differences between the control and perturbed runs, and the precipitation series have been derived from an incremental scenario based on an intercomparison of the GCMs' precipitation performance in the region. Solar radiation simulated by the ECHAM was not available and, therefore, it was generated using regression techniques relating monthly means of daily extreme temperatures and global radiation sums. The scenarios published in the paper consist of monthly means of all temperatures, their standard deviations, and monthly means of solar radiation and precipitation amounts. Daily weather series, the necessary input to impact models, are created (i) by the additive or multiplicative modification of observed weather daily series or (ii) by generating synthetic time series with the help of a weather generator whose parameters have been modified in accord with the suggested climate change scenarios.
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    URL: http://dx.doi.org/10.1023/A:1023309910927
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    Heat Waves in the South Moravian Region During the Period 1961-1995 (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 57-72 
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    ISSN: 1573-1626
    Keywords: extreme events ; heat wave ; tropical day ; climate change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract Heat waves (periods of extremely hot summer weather) in the region of south Moravia are in the focus of this study. The introduced definition consists of three requirements imposed on the period that is considered a heat wave: at least three days with T MAX ≥30.0°C must be observed; the mean T MAX over the whole period is at least 30.0°C; and T MAX must not drop below 25.0°C. To compare the severity of the individual heat waves, various characteristics (duration, number of tropical days, peak temperature, cumulative temperature excess, precipitation amount) are examined. The heat wave index HWI is defined to express the severity of heat waves in the most comprehensive way. An extraordinary heat wave occurred in July and August 1994; it lasted more than a month at several stations, while the duration of a typical heat wave is only 4 - 7 days. The extremely long unbroken period of tropical days, and even of days with T MAX ≥32.0°C, represents the most distinct feature of the severe 1994 heat wave. With regard to heat wave characteristics, the summer temperature exceptionality of the early 1990s is indubitable.
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    URL: http://dx.doi.org/10.1023/A:1022009924435
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    The sedimentary record of recent (last 500 years) environmental changes in the Seixal Bay marsh, Tagus estuary, Portugal (1998)
    Springer
    Netherlands journal of geosciences 77 (1998), S. 283-293 
    Details
    ISSN: 1573-9708
    Keywords: climate change ; estuary ; foraminifera ; geochemistry ; human impact ; salt marshes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The inner Tagus estuary is essentially a sedimentation basin that receives cohesive sediment from terrestrial, marine, biological and anthropogenic sources. Three short cores from one site in a marsh area of this estuary (Seixal Bay) were analysed for sedimentary, geochemical and micropalaeontological contents (benthic foraminifera and nannoplankton). The length of the cores represents about half a millennium of sedimentation. Textural analysis suggests a highly uniform mud sedimentation for most of the cores but geochemical, mineralogical and micropaleontological results indicate climatic and environmental changes and anthropogenic disturbance. Three Foraminifera zones were identified. The lower part of the lower zone indicates sedimentation in an open channel or a lower domain of an exposed high-energy sandflat. Sediments of the upper part of the lower zone and of the middle zone were deposited in a lower-energy environment, probably associated with a sheltered, vertically aggrading mudflat located within the Seixal Bay. Biological and mineralogical indicators suggest that periods of total or partial closure of this bay occurred. Clay minerals indicate that drier and colder conditions prevailed in the lower half of this zone evolving gradually to a wetter and warmer environment towards the top. The upper zone indicates persistence of low-energy sedimentation and evolution towards the present salt-marsh conditions. Anthropogenic pollution is clear in geochemical proxies at the top of the sedimentary column and was used for dating purposes.
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    URL: http://dx.doi.org/10.1023/A:1003695022853
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    Beyond the year 2000, more tornadoes in western Canada? Implications from the historical record (1995)
    Springer
    Natural hazards 12 (1995), S. 19-27 
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    ISSN: 1573-0840
    Keywords: Tornadoes ; climate change ; prairies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract A comparison of tornado frequency in western Canada before and after 1980 suggests that tornado frequency increases (decreases) with positive (negative) mean monthly temperature anomalies. If climate warming occurs due to increasing greenhouse gases in the atmosphere, the inference that more tornadoes will occur seems reasonable.
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    URL: http://dx.doi.org/10.1007/BF00605279
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