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  • 1
    Electronic Resource
    Electronic Resource
    Assessment of freshwater diatoms as quantitative indicators of past climatic change in the Yukon and Northwest Territories, Canada (1995)
    Springer
    Journal of paleolimnology 13 (1995), S. 21-49 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; temperature ; climatic change ; paleoclimate proxies ; canonical correspondence analysis ; weighted-averaging ; Yukon ; Northwest Territories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract We identified, enumerated, and interpreted the diatom assemblages preserved in the surface sediments of 59 lakes located between Whitehorse in the Yukon and Tuktoyaktuk in the Northwest Territories (Canada). The lakes are distributed along a latitudinal gradient that includes several ecoclimatic zones. It also spans large gradients in limnological variables. Thus, the study lakes are ideal for environmental calibration of modern diatom assemblages. Canonical correspondence analysis, with forward selection and Monte Carlo permutation tests, showed that maximum lake depth and summer surface-water temperature were the two environmental variables that accounted for most of the variance in the diatom data. The concentrations of sodium and calcium were also important explanatory variables. Using weighted-averaging regression and calibration techniques, we developed a predictive statistical model to infer lake surface-water temperature, and we evaluated the feasibility of using diatoms as paleoclimate proxies. This model may be used to derive paleotemperature inferences from fossil diatom assemblages at appropriate sites in the western Canadian Arctic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00678109
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  • 2
    Electronic Resource
    Electronic Resource
    Diatom transfer-functions for quantifying past air temperature, pH and total organic carbon concentration from lakes in northern Sweden (2000)
    Springer
    Journal of paleolimnology 24 (2000), S. 109-123 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; climate change ; temperature ; pH ; transfer functions ; lake sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The relationships between diatoms (Bacillariophyceae) in surface sediments of lakes and summer air temperature, pH and total organic carbon concentration (TOC) were explored along a steep climatic gradient in northern Sweden to provide a tool to infer past climate conditions from sediment cores. The study sites are in an area with low human impact and range from boreal forest to alpine tundra. Canonical correspondence analysis (CCA) constrained to mean July air temperature and pH clearly showed that diatom community composition was different between lakes situated in conifer-, mountain birch- and alpine-vegetation zones. As a consequence, diatoms and multivariate ordination methods can be used to infer past changes in treeline position and dominant forest type. Quantitative inference models were developed to estimate mean July air temperature, pH and TOC from sedimentary diatom assemblages using weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regression. Relationships between diatoms and mean July air temperature were independent of lake-water pH, TOC, alkalinity and maximum depth. The results demonstrated that diatoms in lake sediments can provide useful and independent quantitative information for estimating past changes in mean July air temperature (R2 jack = 0.62, RMSEP = 0.86 °C; R2 and root mean squared error of prediction (RMSEP) based on jack-knifing), pH (R2 jack = 0.61, RMSEP = 0.30) and TOC (R2 jack = 0.49, RMSEP = 1.33 mg l-1). The paper focuses mainly on the relationship between diatom community composition and mean July air temperature, but the relationships to pH and TOC are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008128014721
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  • 3
    Electronic Resource
    Electronic Resource
    Sedimentation patterns of diatoms in Lake Holzmaar, Germany - (on the transfer of climate signals to biogenic silica oxygen isotope proxies) (1999)
    Springer
    Journal of paleolimnology 21 (1999), S. 437-448 
    Details
    ISSN: 1573-0417
    Keywords: diatoms ; temperature ; sediment traps ; seasonal succession ; resuspension ; Lake Holzmaar
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The seasonal sedimentation pattern of diatom valves in Lake Holzmaar was investigated during 1995 by deploying sediment traps at three different lake depths. According to the sedimentation pattern, the major reproduction zone of diatoms was restricted to the upper 6 m of the water body. The population growth started late in April and blooms of Cyclotella cf. comensis Grun., which dominates the plankton diatoms, and Fragilaria crotonensis Kitton were collected in traps during June and September, and July, respectively. During summer, the seasonal sedimentation pattern of each taxon, as collected in the upper traps, was reflected in the concentrations in the lowest trap. However, in May and from September onwards, the community composition in the lowest trap and augmented trapping rates suggest both sediment focusing and resuspension of bottom sediments. The temperature signals as recorded by δ18O values of diatom valves should, therefore, reflect integrated temperatures between 0 and 6 m depth. However, temperatures during summer and autumn are expected to be accentuated in the sedimentary record since the isotopic signal is weighted by both the number and the weight-mass of the valves. During summer, the transfer of these signals by the sedimenting diatoms retains the information pattern recorded, while in spring and autumn/winter additional influxes caused by resuspension may somewhat alter those temperature informations. The proxy signals finally stored in the sediments, may, therefore, not precisely represent the successive temperatures currently recorded during 1995 within mid-lake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008022532458
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  • 4
    Electronic Resource
    Electronic Resource
    The environmental history of a mountain lake (Lago Paione Superiore, Central Alps, Italy) for the last c. 100 years: a multidisciplinary, palaeolimnological study (1996)
    Springer
    Journal of paleolimnology 15 (1996), S. 245-264 
    Details
    ISSN: 1573-0417
    Keywords: palaeolimnology ; acidification ; diatoms ; chrysophytes ; pigments ; chironomids ; temperature ; Alps ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract A palaeoecological study of an oligotrophic alpine lake, Paione Superiore (Italy), provided a record of historical changes in water quality. Historical trends in lake acidification were reconstructed by means of calibration and regression equations from diatoms, chrysophycean scales and pigment ratios. The historical pH was inferred by using two different diatom calibration data sets, one specific to the alpine region. These pH trends, together with the record of sedimentary carbonaceous particles and chironomid remains, indicate a recent acidification of this low alkalinity lake. Concentration of total organic matter, organic carbon, nitrogen, biogenic silica (BSiO2), chlorophyll derivatives (CD), fucoxanthin, diatom cell concentration and number of chironomid head capsules increased during the last 2–3 decades. When expressed as accumulation rates, most of these parameters tended to decrease from the past century to c. 1950, then all except P increased to the present day. A marked increase in sedimentary nitrogen may be related to atmospheric pollution and to the general increases in output of N in Europe. High C/N ratios indicate a prevailing allochthonous source of organic matter. Finally, the increase in measured air temperature from the mid-1800's appeared to be related to lake water pH before industrialization: cold periods generally led to lower pH and vice-versa. The more recent phenomenon of anthropogenic acidification has apparently decoupled this climatic-water chemistry relationship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213044
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  • 5
    Electronic Resource
    Electronic Resource
    The dependence of transport properties ofin situ rocks on pore fluid composition and temperature (1996)
    Springer
    Surveys in geophysics 17 (1996), S. 289-306 
    Details
    ISSN: 1573-0956
    Keywords: Effective properties ; pore fluids ; cracked rock ; permeability ; stress ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Fluids saturating cracked rocks within the crust can vary widely in composition and physical properties, which depend greatly on pressure and temperature. External non-hydrostatic stress applied to a cracked medium may result in a significant change of crack volume (and hence, for the undrained regime, pore-fluid pressure) due to the processes of crack closure (opening), and thus lead to a drastic change of the overall physical parameters of a rock. The purpose of the study is to estimate theoretically, using the effective-medium theory, the macroscopic seismic and transport parameters (such as permeability) of cracked rocks (granites) saturated with hydrocarbon gases, oils, brines and water. Variations of crack geometry and fluid parameters in the closed system (at constant fluid mass) under uniaxial compression are considered as well. The results show that composition of a saturating fluid as well as fluid temperature greatly influence the effective permeability and shear velocities of a rock mass, while thermal conductivity is not so sensitive to variations of fluid parameters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01904045
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  • 6
    Electronic Resource
    Electronic Resource
    Evaluation of climatic change through harmonic analysis (1994)
    Springer
    Natural hazards 9 (1994), S. 5-16 
    Details
    ISSN: 1573-0840
    Keywords: Fourier transform ; maximum entropy spectral analysis ; precipitation ; temperature ; climatic change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract In the present work, a precipitation and temperature series from Barcelona (Spain) are analysed in order to detect the possible existence of climatic changes or cycles. The analysis is carried out both from the temporal and spectral standpoints. The techniques used range from the classical periodogram and Blackman-Tukey method through to the Maximum Entropy method. The results do not show the existence of climatic cycles, though they do show a clear tendency toward increased precipitation and decreased temperature, since the last years of series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00662588
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrothermal studies in a new diamond anvil cell up to 10 GPa and from −190°C to 1200°C (1993)
    Springer
    Pure and applied geophysics 141 (1993), S. 487-495 
    Details
    ISSN: 1420-9136
    Keywords: Pressure ; temperature ; hydrothermal ; H2O ; equation of state ; diamond anvil cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The new hydrothermal diamond anvil cell (HDAC) has been designed for optical microscopy and X-ray diffraction at pressures up to 10 GPa and temperatures between −190°C and 1200°C. Laser light reffected from the top and bottom anvil faces and the top and bottom solid sample faces produce interference fringes that provide a very sensitive means of monitoring the volume of sample chamber and for observing volume and refractive index changes in solid samples due to transitions and reactions. Synchrotron radiation has been used to make X-ray diffraction patterns of samples under hydrothermal conditions. Individual heaters and individual thermocouples provide temperature control with an accuracy of ±0.5°C. Liquid nitrogen directly introduced into the HDAC has been used to reduce the sample temperature to −190°C. The α-β phase boundary of quartz has been used to calculate the transition pressures from measured transition temperatures. With this method we have redetermined 5 isochores of H2O up to 850°C and 1.2 GPa at which the solution rate of the quartz became so rapid that the quartz dissolved completely before the α-β transition could be observed. When silica solutions were cooled, opal spherules and rods formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00998341
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  • 8
    Electronic Resource
    Electronic Resource
    Improvements to Griggs-type apparatus for mechanical testing at high pressures and temperatures (1993)
    Springer
    Pure and applied geophysics 141 (1993), S. 523-543 
    Details
    ISSN: 1420-9136
    Keywords: Pressure ; temperature ; stress ; measurement ; acoustic emissions ; deformation ; techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract New and improved techniques and apparatus for testing the mechanical properties of materials at high presures and temperatures are described. These include an improved Griggs-type deformation apparatus designed to operate to 5 GPa and associated servo-controlled hydraulic drive and electronics, the design of hydrostatic (molten alkali halide mixtures) pressure assemblies to measure flow stresses as low as a few MPa, the characterization of temperature gradients and friction in such assemblies, measurement of the melting curve of an alkali halide mixture used as a confining pressure medium, and the measurement of acoustic emissions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00998344
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of temperature and sliding rate on frictional strength of granite (1986)
    Springer
    Pure and applied geophysics 124 (1986), S. 445-469 
    Details
    ISSN: 1420-9136
    Keywords: Shear strength ; temperature ; deformation rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Layers of artificial granite gouge have been deformed on saw-cut granite surfaces inclined 30° to the sample axes. Samples were deformed at a constant confining pressure of 250 MPa and temperatures of 22 to 845°C. The velocity dependence of the steady-state coefficient of friction (μss) was determined by comparing sliding strengths at different sliding rates. The results of these measurements are consistent with those reported bySolberg andByerlee (1984) at room temperature andStesky (1975) between 300 and 400°C. Stesky found that the slip-rate dependence of (μss) increased above 400°C. In the present study, however, the velocity dependence of (μss) was nearly independent of temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877211
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  • 10
    Electronic Resource
    Electronic Resource
    Comparison of industrial and high-resolution thermal data in a sedimentary basin (1990)
    Springer
    Pure and applied geophysics 133 (1990), S. 251-267 
    Details
    ISSN: 1420-9136
    Keywords: Heat flow ; sediments ; temperature ; gradients ; conductivity ; industrial data ; scientific data ; hydrodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Temperature, temperature gradient and heat flow, derived from four wells in the Western Canada Sedimentary Basin have been compared with similar quantities derived from maps constructed from industrial data. Individual industrial temperature data may differ from the high-resolution temperature log by up to 30 K, but linear regression of the collected data agrees within 10 K at all points observed. Some evidence suggests that measured conductivities, using drill-cuttings, are biased toward average values. Derived heat flows show agreement of heat flow within 10% within the Mesozoic section. In the Paleozoic section differences are greater, and more varied, with insufficient data for general conclusions. Both styles of measurement provide opportunities for interpretation, each contributing to thermal analysis of sedimentary basins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877162
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  • 11
    Electronic Resource
    Electronic Resource
    An investigation of the dependence of structural parameters of the middle atmosphere on the intensity of photochemical and dynamical processes (1988)
    Springer
    Pure and applied geophysics 127 (1988), S. 381-401 
    Details
    ISSN: 1420-9136
    Keywords: Middle atmosphere ; temperature ; neutral and ion composition ; turbulent transfer ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Using a numerical model for temperature and neutral and ion composition behaviour at middle atmospheric heights, an analysis has been made of the dependence of atmospheric structural parameters on temperature, solar activity, and on turbulent transfer intensity. For mesospheric heights, an inverse dependence of the nitric oxide density on the temperature has been found. It is thus possible to explain experimentally obtained temperature variations over a cyclc of solar activity at mesospheric and lower thermospheric heights. Numerical simulation results indicate that the temperature in the height range ∼75–120 km depends considerably on both the absolute values of turbulent transfer coefficients and their vertical gradients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00879818
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  • 12
    Electronic Resource
    Electronic Resource
    Continuous measurements of stress and temperature during testing of a fibre shotcrete pressure plug (1999)
    Springer
    Geotechnical and geological engineering 17 (1999), S. 335-349 
    Details
    ISSN: 1573-1529
    Keywords: underground gas storage ; pressure barrier ; fibre shotcrete ; stress ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The paper describes an investigation of pressure barriers (plugs) for an underground gas storage facility which were to be constructed from fibre shotcrete. An extensive measurement program on a test plug was carried out to verify the suitability of fibre shotcrete for this purpose. The results of stress and temperature measurements carried out during the construction of the test plug and during cyclic loading of the plug to a water pressure up to 13 MPa are presented. The measurement program provided information on the stress and temperature development inside the plug body during hydration and hardening and also on the residual tensile stresses at the interface between the plug and the rock mass after the end of hydration. Another important output was information on the quality of the plug-rock mass interface, which was critical for a possible leakage. The results obtained during the cyclic loading of the plug revealed uneven stress distribution at the contact and in the adjacent rock mass. It also provided information on the rate of stress redistribution at the contact and inside the rock mass. The results were used to modify the technology of the shotcrete technique to be applied in the final plugs. The gas storage facility using the modified design has been in trial operation since the end of 1998.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008929726458
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  • 13
    Electronic Resource
    Electronic Resource
    On the Spectral Decomposition of Geopotential and Temperature Fields in the Stratosphere (1998)
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 147-158 
    Details
    ISSN: 1573-1626
    Keywords: stratosphere ; spectral decomposition ; geopotential ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The spectral structure of stratospheric fields (temperature and geopotential) is analyzed in terms of spherical harmonics in an effort to study the long-term behaviour of large-scale circulation patterns, as well as their connections to some extra-terrestrial effects. The daily meteorological data from the Free University Berlin (FUB) cover more or less the period 1976–1996 and are available for stratospheric levels of 50, 30 and 10 hPa. The analysis of the annual cycle of spherical harmonics is introduced, and changes of the principal wave components are compared with the changes in different sets of solar, geomagnetic and global circulation indices. This paper also deals with interannual variability with special emphasis on quasibiennial oscillations (QBO) and El Nino and Southern Oscillations (ENSO). Although this is a rather preliminary study, the decomposition of the stratospheric field into complex spherical harmonics seems to be a powerful technique in investigating and qualifying the response of the global atmospheric system to the changes in solar and geomagnetic activity, and in qualifying the relationships between large-scale circulation patterns and various oscillations such as QBO or ENSO, Using this technique, reasonable strong connections were found between wave numbers and interannual factors, and these connections were tentatively interpreted in terms of statistics. A very high degree of correlation was found for the four-trough shape of the polar vortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023305020573
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  • 14
    Electronic Resource
    Electronic Resource
    Changes of Ozone Content at Middle Latitudes During Forbush Decreases in Cosmic Rays (1998)
    Springer
    Studia geophysica et geodaetica 42 (1998), S. 521-532 
    Details
    ISSN: 1573-1626
    Keywords: stratospere ; troposphere ; solar-terrestrial disturbances ; odd nitrogen ; temperature ; atmospheric dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The variations of total ozone at Alma-Ata (43°N, 76 °E) and ozone profiles obtained by balloon sounding at Tateno (36°N, 140°E), Wallops Island (38°N, 75°W) and Cagliari (39°N, 9°E) in the periods of Forbush decreases (FD) in galactic cosmic rays have been analysed. A decrease of total ozone was observed in the initial stage of the FD and an increase 10–11 days later. The average total deviations calculated using the superposed epoch method for 9 FD events are equal to 30 D. U. in the positive and to −18 D. U. in the negative phase. The changes of average ozone profiles, associated with 26 FD events, are more significant in the lower stratosphere and upper troposphere. The decrease of the partial ozone pressure at a height of 12–15 km is about 30 υmb. These vertical variations of ozone coincide with the average changes of the respective temperature profiles. A cooling, on the average, of 3°C was observed at 12–15 km, and a heating of 4°C below this level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023301322428
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  • 15
    Electronic Resource
    Electronic Resource
    Momentum and energy balance equations for compacting sediments (1976)
    Springer
    Mathematical geology 8 (1976), S. 305-322 
    Details
    ISSN: 1573-8868
    Keywords: finite differences ; mathematics ; numerical analysis ; geophysics ; hydrology ; pressure ; temperature ; compacting sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Coupled energy and momentum balance equations are derived for a one-dimensional sequence of compacting sediments. These transient, nonlinear partial differential equations represent the one-dimensional equations of state for an accumulating sedimentary basin. A numerical solution is presented which provides a first-order approximation for porosity, temperature, and fluid pressures in the northern Gulf of Mexico. It seems that compaction disequilibrium is the primary mechanism for development of excess fluid pressures. Furthermore, the coupling of the equations demonstrates that temperature and pressure cannot be treated independently as may have been done in diagenetic studies. Some areas for further investigations are indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01029275
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  • 16
    Electronic Resource
    Electronic Resource
    Heat Transfer in Nonsaturated Porous Media. Modelling by Homogenisation (1998)
    Springer
    Transport in porous media 30 (1998), S. 301-321 
    Details
    ISSN: 1573-1634
    Keywords: temperature ; homogenisation ; modelling ; unsaturated
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract This paper is devoted to the modelling of a temperature field in nonsaturated porous media in the absence of phase change. We establish the energy equation at the macroscopic level, from a description at the pore level by using the homogenisation method of multiple-scale asymptotic expansions. Different macroscopic models are obtained depending on the values of the local Péclet number and the local Fourier number. An example of the application of the different model catalogue is presented which concerns the modelling of the hot pressing of a paper web.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006540912415
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  • 17
    Electronic Resource
    Electronic Resource
    Hysteresis in the temperature response of carbon dioxide and methane production in peat soils (1998)
    Springer
    Biogeochemistry 43 (1998), S. 253-272 
    Details
    ISSN: 1573-515X
    Keywords: carbon dioxide ; hysteresis ; methane ; peat ; temperature ; wetlands
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The ability to predict the effects of climate change on trace gas fluxes requires a knowledge of microbial temperature responses. However, the response of a microbial community to temperature in a given substrate may be complicated by its thermal history. To examine the effect of sequentially changing temperature on methane and carbon dioxide production in different peat types, we incubated anaerobic peat samples from 3 types of northern peatlands, a bog, a sedge fen and a cedar swamp, in both rising and falling temperature regimes. Graphic and statistical comparisons of the different temperature regimes suggest hysteresis in microbial response to temperature, although the absolute rates at any given temperature often did not differ. Where regressions for temperature response (Arrhenius plots) were significant, they generally differed between temperature regimes. The greatest differences among treatments occurred during the first half of the 40-d incubation. Increases in carbon dioxide production were similar across all peat types, but methanogenesis varied widely: methane production was uniformly low in the bog peat but increased sharply with temperature in the other two peat types. The complicating effect of history or chronology on substrate responses to environmental stimuli may restrain our ability to model the responses of complex systems to changing conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006097808262
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  • 18
    Electronic Resource
    Electronic Resource
    Soil surface CO2 flux in a Minnesota peatland (1992)
    Springer
    Biogeochemistry 18 (1992), S. 37-51 
    Details
    ISSN: 1573-515X
    Keywords: carbon dioxide ; microhabitat ; peat ; temperature ; water table
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Soil surface CO2 flux was measured in hollow and hummock microhabitats in a peatland in north central Minnesota from June to October in 1991. We used a closed infrared gas exchange system to measure soil CO2 flux. The rates of CO2 evolution from hummocks (9.8 ± 3.5 g m−2 d−1, [mean ± SE]) were consistently higher than those from hollows (5.4 ± 2.9 g m−2 d−1) (the hummock values included the contribution of moss dark respiration, which may account for 10–20% of the total measured flux). The soil CO2 flux was strongly temperature-dependent (Q10 ≈ 3.7) and appeared to be linearly related to changes in water table depth. An empirical multiplicative model, using peat temperature and water table depth as independent variables, explained about 81% of the variance in the CO2 flux data. Using the empirical model with measurements of peat temperature and estimates of hollow/hummock microtopographic distribution (relative to water table elevation), daily rates of “site-averaged” CO2 evolution were calculated. For the six-month period (May–October), the total soil CO2 released from this ecosystem was estimated to be about 1340 g CO2 m−2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00000425
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  • 19
    Electronic Resource
    Electronic Resource
    Effects of air pollutant-temperature interactions on mineral-N dynamics and cation leaching in reciplicate forest soil transplantation experiments (1997)
    Springer
    Biogeochemistry 39 (1997), S. 295-326 
    Details
    ISSN: 1573-515X
    Keywords: acidification ; aluminium ; Arrhenius’ law ; calcium ; cation leaching ; climate ; ion equilibrium ; forest soil ; N-cycle ; N-deposition ; nitrification ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Increased emissions of nitrogen compounds have led to atmosphericdeposition to forest soils exceeding critical loads of N overlarge parts of Europe. To determine whether the chemistry offorest soils responds to changes in throughfall chemistry, intactsoil columns were reciprocally transplanted between sites, withdifferent physical conditions, across a gradient of N and Sdeposition in Europe. The transfer of a single soil to the various sites affected itsnet nitrification. This was not simply due to the nitrificationof different levels of N deposition but was explained bydifferences in physical climates which influenced mineralizationrates. Variation in the amount of net nitrification between soiltypes at a specific site were explained largely by soil pH. Within a site all soil types showed similar trends in netnitrification over time. Seasonal changes in net nitrificationcorresponds to oscillations in temperature but variable time lagshad to be introduced to explain the relationships. WithArrhenius‘ law it was possible to approximate gross nitrificationas a function of temperature. Gross nitrification equalled netnitrification after adaptation of the microbial community oftransplanted soils to the new conditions. Time lags, andunderestimates of gross nitrification in autumn, were assumed tobe the result of increased NH 4 + availability due either tochanges in the relative rates of gross and net N transformationsor to altered soil fauna-microbial interactions combined withimproved moisture conditions. Losses of NO 3 - were associated with Ca2+and Mg2+ in non-acidified soil types and with losses ofAl3+ in the acidified soils. For single soils the ionequilibrium equation of Gaines-Thomas provided a useful approximationof Al3+ concentrations in the soil solution as a functionof the concentration of Ca2+. The between site deviationsfrom this predicted equilibrium, which existed for single soils, couldbe explained by differences in throughfall chemistry which affectedthe total ionic strength of the soil solution. The approach of reciprocally transferring soil columnshighlighted the importance of throughfall chemistry, interactingwith the effect of changes in physical climate on forest soilacidification through internal proton production, in determiningsoil solution chemistry. A framework outlining the etiology offorest die-back induced by nitrogen saturation is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005814929879
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  • 20
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    Methane emissions from wet grasslands on peat soil in a nature preserve (1999)
    Springer
    Biogeochemistry 44 (1999), S. 205-220 
    Details
    ISSN: 1573-515X
    Keywords: grassland ; ground water level ; methane ; peat ; temperature ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The area of wet grasslands on peat soil in the Netherlands is slowly increasing at the expense of drained, agriculturally used grasslands. This study aimed (i) to assess the contribution of wet grasslands on peat soil to methane (CH4) emissions, and (ii) to explain differences among sites and between years in order to improve our understanding of controlling factors. For these purposes, a field study was conducted in the period 1994–1996 in the nature preserve “Nieuwkoopse Plassen”, which is a former peat mining and agricultural area. Net CH4 emissions were measured weekly to monthly with vented closed flux chambers at three representative sites, and at ditches near these sites. Three-years average of CH4 emissions was 7.9 g CH4 m- 2 yr-1 for Drie Berken Zudde, 13.3 for Koole, and 20.4 for Brampjesgat. Ditches near the sites emitted 4.2–22.5 g CH4 m-2 yr-1. The time-course of CH4 emissions for all experimental sites and years was fit with a multiple linear regression model with ground water level and soil temperature as independent variables. Lowering or raising the ground water level by 5 cm could decrease or increase CH4 emissions by 30–50%. Therefore, ground water level management of these grasslands should be done with care.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006061814731
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  • 21
    Electronic Resource
    Electronic Resource
    Will changes in soil organic carbon act as a positive or negative feedback on global warming? (2000)
    Springer
    Biogeochemistry 48 (2000), S. 21-51 
    Details
    ISSN: 1573-515X
    Keywords: carbon cycle ; decomposition ; global change ; soil organic matter ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The world's soils contain about 1500 Gt of organic carbon to a depth of 1m and a further 900 Gt from 1--2m. A change of total soil organic carbon by just 10% would thus be equivalent to all the anthropogenic CO2 emitted over 30 years. Warming is likely to increase both the rate of decomposition and net primary production (NPP), with a fraction of NPP forming new organic carbon. Evidence from various sources can be used to assess whether NPP or the rate of decomposition has the greater temperature sensitivity, and, hence, whether warming is likely to lead to an increase or decrease in soil organic carbon. Evidence is reviewed from laboratory-based incubations, field measurements of organic carbon storage, carbon isotope ratios and soil respiration with either naturally varying temperatures or after experimentally increasing soil temperatures. Estimates of terrestrial carbon stored at the Last Glacial Maximum are also reviewed. The review concludes that the temperature dependence of organic matter decomposition can be best described as: d(T) = exp[3.36 (T − 40)/(T + 31.79)] where d(T) is the normalised decomposition rate at temperature T (in °C). In this equation, decomposition rate is normalised to ‘1’ at 40 °C. The review concludes by simulating the likely changes in soil organic carbon with warming. In summary, it appears likely that warming will have the effect of reducing soil organic carbon by stimulating decomposition rates more than NPP. However, increasing CO2 is likely to simultaneously have the effect of increasing soil organic carbon through increases in NPP. Any changes are also likely to be very slow. The net effect of changes in soil organic carbon on atmospheric CO2 loading over the next decades to centuries is, therefore, likely to be small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006238902976
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  • 22
    Electronic Resource
    Electronic Resource
    Far infrared remote sounding of stratospheric temperature and trace gas distributions (1984)
    Springer
    Journal of atmospheric chemistry 2 (1984), S. 145-161 
    Details
    ISSN: 1573-0662
    Keywords: Stratosphere ; remote sensing ; trace gases ; temperature ; Far infrared ; remote sensing ; stratosphere ; Spectroscopy ; stratosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The thermal emission spectrum of the Earth's stratosphere in the far infrared exhibits rotational transitions of a large number of trace constituents in addition to the magnetic dipole lines of molecular oxygen. Stratospheric lines that have been identified in the far infrared spectrum include H2O, O3, HNO3, N2O, CO, HCl, HF, HCN and OH. This paper discusses the potential usefulness of far infrared thermal emission measurements for simultaneous retrieval of temperature and constituent distributions. A description of the high-resolution Michelson interferometer currently employed for balloon-borne far infrared stratospheric studies is given, along with a summary of the mode of limbscan observations and an example of an observed spectrum. Numerical results based on synthetic limb radiance data for model atmospheres are presented. Formal inversion techniques with a radiative transfer model based on line-by-line transmittance calculations are employed. Temperature profiles are retrieved from synthetic spectra by an inversion of the O2 magnetic dipole lines. Vertical trace gas mixing ratio profiles are determined from an analysis of the corresponding spectral emission features. Numerical results based on synthetic limb radiance data are presented in order to assess the retrieval accuracies of the temperature profiles and the vertical mixing ratio profiles of O3, HCl, and OH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114128
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  • 23
    Electronic Resource
    Electronic Resource
    The NO2-O3 system at sub-ppm concentrations: Influence of temperature and relative humidity (1985)
    Springer
    Journal of atmospheric chemistry 2 (1985), S. 387-403 
    Details
    ISSN: 1573-0662
    Keywords: Night-time NO2 oxidation ; nitrate radical ; nitrogen pentoxide ; wall scavening ; stoichiometry ; kinetic study ; temperature ; relative humidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The stoichiometry and kinetics of the reaction of NO2 with O3 at sub-ppm concentration level have been investigated as a function of temperature and relative humidity. The experiments were performed in a continuous flow reactor using chemiluminescent and wet chemical methods of analysis. The rate constant found can be described by the Arrhenius expression: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaiikaiaaik% dacaGGUaGaaGyoaiaaiEdacqGHXcqScaaIWaGaaiOlaiaaigdacaaI% 0aGaaiykaiabgEna0kaaigdacaaIWaWaaWbaaSqabeaacqGHsislca% aIXaGaaG4maaaakiaabwgacaqG4bGaaeiCaiaacIcadaWcgaqaaiaa% cIcacqGHsislcaaIYaGaaGOnaiaaikdacaaIWaGaeyySaeRaaGyoai% aaicdacaGGPaaabaGaamivaiaacMcacaqGGaGaae4yaiaab2gadaah% aaWcbeqaaiaabodaaaGccaqGGaWaaSGbaeaacaqGTbGaae4BaiaabY% gacaqGLbGaae4yaiaabwhacaqGSbGaaeyzamaaCaaaleqabaGaaeyl% aiaabgdaaaaakeaacaqGZbWaaWbaaSqabeaacaqGTaGaaeymaaaaaa% aaaaaa!62A3!\[(2.97 \pm 0.14) \times 10^{ - 13} {\text{exp}}({{( - 2620 \pm 90)} \mathord{\left/ {\vphantom {{( - 2620 \pm 90)} {T){\text{ cm}}^{\text{3}} {\text{ }}{{{\text{molecule}}^{{\text{ - 1}}} } \mathord{\left/ {\vphantom {{{\text{molecule}}^{{\text{ - 1}}} } {{\text{s}}^{{\text{ - 1}}} }}} \right. \kern-\nulldelimiterspace} {{\text{s}}^{{\text{ - 1}}} }}}}} \right. \kern-\nulldelimiterspace} {T){\text{ cm}}^{\text{3}} {\text{ }}{{{\text{molecule}}^{{\text{ - 1}}} } \mathord{\left/ {\vphantom {{{\text{molecule}}^{{\text{ - 1}}} } {{\text{s}}^{{\text{ - 1}}} }}} \right. \kern-\nulldelimiterspace} {{\text{s}}^{{\text{ - 1}}} }}}}\] and are independent of the relative humidity. As commonly encountered in previous studies a lower-than-two reaction stoichiometry is observed. Heterogeneous reactions occurring at the reactor wall seem to be essential in the reaction mechanism. The NO3 wall conversion to NO2 and the N2O5 wall scavenging in the presence of H2O are suggested to account for the observed stoichiometric factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00130750
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  • 24
    Electronic Resource
    Electronic Resource
    Seasonal Variation in Amount and Composition of Monoterpenes Emitted by Young Pinus pinea Trees – Implications for Emission Modeling (2000)
    Springer
    Journal of atmospheric chemistry 35 (2000), S. 77-99 
    Details
    ISSN: 1573-0662
    Keywords: monoterpene emission ; Mediterranean pine ; seasonal variation ; light ; temperature ; algorithms ; model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Current inventories of terpenes released from vegetation consider only the short-term influences of light and temperature on emissions to simulate temporal variation during the year. We studied whole canopy emissions from young Pinus pinea during a 15-month enclosure in greenhouse chambers and examined data for other long-term influences. Mean daytime emission rates strongly increased during spring, reached an annual maximum of ≈ 200 pmol m−2 total needle area s−1 (1.1 μg g−1 leaf dry weight h−1) between mid June and mid August, strongly declined in fall and reached an annual minimum of ≈ 1 pmol m−2 s−1 (0.006 μg g−1 h−1) between January and February. Normalization to standard temperature and light conditions did not change the annual time course of emissions, but reduced summer to winter ratio from a factor of 200 to about 45. Seasonal variation was characterized also by changes in terpene composition: among the six main compounds, three (t-β-ocimene, linalool, 1.8-cineol) were exclusively emitted during sunlit hours in the main vegetation period, whereas the other (limonene, α-pinene, myrcene) were emitted day and night and throughout the seasons. The results suggest that different terpene sources in P. pinea foliage exist and that a great part of the annual emission course observed here results from seasonal influences on these sources. A global model to simulate plant emissions is proposed, which accounts for seasonal influences on emissions in addition to the short-term effects of temperature and light. The model is tested on field data and discussed for its general application.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006233010748
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  • 25
    Electronic Resource
    Electronic Resource
    Extremely low temperatures in the stratosphore and very low total ozone amount above northern and central Europe during winter 1989 (1991)
    Springer
    Journal of atmospheric chemistry 12 (1991), S. 381-390 
    Details
    ISSN: 1573-0662
    Keywords: Ozone ; total ozone ; temperature ; stratosphere ; stratospheric warming ; Antarctic ozone hole ; polar stratospheric clouds ; ozone depletion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract On 1 February 1989, -83.5°C was recorded in 27.8 hPa over Hohenpeißenberg, the lowest temperature in the 22-year series. This was measured together with a very low total ozone amount of 266 DU. This may be compared with nearly twice this amount on 27 February 1989. The situation was very unusual: following an extremely cold winter in the Arctic stratosphere, the stratospheric cold pole was located over southern Scandinavia on 1 February in a very southerly position. The analyzed temperatures of -92 °C in 30 hPa were also unusual. Even though the low ozone amounts over Hohenpeißenberg were probably dynamically caused, an additional very small ozone decrease due to heterogeneous reactions in altitudes from 23–28 km, where the temperatures lie below -80 °C, cannot be ruled out. Extinction measurements by the orbitting SAGE II instrument indeed show polar stratospheric clouds over Europe near 50° N during the period 31 January–2 February. Also, polar stratospheric clouds were previously observed over Kiruna at similarly low temperatures and signs of a corresponding small ozone decrease were noted there.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00114775
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  • 26
    Electronic Resource
    Electronic Resource
    Modeling the temperature response of nitrification (1996)
    Springer
    Biogeochemistry 35 (1996), S. 433-445 
    Details
    ISSN: 1573-515X
    Keywords: ammonium oxidation ; growth rate ; maintenance energy ; modeling ; nitrification ; soil nitrate ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract To model nitrification rates in soils, it is necessary to have equations that accurately describe the effect of environmental variables on nitrification rates. A variety of equations have been used previously to describe the effect of temperature on rates of microbial processes. It is not clear which of these best describes the influence of temperature on nitrification rates in soil. I compared five equations for describing the effects of temperature on nitrification in two soils with very different temperature optima from a California oak woodland-annual grassland. The most appropriate equation depended on the range of temperatures being evaluated. A generalized Poisson density function best described temperature effects on nitrification rates in both soils over the range of 5 to 50 °C; however, the Arrhenius equation best described temperature effects over the narrower range of soil temperatures that normally occurs in the ecosystem (5 to 28 °C). Temperature optima for nitrification in most of the soils were greater than even the highest soil temperatures recorded at the sites. A model accounting for increased maintenance energy requirements at higher temperatures demonstrates how net energy production, rather than the gross energy production from nitrification, is maximized during adaptation by nitrifier populations to soil temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183035
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  • 27
    Electronic Resource
    Electronic Resource
    Methane emissions from wet grasslands on peat soil in a nature preserve (1999)
    Springer
    Biogeochemistry 44 (1999), S. 205-220 
    Details
    ISSN: 1573-515X
    Keywords: grassland ; ground water level ; methane ; peat ; temperature ; wetland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The area of wet grasslands on peat soil in the Netherlands is slowly increasing at the expense of drained, agriculturally used grasslands. This study aimed (i) to assess the contribution of wet grasslands on peat soil to methane (CH4) emissions, and (ii) to explain differences among sites and between years in order to improve our understanding of controlling factors. For these purposes, a field study was conducted in the period 1994–1996 in the nature preserve “Nieuwkoopse Plassen”, which is a former peat mining and agricultural area. Net CH4 emissions were measured weekly to monthly with vented closed flux chambers at three representative sites, and at ditches near these sites. Three-years average of CH4 emissions was 7.9 g CH4 m−2 yr−1 for Drie Berken Zudde, 13.3 for Koole, and 20.4 for Brampjesgat. Ditches near the sites emitted 4.2–22.5 g CH4 m−2 yr−1. The time-course of CH4 emissions for all experimental sites and years was fit with a multiple linear regression model with ground water level and soil temperature as independent variables. Lowering or raising the ground water level by 5 cm could decrease or increase CH4 emissions by 30–50%. Therefore, ground water level management of these grasslands should be done with care.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00992979
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  • 28
    Electronic Resource
    Electronic Resource
    Dynamics of the Subsurface Temperature Field Caused by Mining-Related Groundwater Management (2000)
    Springer
    Studia geophysica et geodaetica 44 (2000), S. 442-459 
    Details
    ISSN: 1573-1626
    Keywords: temperature ; groundwater ; sedimentary basin ; exploitation ; transient effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences , Physics
    Notes: Abstract The subsurface temperature field was studied on a set of 46 borehole logs measured in the vicinity of uranium deposits in the Bohemian Cretaceous Basin. Vertical variations of the steady state temperature and the temperature gradient are governed by thermal conductivity which strongly varies in dependence on lithology. Large departures from undisturbed temperature detected in many holes are associated with uranium mining. A positive anomaly is observed in leaching fields where large amounts of acid are injected into the uranium-bearing Cenomanian. A negative anomaly is linked to the operation of hydraulic barriers which enclose the mining area and helps to contain pollution by pumping clean water into the Cenomanian aquifer. The spatial distribution of the observed temperature anomalies helps to map the migration of the fluids used in both processes. The temperature disturbance is propagated from the Cenomanian aquifer up through overlying impermeable sediments. The good fit of transient conductive models to the measured temperatures rules out heat advection and hence upward water flow towards and contamination of the upper Middle Turonian aquifer in the vicinity of the holes studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022168705973
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