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91.
The thermal pollution patch of Hadera power plant was used as a natural laboratory to evaluate the potential long-term effects of rise in Eastern Mediterranean SST on living benthic foraminifera. Their sensitivity to environmental changes makes foraminifera ideal for this study. Ten monthly sampling campaigns were performed in four stations located along a temperature gradient up to 10 °C from the discharge site of heated seawater to a control station. The SST along this transect varied between 25/18 °C in winter and 36/31 °C in summer. A significant negative correlation was found between SST in all stations and benthic foraminiferal abundance, species richness and diversity. The total foraminiferal abundance and species richness was particularly low at the thermally polluted stations especially during summer when SST exceeded 30 °C, but also throughout the entire year. This indicates that thermal pollution has a detrimental effect on benthic foraminifera, irrelevant to the natural seasonal changes in SST. 相似文献
92.
Stephen D. Sebestyen Nina K. Lany Daniel Tyler Roman Jacob M. Burdick Richard L. Kyllander Elon Sandy Verry Randall K. Kolka 《水文研究》2021,35(3):e14092
The Marcell Experimental Forest (MEF) in northern Minnesota, USA, with hydrological research and monitoring of peatland catchments in a low-topographic relief landscape, contrasts with the mountainous terrain that typifies most research catchments. Six research catchments were instrumented and hydrological and meteorological monitoring was initiated during 1960. Paired-catchment studies, which started during 1969, have been used to assess land management and environmental change effects on forests, water availability, and biogeochemistry. Over the decades, the research and collaborations have proliferated to include new monitoring and ecosystem experiments. We provide an overview of available datasets and access information for hydrological and meteorological data. Data on streamflow, water table elevation, precipitation, snow, ground frost, air temperature, soil moisture, upland runoff, and water chemistry are discoverable with associated metadata and are archived through several Web-based, community repositories. The research programme is ongoing and we anticipate updates on an annual or more frequent basis. Additionally, we aim to release other physical, chemical, and isotopic measurements associated with long-term catchment monitoring and studies at the MEF. 相似文献
93.
Landscape images are a way to register geoheritage, and we have applied it here in a consideration of the landscapes of the Netherlands. Before the 1950s these landscapes were documented chiefly by landscape painters; with useful photographs of limited availability. We have looked through a large number of paintings of Dutch landscapes to assess their geoheritage value, and present here a first reconnaissance. 相似文献
94.
Peter Rosén Hendrik Vogel Laura Cunningham Nina Reuss Daniel J. Conley Per Persson 《Journal of Paleolimnology》2010,43(2):247-259
We demonstrate the use of Fourier transform infrared spectroscopy (FTIRS) to make quantitative measures of total organic carbon
(TOC), total inorganic carbon (TIC) and biogenic silica (BSi) concentrations in sediment. FTIRS is a fast and cost-effective
technique and only small sediment samples are needed (0.01 g). Statistically significant models were developed using sediment
samples from northern Sweden and were applied to sediment records from Sweden, northeast Siberia and Macedonia. The correlation
between FTIRS-inferred values and amounts of biogeochemical constituents assessed conventionally varied between r = 0.84–0.99 for TOC, r = 0.85–0.99 for TIC, and r = 0.68–0.94 for BSi. Because FTIR spectra contain information on a large number of both inorganic and organic components,
there is great potential for FTIRS to become an important tool in paleolimnology. 相似文献
95.
Ulla Kokfelt Nina Reuss Eric Struyf Mats Sonesson Mats Rundgren G?ran Skog Peter Rosén Dan Hammarlund 《Journal of Paleolimnology》2010,44(1):327-342
Permafrost in peatlands of subarctic Sweden is presently thawing at accelerated rates, which raises questions about the destiny
of stored carbon and nutrients and impacts on adjacent freshwater ecosystems. In this study we use peat and lake sediment
records from the Stordalen palsa mire in northern Sweden to address the late Holocene (5,000 cal BP-present) development of
the mire as well as related changes in carbon and nutrient cycling. Formation, sediment accumulation and biogeochemistry of
two studied lakes are suggested to be largely controlled by the development of the mire and its permafrost dynamics. Peat
inception took place at ca. 4,700 cal BP as a result of terrestrialisation. Onset of organic sedimentation in the adjacent
lakes occurred at ca. 3,400 and 2,650 cal BP in response to mire expansion and permafrost aggradation, respectively. Mire
erosion, possibly due to permafrost decay, led to re-deposition of peat into one of the lakes after ca. 2,100 cal BP, and
stimulated primary productivity in the other lake at ca. 1,900–1,800 cal BP. Carbonate precipitation appears to have been
suppressed when acidic poor fen and bog (palsa) communities dominated the catchment mire, and permafrost-induced changes in
hydrology may further have affected the inflow of alkaline water from the catchment. Elevated contents of biogenic silica
and diatom pigments in lake sediments during periods of poor fen and bog expansion further indicate that terrestrial vegetation
influenced the amount of nutrients entering the lake. Increased productivity in the lake likely caused bottom-water anoxia
in the downstream lake and led to recycling of sediment phosphorous, bringing the lake into a state of self-sustained eutrophication
during two centuries preceding the onset of twentieth century permafrost thaw. Our results give insight into nutrient and
permafrost dynamics in a subarctic wetland and imply that continued permafrost decay and related vegetation changes towards
minerotrophy may increase carbon and nutrient storage of mire deposits and reduce nutrient fluxes in runoff. Rapid permafrost
degradation may on the other hand lead to widespread mire erosion and to relatively short periods of significantly increased
nutrient loading in adjacent lakes. 相似文献
96.
Important though indirect information about the internal structure of Venus is provided by its topography and geoid. In the last decades this information has been used to constrain the Venus mantle viscosity structure and its dynamic regime. Recently, the geodynamic inversion of the Venus?? geoid and topography resulted in a group of best fitting viscosity profiles. We use these viscosity models here as an input to our mantle convection code. We carry out simulations of the Venus?? mantle evolution in a 3D spherical shell with depth dependent viscosity and check whether the character of the dynamic topography and the geoid represented by their power spectra fits the observed quantities. We compare the results with several other models obtained for different viscosity stratifications (constant, constant with highly viscous lithosphere, linear increase of viscosity). Further, we estimate the effect of other factors such as internal heating and varying Rayleigh number. We use a 2D spherical axisymmetric convection code to study the effect of lateral viscosity variations. In these 2D models we monitor the topography and the geoid developing above the axisymmetric plume and compare them with the observed elevations of Venus?? geoid and topography in several Regia. Though none of the models fits observed data perfectly, we can generally conclude, that the best fit between the observed and predicted quantities is reached for viscosity profiles with 200 km thick lithosphere followed by a gradual increase of viscosity with depth and with the upper mantle viscosity of 2 × 10 21 Pa s. For all viscosity profiles the predicted geoid and topography spectra match the observed ones only up to the degree 40, thus indicating other than dynamic origin of these quantities for higher degrees. 相似文献
97.
Chris?BallhausEmail author Raúl?O.?C.?Fonseca Carsten?Münker Arno?Rohrbach Thorsten?Nagel Iris?M.?Speelmanns Hassan?M.?Helmy Aurelia?Zirner Antje?K.?Vogel Alexander?Heuser 《Contributions to Mineralogy and Petrology》2017,172(8):68
The extreme depletion of the Earth’s mantle in sulfur is commonly seen as a signature of metal segregation from Earth’s mantle to Earth’s core. However, in addition to S, the mantle contains other elements as volatile as S that are hardly depleted relative to the lithophile volatility trend although they are potentially as siderophile as sulfur. We report experiments in metal-sulfide–silicate systems to show that the CI normalized abundances of S, Pb, and Sn in Earth’s mantle cannot be reproduced by element partitioning in Fe ± S–silicate systems, neither at low nor at high pressure. Much of the volatile inventory of the Earth’s mantle must have been added late in the accretion history, when metal melt segregation to the core had become largely inactive. The great depletion in S is attributed to the selective segregation of a late sulfide matte from an oxidized and largely crystalline mantle. Apparently, the volatile abundances of Earth’s mantle are not in redox equilibrium with Earth’s core. 相似文献
98.
Erika B. Guttmann Ian A. Simpson Nina Nielsen Stephen J. Dockrill 《Geoarchaeology》2008,23(6):799-823
The soils surrounding three Iron Age settlements on South Mainland, Shetland, were sampled and compared for indicators of soil amendment. Two of the sites (Old Scatness and Jarlshof) were on lower‐lying, better‐drained, sheltered land; the third (Clevigarth) was in an acid, exposed environment at a higher elevation. The hypothesis, based on previous regional assessments, soil thicknesses, and excavations at Old Scatness, was that the lowland sites would have heavily fertilized soils and that the thin upland soil would show little if any amendment. Our findings indicate that the Middle Iron Age soils at Old Scatness had extremely high phosphorus levels, while the soil at Jarlshof had lower levels of enhancement. At Clevigarth, where charcoal from the buried soil was 14C dated to the Neolithic and Bronze Age, there was no evidence of arable activity or soil amendment associated with the Iron Age phases of settlement. These observations indicate that not all sites put the same amount of effort into creating rich arable soils. The three sites had very different agricultural capacities, which suggests the emergence of local trade in agricultural commodities in Iron Age Shetland. © 2008 Wiley Periodicals, Inc. 相似文献
99.
100.
Nina Mateshvili Frans J.M Rietmeijer 《Journal of Volcanology and Geothermal Research》2003,120(1-2):55-69
Stratospheric aerosol loading from early 1981 to late 1985 was investigated by remote optical measurements using the twilight sounding method and by in situ mineral dust collections. Both experiments tracked the decay of aerosol abundances after the El Chichón eruption. A comparison between the remote optical observations and dust samplings suggests that aerosol maxima in 1985 were probably associated with a minor eruption of the Bezymianny volcano. Considering the different dynamical behavior of volcanic ash and condensed sulfuric acid aerosol, we traced the origin of collected dust to a minor eruption of Una Una volcano. This collected dust that could not be detected by remote sensing techniques against the high background level due to condensed aerosol from El Chichón highlights the complimentary nature of stratospheric dust collections and the twilight sounding method. 相似文献