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  • Articles  (189)
  • lead
  • sediment
  • Energy, Environment Protection, Nuclear Power Engineering  (122)
  • Geosciences  (69)
  • 1
    Electronic Resource
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    Amsterdam : Elsevier
    Estuarine and Coastal Marine Science 13 (1981), S. 267-275 
    ISSN: 0302-3524
    Keywords: Delaware Bay ; Uranium ; lead ; radionuclides ; salt marshes ; sedimentation rates ; thorium
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 2
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    Amsterdam : Elsevier
    Estuarine and Coastal Marine Science 10 (1980), S. 699-702 
    ISSN: 0302-3524
    Keywords: England coast ; anaerobes ; hydrogen ; nitrogen fixation ; saltmarsh ; sediment ; sulphate ; sulphur bacteria
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 3
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    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 34 (1992), S. 347-363 
    ISSN: 0272-7714
    Keywords: Morlaix River estuary ; estuary ; fatty acids ; particulate organic matter ; sediment ; sewage influence ; sterols
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 4
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    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 34 (1992), S. 593-601 
    ISSN: 0272-7714
    Keywords: Gamma emitters ; Rhone estuary ; biodeposition ; mussel ; sediment ; tritium
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 5
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    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 39 (1994), S. 93-104 
    ISSN: 0272-7714
    Keywords: Boston Harbor ; Cape Cod ; Mya ; bivalves ; indicator species ; lead ; pollution ; shells
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 6
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    Amsterdam : Elsevier
    Environmental Pollution 84 (1994), S. 253-259 
    ISSN: 0269-7491
    Keywords: canvasbacks ; contaminants ; lead ; metals ; waterfowl
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 7
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    Amsterdam : Elsevier
    Environmental Pollution 84 (1994), S. 159-166 
    ISSN: 0269-7491
    Keywords: children ; dust ; lead ; pollution ; soil
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 8
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    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 38 (1994), S. 1-17 
    ISSN: 0272-7714
    Keywords: Dee Estuary ; fluxes ; particle mixing ; resuspension ; sediment ; trace metals
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 9
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    Amsterdam : Elsevier
    Estuarine, Coastal and Shelf Science 35 (1992), S. 105-111 
    ISSN: 0272-7714
    Keywords: comparison ; dry-sieving ; laser analysis ; particle size ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 10
    ISSN: 0272-7714
    Keywords: Hiroshima Bay ; bacteria ; biomass ; community structure ; phospholipid ester-linked fatty acids ; polyunsaturated fatty acids ; sediment ; sulphate-reducing bacteria
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Geography , Geosciences
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  • 11
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    Springer
    Stochastic environmental research and risk assessment 11 (1997), S. 193-210 
    ISSN: 1436-3259
    Keywords: Turbulence ; sediment ; fluvial ; river ; bursting process ; statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Entrainment of sediment particles from channel beds into the channel flow is influenced by the characteristics of the flow turbulence which produces stochastic shear stress fluctuations at the bed. Recent studies of the structure of turbulent flow has recognized the importance of bursting processes as important mechanisms for the transfer of momentum into the laminar boundary layer. Of these processes, the sweep event has been recognized as the most important bursting event for entrainment of sediment particles as it imposes forces in the direction of the flow resulting in movement of particles by rolling, sliding and occasionally saltating. Similarly, the ejection event has been recognized as important for sediment transport since these events maintain the sediment particles in suspension. In this study, the characteristics of bursting processes and, in particular, the sweep event were investigated in a flume with a rough bed. The instantaneous velocity fluctuations of the flow were measured in two-dimensions using a small electromagnetic velocity meter and the turbulent shear stresses were determined from these velocity fluctuations. It was found that the shear stress applied to the sediment particles on the bed resulting from sweep events depends on the magnitude of the turbulent shear stress and its probability distribution. A statistical analysis of the experimental data was undertaken and it was found necessary to apply a Box-Cox transformation to transform the data into a normally distributed sample. This enabled determination of the mean shear stress, angle of action and standard error of estimate for sweep and ejection events. These instantaneous shear stresses were found to be greater than the mean flow shear stress and for the sweep event to be approximately 40 percent greater near the channel bed. Results from this analysis suggest that the critical shear stress determined from Shield's diagram is not sufficient to predict the initiation of motion due to its use of the temporal mean shear stress. It is suggested that initiation of particle motion, but not continuous motion, can occur earlier than suggested by Shield's diagram due to the higher shear stresses imposed on the particles by the stochastic shear stresses resulting from turbulence within the flow.
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  • 12
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    Amsterdam : Elsevier
    Organic Geochemistry 21 (1994), S. 801-808 
    ISSN: 0146-6380
    Keywords: IRMS ; carbon isotope ; n-alkanes ; oil pollution ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences
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  • 13
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    Amsterdam : Elsevier
    Organic Geochemistry 8 (1985), S. 313-320 
    ISSN: 0146-6380
    Keywords: branched alkenes ; cleistanthane ; hydrocarbons ; hypersaline ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences
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  • 14
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    Amsterdam : Elsevier
    Organic Geochemistry 21 (1994), S. 517-523 
    ISSN: 0146-6380
    Keywords: Japan Sea ; hopane ; molecular parameter ; sediment ; silica ; sterane
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences
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  • 15
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    Amsterdam : Elsevier
    Organic Geochemistry 10 (1986), S. 711-716 
    ISSN: 0146-6380
    Keywords: acid hydrolysis ; carbon/nitrogen ratio ; deltaic environment ; fatty acid ; n-alkane ; organic matter ; particle size fractionation ; sediment
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Geosciences
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  • 16
    ISSN: 1437-3262
    Keywords: Spreading ridge subduction ; Chile Triple Junction ODP Leg [4] ; Tectonics ; Pacific Ocean ; South America Chile ; forearc ; ophiolite ; sediment ; deformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract An active oceanic spreading ridge is being subducted beneath the South American continent at the Chile Triple Junction. This process has played a major part in the evolution of most of the continental margins that border the Pacific Ocean basin. A combination of high resolution swath bathymetric maps, seismic reflection profiles and drillhole and core data from five sites drilled during Ocean Drilling Program (ODP) Leg 141 provide important data that define the tectonic, structural and stratigraphic effects of this modern example of spreading ridge subduction. A change from subduction accretion to subduction erosion occurs along-strike of the South American forearc. This change is prominently expressed by normal faulting, forearc subsidence, oversteepening of topographic slopes and intensive sedimentary mass wasting, overprinted on older signatures of sediment accretion, overthrusting and uplift processes in the forearc. Data from drill sites north of the triple junction (Sites 859–861) show that after an important phase of forearc building in the early to late Pliocene, subduction accretion had ceased in the late Pliocene. Since that time sediment on the downgoing oceanic Nazca plate has been subducted. Site 863 was drilled into the forearc in the immediate vicinity of the triple junction above the subducted spreading ridge axis. Here, thick and intensely folded and faulted trench slope sediments of Pleistocene age are currently involved in the frontal deformation of the forearc. Early faults with thrust and reverse kinematics are overprinted by later normal faults. The Chile Triple Junction is also the site of apparent ophiolite emplacement into the South American forearc. Drilling at Site 862 on the Taitao Ridge revealed an offshore volcanic sequence of Plio-Pleistocene age associated with the Taitao Fracture Zone, adjacent to exposures of the Pliocene-aged Taitao ophiolite onshore. Despite the large-scale loss of material from the forearc at the triple junction, ophiolite emplacement produces a large topographic promontory in the forearc immediately after ridge subduction, and represents the first stage of forearc rebuilding.
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  • 17
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    Journal of paleolimnology 19 (1998), S. 255-264 
    ISSN: 1573-0417
    Keywords: Lake Winnipeg ; magnetic resonance ; MRI ; SPRITE ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract As part of the Geologic Survey of Canada (GSC) Lake Winnipeg Study, we have successfully imaged the Lake Agassiz to Lake Winnipeg transition in Section 4 of Core Namao 94-900-122a (i.e., from 313 cm to 465 cm), using a newly-developed magnetic resonance imaging (MRI) technique called SPRITE (Single-Point, Ramped Imaging with T1 Enhancement). Whole core, gamma-ray attenuation measurements have been used to calculate the bulk porosity of the sediment at 1 cm intervals for comparison with the SPRITE images. Image contrast and image intensities observed in the SPRITE images of Section 4 are related to local porosity and magnetic susceptibility variations. In general, regions of the core with low signal intensity contain high porosity and low magnetic susceptibility. The best contrast between sediment layers is observed from regions of the core with high magnetic susceptibility. High signal intensity is observed from regions with low porosity and/or high magnetic susceptibility.
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  • 18
    ISSN: 1573-0417
    Keywords: sediment ; physical properties ; core-correlation ; stratigraphy ; acoustics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract High resolution sediment physical properties, measured on gravity and piston cores collected during cruises to Lake Winnipeg, include bulk density, acoustic velocity, magnetic susceptibility, shear strength and colour reflectance. The high resolution data are used here to construct complete stratigraphic (composite) sections of Lake Winnipeg sediments from a series of individual, discontinuous cores for the North and South Basins. These composite sections are used to evaluate basin-wide glacial and post-glacial depositional histories and to compare the northern and southern basin histories. In addition, these sections provide a baseline depth reference for interpretation of the biostratigraphy, paleomagnetic record and rock magnetic stratigraphy. Some of the data (density and shear strength) are also be used to estimate sediment stress history for the two major lithostratigraphic units and their variations across the basin.
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  • 19
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    Journal of paleolimnology 9 (1993), S. 109-127 
    ISSN: 1573-0417
    Keywords: paleolimnology ; carotenoid ; chlorophyll ; pigment ; sediment ; fossil ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Limnological surveys show that fossil pigment concentration is an accurate predictor of algal production. However, experimental and mass flux studies indicate that 〉90% of pigment is degraded to colourless compounds before permanent burial. To reconcile these views, this paper reviews current literature on pigment degradation and proposes a hierarchical control model for pigment deposition and fossil abundance. Over the widest range of production, pigment deposition and fossil concentration are proportional to algal standing crop. However, within a narrower range, the actual concentration of pigment in sediments is regulated by photo- and chemical oxidation. Three phases of loss exist: rapid oxidation in the water column (T1/2=days); slower post-depositional loss in surface sediments (T1/2=years); and very slow loss of double bonds in deep sediments (T1/2=centuries). Despite losses during deposition, fossil and algal abundance remain correlated through time, so long as there is no change in basin morphometry, light penetration, stratification or deepwater oxygen content. At the finest scale, food-web processes can increase the preservation of pigments from edible algae by incorporating pigments into feces that sink rapidly and bypass water column losses. As a consequence of selective loss during deposition and initial burial, carotenoid relative abundance is an unreliable measure of phytoplankton community composition. Instead, absolute concentration — scaled to the historical maximum — should be used for fossil interpretations.
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  • 20
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    Journal of paleolimnology 9 (1993), S. 179-188 
    ISSN: 1573-0417
    Keywords: distribution coefficient ; Kd ; 210Pb ; 210Po ; freshwater ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We have measured the distribution coefficient (Kd) of210Po and210Pb in laboratory systems and in natural freshwater systems. In the laboratory systems, an inverse relationship was observed between the particle concentration of sand or lake sediment, and the distribution coefficients of210Po and210Pb. The slope of the log-linearK d vs particle concentration relation is consistent with existingK d-particle concentration theories. These laboratory observations are consistent with similar measurements in two lakes. TheK d values of Po and Pb for the bottom sediment-pore water system with a high particle concentration were 10 to 100 times lower than those for dilute concentrations of particles suspended in the lake water. TheK d of210Pb in the sediments was 〉104 so that the diffusive transport of210Pb has only a small influence on the interpretation of210Pb concentration-depth profiles and the210Pb dating of these sediments.
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  • 21
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    Journal of paleolimnology 1 (1988), S. 215-227 
    ISSN: 1573-0417
    Keywords: Carotenoids ; degradation ; myxoxanthophyll ; β-carotene ; sediment ; paleolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Reversed-phase thin layer chromatography was used to quantify carotenoid degradation resulting from the in vitro decomposition of Oscillatoria utermöhlii. Laboratory conditions simulated lacustrine sediments. The effects of light, oxygen, temperature and the presence of a sedimentary bacterial flora on the rate and extent of degradation were evaluated. Under anaerobic conditions, bacterially-mediated decomposition of O. utermöhlii did not result in statistically significant (P〉0.05) declines in the concentrations of most carotenoids at either 6 °C after 37 weeks or 21 °C after 26 weeks. Light, in the absence of oxygen, did not promote carotenoid degradation. Carotenoid concentrations declined linearly with time (25%–62% lost by 37 weeks) in a dark environment exposed to the atmosphere at 6 °C, but only if algae were exposed to lake sediments or water containing natural, lacustrine bacterial populations. No distinct difference between the rates of carotene and xanthophyll destruction was noted, although myxoxanthophyll was more labile than other cyanophyte carotenoids, especially at 21 °C (85% loss by 26 weeks). Based on these results and published descriptions of algal decomposition kinetics, I conclude that; 1) the high sedimentary carotenoid concentrations typical of productive lakes may reflect a preferential loss of nonpigmented organic matter and, 2) sedimentary bacterial activity alone may not affect the reliability of carotenoids as paleolimnological indicators of past algal abundances in lakes with completely anoxic sediments.
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  • 22
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    Journal of paleolimnology 16 (1996), S. 133-149 
    ISSN: 1573-0417
    Keywords: climate ; hydrology ; paleoclimate ; sediment ; arctic ; Ellesmere Island
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Streamflow, suspended sediment transport and meteorological variables at two elevations were measured through the 1990–1992 field seasons at Lake C2, Northern Ellesmere Island, as part of the Taconite Inlet Lakes Project. The objectives were to determine the extent to which suspended sediment flux responded to climatic variability, and to ascertain which meteorological variable was most strongly associated with daily discharge and sediment load. This study provided a partial test of our hypothesis that the annually-laminated sediments of Lake C2 contain a paleoclimate signal. Streamflow to the lake was almost exclusively the result of snowmelt, in response to inputs of atmospheric energy as measured by air temperature at the median watershed elevation (520 m). Sea-level air temperature, global solar and net all-wave irradiance were less clearly associated with discharge. Fluctuations of discharge and suspended sediment concentration were nearly synchronous, and non-linearly related. Daily sediment discharge was therefore linked by streamflow, with a time lag, to the energy available for snowmelt. Mean daily air temperature and cumulative degree-days above 0 °C, at 520 m elevation, were successfully used to predict the daily and seasonal discharge of runoff and sediment to the lake.
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  • 23
    ISSN: 1573-0417
    Keywords: trends ; sediment cores ; PCB ; pesticides ; lead ; water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Historical trends in selected water-quality variables from 1912 to 1994 in White Rock Creek Basin were identified by dated sediment cores from White Rock Lake. White Rock Lake is a 4.4-km2 reservoir filled in 1912 and located on the north side of Dallas, Texas, with a drainage area of 259 km2. Agriculture dominated land use in White Rock Creek Basin before about 1950. By 1990, 72% of the basin was urban. Sediment cores were dated using cesium-137 and core lithology. Major element concentrations changed, and sedimentation rates and percentage of clay-sized particles in sediments decreased beginning in about 1952 in response to the change in land use. Lead concentrations, normalized with respect to aluminum, were six times larger in sediment deposited in about 1978 than in pre-1952 sediment. Following the introduction of unleaded gasoline in the 1970s, normalized lead concentrations in sediment declined and stabilized at about two and one-half times the pre-1952 level. Normalized zinc and arsenic concentrations increased 66 and 76%, respectively, from before 1952 to 1994. No organochlorine compounds were detected in sediments deposited prior to about 1940. Concentrations of polychlorinated biphenyls (PCB) and DDE (a metabolite of DDT) increased rapidly beginning in the 1940s and peaked in the 1960s at 21 and 20 µg kg-1, respectively, which is coincident with their peak use in the United States. Concentrations of both declined about an order of magnitude from the 1960s to the 1990s to 3.0 and 2.0 µg kg-1, respectively. Chlordane and dieldrin concentrations increased during the 1970s and 1980s. The largest chlordane concentration was 8.0 µg kg-1 and occurred in a sediment sample deposited in about 1990. The largest dieldrin concentration was 0.7 µg kg-1 and occurred in the most recent sample deposited in the early 1990s. Agricultural use of chlordane and dieldrin was restricted in the 1970s; however, both were used as termiticides, and urban use of chlordane continued at least until 1990. Recent use of dieldrin and aldrin, which degrades to dieldrin, has not been reported; however, increasing trends in dieldrin since the 1970s suggest recent urban use could have occurred.
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  • 24
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    Journal of paleolimnology 23 (2000), S. 213-221 
    ISSN: 1573-0417
    Keywords: geochemistry ; heavy metals ; palaeolimnology ; sediment ; soil ; X-ray fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Energy dispersive isotope-source X-ray fluorescence (XRF) analysers are little used in academic environmental research, in spite of being ideally suited to a number of tasks. In this paper an XRF method is tested by measuring a wide range of environmental materials of known elemental composition. Precision, accuracy and detection limits are presented. Using isotope-source X-ray fluorescence analysis, the total concentrations of Si, Ti, Ca, K, Fe, Mn, Cl, S, Nb, Ni, Pb, Rb, Sr, Zn and Zr can be determined in soils and sediments at a rate of 〉70 samples per day. The combination of speed and accuracy makes the technique ideal for three classes of application within environmental research. First, in sediments and soils that are highly heterogeneous, reliable characterisation is more dependent upon the number of samples measured than on measurement precision or accuracy. Under these circumstances the method is sufficiently accurate to be used alone. This is also the case where there is high and wide ranging contamination of sediment or soil by Pb and Zn. Second, major elements (Si, Ti, Fe, Ca, K and S) can be measured with sufficient accuracy in sediments and soils to aid the interpretation of other sediment chemical analyses. Third, the technique is ideal for the rapid screening of sediment or soil, allowing effective targeting of samples for more time consuming or expensive analyses. The XRF method presented here offers rapid, non-destructive total elemental analysis of sediments and soils that is sufficiently accurate to be useful in environmental research.
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  • 25
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    Journal of paleolimnology 5 (1991), S. 263-266 
    ISSN: 1573-0417
    Keywords: scaled chrysophytes ; road salt ; Fonda Lake ; Michigan ; paleolimnology ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Chrysophyte scales were identified and enumerated from the recent sediments of Fonda Lake, Michigan. This lake has undergone marked salinification due to chloride intrusion from an adjacent salt-storage facility established in 1953. From 1950 to 1980, Mallomonas caudata dominated at all levels; this taxon appears to be chloride-indifferent. M. elongata and M. pseudocoronata appeared to be chloride-intolerant as they declined drastically in abundance when chloride levels attained a maximum (ca. 1968–1972). M. tonsurata, on the other hand, was more competitive during this period of maximum [Cl\s-]. This preliminary study suggests that chrysophyte scales may be useful paleoindicators of salinity.
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  • 26
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    Journal of paleolimnology 7 (1992), S. 127-135 
    ISSN: 1573-0417
    Keywords: bacteria ; dormancy ; longevity ; sediment ; spores ; palaeoecology ; palaeolimnology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Lake sediments contain viable allochthonous bacteria that can be cultured and used for palaeoecological studies. To be a good palaeoindicator, a bacterium must be able to survive in sediments for long periods of time, but also be unable to reproduce in the lake bottom. Bacteria can survive the unfavourable environmental conditions in lake sediments as resting cells. The endospore is the most specialized form and gives the bacterium an extreme longevity. The oldest viable endospores isolated from lake sediments that we are aware of are about 9000 years old. Several species, mainly in the genera Thermoactinomyces, Bacillus and Clostridium, form endospores. Clostridium perfringens has been used as palaeoindicator for sewage pollution, while Thermoactinomyces vulgaris is an indicator for past agricultural activity in the boreal forest zone and a potential climatic indicator in other vegetation zones. Although isolation and enumeration of bacterial endospores from lake sediments is rather easy and has considerable potential as a powerful tool in palaeoecology, the number of studies using palaeoecological approaches is limited.
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  • 27
    ISSN: 1573-0417
    Keywords: magnetic measurements ; Dianchi Lake ; sediment ; Palaeoenvironmental change ; particle-sizebased characterisation ; China
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Mineral magnetic measurements have been made on a long sediment core from Dianchi Lake, Southwest China. They have been used for sediment stratigraphy, for bulk lithological classification and for detailed particle-size-based characterisation. These results are set alongside those derived from geochemical, granulometric and pollen analysis to reconstruct the environmental processes recorded in the radiocarbon dated sediment column. It is suggested that the variations of magnetic properties in this sediment core are mainly the result of changes in particle size constitution or organic content, implying shifts in the sedimentary environment. Three distinctive stratigraphic horizons, with several subdivisions, have been identified on the basis of the magnetic measurements. They are coincident with the pollen assemblage zones, indicating the different climatic periods in the Kunming Basin since late Pleistocene times. This paper proposes that a major shift in sedimentation, from lake to reedswamp, occurred in approximately 10 000–12 000 BP, in response to climatic change.
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  • 28
    ISSN: 1573-0417
    Keywords: diatoms ; pollen ; sediment ; reservoir limnology ; land-use change ; Texas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract White Rock Lake reservoir in Dallas, Texas contains a 150-cm sediment record of silty clay that documents land-use changes since its construction in 1912. Pollen analysis corroborates historical evidence that between 1912 and 1950 the watershed was primarily agricultural. Land disturbance by plowing coupled with strong and variable spring precipitation caused large amounts of sediment to enter the lake during this period. Diatoms were not preserved at this time probably because of low productivity compared to diatom dissolution by warm, alkaline water prior to burial in the sediments. After 1956, the watershed became progressively urbanized. Erosion decreased, land stabilized, and pollen of riparian trees increased as the lake water became somewhat less turbid. By 1986 the sediment record indicates that diatom productivity had increased beyond rates of diatom destruction. Neither increased nutrients nor reduced pesticides can account for increased diatom productivity, but grain size studies imply that before 1986 diatoms were light limited by high levels of turbidity. This study documents how reservoirs may relate to land-use practices and how watershed management could extend reservoir life and improve water quality.
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  • 29
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    Journal of paleolimnology 7 (1992), S. 145-156 
    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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  • 30
    ISSN: 1573-0417
    Keywords: palaeolimnology ; environmental change ; sediment ; eutrophication ; chironomids ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The sedimentary chironomid stratigraphy in short-core samples covering approx. the past 150 years was studied in the northernmost basin of Lake Päijänne, southern Finland (62° 11′ N, 25° 48′ E). The basin has received effluent loading from the wood-processing industry and municipal waste water. Four developmental stages were distinguished based on the changes in chironomid assemblages: 1. Pre-industrial stage (dated by the210Pb method as covering approximately the period 1838–1936), 2. Stage of increasing pollution (approx. 1944–1973), 3. The ‘black decade’, or the period of worst pollution (approx. 1973–1983), and 4. Water protection stage (approx. 1983 onwards). During the first stage the basin suffered very little human interference and was oligotrophic, with values of 4.00–4.28 for Wiederholm's Benthic Quality Index (BQI). During the second stage it altered between weak mesotrophy and moderate mesotrophy, and the former profundal assemblages characterized byHeterotrissocladius subpilosus andMicropsectra were replaced bySergentia coracina andChironomus anthracinus gr. The BQI ranged from 2.75 to 3.50. This process led to the extirpation ofH. subpilosus. Eutrophication of the basin reached its climax during the ‘black decade’, representing moderate eutrophy with a BQI of 2.15. The profundal assemblages were composed mainly ofChironomus anthracinus gr. andC. plumosus gr. The adoption of more effective waste water purification processes in both the wood-processing industry and the municipal treatment plant markedly reduced effluent loading, especially BOD loading during the fourth stage, and this led to a recovery in the basin. At present it is mesotrophic, with a BQI of 2.90–3.00, and its biological conditions resemble those of the second stage in the 1950's and 1960's.
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  • 31
    ISSN: 1573-0417
    Keywords: jpalaeolimnology ; boreal lake ; diffuse loading ; eutrophication ; sediment ; trophic state ; diatoms ; chironomids ; Finland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The recent environmental history of Lake Lappajärvi in western Finland (63°00′ N, 23°30′ E, area 149 km2), a humic, brown water lake with an average phosphorus content of ca. 20 μg l–1, was studied from short core sediment samples taken from the two main basins of the lake. Based on the stratigraphy of diatoms and chironomids and the sediment quality it was possible to distinguish four developmental stages during the past century: (1) a pre-industrial stage covering the time up to about 1935; (2) a stage of increasing nutrient loading (ca. 1936–1960); (3) a stage of pronounced erosion from lake level regulation and extensive ditching of the catchment area (ca. 1960–1970); and (4) a meso-eutrophic stage from ca. 1970 onwards. Acidophilous Aulacoseira distans coll. and other species typical of dystrophic, nutrient-poor lakes characterized the diatom assemblages during the first stage, and the profundal zoobenthic assemblages, characterized by Heterotrissocladius subpilosus and Micropsectra, indicated good hypolimnetic oxygen conditions and a low sedimentation of organic matter (approx. less than 50 g m–2 a–1). The increased loading rapidly led to changes both in diatoms and chironomids (e.g., to an early extinction of H. subpilosus in the 1950s). The process finally led to eutrophication with a successive proliferation of diatom species such as Asterionella formosa followed by Aulacoseira ambigua, Fragilaria crotonensis, and finally Melosira varians. The relative proportion of alkaliphilous species reached a maximum in the final stage and the original profundal chironomid fauna was replaced by Chironomus anthracinus gr. and C. plumosus which are typical of profundal areas suffering from temporal oxygen deficit. It is notable that the considerable decrease in waste water loading from the point sources (80–86% ) during the past two decades has not led to a recovery in the lake. This highlights the importance of diffuse loading from agriculture, forestry and other human activities even to this comparatively large lake.
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  • 32
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    Pure and applied geophysics 144 (1995), S. 525-536 
    ISSN: 1420-9136
    Keywords: Tsunami ; coastal sedimentation ; sorting processes ; particle size ; modal population ; geomorphology ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract This paper presents the result of a detailed granulometric investigation of sediments deposited by a modern tsunami, the 1992 tsunami in Flores, Indonesia. Eyewitness accounts indicate that sediments were deposited upon coastal lowlands over wide areas as a result of the tsunami inundation. Distinctive vertical and lateral variations in particle size composition are characteristic features of the tsunami deposits and these are intimately related to sedimentary processes associated with flood inundation. The geomorphological and sedimentary evidence is used here to establish a preliminary model of tsunami sedimentation. This information is believed to be of great value in understanding sedimentary processes associated with tsunami flooding and in the interpretation of palaeo-tsunami deposits.
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  • 33
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    Pure and applied geophysics 128 (1988), S. 683-724 
    ISSN: 1420-9136
    Keywords: Continental crust ; crustal evolution ; isotopes ; mantle ; recycling ; sediment ; subduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In order to understand the evolution of the crust-mantle system, it is important to recognize the role played by the recycling of continental crust. Crustal recycling can be considered as two fundamentally distinct processes: 1) intracrustal recycling and 2) crust-mantle recycling. Intracrustal recycling is the turnover of crustal material by processes taking place wholly within the crust and includes most sedimentary recycling, isotopic resetting (metamorphism), intracrustal melting and assimilation. Crust-mantle recycling is the transfer of crustal material to the mantle with possible subsequent return to the crust. Intracrustal recycling is important in interpreting secular changes in sediment composition through time. It also explains differences found in crustal area-age patterns measured by different isotopic systems and may also play a role in modeling crustal growth curves based on Nd-model ages. Crustal-mantle recycling, for the most part, is a subduction process and may be considered on three levels. The first is recycling with only short periods of time in the mantle (〈10 m.y.). This may be important in explaining the origin of island-arc and related igneous rocks; there is growing agreement that 1–3% recycled sediment is involved in their origin. Components of recycled crustal material, with long-term storage (up to 2.5 b.y.) in the mantle as distinct entities, has been suggested for the origin of ocean island and ultrapotassic volcanics but there is considerably less agreement on this interpretation. A third proposal calls for the return of crustal material to the mantle with efficient remixing in order to swamp the geochemical and isotopic signature of the recycled component by the mantle. This type of recycling is required for steady-state models of crustal evolution where the mass of the continents remains constant over geological time. It is unlikely if crust-mantle recycling has exceeded 0.75 km3/yr over the past 1–2 Ga. Good evidence exists that selective recycling is an important process. Sedimentary rocks preserved in different tectonic settings are apparently recycled at different rates, resulting in a bias in the sediment types preserved in the geologic record. Selective recycling has important implications for the interpretation of Nd model ages of old sedimentary rocks and in the analysis of accreted terranes. Although there is evidence that continental crust was formed prior to 3.8 Ga, the oldest preserved rocks do not exceed this age. It is likely that the intense meteorite bombardment, which affected the earth during the period 4.56–3.8 Ga, coupled with rapid mantle convection, which resulted from greater heat production, caused the destruction and probable recycling into the mantle of any early formed crust. Although crust-mantle recycling is seen as a viable process, it is concluded that crustal growth has exceeded crust-mantle recycling since at least 3.8 Ga. Intracrustal recycling has not been given adequate consideration in models of crustal growth based on isotopic data (particularly Nd model ages). It is concluded that crustal growth curves based on Nd model ages, while vastly superior to those based on K/Ar or Rb/Sr, tend to underestimate the volume of old crust, due to crust-mantle and/or intracrustal recycling.
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  • 34
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    Mineralogy and petrology 39 (1988), S. 289-305 
    ISSN: 1438-1168
    Keywords: Silver ; lead ; zinc ; tin sulphides ; microprobe analyses ; fluid inclusions ; granitoid-related mineralization ; New South Wales, Australia ; Silber ; Blei ; Zink ; Zinnsulfide ; Mikrosonden-Analysen ; Flüssigkeits-Einschlüsse ; granit-bezogene Vererzung ; New South Wales, Australien
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Die Wallah Wallah Silber-Mine, Rye Park, New South Wales, Australien, ist an epigenetische Gangvererzungen gebunden. Diese sitzen in deformierten ordovizischen Nebengesteinen auf und sind von mittel-temperierten (280–380°C) Fluiden niedriger Salinität abgesetzt worden. Die Erze führen Zinkblende, Bleiglanz und Arsenkies als Hauptkomponenten, sowie, in kleineren Mengen, silberreichen Tetraedrit, silberführenden Zinnkies, Teallit, und Spuren von Zinnstein. Die Mineralogie und Geochemie der Erze, die geologische Situation und die regionale metallogenetische Entwicklung weisen darauf hin, daß die erzbringenden Lösungen und die Metalle einem fraktionierten Granit entstammen, der einen Teil des Wyangala Batholithen bildet. Die Lagerstätte scheint zu einem größeren, aber nur sporadisch entwickelten, magmatisch-hydrothermalen System zu gehören, das erstmals in diesem Gebiet nachgewiesen werden konnte.
    Notes: Summary The Wallah Wallah lead-zinc-silver deposit near Rye Park, New South Wales, Australia, consists of epigenetic, vein-type mineralization developed in deformed Ordovician host rocks by deposition from medium temperature (280–380°C), low salinity fluids. In addition to dominant sphalerite, galena and arsenopyrite, the ores contain Ag-rich tetrahedrite, Ag-bearing stannite, teallite and trace cassiterite. The mineralogy and geochemistry of the ores, together with features of the geological setting and the regional metallogeny indicate that the oreforming fluids and metals were largely derived from a fractionated granitoid source, in or along the western margin of the Wyangala Batholith. The deposit appears to be part of a wider, but sporadically developed, magmatic-hydrothermal mineralising system, not previously recognised in this area.
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  • 35
    ISSN: 1573-1421
    Keywords: lake ; wetland ; trace element ; biogeochemistry ; water ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Mn, Sr, Ba, Rb, Cu, Zn, Pb and Cd concentrations have been measured seasonally in the water and deposited sediments of the system comprising: Zala river (main input) — Lakes Kis-Balaton 1 and 2 (small artificial lakes created in a former bay of Lake Balaton) — Keszthely bay (hypertrophic part of Lake Balaton). The concentrations of the trace elements together with pH, alkalinity, dissolved cations (Ca2+, Mg2+, Na+, and K+), dissolved inorganic ligands (Cl−, SO4 2−), particulate Al, Ca, inorganic and organic carbon are used to assess the contamination of the study area and biogeochemical processes controlling trace element concentrations. Thermodynamic speciation calculations have also been utilized to enhance our understanding of the system. In the sediments Rb, Ba, Cu and Zn concentrations were mainly controlled by the abundance of the aluminosilicate fraction. Strontium was mainly associated with the calcium carbonate fraction. The aluminosilicate fraction constitutes a major sink for Mn and Cd but the concentration of these elements are also strongly related to calcite precipitation. The main processes that control the dissolved distribution of trace elements in the Balaton system were: solid phase formation (carbonate) for Mn; coprecipitation with calcite for Sr, Ba, Rb and possibly Mn and Cd; adsorption/desorption processes (pH dependent) for Zn and Pb; solubilization of Mn and precipitation of Cd and Cu in reed covered wetland areas where anoxic conditions were probably existing during the warm season. A preliminary budget of atmospheric and river input to Lake Balaton has also been outlined. Although Lake Balaton, is subjected to anthropogenic inputs mainly from agricultural and domestic activities, their impact on trace element concentrations in the Balaton system is very limited due to the efficiency of removal processes (i.e. adsorption and co-precipitation) and to high sedimentation rates and strong sediment re-suspension. Anthropogenic inputs are only detected for Pb.
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  • 36
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    Aquatic geochemistry 2 (1996), S. 29-49 
    ISSN: 1573-1421
    Keywords: Amino acid ; sediment ; porewater ; dissolved organic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Dissolved and particulate fractions extracted from a lake diatom ooze were examined for individual amino acids. The study focused on combined amino acids, the predominant form in the interstitial dissolved pool (〉 90%). An abundance of glycine and β-alanine was observed in porewater samples of sediments both squeezed manually and gathered with in-situ dialysis (“peeper”). Sedimentpress squeezing and leaching of the sediment by water gave higher total quantities and different compositions (with more aliphatic and aromatic protein amino acids, α-alanine being predominant). These two methods modify the original composition, presumably due to the formation of Fe-oxides and dissolution of sediment organic fractions, the alteration being aggravated if squeezing is delayed. Filtration after acidification of porewaters enabled us to distinguish two compartments: a protein-like agglutinated fraction, and a filtrate with a high glycine and β-alanine content. Further division of the filtrate by adsorption on XAD or cation-exchange resins did not reveal additional fractions with different individual amino acid compositions. A link is suggested between the agglutinated fraction and the special composition of the porewaters extracted with sediment-press. Dissolved organic carbon (DOC) and total dissolved hydrolysable amino acids (TDHAA) (≈ 10 mg/l and ≈ 13 μM, respectively) did not increase with depth, as opposed to dissolved inorganic carbon and volatile carbon. Amino acid-C accounted for less than 4% of DOC in porewaters. Individual amino acid compositions in the sediments were similar in all grain size fractions. Chemically extracted fractions had specific compositions: (l) organic fractions (alkali extracts and HF-insoluble residues) have a similar protein amino acid composition; (2) acid extracts have more acidic amino acids (HCI) or more glycine and non protein amino acids (BF). The similarity of amino acid compositions in the sediment HF-soluble fraction and the dissolved pool is discussed with respect to interactions between iron-silicate authigenic phases and porewaters.
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    Water, air & soil pollution 99 (1997), S. 81-88 
    ISSN: 1573-2932
    Keywords: channel ; bend ; sediment ; size ; gradation ; sorting ; bed ; topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Variations of sediment size and its gradation of the bed surface layer in a channel bend with nonuniform sediment are investigated experimentally. Four groups of sediment with the same initial median diameter (D0) but different initial size gradation (σ0) have been used for experiments which were run until the equilibrium bed topography was achieved. Analyses of experimental data have yielded the following results: (1) The time of equilibrium for bed evolution decreases as σ0 increases; (2) the median size of sediment (D) for a given section in the bend increases with increasing distance from the inner bank towards the outer bank, and it also increases with increasing σ0; (3) the value of D/D0 along the inner bank decreases with increasing σ0, and it also shows a gradual decrease in the upper half of the bend and a slight recovery in the lower half; and (5) the transverse variation of σ value exhibits a general trend increasing from the inner bank towards the outer bank.
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  • 38
    ISSN: 1573-2932
    Keywords: phosphorus ; P flux ; microbial activity ; redox ; simulation ; Lake Kinneret ; sediment ; accumulative P release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment-water interface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation of the bacteria at the SWI.
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  • 39
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    Water, air & soil pollution 99 (1997), S. 457-464 
    ISSN: 1573-2932
    Keywords: sediment ; phosphorus ; fractionation ; release ; humic lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Lake Flosek (north-eastern part of Poland) is a small shallow and without outflow lake which has been limed in 1970. The concentration of Ca was increased from 3-4 mg L-1 to 17 mg L-1 in the water and from 0.2-0.3% dry weight to 0.9-1.7% dry weight in sediments (5 cm upper layer) due to CaCO3 addition to the lake. In the spring-summer seasons of 1992 and 1993, an experimental study was conducted in Lake Flosek to assess the capacity of bottom sediments to uptake and release mineral phosphorus. The rate of phosphorus exchange between sediments and near-bottom water was experimentally measured under conditions of high (100%), and of reduced (10%) oxygen saturation in near-bottom water. To determine the component of sediments responsible for the uptake of most phosphorus, the proportions of phosphorus forms in sediments were analysed. Sediments of Lake Flosek showed a slight tendency to release phosphates. The rate of this process was similar under high (100%) and low (10%) oxygen saturations ranging from - 0.161 to + 0.200 mg P m-2 d-1. This is much lower (by 1-2 orders of magnitude) than reported from other harmonic, non-humic lakes. In the total phosphorus pool, the highest content of phosphorus was found in the organic and residual phosphorus fractions (over 70% of the total phosphorus in sediments). The largest part of the readily extractable phosphorus was found in the fraction bound to Al and humic substances (41%). Both these fractions determine a weak exchange of phosphorus between sediments and water. No difference in P-release related to P-fraction compound was found in the cores taken from three sites in the lake.
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  • 40
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    Water, air & soil pollution 99 (1997), S. 477-486 
    ISSN: 1573-2932
    Keywords: sediment ; nitrogen ; phosphorus ; organic matter ; cluster analysis ; Gulf of Finland ; estuaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m-2 a-1 of N and 1.7 g m-2 a-1 of P corresponding 22 000 t a-1 of N and 6 100 t a-1 of P for the whole eastern Gulf.
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  • 41
    ISSN: 1573-2932
    Keywords: reservoir of heated water ; contamination ; cadmium ; copper ; nickel ; sediment ; water ; enrichment factor ; geoaccumulation index ; contamination factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, the contamination degree of the Rybnik Reservoir with cadmium, copper and nickel was analyzed. Quality of the water from the reservoir was determined by drawing comparisons between the metal content in the water and both the officially permitted levels (contamination factor) and levels of metals occurring in the water of non-contaminated areas (enrichment factor). Contamination of bottom sediment with chosen metals was analyzed with reference to the metal content in mudstone (geoaccumulation index, enrichment factor, contamination factor). Trends towards changing the metal content in the bottom sediment was analyzed by determining the enrichment factor of the surface layer of the bottom sediments in relation to a deeper layer. Enrichment of the bottom sediments with metals coming from the water was also determined.
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  • 42
    ISSN: 1573-2932
    Keywords: Aquaculture ; aggregation ; flocculation ; grain size ; sediment ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.
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  • 43
    ISSN: 1573-2932
    Keywords: mercury ; methylmercury ; sediment ; polychaete ; Nereis diversicolor ; methylation ; bioaccumulation ; Scheldt estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Total mercury (Hg) and methylmercury (MeHg) concentrations were determined in sediments and in the polychaete worm Nereis diversicolor at 13 stations of a brackish water intertidal mudflat of the Scheldt estuary. Hg and MeHg concentrations in sediments ranged from 144 to 1192 ng g−1 dw and from 0.8 to 6 ng g−1 dw, respectively. Both Hg and MeHg concentrations increased with an increase of organic matter (OM) content and fine grain fraction. In contrast, Hg accumulation by N. diversicolor was significantly (p 〈 0.05) higher at stations with sandy sediments (mean value: 125 ng g−1 dw) than at stations with muddy sediments (mean value, 80 ng g−1), probably because Hg availability for bioaccumulation at muddy stations was reduced by high OM content of the muddy sediments. MeHg accounted for an average of 0.7% of the total Hg in sediments and 18% of the total Hg in N. diversicolor. Seasonal variations significantly affected Hg concentrations in sediments and MeHg in N. diversicolor. Total Hg concentrations in sediments were significantly (p 〈 0.05) higher in autumn and winter than in spring and summer whereas MeHg concentrations were lowest in winter compared to the other seasons. On the other hand, total Hg concentrations in the worms were lowest in spring whereas MeHg concentrations were significantly (p 〈 0.01) higher in spring and summer than in autumn and winter.
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  • 44
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    Water, air & soil pollution 99 (1997), S. 245-254 
    ISSN: 1573-2932
    Keywords: PCB ; organochlorine pesticide ; sediment ; organic carbon content ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCB congeners and organochlorine pesticides (DDT, lindane and HCB) distribution were studied in Lake Orta sediments. The results indicated a contaminated area in the nor-them part of the sub-basin. The observed high levels of organochlorine compounds (OCs) may he explained by the focusing phenomenon, ie. the preferential transport of lighter and smaller particles from the emission sources to this area. The PCBs and DDT values were correlated with the organic carbon content and the heavy metal contamination. The toxicity of the sediment samples was related also to PCB content. PCBs and OCs pollution of Lake Orta was of the same order of magnitude as in Lake Como, which is the most contamined lake in Northern Italy.
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  • 45
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    Water, air & soil pollution 95 (1997), S. 381-397 
    ISSN: 1573-2932
    Keywords: lead ; Hubbard Brook ; spodosol ; forest floor ; particles and colloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A dynamic simulation based on a simple box model was made to predict Pb transport in spodosols of the Hubbard Brook Experimental Forest. Simulated results suggest that labile Pb in the forest floor may be undergoing a rapid loss, and that Pb content may reach an equilibrium within ∼100 years with a steady-state level of approximately 0.2 kg ha-1 (concentration = 1.3 μg g-1). The predicted Pb loss from the forest floor is much higher than the observed Pb export based on zero-tension lysimeters, which are designed to optimize measurement of dissolved substances. It is suspected that lysimeters might have failed to effectively collect particles and colloids. The dissolved Pb2+ loss from the forest floor, which is governed by nonlinear retardation, is insignificant relative to total Pb losses, so linear rate removal of particles and colloids from the forest floor is an adequate approximation of Pb transport. The mineral soil is currently acting as a net sink for the Pb released from the forest floor. The model suggests that Pb content in and Pb output from the mineral soil has been increasing since the 1970s. This increase should continue until a steady-state is reached in about 100 years. Unlike the forest floor, the mineral soil loses its Pb via dissolved forms that are regulated by nonlinear adsorption/desorption retardation.
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  • 46
    ISSN: 1573-2932
    Keywords: fish farms ; fecal waste ; sediment ; geochemistry ; metabolism ; macrofauna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Benthic observations were carried out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference or control locations) were at distances 〉 50 m from net-pens. Total S− and redox potential (Eh) in surface sediment and Benthic O2 uptake and CO2 release were sensitive indicators of benthic organic enrichment. High variability between replicate measurements of sediment gas exchange could reflect spatial patchiness in sedimentation of fecal waste and food pellets under fish pens. Biomass of deposit feeders was significantly increased at cage sites but total macrofauna biomass was similar at cage and reference locations. Surface sediment water content, modal grain size, pore water salinity and sulfate, and total biomass of macrofauna were the least sensitive indicators of enrichment.
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    Environmental geochemistry and health 17 (1995), S. 39-49 
    ISSN: 1573-2983
    Keywords: Isotope measurement ; lead ; strontium ; environmental waters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract A simple procedure using both cation and anion exchange chromatography has been applied in the study of lead and strontium isotope composition in rain and stream water samples from remote catchments in Scotland. Whereas the soil released strontium to stream waters, lead was removed from rain water and the concentrations in stream waters were very low. Highly precise analysis by thermal ionisation mass spectrometry proved necessary in the determination of strontium isotope composition. The 87Sr/86Sr ratio in rain water was close to that of marine strontium but the ratios in stream waters were constant and highly characteristic for the stream. In the case of the stream at the Sourhope site, the ratio (0.70798 ± 0.00005) was less than that in rain water and probably resulted from the weathering of one specific mineral. The results suggested that the 87Sr/86Sr ratios could be used as a stable isotope tracer of waters and to provide information on the weathering processes. Two major anthropogenic components of lead were identified in water samples. One had its origin in petrol additives whereas the other was probably of industrial origin. The low 206Pb/207Pb ratios observed in stream waters confirmed the lead as being of anthropogenic origin and the data suggested that there was a movement, albeit very small, of lead from the soil to waters.
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    Environmental geochemistry and health 18 (1996), S. 113-121 
    ISSN: 1573-2983
    Keywords: Heavy metals ; arsenic ; cadmium ; copper ; lead ; soils ; neutron activation analysis ; X-ray fluorescence atomic absorption spectrophotometry ; bauxite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract A regional survey of Jamaican surface soils has been conducted in which more than 200 samples were collected at a sample density of 1 per 64 km2 across the island and analysed for total concentrations of 31 elements by instrumental neutron activation analysis (INAA), energy dispersive X-ray fluorescence (EDXRF) analysis and atomic absorption spectrophotometry (AAS). The aim of the survey was to begin the construction of a high-precision geochemical database to provide information on elemental levels in soils for application to environmental studies, agriculture, and human and animal health. Results on the regional scale are presented for As, Cd, Cu, Hg and Pb. Although Jamaican surface soils are enriched in several heavy metals compared with world soil means and crustal abundances, lead is of particular importance at this stage because of its occurrence in residential areas. Except for Cu, the distribution maps of these elements are highly correlated with bauxite which in Jamaica is associated with white limestone geology and residualterra rossa soils.
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  • 49
    ISSN: 1573-2983
    Keywords: total hydrocarbon ; fluorescence ; coastal waters ; sediment ; Peninsular Malaysia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract To determine the level of total hydrocarbon concentrations (THCs) along the eastern coastal regions of Peninsular Malaysia, samples of subsurface seawater (1 m) and surface sediments were collected from several sampling stations between June and August 1993. THCs in seawater and sediments as determined by fluorescence spectroscopy ranged from 1.4 to 21.8 µg L-1 (Seligi crude oil equivalents) and from 0.79 to 20.0 mg kg-1 (dry weight Seligi crude oil equivalents) respectively. In comparison to results obtained in similar surveys in Malaysian waters, the levels of THCs found in the present study were significantly lower indicating lower hydrocarbon contamination in the area studied.
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  • 50
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    Environmental geochemistry and health 20 (1998), S. 45-51 
    ISSN: 1573-2983
    Keywords: Polarography ; chromium ; lead ; speciation ; sediment ; heavy metals ; trace elements in water ; bullfrogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract In this investigation, polarographic analyses of water, sediment, and animal samples from Devil's Swamp near Baton Rouge, Louisiana, have been conducted. The focus of this work has been on detection of lead and chromium levels. Lead has been found to be relatively uniformly distributed among the various size fractions of the sediment and is present at a mean level of 18.7 µg g-1. In the water the concentration is about 15 µg L-1 of which 75% is bound in suspended particulates and the remainder is dissolved. Preliminary results indicate that more chromium than lead is present in bone and muscle of bullfrogs, and, for each metal, there is a higher concentration in muscle than bone. The mean lead muscle tissue concentration is 550 µg kg-1, which suggests that bioaccumulation of this metal is occurring, assuming that water contact or ingestion are the main routes of exposure. An important aspect of this research has been optimizing polarographic methodology for performing chromium speciation studies. Methods for determining the amounts of hexavalent and trivalent chromium in mixtures containing the two have been developed.
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  • 51
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    Environmental geochemistry and health 20 (1998), S. 179-184 
    ISSN: 1573-2983
    Keywords: Atomic absorption spectrometry ; bioindicators ; hair ; lead
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract Blood lead concentration is still most commonly used to assess the degree of exposure to environmental lead. However, blood lead levels are relatively transient and so tissues such as hair which store lead over longer periods need to be explored as bioindicators of lead toxicity. The results of such an investigation into hair are presented. These results indicate that there are significant differences in scalp-hair levels between the African, East Indian and Chinese racial groups in the multiracial adult population of Trinidad, West Indies. However, no significant differences were found for the pubic hair levels among the three races. The percentage of sulphur or the carbon: sulphur ratios in scalp hair did not influence the scalp-hair lead levels in the general population, although a significant difference in the carbon:sulphur ratios was observed between the African and East Indian racial groups.
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  • 52
    ISSN: 1573-2967
    Keywords: Activated carbon ; lead ; chromium ; adsorption ; adsorbent ; wastewater treatment ; low cost adsorbent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The waste slurry generated in fertilizer plants in India has been converted into a cheap carbonaceous adsorbent material. The prepared adsorbent has been characterised and used for the removal of lead and chromium metals. The kinetics of adsorption and the extent of adsorption at equilibrium are dependent on the physical and chemical characteristics of the adsorbate, adsorbent and experimental system. Results of laboratory scale studies conducted to delineate the effect of such parameters on the kinetics of adsorption of metal ions are reported. Parameters evaluated include: hydronium ion concentration, temperature, initial adsorbate concentration, size of adsorbent, and amount of adsorbent. On the basis of these studies the various physical parameters such as effective diffusion coefficient, activation energies and entropy of activation are evaluated, as these provide some information regarding the mechanistic aspects. Mass transfer coefficient values suggest a rapid transport of the adsorbate from bulk to solid phase.
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  • 53
    ISSN: 1573-3017
    Keywords: spectacled eider (Somateria fischeri) ; threatened ; lead ; Alaska
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We collected, 342 blood samples from spectacled eiders (Somateria fischeri) on their breeding grounds in western Alaska from late May through to early August 1993–1995. Lead concentrations of ≥0.50 p.p.m. wet weight were found in the blood of 20% of the adult female eiders, 2% of the adult males and 6% of the ducklings. Lead was detected (≥0.02 p.p.m.) more frequently in the blood of adult females than in adult males or ducklings and the maximum concentrations were 14.37, 0.50 and 4.28 p.p.m. wet weight, respectively. In adult females, there was a significant difference in the proportion of detectable blood lead concentrations between three collection times (arrival/nesting, hatch and brood rearing), with the highest proportion (92%) occurring at hatch. Nine hens with blood lead concentrations of ≥0.50 p.p.m. were captured a second time several weeks to 1 year later. In the hens sampled twice at intervals of several weeks, the blood lead concentrations increased and declined at mean daily rates of 1.10 and 0.94, respectively. The lead concentrations in the blood of adults were not correlated with body weights. Radiographs were taken of 119 eiders and corresponding blood samples from 98 of these birds were analysed for lead. Ingested shot was seen in X-rays of 12 adults and three ducklings and, of the 13 blood samples tested, all had detectable lead concentrations. Of the birds without radiographic evidence of ingested shot, 84% of the adult females, 19% of the adult males and 17% of the ducklings had detectable lead concentrations in their blood. Breeding ground exposure of waterfowl to lead shot is unusual and is of particular concern in spectacled eiders because of their threatened status and declining numbers in western Alaska.
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  • 54
    ISSN: 1573-3017
    Keywords: lead ; waterfawl ; sediment ; toxicity ; mining ; risk assessment ; swans ; ALAD ; protoporphyrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract For many years, waterfowl have been poisoned by lead after ingesting contaminated sediment in the Coeur d'Alene River Basin, in Idaho. Results of studies on waterfowl experimentally fed this sediment were combined with results from field studies conducted in the Basin to relate sediment lead concentration to injury to waterfowl. The first step in the model estimated exposure as the relation of sediment lead concentration to blood lead concentration in mute swans (Cygnus olor), ingesting 22% sediment in a rice diet. That rate corresponded to the 90th percentile of sediment ingestion estimated from analyses of feces of tundra swans (Olor columbianus) in the Basin. Then, with additional laboratory studies on Canada geese (Branta canadensis) and mallards (Anas platyrhynchos) fed the sediment, we developed the general relation of blood lead to injury in waterfowl. Injury was quantified by blood lead concentrations, ALAD (δ-aminolevulinic acid dehydratase) activity, protoporphyrin concentrations, hemoglobin concentrations, hepatic lead concentrations, and the prevalence of renal nuclear inclusion bodies. Putting the exposure and injury relations together provided a powerful tool for assessing hazards to wildlife in the Basin. The no effect concentration of sediment lead was estimated as 24 mg/kg and the lowest effect level as 530 mg/kg. By combining our exposure equation with data on blood lead concentrations measured in moribund tundra swans in the Basin, we estimated that some mortality would occur at a sediment lead concentration as low as 1800 mg/kg.
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  • 55
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    Mathematical geology 19 (1987), S. 291-307 
    ISSN: 1573-8868
    Keywords: flow resistance ; random field ; sediment ; similitude
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract The microtopographic roughness of coarse sediment on a stream bed offers a resistance to flow that is proportional to the intensity of turbulent water motion near the bed. To predict resistance from descriptions of roughness, it is important to determine when roughness structures may be considered geometrically similar. Gravel-cobble sediment mixtures display a first-order autoregressive structure. Characteristic horizontal and vertical dimensions can be defined easily for this structure and used to test for similarity between roughnesses. Describing roughness as a random field obviates heuristic distinctions between skin and small bedform roughnesses in coarse sediment channels.
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  • 56
    ISSN: 1573-868X
    Keywords: Osaka Bay ; sediment ; carbon ; nitrogen ; organic matter ; stable isotope ratio ; terrestrial organic matter ; TOC ; POC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Carbon and nitrogen stable isotope ratios (δ13C and δ15N) of surface sediments were measured within Osaka Bay, in the Seto Inland Sea in Japan, in order to better understand the sedimentation processes operating on both terrestrial and marine organic matter in the Bay. The δ13C and δ15N of surface sediments in the estuary of the Yodo River were less than −23‰ and 5‰ respectively, but increased in the area up to about 10 km from the river mouth. At greater distances they became constant (giving δ13C of about −20‰ and δ15N about 6‰). It can be concluded that large amounts of terrestrial organic matter exist near the mouth of the Yodo River. Stable isotope ratios in the estuary of the Yodo River within 10 km of the river mouth were useful indicators allowing study of the movement of terrestrial organic matter. Deposition rates for total organic carbon (TOC) and total nitrogen (TN) over the whole of the Bay were estimated to be 63,100 ton C/year and 7,590 ton N/year, respectively. The deposition rate of terrestrial organic carbon was estimated to be 13,200 (range 2,000–21,500) ton C/year for the whole of Osaka Bay, and terrestrial organic carbon was estimated to be about 21% (range 3–34) of the TOC deposition rate. The ratio of the deposition rate of terrestrial organic carbon to the rate inflow of riverine TOC and particulate organic carbon (POC) were estimated to be 19% (range 3–31) and 76% (range 12–100), respectively.
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  • 57
    ISSN: 1573-1421
    Keywords: sediment ; heavy metals ; remobilization ; EDTA ; ATMP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract EDTA and ATMP are synthetic chelatingagents used in many industrial applications. Becauseof their low biodegradability, they are present inmany aquatic systems where their strong complexingcapacities can modify the transfer of toxic heavymetals between solid and liquid phases. The remobilization of Cu, Pb and Cd from pollutedsuperficial river sediments in the presence of twosynthetic organic ligands (a polycarboxylate, EDTA,and a phosphonate, ATMP) is investigated as a functionof reaction time to determine the time necessary toreach dissolutive equilibrium, and as a fonction ofthe complexing agent concentration. The dissolutive equilibrium times are similar (10 to20 hours) and the solubilizing power of ATMP isslightly lower than that of EDTA. The curves ofsolubilization of metals in the presence of thecomplexing agents present a shape of a “chelateconcentration” desorption edge, for a chelate rangebetween 10-5 to 10-3 mol L-1, thesolubilised metals increasing dramatically. Thisremobilization is the result of a competition betweenassociation with the solid phase and dissolvedcomplexation. With EDTA, the desorption order ofmetals seems to be imposed by association with thesolid. For ATMP is it the chelate complexing strengthwhich determines this order.
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  • 58
    ISSN: 1573-515X
    Keywords: denitrification ; Mediterranean ; petroleum enrichment ; sediment ; sulfate-reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The denitrifying activity was measured in different types of sediment from the Mediterranean coast of France before, and after, a massive contamination (30–100 g kg-1 sediment) of hydrocarbons. A closed system was used in order to maintain anoxic conditions and to control substrates and gaseous products concentrations. We have demonstrated that the respiratory metabolism was inhibited in all cases following an incubation time of 20 to 50 days. At this time, the addition of lactate restore the denitrifying activity. The inhibitory effect of crude oil was not related to an alteration of bacterial cells, but to changes in environmental conditions allowing denitrification. The presence of hydrocarbons in the sediments causes a decrease in the redox potential and a concomitant stimulation of the sulfate reduction.
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  • 59
    ISSN: 1573-515X
    Keywords: cumulative ; flow ; GIS ; landscape ; lead ; nitrogen ; phosphorus ; suspended solids ; watershed ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis—St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4 flow-weighted total P, and a decreased proportion of phosphorus in dissolved form(p 〈 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.
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  • 60
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    Biogeochemistry 30 (1995), S. 9-29 
    ISSN: 1573-515X
    Keywords: denitrification ; floodplain ; flood ; river ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract At the floodplain scale, spatial pattern and successional development of riparian vegetation are under the control of geomorphic processes. The geomorphic and hydraulic characteristics of stream channels affect the sorting of organic material and inorganic sediment through erosion/sedimentation during floods. In turn, the proportion of fine sediments fractions differs by location within a given community of riparian forest succession. In this paper we tested the effect of geomorphic features of floodplains, through soil grain size sorting, on the nitrogen cycling in riparian forest soils. Two typical riparian forests formed by vertical accretion deposits from repeated addition of sediments from overbank flow have been chosen along the River Garonne, southwest France. These riparian forests had equivalent vegetation, flood frequency and duration, differing only in soil grain size composition: one riparian forest had sandy soils and the other had loamy soils. The evolution of the main soil physical and chemical parameters as well as denitrification (DNT), N uptake (N U ) and mineralization (N M ) rates were measured monthly over a period of 13 months in the two study sites. The loamy riparian forest presented a better physical retention of suspended matter during floods. Moreover,in situ denitrification rates (DNT) and N uptake by plants (N U ) measured in the loamy riparian forest soils were significantly greater than in the sandy soils. Although DNT and N U could be in competition for available nitrogen, the peak rates of these two processes did not occur at the same period of the year, N U being more important during the dry season when DNT was minimum, while DNT rates were maximum following the spring floods. N retention by uptake (N U ) and loss by DNT represented together the equivalent of 32% of total organic nitrogen deposited during floods on the sandy riparian forest soils and 70% on the loamy ones. These significant differences between the two sites show that, at the landscape level, one should not estimate the rates of N U and DNT, in riparian forests soils only on the basis of vegetation, but should take also into account the geomorphic features of the floodplain.
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  • 61
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    Biogeochemistry 6 (1988), S. 211-237 
    ISSN: 1573-515X
    Keywords: arsenic speciation ; interstitial water ; organoarsenicals ; sediment ; mine-tailings ; Rupert Inlet ; Alice Arm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Arsenic speciation data are presented for pore waters squeezed from some native and anthropogenically influenced sediments. Ten stations were sampled with a box corer (to 20 cm) at two British Columbia coastal sites that are influenced by mine-tailings discharges. These are Rupert Inlet and Alice Arm as well as their associated systems of Quatsino Sound/Holberg Inlet and Hastings Arm respectively. Total dissolved arsenic concentrations (ΣAs D) usually exhibited subsurface maxima at 5–10 cm and were generally related to solid phase arsenic (As p) levels, but there was also a dependence on the nature of the substrate. Tailings exhibited both the lowest (Rupert Inlet) and the highest (Alice Arm) ΣAs D values. Inorganic arsenicals, arsenate (AsV) and arsenite (AsIII) constituted the majority (〉90%) of the dissolved species butevery sample contained organoarsenicals. This is the first report of mono-, di- and tri-methylated arsenic species in marine interstitial water. A strong positive correlation between the sum of the methylarsenic compounds (ΣMeAs) and the total dissolved arsenic (ΣAs D) was found, indicating in situ microbial methylation similar to that observed in non-aquatic systems. Flux values for arsenic at the sediment-water interface suggest that, at present, there is no significant mobilization of arsenic from these mine-derived sediments into the water column.
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  • 62
    ISSN: 1573-515X
    Keywords: methylmercury ; selenium ; bioaccumulation ; bioavailability ; sediment ; Lumbriculus variegatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The accumulation of methylmercury (MeHg) to an oligochaete worm Lumbriculus variegatus (Müller) was measured in two different lake sediments in the laboratory. 14C-labelled MeHg was added to sediments at the nominal concentration of 95 ng/g dw sediment. Groups of six oligochaete worms were exposed in glass beakers to 35 g of spiked sediment for 14 days. The two sediments had organic carbon concentrations of 3.4% and 9.9% and natural selenium concentrations of 1.45 and 0.28 mg/kg (dw), respectively. After two weeks exposure, both the accumulation rate of MeHg and the body residue in the worms were much lower in the sediment having a high organic carbon content. The effect of selenium concentration in the sediment on bioaccumulation of MeHg in Lumbriculus variegatus was measured in one sediment (organic carbon 3.4% and Se 1.45 mg/kg) by adding sodiumselenite (Na2SeO3) at different concentrations. The added amounts of selenium were 0, 0.1, 0.5, 2.5, 15.0, and 50.0 mg Se/kg dry sediment. In this exposure the nominal concentration of MeHg was 102 ng/g dw sediment. The two lowest selenium concentrations did not affect the bioaccumulation of MeHg. But, the dose of 2.5 mg Se/kg resulted in a 25% reduction in the body residue after two weeks exposure. When 15 and 50 mg Se/kg were added to the sediment the accumulation of MeHg in the organisms was decreased by 75% and 86%, respectively, as compared to the reference.
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  • 63
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    Biogeochemistry 1 (1984), S. 63-77 
    ISSN: 1573-515X
    Keywords: sulfate reduction ; sediment ; lake acidification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Sulfate reduction occurred from 0–3 cm below the surface of the epilimnetic sediments of three northwestern Ontario lakes, including L.223, which has been experimentally acidified by additions of sulfuric acid. Shallow water sites were conducive to SO4 2− reduction because decomposition in these predominantly sandy sediments caused oxygen concentrations to decrease rapidly within mm below the interface. The occurrence of methanogenesis just below the depth of minimum SO4 2- concentration demonstrated that availability of organic carbon was not a limiting factor for sulphate reduction. Laboratory studies showed that SO4 2- reduction rates in mixed sediments were lower at pH 4 than at pH 6. However, sulfate gradients in sediments indicated that there was no effect of acidification on sulfate reduction in situ. This was probably because microbial H+ consumption in the epilimnetic sediments maintained steep pH gradients below the sediment-water interface. The pH increased from = 5.0 to 6.5 or higher by a depth of 3.0 cm into the sediments.
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  • 64
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    Biogeochemistry 26 (1994), S. 1-24 
    ISSN: 1573-515X
    Keywords: C:N ratio ; decomposition ; plants ; sediment ; STG ; thermogravimetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The applicability of a recently presented method (Stepwise Thermogravimetry, STG) to characterize biogenic organic matter (Kristensen 1990) was tested in comparative decomposition experiments. The initial microbial decay of pre-dried, fresh detritus from 6 different plant materials (2 macroalgae, 2 seagrasses, and 2 tree leaves) was examined for 70 days in aerobic seawater slurries. In addition, slurries of sediment detritus of low reactivity, representing the late stage of plant decay, were allowed to decompose aerobically and anaerobically for 200 days. Macroalgae lost 40–44% carbon over 70 days, whereas seagrasses lost 29–33% and tree leaves lost 0–8%. After a 3–5 days leaching phase, the temporal pattern of POC and PON loss from the plant detritus was exponential with higher rates for the former resulting in a 5–28% reduced C:N ratio. The Rp index decreased (〈20%) during the initial leaching phase followed by a 30–40% increase to the end. Initial Rp was directly proportional to decay rate. POC loss in the anaerobic sediment slurry was 10% over the 200 day period (the aerobic was hampered by low pH). Preferential loss of PON caused a 30% increase in C:N ratio. The Rp index of sediment detritus also increased with 30%. Although the present laboratory experiments not fully simulate the natural environment, the Rp-C:N relationship obtained from the two slurry experiments can illustrate the general pattern of plant decay from fresh to refractory (humic) detritus. During initial aerobic decay, rapid leaching and microbial growth causes a decrease in both Rp and C:N (‘Rapid growth’, phase 1). When all labile substrates have been consumed and the slower decay is controlled by enzymatic attack on particles with an associated production of humic compounds and accumulation of nitrogen rich bacterial cell remains, Rp increases and C:N decreases (‘Slow growth’, phase 2). Later, when condensed humic compounds have accumulated, decay ceases. Most carbon is now bound in forms which are of low availability to bacteria and a preferential mineralization of nitrogen occurs; both Rp and C:N increases (‘Condenzation’, phase 3).
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  • 65
    ISSN: 1573-515X
    Keywords: arctic ; chronology ; core ; deposition ; mercury ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Sediment cores were collected from lakes in central and northern Canada and from Hudson Bay to compare current and historic net depositions of mercury. Cores from most locations were enriched in mercury in the upper layers deposited recently relative to deeper, historic layers. The lakes with the greatest enrichments in mercury were located in central/southern Canada. This enrichment was interpreted as being of anthropogenic origin. Mercury inputs at the Experimental Lakes Area (ELA) in northwestern Ontario inferred from a core profile agreed well with inputs calculated independently from precipitation and runoff data. Anthropogenic inputs of mercury to northwestern Ontario were calculated to be about 9 µg m-2 y-1. Considering all the locations over the geographic range, the core profiles infer that fluxes of mercury have increased on average by about 2 fold over the past half century. This is consistent with results from other sites in North America and Europe.
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  • 66
    ISSN: 1573-515X
    Keywords: diagenesis ; modelling ; organic matter ; pore water ; redox ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO3 in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.
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  • 67
    ISSN: 1573-515X
    Keywords: sulfate reduction rate ; radiotracer method ; S-35 ; chromium reduction ; acid volatile sulfide ; elemental sulfur ; pyrite ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A procedure which includes the Total Reduced Inorganic Sulfur (TRIS) in a single distillation step is described for the radiotracer measurement of sulfate reduction in sediments. The TRIS includes both Acid Volatile Sulfide (AVS: H2S + FeS) and the remaining Chromium Reducible Sulfur (CRS: S0, FeS2). The single-step distillation was simpler and faster than the consecutive distillations of AVS and CRS. It also resulted in higher (4–50%) sulfate reduction rates than those obtained from the sum of35S in AVS and CRS. The difference was largest when the sediment had been dried after AVS but before CRS distillation. Relative to the35S-AVS distillation alone, the35S-TRIS single-step distallation yielded 8–87% higher reduction rates. The separation and recovery of FeS, S0 and FeS2 was studied under three distillation conditions: 1) cold acid, 2) cold acid with Cr2+, and 3) hot acid with Cr2+. The FeS was recovered by cold acid alone while pyrite was recovered by cold acid with Cr2+. A smaller S0 fraction, presumably of the finer crystal sizes, was recovered also in the cold acid with Cr2+ while most of the S0 required hot acid with Cr2+ for reduction to H2S.
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  • 68
    ISSN: 1573-1502
    Keywords: air quality ; particulates ; sulfur dioxide ; lead ; Monte Carlo ; benefits transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract This study is an initial effort to estimate one important category of benefits of environmental improvements in Central and Eastern Europe (CEE), those related to the effects of air pollution on human health. Our estimates are derived from data on ambient air quality in selected CEE locations, together with a model that links these ambient conditions to physical impacts on health and attaches economic values (in dollar terms) to these impacts. Given data limitations, our focus here is on three pollutants: particulates (PM), sulfur dioxide (SO2), and lead (Pb). Our data set includes ambient concentrations for these pollutants in four CEE countries: Bulgaria, Hungary, Poland, and Ukraine. Given the ambient data, dose-response functions taken from the clinical and epidemiological literature in the U.S., Canada, and Western Europe are used to generate estimates of the change in physical effects. These effects then are given an economic value by applying two approaches for scaling unit valuation figures applicable to the U.S. A Monte Carlo model is constructed to propagate the uncertainties of the dose-response functions and unit values to obtain confidence intervals on the total benefits from pollutant reductions in each country. We examine scenarios where the CEE countries improve ambient conditions for the pollutants in question to meet European Community (EC) standards and then compare these scenarios to ones involving uniform percentage ambient reductions across locations in each country.
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  • 69
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    Natural hazards 5 (1992), S. 279-292 
    ISSN: 1573-0840
    Keywords: Rwanda ; Ruhengeri Prefecture ; Zaire-Nile Divide ; landslides ; flooding ; sediment ; soil loss ; storm rainfall ; return intervals ; erosion control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In early May 1988, five prefectures in western Rwanda experienced catastrophic levels of precipitation, landslide, and flooding activity that resulted in a severe loss of life, property, and livelihood. Using data from runoff plot and hydrological monitoring stations of the Ruhengeri Resource Analysis and Management Project, the events and circumstances leading to these phenomena are reconstructed. These data show that mass wasting processes were preceded by more than 140 mm of precipitation during 4–7 May, which may have saturated local soils. A small earth tremor on 7 May, (Richter scale of 3) contributed to the onset of the catastrophic debris avalanche, torrent, and earthflow activity that commenced 24 h later. The more than 50 mm of precipitation that fell during 9 May, including a maximum 30 min intensity of 24 mm, resulted in continued surficial soil loss that averaged 34 t/ha on seven cropped, Wischmeier-type runoff plots with biological erosion control contours. The Nyamutera River, which drains the impacted area, delivered 567000 tons of suspended sediment to its mouth between 7 and 13 May. This corresponds to a basin-wide lowering of 12600 t/km2, or more than half of the basin's annual suspended sediment yield. Theoretical distributions of maximum 24 h precipitation events suggest that Nyakinama and other regions in Ruhengeri are particularly prone to similar high volume events, exacerbating an already serious soil loss problem throughout the prefecture. Because contemporary land use practices directly contributed to the severity of the 1988 event, further applied research that identifies technologies capable of reducing soil loss, augmenting soil fertility, and minimizing the impacts of high magnitude and high volume rainfall is greatly needed.
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  • 70
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    Journal of atmospheric chemistry 14 (1992), S. 205-222 
    ISSN: 1573-0662
    Keywords: Antarctica ; snow ; lead ; heavy metals ; global pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Concentrations of Pb, Cd, Cu and Zn have been measured using improved ultraclean procedures in a succession of twenty six snow samples integrating a 40 yr time sequence from 1940 to 1980 which were collected from the walls of a 6 m deep pit at stake D 55 in Adelie Land, East Antarctica. Measured concentrations, which are among the lowest ones ever measured in Antarctic snows, are found not to have significantly increased during the investigated time period, with the possible exception of Pb for which there might have been a significant increase after the mid 1960's. For this last metal, measured concentrations in the 1940's are about 6-fold higher than in Antarctic Holocene ice several thousand years old, which indicates that a large fraction of the anthropogenic increase for Pb probably occurred before the 1940's.
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  • 71
    ISSN: 1572-9729
    Keywords: iron oxyhydroxide ; pyrite ; sediment ; sequential extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A popular sequential extraction procedure (Tessier et al. 1979) designed t o extract metals partitioned in various sediment phases, was evaluated for its selectivity. Amorphous FeOOH, FeS, and FeS2 were added separately to natural lake sediments and sequentially extracted. The selectivity of the sequential procedure for the added solid phases was evaluated by determining the difference in the mass of Fe extracted from treated and control sediments. In the experiments where sulfide minerals were added, total S was measured in the residual solids in order to confirm selectivity of the method. Concentrations of total carbon remaining in the solid phase after each extraction step were also measured to determine the selectivity of the sequential procedure for carbon. The procedure was moderately selective for Fe added as FeOOH; a mean of 77 ± 12% (p 〈 0.05) of the Fe added was extracted in the step designed to reduce Fe-Mn oxyhydroxides. In experiments where FeS was added, a mean of 69 ± 11% (p 〈 0.05) of the Fe added as FeS was extracted in the fraction designed to oxidize sulfides and organic matter. Approximately 25% of the Fe added as FeS may have been extracted prematurely. Although less precise, total S analyses confirmed that much of the FeS was extracted in the oxidation step, yielding 104 ± 87% (p 〈 0.05) of the S added as FeS. The procedure was highly selective for FeS2; 92 ± 14% (p 〈 0.05) of the Fe added as pyrite was extracted in the sulfide extraction step. Extraction of 80 ± 54% (p 〈 0.05) of S added as pyrite confirmed that FeS2 were selectively extracted in the sulfide extraction step. Carbon in the sediments was also selectively extracted in the oxidation step (77 ± 2.4% of total C; p 〈 0.05). The applications and limitations of sequential extraction procedures as limnological research tools are discussed in light of our results.
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  • 72
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    Biodegradation 17 (1992), S. 205-219 
    ISSN: 1572-9729
    Keywords: simultaneous extraction ; sediment ; trace metal partitioning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A simultaneous (SIM) sediment extraction procedure for low carbonate sediments, which partitions sediment-bound trace metals (Fe, Mn, Zn, Cu, and Cd) into easily reducible (associated with Mn oxides), reducible (associated with Fe oxides) and alkaline extracted (bound to organic) metal is presented. The SIM method was compared to the sequential (SEQ) extraction procedure of Tessier et al. (1979). Both methods showed good agreement for the partitioning of Zn and Cd among the easily reducible, reducible and organic components of sediment. Both methods also showed the same general distribution of Mn, Fe and Cu among the three sediment components, however concentrations of metals recovered by the two methods differed; less Mn and Fe and more Cu was recovered from sediments by the SEQ vs. the SIM procedure. Less recovery of Mn is in part attributed to the loss of this metal in the `in between' reagent rinses required in the SEQ procedure. Greater recovery of Cu by the SEQ vs. the SIM method may be due to the pretreatment of sediment with strong reducing agents prior to the step used for liberating organically bound metals. Advantages of a SIM over the SEQ include rapid sample processing time (i.e. the treatment of 40 samples per day vs. 40 samples in three days), plus minimal sample manipulation. Hence, for partitioning metals into easily reducible, reducible and organic sediment components in sediments low in carbonate, we recommend the use of a SIM extraction over that of a SEQ procedure.
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  • 73
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    Biodegradation 22 (1993), S. 81-105 
    ISSN: 1572-9729
    Keywords: estuarine ; oligohaline ; sediment ; sulfate reduction ; sulfur ; sulfide oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Inorganic sulfur turnover was examined in oligohaline (salinity 〈 2 g kg-1) Chesapeake Bay sediments during the summer. Cores incubated for 〈 3 hr exhibited higher sulfate reduction (SR) rates (13–58 mmol m-2 d-1) than those incubated for 3–8 hr (3–8 mmol m-2 d-1). SR rates (determined with35SO 4 2- ) increased with depth over the top few cm to a maximum at 5 cm, just beneath the boundary between brown and black sediment. SR rates decreased below 5 cm, probably due to sulfate limitation (sulfate 〈 25 μM). Kinetic experiments yielded an apparent half-saturating sulfate concentration (Ks) of 34 μM, ≈ 20-fold lower than that determined for sediments from the mesohaline region of the estuary. Sulfate loss from water overlying intact cores, predicted on the basis of measured SR rates, was not observed over a 28-hr incubation period. Reduction of35SO 4 2- during diffusion experiments with intact core segments from 0–4 and 5–9 cm horizons was less than predicted by non-steady state diagenetic models based on35SO 4 2- reduction in whole core injection experiments. The results indicate that net sulfate flux into sediments was an order of magnitude lower than the gross sulfur turnover rate. Solid phase reduced inorganic sulfur concentrations were only 2–3 times less than those in sediments from the mesohaline region of the Bay, despite the fact that oligohaline bottom water sulfate concentrations were 10-fold lower. Our results demonstrate the potential for rapid SR in low salinity estuarine sediments, which are inhabited by sulfate-reducing bacteria with a high affinity for sulfate, and in which sulfide oxidation processes replenish the pore water sulfate pool on a time scale of hours.
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  • 74
    ISSN: 1573-0662
    Keywords: lead ; pollution ; mid-Atlantic bight ; radionuclide ; air mass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Atmospheric depositional fluxes of 7Be and210Pb (bulk) and stable Pb (wet) were measuredsimultaneously for one year (from September 1995–August 1996) atStillpond, Maryland on the uppereastern shore of the Chesapeake Bay. The annual total(bulk) depositional fluxes of 210Pb and 7Bewere 0.78 and 13 dpm cm-2, respectively, andagree well with other previously reported results atnearby locations such as Norfolk, VA and Lewes, DE. The wet depositional flux of stable Pb (58 ng cm-2 yr-1)was also similar to thatmeasured at other Chesapeake sites during 1990–1991(55 ng cm-2 yr-1, for both Wye and Elms,Maryland). This suggests that a constant Pb flux hasbeen reached since the mandatory use of unleadedgasoline was instituted. The concentrations of7Be, 210Pb, and to a lesser extent stable Pbwere diluted exponentially by precipitation, based onconcentrations versus precipitation plots. Due tohigher enrichment of 210Pb in the lowertroposphere, the dilution effect was largest on210Pb (i.e., controlled mainly by below-cloudscavenging processes), and thus its depositional fluxincrease is negligible as precipitation amountincreases. A good correlation between the amount ofprecipitation and total depositional flux of 7Beand stable Pb, which are more enriched in the uppertroposphere, suggests that precipitation amount isimportant in controlling their fluxes (i.e.,controlled by both below-cloud scavenging and in-cloudcondensation processes). Based on 7Be versus210Pb plots, it appears that 7Be, relativeto 210Pb, is less efficiently scavenged bysnowfall. Our results suggest that in addition toprecipitation amounts, marine air-mass transport orsnowfall may be important factors in controlling theseasonal variability of the fallout fluxes of tracemetals in coastal areas.
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  • 75
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    Biogeochemistry 2 (1986), S. 377-381 
    ISSN: 1573-515X
    Keywords: sediment ; pH ; acidity ; neutralization ; lake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The pH of sediments underlying acidified lake waters does not necessarily reflect the acidification of the water. Profiles of sediments in Lake Anna, Virginia showed interstitial pH values between 6.0 and 7.0 within the top 4 cm, even though the sediments are constantly exposed to overlying waters with pH values as low as 3.5. The amount of acidity neutralized by sediment processes is 2 orders of magnitude greater than previously reported observations. The results indicate that caution must be used in drawing conclusions about sediments biogeochemical processes based on the pH of overlying waters.
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  • 76
    ISSN: 1573-515X
    Keywords: arsenic ; iron ; manganese ; sulfate reduction ; sediment ; early diagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Vertical profiles of total dissolved arsenic, manganese and iron, pH, Eh and rates of sulfate reduction were determined in a freshly-collected box core from a 335m depth station in the Laurentian Trough. The relationships observed between the profiles were further examined in the laboratory by measuring these same parameters with time in surficial sediment slurries as the Eh decreased in response to biological activity or chemical alteration. Both field and laboratory observations have shown that arsenic is released predominantly as As(III) into reducing sediment porewaters. This occurs after the dissolution of manganese oxides and at the same time as the dissolution of iron oxyhydroxides and the onset of sulfate reduction. Laboratory experiments indicated that sulfate reduction and the production of sulfide ions are not solely responsible for the release of arsenic to the porewaters, although this process is necessary to create and maintain a highly reducing environment conducive to rapid iron dissolution. The diagenesis of arsenic in Laurentain Trough sediments involves the simultaneous release of arsenic and iron at a subsurface depth, followed by its removal from porewaters by precipitation and adsorption reactions after migration by diffusion along concentration gradients. A qualitative model is presented to describe the behavior of arsenic in coastal marine sediments.
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    Biogeochemistry 6 (1988), S. 21-29 
    ISSN: 1573-515X
    Keywords: lead ; trace metals ; tree rings ; urban forests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Lead (Pb) concentrations in wood ring segments of Carya spp. in two urban forests in Atlanta, GA, have decreased approximately 20 percent in the last decade. This pattern is consistent with reduced atmospheric Pb over the same period. We have determined that changes in Pb concentrations in wood of urban hickory trees dramatically documents the historical periods of early urbanization, the addition of Pb to gasoline, and the recent period of restricted use of leaded gasoline.
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  • 78
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    Biogeochemistry 40 (1998), S. 249-265 
    ISSN: 1573-515X
    Keywords: estuaries ; mercury ; methylmercury ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract An overview of a comprehensive study of the behavior and fate of mercury in the estuarine Patuxent River is presented. Total Hg (HgT) and methylmercury (MeHg) exhibited weakly non-conservative behavior in the estuary. Total Hg concentrations ranged from 6 ng L-1 in the upper reaches of the sub-urbanized tidal freshwater river to 〈0.5 ng L-1 in the mesohaline lower estuary. Filterable (0.2 µm) HgT ranged from 0.2 to 1.5 ng L-1. On average, MeHg accounted for 〈5% of unfiltered HgT and 〈2% of filterable HgT. Dissolved gaseous section Hg (DGHg) concentrations were highest (up to 150 pg L-1) in the summer in the mesohaline, but were not well correlated with primary production or chlorophyll a, demonstrating the complex nature of Hg0 formation and cycling in an estuarine environment. Organic matter content appeared to control the HgT content of sediments, while MeHg in sediments was positively correlated with HgT and organic matter, and negatively correlated with sulfide. MeHg in sediments was low (0.1 to 0.5% of HgT). Preliminary findings suggest that net MeHg production within sediments exceeds net accumulation. Although HgT in pore waters increased with increasing sulfide, bulk MeHg concentrations decreased. The concentration of MeHg in sediments was not related to the concentration of HgT in pore waters. These observations support the hypothesis that sulfide affects the speciation and therefore bioavailability of dissolved and/or solid-phase Hg for methylation. Comparison with other ecosystems, and the negative correlation between pore water sulfide and sediment MeHg, suggest that sulfide limits production and accumulation of MeHg in this system.
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  • 79
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    Water, air & soil pollution 95 (1997), S. 381-397 
    ISSN: 1573-2932
    Keywords: lead ; Hubbard Brook ; spodosol ; forest floor ; particles and colloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A dynamic simulation based on a simple box model was made to predict Pb transport in spodosols of the Hubbard Brook Experimental Forest. Simulated results suggest that labile Pb in the forest floor may be undergoing a rapid loss, and that Pb content may reach an equilibrium within ∼100 years with a steady-state level of approximately 0.2 kg ha−1 (concentration = 1.3 μg g−1). The predicted Pb loss from the forest floor is much higher than the observed Pb export based on zero-tension lysimeters, which are designed to optimize measurement of dissolved substances. It is suspected that lysimeters might have failed to effectively collect particles and colloids. The dissolved Pb2+ loss from the forest floor, which is governed by nonlinear retardation, is insignificant relative to total Pb losses, so linear rate removal of particles and colloids from the forest floor is an adequate approximation of Pb transport. The mineral soil is currently acting as a net sink for the Pb released from the forest floor. The model suggests that Pb content in and Pb output from the mineral soil has been increasing since the 1970s. This increase should continue until a steady-state is reached in about 100 years. Unlike the forest floor, the mineral soil loses its Pb via dissolved forms that are regulated by nonlinear adsorption/desorption retardation.
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  • 80
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    Water, air & soil pollution 95 (1997), S. 337-351 
    ISSN: 1573-2932
    Keywords: transport ; soil columns ; breakthrough curves ; lead ; proton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Column experiments have been extensively used in transport studies of major cations but few investigations are available on migration through soils of strongly retained species that are environmentally relevant (like heavy metals). By presenting some selected experiments (lead and proton step-breakthrough tests in different conditions), this study shows that the soil-column technique is also applicable in the case of species which exhibit very large retention factors. The use of very small soil columns (about 0.4 mL of pore volumes) combined with relatively high flow rates (0.1–0.3 mL min−1 ) allows to observe the entire breakthrough curve (adsorption and desorption front up to 5000 pore volumes) in reasonable experimental time, in reproducible conditions and without experimental drawbacks. In the adopted experimental conditions no kinetic effects, related to diffuse transport and sorption reaction were recognized; moreover, Peclet number was higher than 60. Consequently, it was possible to calculate the equilibrium isotherms from the diffuse fronts of the breakthrough. Knowledge that can be derived, concerning the reversibility of the adsorption process, the influence of complexation on the adsorption, the kinetics of complex formation, and the effect of dissolution on proton transport, is also discussed.
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  • 81
    ISSN: 1573-2932
    Keywords: atmospheric aerosol ; acid digestion procedure ; atomic absorption spectrometry ; heavy metal ; lead
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents a simple, reliable, economical, safe, accurate and reproducible method for atmospheric aerosol lead determination in glass fiber filters, consisting on an acid digestion procedure and atomic absorption spectrometry quantification. The acid digestion is accelerated by the use of a microwave oven with capped Teflon PFA vessels, and a two steps power and time program. The mixture of 10 mL HNO3 and 1 mL HF was selected between many tries, for both economic and environmental reasons. The use of direct standards for quantification is proposed instead of added standards on filters, using background correction (deuterium lamp). The filter lead content quantification was carried out through blank analyses. Lead determinations were carried out then in 2629 samples of atmospheric aerosol at three sampling points in the city of Cartagena (Spain), from 1990 to 1994. We present the annual average of these values for each year and sampling location.
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  • 82
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    Water, air & soil pollution 98 (1997), S. 255-273 
    ISSN: 1573-2932
    Keywords: atmosphere ; Korea ; lead ; Pb/Fe ratio ; urban/nonurban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The geographical and temporal distribution patterns of atmospheric lead (Pb) were investigated using the data acquired from four sampling locations in Won Ju City, Kang Won Do, Korea (February 1991 to August 1995). The monthly atmospheric Pb concentrations of four study sites were found in the range of 0.0005–0.250 (site #1: grassland, N=47), 0.013–0.405 (site #2: residential, N=53), 0.004–0.420 (site #3: commercial, N=50), and 0.004-1.881 µg m−3 (site #4: industrial, N=52). From all four sampling stations, maximum concentrations of Pb commonly occurred during winter, whilst minimum concentrations were typically observed during summer. Although seasonal differences in meteorological conditions are important to explain such temporal distribution trends, the increase in Pb levels during the spring season, especially during the month of April appears to reflect the influence of soil dust evasion from China. While Pb distributions were strongly affected by seasonality, examination of inter-annual variation trends revealed that the Pb levels had been gradually decreasing over the study periods and that such phenomenon was ubiquitous throughout all the study sites. The annual decrease rates of Pb, computed from the regression analysis, spanned from -0.014 (grassland) to -0.055 µg m−3 yr−1 (industrial). The existence of strong geographical variabilities was also confirmed by the development of a concentration gradient across the four sampling sites on the order: industrial (0.326±0.307, N=52) ≫ commercial (0.157±0.104, N=50) 〉 residential (0.149±0.102, N=53) 〉 grassland (0.088±0.060, N=47). A series of statistical analysis on the data sets in concert with computation of Pb/Fe elemental ratios indicate that the industrial sources may not directly be influencing the Pb levels of the other studied sites. Albeit changes in its long-term distribution trends, the data collected from this study confirm that atmospheric Pb may be classified as a group of constituents whose distribution is rather predictable spatiotemporally due both to: (1) strong repetitiveness of seasonal distribution trends and (2) relative spatial homogeneities that are associated with its unique physicochemical properties.
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  • 83
    ISSN: 1573-2932
    Keywords: reservoir of heated water ; contamination ; cadmium ; copper ; nickel ; sediment ; water ; enrichment factor ; geoaccumulation index ; contamination factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract In this paper, the contamination degree of the Rybnik Reservoir with cadmium, copper andnickel was analyzed. Quality of the water from the reservoir was determined by drawingcomparisons between the metal content in the water and both the officially permitted levels(contamination factor) and levels of metals occurring in the water of non-contaminated areas(enrichment factor). Contamination of bottom sediment with chosen metals was analyzed withreference to the metal content in mudstone (geoaccumulation index, enrichment factor,contamination factor). Trends towards changing the metal content in the bottom sediment wasanalyzed by determining the enrichment factor of the surface layer of the bottom sediments inrelation to a deeper layer. Enrichment of the bottom sediments with metals coming from the waterwas also determined.
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  • 84
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    Water, air & soil pollution 99 (1997), S. 515-522 
    ISSN: 1573-2932
    Keywords: sediment ; dredging ; trace metal ; nutrients ; bacteria ; reoxidation ; remobilization ; microbial processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Polluted sediments are periodically subjected to resuspension processes resulting from natural events (e.g. storms, strong waves) as well as from anthropogenically induced activities (e.g. dredging). The main part of the resuspended material is initially in an anoxic state and will be reoxidized more or less quickly in the oxic water column. In laboratory experiments reflecting, as far as possible, natural conditions (e.g. constant pH) the release of Cd, Cu and Zn during this reoxidation phase was investigated. Up to 2% of the particulate bound heavy metals were remobilized from the sediments. In addition the evolution of the concentrations of the anions PO4, SO4, NO3 and NH4 were measured to examine the influence of microbial processes on the release of trace elements. Cell counts and microbial activity of certain micro-organisms during the release processes were also investigated. The investigations illustrated that biological activity has a significant effect on release. In all sediment samples the release of cadmium was delayed in comparison with the other elements even in sediments from different river systems. The influence of different microbial processes on this divergent behavior was examined. The significance of dredging activities to the remobilization processes during reoxidation of anoxic sediments in the Elbe River is discussed.
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  • 85
    ISSN: 1573-2932
    Keywords: Diagenesis ; resuspension ; sediment ; pore-water ; marine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents the results of a study on nutrient exchange at the sediment-water interface which is caused by early diagenesis and resuspension of bottom sediments. The research was carried out on anoxic silty-clay sediment cores collected south of the Po river delta (Northern Adriatic Sea, Italy) in late summer. The early diagenetic processes were investigated by means of the integrated study of pore-water chemistry and solid phase composition. Exchange at the sediment-water interface was studied by comparing the fluxes measured in incubated cores with the fluxes calculated by modelling pore-water profiles. Nutrient exchange during resuspension was analysed by simulating a storm event in the laboratory. The high production of nutrients near the sediment-water interface is mainly caused by the anoxic degradation of organic matter and the successive reductions of Mn and Fe-oxyhydroxides and, to a lesser extent, of sulphate. The oxic degradation of organic matter occurs only at the sediment-water interface. In the incubation experiment the increases of phosphate, ammonia, nitrate, silica, and Fe in bottom waters were measured. The comparison between calculated and measured fluxes showed that: a) the fluxes are mainly controlled by molecular diffusion; b) phosphate and Fe sink because of the Fe-oxyhydroxide precipitation and c) nitrification process influences the ammonia and nitrate fluxes. Resuspension caused the release of: a) phosphate through surficial desorption and authigenic apatite dissolution; b) ammonia by means of the oxic degradation of organic matter; and c) dissolved silica generated by biogenic silica dissolution. Resuspension also caused a weak removal of Fe. The more oxic conditions following resuspension favoured the formation of a Fe-oxyhydroxide film at the sediment-water interface which inhibited the phosphate fluxes from sediments to the water column.
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  • 86
    ISSN: 1573-2932
    Keywords: Aquaculture ; aggregation ; flocculation ; grain size ; sediment ; trace metal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Grain size is the most basic of classification criteria for sediments. The size distribution of a given sediment records the physical transport processes involved in its formation. By using precise grain size analysis and the model of Kranck et al. (1996a,b), it is possible to break down a sediment into the three major components from which it was formed: material deposited as flocs, material deposited as single grains from suspension, and material carried under higher energy conditions. With this method, both the amount of material deposited in a flocculated state and the maximum size, or floc limit, of the particles composing the floc can be determined. Changes in floc limit indicate changes in the aggregation dynamics of the system. As most trace metals and many other contaminants associate closely with the fine particle fraction of sediments, it is important to determine both the areal distribution and reworking history of the floc settled portion of a sediment. This paper discusses the application of the method to coastal inlets in Atlantic Canada and examines the relationship between proportion of floc-settled material and trace metal concentrations. Disaggregated inorganic grain size distributions are also used to illustrate changes in the aggregation dynamics in areas of intense aquaculture.
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    Water, air & soil pollution 99 (1997), S. 717-725 
    ISSN: 1573-2932
    Keywords: chlorinated pesticides ; PCB ; sediment ; Himalayan lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract PCBs and organochlorine pesticides were determined in water, sediment and zooplankton of two Himalayan lakes, located at different altitudes and connected to each other in such a way that Superior Lake acts as a sedimentation basin for Inferior Lake. Surficial sediments of both lakes show PCB contamination comparable to lakes of industrialised areas. Biota appear to be the main machanism responsible for micropollutant burial in the sediments of Inferior Lake, whereas inorganic particles are more relevant in Superior Lake. Physical and chemical properties of individual chemicals, particularly Henry's law constant and Kow values, seem to regulate distribution in different environmental compartments.
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    Water, air & soil pollution 99 (1997), S. 81-88 
    ISSN: 1573-2932
    Keywords: channel ; bend ; sediment ; size ; gradation ; sorting ; bed ; topography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Variations of sediment size and its gradation of the bed surface laver in a channel bend with nonuniform sediment are investigated experimentally. Four groups of sediment with the same initial median diameter (D o ) but different initial size gradation (σ o ) have been used for experiments which were run until the equilibrium bed topography was achieved. Analyses of experimental data have yielded the following results: (1) The time of equilibrium for bed evolution decreases asσ o increases: (2) the median size of sediment (D) for a given section in the bend increases with increasing distance from the inner bank towards the outer bank, and it also increases with increasingσ o ; (3) the value of D/D o along the inner bank decreases with increasingσ o , and it also shows a gradual decrease in the upper half of the bend and a slight recovery in the lower half, and (5) the transverse variation ofσ value exhibits a general trend increasing from the inner bank towards the outer bank.
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    Water, air & soil pollution 94 (1997), S. 373-384 
    ISSN: 1573-2932
    Keywords: lead ; lead arsenate ; orchards ; soil ; Michigan ; automobile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The Pb content in orchard soils at Mission Peninsula, Michigan was determined to assess the impact of historical lead arsenate applications. Soil samples at 72 sites located in five orchards were collected at depths of 2-, 20-, 50-, and 100 cm. Atomic absorption spectroscopy was used to quantify Pb levels (μg g-1). Mean surface Pb levels at individual orchards ranged from〈 1–136 μg g-1 and rapidly decreased with depth, to 〈1–5 μg g-1 at 100 cm. The impact of textural class and slope angle on Pb levels was also analyzed. Correlation coefficients linking Pb levels with textural class were weak, ranging from 0.21 to –0.07. Varying slope steepness and slope position within orchards failed to affect the spatial pattern of soil Pb. Soil Pb levels were also compared at 5 sites along local roads with varying levels of automobile traffic. Samples were collected 1 m from the roadside at the same depth intervals studied in orchards. Average daily traffic along the busiest roadsites ranged from 8200 to 16 000; these sites had Pb levels of 90–210 μg g-1. Such locales had Pb levels similar to the more intensively sprayed orchards.
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  • 90
    ISSN: 1573-2932
    Keywords: phosphorus ; P flux ; microbial activity ; redox ; simulation ; Lake Kinneret ; sediment ; accumulative P release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Different factors which interactively control the flux of soluble reactive phosphorus (SRP) at the sediment water irterface (SWI) of Lake Kinneret were studied seasonally. The influence of pH, Eh and microbial activity on SRP flux at the SWI was investigated by manipulating the conditions in the overlying water of intact sediment cores. The calculated diffusive SRP flux out of the sediment was lower in cores sampled during winter and spring than during the period of amixis. Potential SRP release, as measured in the absence of microbial activity, was strongly enhanced upon the transition from oxic to anoxic conditions indicating P release from iron(III)-bound phosphorus. In spring and summer cores, an enhanced SRP flux from sediments at pH 7 in comparison to pH 8 indicated P release from carbonate-bound P which sedimented previously as result of high pH values during the algal spring bloom. Microbial uptake at the SWI was the most important sink for SRP and no net-flux occured under oxic conditions. The higher net-flux of P under anoxic conditions was linked to carbon limitation ofthe bacteria at the SWI.
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  • 91
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    Water, air & soil pollution 94 (1997), S. 373-384 
    ISSN: 1573-2932
    Keywords: lead ; lead arsenate ; orchards ; soil ; Michigan ; automobile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The Pb content in orchard soils at Mission Peninsula, Michigan was determined to assess the impact of historical lead arsenate applications. Soil samples at 72 sites located in five orchards were collected at depths of 2−, 20-, 50−, and 100 cm. Atomic absorption spectroscopy was used to quantify Pb levels (jig g−1). Mean surface Pb levels at individual orchards ranged from 〈1–136 pg g−1 and rapidly decreased with depth, to 〈 1-5 μg g−1 at 100 cm. The impact of textural class and slope angle on Pb levels was also analyzed. Correlation coefficients linking Pb levels with textural class were weak, ranging from 0.21 to −0.07. Varying slope steepness and slope position within orchards failed to affect the spatial pattern of soil Pb. Soil Pb levels were also compared at 5 sites along local roads with varying levels of automobile traffic. Samples were collected 1 m from the roadside at the same depth intervals studied in orchards. Average daily traffic along the busiest roadsites ranged from 8200 to 16 000; these sites had Pb levels of 90–210 μg g−1. Such locales had Pb levels similar to the more intensively sprayed orchards.
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  • 92
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    Water, air & soil pollution 99 (1997), S. 477-486 
    ISSN: 1573-2932
    Keywords: sediment ; nitrogen ; phosphorus ; organic matter ; cluster analysis ; Gulf of Finland ; estuaries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Dry weight (DW), ignition loss (IL) and concentrations of total nitrogen (TN) and total phosphorus (TP) of the sediment surface layer (0 to 10 cm, 1 cm slices) were analyzed from 20 sites in the eastern Gulf of Finland. The distance of the sampling sites from the mouth of the River Neva explained the nutrient concentrations of the sediments well, while the effect of water depth was negligible. The increase of TN and the decrease of TP along the transect from the river mouth towards the open Gulf were caused by the diminishing share of allochthonous material supplied from the River Neva. The mean TN concentration of the different accumulation areas was about 40 % higher in the sediment surface than in the deeper layer (9 to 10 cm). The corresponding difference for TP varied from 53 to 56 %. The results suggest considerable netflux of nutrients from sediment to water. The net sediment accumulation of nutrients were estimated as 6.0 g m−2 a−1 of N and 1.7 g m−2 a−1 of P corresponding 22 000 t a− of N and 6 100 t a−1 of P for the whole eastern Gulf.
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  • 93
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    Water, air & soil pollution 99 (1997), S. 515-522 
    ISSN: 1573-2932
    Keywords: sediment ; dredging ; trace metal ; nutrients ; bacteria ; reoxidation ; remobilization ; microbial processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Polluted sediments are periodically subjected to resuspension processes resulting from natural events (e.g. storms, strong waves) as well as from anthropogenically induced activities (e.g. dredging). The main part of the resuspended material is initially in an anoxic state and will be reoxidized more or less quickly in the oxic water column. In laboratory experiments reflecting, as far as possible, natural conditions (e.g. constant pH) the release of Cd, Cu and Zn during this reoxidation phase was investigated. Up to 2% of the particulate bound heavy metals were remobilized from the sediments. In addition the evolution of the concentrations of the anions PO4, SO4, NO3 and NH4 were measured to examine the influence of microbial processes on the release of trace elements. Cell counts and microbial activity of certain micro-organisms during the release processes were also investigated. The investigations illustrated that biological activity has a significant effect on release. In all sediment samples the release of cadmium was delayed in comparison with the other elements even in sediments from different river systems. The influence of different microbial processes on this divergent behavior was examined. The significance of dredging activities to the remobilization processes during reoxidation of anoxic sediments in the Elbe River is discussed.
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  • 94
    ISSN: 1573-2932
    Keywords: Diagenesis ; resuspension ; sediment ; pore-water ; marine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper presents the results of a study on nutrient exchange at the sediment-water interface which is caused by early diagenesis and resuspension of bottom sediments. The research was carried out on anoxic silty-clay sediment cores collected south of the Po river delta (Northern Adriatic Sea, Italy) in late summer. The early diagenetic processes were investigated by means of the integrated study of pore-water chemistry and solid phase composition. Exchange at the sediment-water interface was studied by comparing the fluxes measured in incubated cores with the fluxes calculated by modelling pore-water profiles. Nutrient exchange during resuspension was analysed by simulating a storm event in the laboratory. The high production of nutrients near the sediment-water interface is mainly caused by the anoxic degradation of organic matter and the successive reductions of Mn and Fe-oxyhydroxides and, to a lesser extent, of sulphate. The oxic degradation of organic matter occurs only at the sediment-water interface. In the incubation experiment the increases of phosphate, ammonia, nitrate, silica, and Fe in bottom waters were measured. The comparison between calculated and measured fluxes showed that: a) the fluxes are mainly controlled by molecular diffusion; b) phosphate and Fe sink because of the Fe-oxyhydroxide precipitation and nitrification process influences the ammonia and nitrate fluxes. Resuspension caused the release of: a) phosphate through surficial desorption and authigenic apatite dissolution; b) ammonia by means of the oxic degradation of organic matter; and c) dissolved silica generated by biogenic silica dissolution. Resuspension also caused a weak removal of Fe. The more oxic conditions following resuspension favoured the formation of a Fe-oxyhydroxide film at the sediment-water interface which inhibited the phosphate fluxes from sediments to the water column.
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  • 95
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    Water, air & soil pollution 95 (1997), S. 337-351 
    ISSN: 1573-2932
    Keywords: transport ; soil columns ; breakthrough curves ; lead ; proton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Column experiments have been extensively used in transport studies of major cations but few investigations are available on migration through soils of strongly retained species that are environmentally relevant (like heavy metals). By presenting some selected experiments (lead and proton step-breakthrough tests in different conditions), this study shows that the soil-column technique is also applicable in the case of species which exhibit very large retention factors. The use of very small soil columns (about 0.4 mL of pore volumes) combined with relatively high flow rates (0.1–0.3 mL min-1 ) allows to observe the entire breakthrough curve (adsorption and desorption front up to 5000 pore volumes) in reasonable experimental time, in reproducible conditions and without experimental drawbacks. In the adopted experimental conditions no kinetic effects, related to diffuse transport and sorption reaction were recognized; moreover, Peclet number was higher than 60. Consequently, it was possible to calculate the equilibrium isotherms from the diffuse fronts of the breakthrough. Knowledge that can be derived, concerning the reversibility of the adsorption process, the influence of complexation on the adsorption, the kinetics of complex formation, and the effect of dissolution on proton transport, is also discussed.
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  • 96
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    Water, air & soil pollution 98 (1997), S. 255-273 
    ISSN: 1573-2932
    Keywords: atmosphere ; Korea ; lead ; Pb/Fe ratio ; urban/nonurban
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The geographical and temporal distribution patterns of atmospheric lead (Pb) were investigated using the data acquired from four sampling locations in Won Ju City, Kang Won Do, Korea (February 1991 to August 1995). The monthly atmospheric Pb concentrations of four study sites were found in the range of 0.005-0.250 (site #1: grassland, N=47), 0.013–0.405 (site #2: residential, N=53), 0.004–0.420 (site #3: commercial, N=50), and 0.004-1.881 µg m-3 (site #4: industrial, N=52). From all four sampling stations, maximum concentrations of Pb commonly occurred during winter, whilst minimum concentrations were typically observed during summer. Although seasonal differences in meteorological conditions are important to explain such temporal distribution trends, the increase in Pb levels during the spring season, especially during the month of April appears to reflect the influence of soil dust evasion from China. While Pb distributions were strongly affected by seasonality, examination of inter-annual variation trends revealed that the Pb levels had been gradually decreasing over the study periods and that such phenomenon was ubiquitous throughout all the study sites. The annual decrease rates of Pb, computed from the regression analysis, spanned from –0.014 (grassland) to –0.055 µg m-3 yr-1 (industrial). The existence of strong geographical variabilities was also confirmed by the development of a concentration gradient across the four sampling sites on the order: industrial (0.326±0.307, N=52) ≫ commercial (0.157±0.104, N=50) 〉 residential (0.149±0.102, N=53) 〉 grassland (0.088±0.060, N=47). A series of statistical analysis on the data sets in concert with computation of Pb/Fe elemental ratios indicate that the industrial sources may not directly be influencing the Pb levels of the other studied sites. Albeit changes in its long-term distribution trends, the data collected from this study confirm that atmospheric Pb may be classified as a group of constituents whose distribution is rather predictable spatiotemporally due both to: (1) strong repetitiveness of seasonal distribution trends and (2) relative spatial homogeneities that are associated with its unique physicochemical properties.
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  • 97
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    Environmental monitoring and assessment 50 (1998), S. 249-254 
    ISSN: 1573-2959
    Keywords: lacustrine ; metal accumulation ; riverine ; sediment ; snail ; tissue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Cadmium, chromium, iron, manganese, nickel, lead and zinc concentrations were determined in sediment and body tissues, viz. digestive gland, mantle and shell, of the freshwater snail, Angulyagra oxytropis (Benson) (Gastropoda : Viviparidae), from River Barak and one of its floodplain lakes in Cachar district, Assam State, Northeastern India. The concentrations of all the metals except iron are significantly higher in the lake sediment. When compared to their riverine counterparts, the lacustrine snails contain higher concentrations of cadmium, chromium and iron in their mantle; nickel and zinc in digestive gland; manganese in both digestive gland and mantle; and lead in all the three tissues examined. The accumulation patterns of most of the metals varied considerably between the two sites. The implications of these findings in storage, sequestration and detoxification of metals by this animal are discussed. The study also indicates that A. oxytropis may be a potential biological indicator of metal contamination in freshwater ecosystems.
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  • 98
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    Environmental geochemistry and health 19 (1997), S. 0-0 
    ISSN: 1573-2983
    Keywords: Atmospheric particulates ; bromine ; Jamaica ; lead
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract The results of a survey of air particulates at 23 sites across Jamaica for total suspended particulates (TSP), Al, Br, Cl, Na, Pb, and V, by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF) are reported. The geometric mean of TSP values, 35 g m-3, is well within the World Health Organisation's standard of 60 g m-3 for TSP, but in areas of high vehicular traffic density the TSP values exceeded this limit. The correlation coefficient between Br and Pb concentrations in the particulates was 0.92 and the Br/Pb ratio of 0.38 compares well with a ratio of 0.39 found in commercial petrol indicating that the exhaust from vehicular traffic is the major source of Pb in atmospheric particulate matter in Jamaica.
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  • 99
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    Environmental monitoring and assessment 64 (2000), S. 409-419 
    ISSN: 1573-2959
    Keywords: monitoring ; assessment ; water ; sediment ; bioaccumulation ; toxicity ; pesticides ; mercury ; PCB
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The San Francisco Estuary Regional Monitoring Program for Trace Substances (RMP) began in 1993 and is sponsored by 74 local, state, and federal agencies and companies through their discharge or Bay use permits. The RMP monitors water, sediment, toxicity, and bivalve bioaccumulation at 25 sites in the Bay that are considered to represent "background" conditions. Several major environmental issues have been identified by the RMP. Polychlorinated biphenyls and mercury were often above water quality guidelines, and often occurred in fish tissues above U.S. Environmental Protection Agency (U.S. EPA) screening values. Concentrations do not appear to be decreasing, suggesting continuing inputs. Episodes of aquatic toxicity often occurred following runoff events that transport contaminants into the Bay from urbanized and agricultural portions of the watershed. Sediment toxicity occurred throughout the Bay, and has been correlated with concentrations of specific contaminants (chlordanes, polynuclear aromatic hydrocarbons) at some locations; mixtures of contaminants were probably also important. Since the RMP does not monitor all ecosystem components, assessments of the overall condition of the Bay cannot be made. However, in terms of contamination, the RMP samples suggest that the South Bay, and North Bay sites are moderately contaminated.
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  • 100
    ISSN: 1573-2983
    Keywords: Sweden ; lead smelter ; metal concentrations ; lead
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Medicine
    Notes: Abstract Scandinavia has one secondary lead smelter that recycles lead from approximately 85% of used car batteries in Scandinavia and which has been active since the 1940s. The smelter, situated in Landskrona, has undergone a comprehensive clean up programme during the last decade, during which time production has doubled, while at the same time discharges of dust and lead to the atmosphere have decreased. Top and depth soil samples were taken on a 0.5 km × 0.5 Km grid throughout the city of Landskrona, which covers an area of approximately 15 km2. Samples were analysed by ICP‐AES for a number of elements including Pb, Zn, Cu, Cd, As, Sb and Hg. Road dust samples from selected sites were collected and similarly analysed. Blood samples were taken from 37 volunteer schoolchildren (aged 8–11) from two schools in Landskrona. House dust samples were taken from each child's home. Soil samples were taken from homes which had gardens, public and school play areas. Elevated heavy metal concentrations were found in close proximity to the secondary lead smelter, and this soil enrichment influences the whole of the town, modified to some extent by the prevailing wind. The smelter does not influence the soil lead concentration at distances greater than 3.5 km, where the soil reflects the background value for the area. Road dust samples also show decreases in lead concentrations with distance from the smelter. The average level of lead in house dust was considerably lower than that found in Birmingham, UK. Blood lead levels in the child population ranged from 1.5–5.1 μg dl−1, with a mean of 3.05 μg dl−1, showing a distinct decrease from those measured in 1978–82. No significant difference in blood lead concentrations with distance of the home from the smelter, nor between attenders at the two schools was revealed in the limited number of children studied.
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