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排序方式: 共有218条查询结果,搜索用时 31 毫秒
121.
Maximilian Berthold Ulf Karsten Mario von Weber Alexander Bachor Rhena Schumann 《Ambio》2018,47(1):146-158
The EU-water framework directive aims at nutrient reductions, since anthropogenically induced eutrophication is a major threat for coastal waters. However, phytoplankton biomass in southern Baltic Sea coastal water bodies (CWB) remains high and the underlying mechanisms are not well understood. Therefore, a CWB data set was analysed regarding changes in phytoplankton biomass and nutrient concentration of nitrogen (N) and phosphorus (P) from 2000 to 2014. It was expected to find imbalances between produced phytoplankton biomass and total nutrient concentrations. Inner CWB were cyanobacteria-dominated and showed up to five times higher chlorophyll a-concentrations compared to outer CWB with similar total phosphorus-concentrations. Phytoplankton tended to be P-limited during spring and N-limited during summer. Phytoplankton biomass and nutrient concentrations were even higher during very humid years, which indicated a close coupling of the CWB with their catchment areas. This study suggests that re-mesotrophication efforts need to consider the importance of changed phytoplankton composition and nutrient availabilities. 相似文献
122.
Karsten Klint Jensen 《Journal of Agricultural and Environmental Ethics》2017,30(5):615-623
That death is not a welfare issue appears to be a widespread view among animal welfare researchers. This paper demonstrates that this view is based on a mistaken assumption about harm, which is coupled to ‘welfare’ being conceived as ‘welfare at a time’. Assessments of welfare at a time ignore issues of longevity. In order to assess the welfare issue of death, it is necessary to structure welfare assessment as comparisons of possible lives of the animals. The paper also demonstrates that excluding the welfare issues of being deprived of life from the ethical assessment of killing distorts the ethical considerations. 相似文献
123.
Karsten E. Braun Burkhard Schmidt 《Journal of environmental science and health. Part. B》2017,52(2):122-130
The fate of 14C-labeled herbicide prosulfocarb was studied in an agricultural soil and in a sediment-water system, the sediment part of which was derived from Yangtze Three Gorges Reservoir, China. Time-course studies were performed for 28 d and 49 d, respectively. Main transformation routes of 14C-prosulfocarb were mineralization to 14CO2 and formation of nonextractable residues amounting to 12.13% and 10.43%, respectively, after 28 days (soil), and 9.40% and 11.98%, respectively, after 49 d (sediment-water system). Traces of prosulfocarbsulfoxide were detected by means of TLC, HPLC, and LC-MS; other transformation products were not found. Initial extraction of soil assays using 0.01 M CaCl2 solution showed that the bioavailability of the herbicide was considerably low; immediately after application (0.1 d of incubation), only 4.78% of applied radioactivity were detected in this aqueous fraction. DT50 values of 14C-prosulfocarb estimated from radio-TLC and -HPLC analyses were above 28 d in soil and ranged between 29 d and 49 d in the sediment-water system. Partitioning of 14C from water to sediment phase occurred with DT50 slightly above 2 d. With regard to the sediment-water system, adsorption occurred with log Koc = 1.38 (calculated from 2 day assays) and 2.35 (49 d assays). As similarly estimated from portions of 14C found in CaCl2 extracts of the 0.1 d assays, 14C-prosulfocarb's log Koc in soil was 2.96. With both experiments, similar portions of nonextractable radioactivity were associated with all soil organic matter fractions, i.e. nonhumics, fulvic acids, humic acids, and humin/minerals. Throughout all sample preparation, the experiments were severely impaired by losses of radioactivity especially with concentration of samples containing water in vacuo. All findings pointed to volatility of parent prosulfocarb in presence of water rather than volatility of transformation products. According to literature data, this behavior of prosulfocarb was not expected, though volatility was demonstrated under field conditions. 相似文献
124.
Angela Lausch Marion Pause Daniel Doktor Sebastian Preidl Karsten Schulz 《Environmental monitoring and assessment》2013,185(11):9419-9434
In numerous studies, spatial and spectral aggregations of pixel information using average values from imaging spectrometer data are suggested to derive spectral indices and the subsequent vegetation parameters that are derived from these. Currently, there are very few empirical studies that use hyperspectral data, to support the hypothesis for deriving land surface variables from different spectral and spatial scales. In the study at hand, for the first time ever, investigations were carried out on fundamental scaling issues using specific experimental test flights with a hyperspectral sensor to investigate how vegetation patterns change as an effect of (1) different spatial resolutions, (2) different spectral resolutions, (3) different spatial and spectral resolutions as well as (4) different spatial and spectral resolutions of originally recorded hyperspectral image data compared to spatial and spectral up- and downscaled image data. For these experiments, the hyperspectral sensor AISA-EAGLE/HAWK (DUAL) was mounted on an aircraft to collect spectral signatures over a very short time sequence of a particular day. In the first experiment, reflectance measurements were collected at three different spatial resolutions ranging from 1 to 3 m over a 2-h period in 1 day. In the second experiment, different spectral image data and different additional spatial data were collected over a 1-h period on a particular day from the same test area. The differently recorded hyperspectral data were then spatially and spectrally rescaled to synthesize different up- and down-rescaled images. The normalised difference vegetation index (NDVI) was determined from all image data. The NDVI heterogeneity of all images was compared based on methods of variography. The results showed that (a) the spatial NDVI patterns of up- and downscaled data do not correspond with the un-scaled image data, (b) only small differences were found between NDVI patterns determined from data recorded and resampled at different spectral resolutions and (c) the overall conclusion from the tests carried out is that the spatial resolution is more important in determining heterogeneity by means of NDVI than the depth of the spectral data. The implications behind these findings are that we need to exercise caution when interpreting and combining spatial structures and spectral indices derived from satellite images with differently recorded geometric resolutions. 相似文献
125.
Andreas M. Zipperle James A. Coyer Karsten Reise Eelo Gitz Wytze T. Stam Jeanine L. Olsen 《Marine Biology》2009,156(10):2139-2148
Genotypic structure and temporal dynamics of the dwarf seagrass, Zostera noltii, were studied in an intertidal meadow that has persisted since prior to 1936 near the Wadden Sea island of Sylt. Samples were
collected from two 10 × 10 m plots separated by 250 m from May 2002 to June 2005 and from four 1 × 1 m plots from June 2003
to September 2004. All the samples were genotyped with nine microsatellite loci. No genotypes were shared between the plots
separated by 250 m. Genetic diversity was higher in the Wadden Sea than in the other regions of its geographic range. The
average clone size (genets) (SD) in the two plots was 1.38 (0.26) and 1.46 (0.4) m2, respectively, with a range up to 9 m2
and <20% persisted for >4 years. A high genetic and genotypic diversity was maintained by annual recruitment of seedlings
despite a dramatic decrease in ramet density that coincided with the severe heat stress event of 2003. Fine-scale (1 m2) analysis
suggested that extensive loss of seagrass cover precluded space competition among the genets, while a persistent seed bank
prevented local extinction. Long-term persistence of Z. noltii meadows in the intertidal Wadden Sea was achieved by high genet turnover and frequent seedling recruitment from a seed bank,
in contrast to the low diversity observed in large and long-living clones of Z. noltii and other seagrasses in subtidal habitats. 相似文献
126.
Neumann T Eilola K Gustafsson B Müller-Karulis B Kuznetsov I Meier HE Savchuk OP 《Ambio》2012,41(6):574-585
In the future, the Baltic Sea ecosystem will be impacted both by climate change and by riverine and atmospheric nutrient inputs. Multi-model ensemble simulations comprising one IPCC scenario (A1B), two global climate models, two regional climate models, and three Baltic Sea ecosystem models were performed to elucidate the combined effect of climate change and changes in nutrient inputs. This study focuses on the occurrence of extreme events in the projected future climate. Results suggest that the number of days favoring cyanobacteria blooms could increase, anoxic events may become more frequent and last longer, and salinity may tend to decrease. Nutrient load reductions following the Baltic Sea Action Plan can reduce the deterioration of oxygen conditions. 相似文献
127.
Cristina Valhondo Jesús Carrera Carlos Ayora Manuela Barbieri Karsten Nödler Tobias Licha Maria Huerta 《Environmental science and pollution research international》2014,21(20):11832-11843
Artificial recharge improves several water quality parameters, but has only minor effects on recalcitrant pollutants. To improve the removal of these pollutants, we added a reactive barrier at the bottom of an infiltration basin. This barrier contained aquifer sand, vegetable compost, and clay and was covered with iron oxide dust. The goal of the compost was to sorb neutral compounds and release dissolved organic carbon. The release of dissolved organic carbon should generate a broad range of redox conditions to promote the transformation of emerging trace organic contaminants (EOCs). Iron oxides and clay increase the range of sorption site types. In the present study, we examined the effectiveness of this barrier by analyzing the fate of nine EOCs. Water quality was monitored before and after constructing the reactive barrier. Installation of the reactive barrier led to nitrate-, iron-, and manganese-reducing conditions in the unsaturated zone below the basin and within the first few meters of the saturated zone. Thus, the behavior of most EOCs changed after installing the reactive barrier. The reactive barrier enhanced the removal of some EOCs, either markedly (sulfamethoxazole, caffeine, benzoylecgonine) or slightly (trimethoprim) and decreased the removal rates of compounds that are easily degradable under aerobic conditions (ibuprofen, paracetamol). The barrier had no remarkable effect on 1H-benzotriazole and tolyltriazole. 相似文献
128.
Heavy metal concentrations in particle size fractions from street dust of Murcia (Spain) as the basis for risk assessment 总被引:3,自引:0,他引:3
Acosta JA Faz Á Kalbitz K Jansen B Martínez-Martínez S 《Journal of environmental monitoring : JEM》2011,13(11):3087-3096
Street dust has been sampled from six different types of land use of the city of Murcia (Spain). The samples were fractionated into eleven particle size fractions (<2, 2-10, 10-20, 20-50, 50-75, 75-106, 106-150, 150-180, 180-425, 425-850 μm and 850-2000 μm) and analyzed for Pb, Cu, Zn and Cd. The concentrations of these four potentially toxic metals were assessed, as well as the effect of particle size on their distribution. A severe enrichment of all metals was observed for all land-uses (industrial, suburban, urban and highways), with the concentration of all metals affected by the type of land-use. Coarse and fine particles in all cases showed concentrations of metals higher than those found in undisturbed areas. However, the results indicated a preferential partitioning of metals in fine particle size fractions in all cases, following a logarithmic distribution. The accumulation in the fine fractions was higher when the metals had an anthropogenic origin. The strong overrepresentation of metals in particles <10 μm indicates that if the finest fractions are removed by a vacuum-assisted dry sweeper or a regenerative-air sweeper the risk of metal dispersion and its consequent risk for humans will be highly reduced. Therefore, we recommend that risk assessment programs include monitoring of metal concentrations in dust where each land-use is separately evaluated. The finest particle fractions should be examined explicitly in order to apply the most efficient measures for reducing the risk of inhalation and ingestion of dust for humans and risk for the environment. 相似文献
129.
Engelhardt A Fischer J Neumann C Pfeifer JB Heistermann M 《Behavioral ecology and sociobiology》2012,66(1):121-134
Primates are unusual in that many females display sexual signals, such as sex skin swellings/colorations and copulation calls,
without any sex role reversal. The adaptive function of these signals remains largely unclear, although it has been suggested
that they provide males with information on female reproductive status. For sex skin swellings, there is increasing evidence
that they represent a graded signal indicating the probability of ovulation. Data on the functional significance of copulation
calls are much scarcer. To clarify the information content of such calls, we recorded copulation calls in wild long-tailed
macaques (Macaca fascicularis) and analysed the structure of these calls during the ovarian cycle. Specifically, we correlated selected call parameters
with the female oestrogen to progestogen ratio (obtained from faecal samples), which are known to be elevated during the female's
fertile phase. In addition, we ran a general linear mixed model for these call parameters, testing factors (cycle phase, occurrence/absence
of ejaculation, male dominance status, occurrence/absence of mate guarding) which potentially influence female copulation
calls in primates. Our results show that copulation calls of female long-tailed macaques signal mating outcome and rank of
the mating partner, but not female reproductive status. They also show for the first time on primates that copulation calls
can convey information on whether a female is mate guarded or not. We suspect that the function of these calls is manipulation
of male mating and mate-guarding behaviour and that in this way the degree of sperm competition and ultimately male reproductive
success is influenced. 相似文献
130.