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71.
Jørgensen PR Urup J Helstrup T Jensen MB Eiland F Vinther FP 《Journal of contaminant hydrology》2004,73(1-4):207-226
Transport and reduction of nitrate in a typically macroporous clayey till were examined at variable flow rate and nitrate flux. The experiments were carried out using saturated, large diameter (0.5 m), undisturbed soil columns (LUC), from a forest and nearby agricultural sites. Transport of nitrate was controlled by flow along the macropores (fractures and biopores) in the columns. Nitrate reduction (denitrification) determined under active flow mainly followed first order reactions with half-lives (t(1/2)) increasing with depth (1.5-3.5 m) from 7 to 35 days at the forest site and 1-7 h at the agricultural site. Nitrate reduction was likely due to microbial degradation of accumulated organic matter coupled with successive consumption of O2 and NO3- in the macropore water followed by reductive dissolution of Fe and Mn from minerals along the macropores. Concentrations of total organic carbon measured in soil samples were near identical at the two study sites and consequently not useful as indicator for the observed differences in nitrate reduction. Instead the high reduction rates at the agricultural site were positively correlated with elevated concentration of water-soluble organic carbon and nitrate-removing bacteria relative to the forest site. After high concentrations of water-soluble organic carbon in the columns from the agricultural site were leached they lost their elevated reduction rates, which, however, was successfully re-established by infiltration of new reactive organics represented by pesticides. Simulations using a calibrated discrete fracture matrix diffusion (DFMD) model could reasonably reproduce the denitrification and resulting flux of nitrate observed during variable flow rate from the columns. 相似文献
72.
Assessment of degradation of 18 antibiotics in the Closed Bottle Test 总被引:11,自引:0,他引:11
Large quantities of antibiotics are used in health care. After administration, they are discharged into the effluent and reach sewage treatment plants (STPs); if they are not degraded, they will eventually enter the environment. Antibiotics can affect bacteria in the environment and thus disturb natural elemental cycles. For this reason, it is necessary to take a closer look at the fate and effects of these substances in the environment. The biodegradability of 18 clinically important antibiotics and their effects on environmental bacteria was studied using the Closed Bottle Test (CBT) (OECD 301 D 1992). In addition, a toxicity control was performed in the CBT and the colony forming units (CFUs) were monitored. Disappearance of some of the 18 antibiotics was monitored by HPLC (high performance liquid chromatography) analysis. The antibiotics were used in two concentrations: (a) according to OECD 301 D in the mg/l-range and (b) on the basis of calculated concentrations in the influent of STPs in the microg/l-range. None of the 18 antibiotics were readily biodegradable. The HPLC analysis showed that some substances were partially or even completely disappeared by a non-biotic mechanism. In the case of some antibiotics, partial biological removal took place in test vessels containing readily biodegradable sodium acetate and the test compound. However, in the toxicity control, toxicity had not been eliminated. 相似文献
73.
Tina M Petersen Monica P Suarez Hanadi S Rifai Paul Jensen Yu-Chun Su Ron Stein 《Water environment research》2006,78(12):2340-2355
This paper examines bacterial levels and their causes in two Houston bayous (Texas). Buffalo and Whiteoak bayous are two of the most contaminated water bodies in Texas for indicator bacteria, based on the frequency and magnitude of contact recreation water quality exceedances. Examination of historical data indicates frequent exceedances, although some improvement has been made since the 1970s. Statistical analyses showed some correlation between in-stream fecal coliform concentrations and rainfall and with land use. Differences in fecal coliform concentrations were found between high- and low-flow conditions in Whiteoak Bayou, while reservoir releases confounded this relationship in Buffalo Bayou. Wastewater treatment plant effluent was found to make up two-thirds to three-fourths of the median flow in both bayous. Effluent sampling was conducted at 72 of the approximately 140 wastewater treatment plants (WWTPs) in the watersheds, providing evidence that WWTP effluent could act to maintain low-flow concentrations of fecal coliform in the bayous. 相似文献
74.
After the end of the Cold War, the Baltic Sea Region (BSR) developed into a highly dynamic area of cross-border cooperation and transnational networking. Three forms of governance beyond the nation state and appropriate case studies are presented here: (1) the Helsinki Convention as an international regime; (2) Baltic 21, the world's first regional Agenda 21, as an international policy network; (3) the Union of the Baltic Cities (UBC) as a transnational network. The achievement of sustainable development in the BSR undoubtedly requires a fruitful combination of national governance and these forms of international and transnational governance. In this respect, international policy networks, such as Baltic 21, and transnational networks, such as the UBC, promise to provide new approaches that can complement international and intergovernmental cooperation between nation states. Furthermore, it must also be taken into account that governance in the BSR will soon become embedded in European governance and lead to the Europeanisation of the Baltic Sea Area. 相似文献
75.
The effects of familiarity and gender on spatial representation 总被引:1,自引:0,他引:1
Tina Iachini Francesco Ruotolo Gennaro Ruggiero 《Journal of environmental psychology》2009,29(2):227-234
This paper reports a study of how familiarity and gender may influence the frames of reference used in memory to represent a real-world regularly shaped environment. Familiar and unfamiliar participants learned the locations of three triads of buildings by walking on a path which encircled each triad. Then they were shown with maps reproducing these triads at five different orientations (from 0° to 180°) and had to judge whether each triad represented correctly the relative positions between the buildings. Results showed that unfamiliar participants performed better when the orientation of triads was closer to the learning perspective (0° and 45°) and corresponded to front rather than to back positions. Instead, familiar participants showed a facilitation for triads oriented along orthogonal axes (0°–180°, 90°) and no difference between front and back positions. These findings suggested that locations of unfamiliar buildings were mentally represented in terms of egocentric frames of reference; instead, allocentric frames of reference defined by the environment were used when the environment was familiar. Finally, males were more accurate and faster than females, and this difference was particularly evident in participants unfamiliar with the environment. 相似文献
76.
Tina Kiefer 《组织行为杂志》2005,26(8):875-897
This paper examines how and why ongoing organizational change is experienced emotionally on an everyday basis and identifies important consequences of such emotional experiences. Three main antecedents to negative emotions in ongoing change are proposed: perceptions of an insecure future; perceptions of inadequate working conditions; and perceptions of inadequate treatment by the organization. Two outcome variables are identified: trust in the organization and withdrawal from the organization. The model is tested with cross‐sectional and follow‐up data from a field study. Regression and path analysis reveal that: a) ongoing changes are associated with negative emotions; b) this relationship between ongoing changes and emotions is mediated by the three proposed antecedents; and c) negative emotions predict employee lack of trust and employee withdrawal, both immediately and one month later. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
77.
Tina Fredsted Mikkel H. Schierup Linn F. Groeneveld Peter M. Kappeler 《Behavioral ecology and sociobiology》2007,61(6):943-954
Mating system and dispersal patterns influence the spatio-genetic structure within and between populations. Among mammals,
monogamy is rare, and its socio-genetic consequences have not been studied in detail before. The goal of our study was to
investigate population history, demographic structure, and dispersal patterns in a population of pair-living fat-tailed dwarf
lemurs, Cheirogaleus medius, a small, nocturnal primate from western Madagascar, and to infer their underlying behavioral mechanisms. Tissue samples
for DNA extraction were obtained from a total of 140 individuals that were captured in two subpopulations about 3 km apart.
Analyses of mtDNA variability at the population level revealed very low levels of genetic variability combined with high haplotype
diversity, which is indicative of a recent population bottleneck. We found no evidence for spatial clustering of same-sexed
individuals with identical haplotypes within each of two subpopulations but significant clustering between them. Thus, a high
level of local subpopulation differentiation was observed (F
ST = 0.230). The sexes showed equal variances in the number of individuals representing each haplotype, as well as equal levels
of aggregation of identical haplotypes. Hence, both sexes disperse from their natal area, one pattern expected in a pair-living
mammal. There is a possibility of behavioral and social flexibility in this species, however, because we documented pronounced
differences in density and sex ratio between the two subpopulations, suggesting that single study sites or populations may
not be representative of a given local population or even species. 相似文献
78.
79.
Tina L. Cheng Jonathan D. Reichard Jeremy T. H. Coleman Theodore J. Weller Wayne E. Thogmartin Brian E. Reichert Alyssa B. Bennett Hugh G. Broders Joshua Campbell Katherine Etchison Daniel J. Feller Richard Geboy Traci Hemberger Carl Herzog Alan C. Hicks Sandra Houghton Jessica Humber Joseph A. Kath R. Andrew King Susan C. Loeb Ariane Massé Katrina M. Morris Holly Niederriter Gerda Nordquist Roger W. Perry Richard J. Reynolds D. Blake Sasse Michael R. Scafini Richard C. Stark Craig W. Stihler Steven C. Thomas Gregory G. Turner Shevenell Webb Bradford J. Westrich Winifred F. Frick 《Conservation biology》2021,35(5):1586-1597
Assessing the scope and severity of threats is necessary for evaluating impacts on populations to inform conservation planning. Quantitative threat assessment often requires monitoring programs that provide reliable data over relevant spatial and temporal scales, yet such programs can be difficult to justify until there is an apparent stressor. Leveraging efforts of wildlife management agencies to record winter counts of hibernating bats, we collated data for 5 species from over 200 sites across 27 U.S. states and 2 Canadian provinces from 1995 to 2018 to determine the impact of white-nose syndrome (WNS), a deadly disease of hibernating bats. We estimated declines of winter counts of bat colonies at sites where the invasive fungus that causes WNS (Pseudogymnoascus destructans) had been detected to assess the threat impact of WNS. Three species undergoing species status assessment by the U.S. Fish and Wildlife Service (Myotis septentrionalis, Myotis lucifugus, and Perimyotis subflavus) declined by more than 90%, which warrants classifying the severity of the WNS threat as extreme based on criteria used by NatureServe. The scope of the WNS threat as defined by NatureServe criteria was large (36% of Myotis lucifugus range) to pervasive (79% of Myotis septentrionalis range) for these species. Declines for 2 other species (Myotis sodalis and Eptesicus fuscus) were less severe but still qualified as moderate to serious based on NatureServe criteria. Data-sharing across jurisdictions provided a comprehensive evaluation of scope and severity of the threat of WNS and indicated regional differences that can inform response efforts at international, national, and state or provincial jurisdictions. We assessed the threat impact of an emerging infectious disease by uniting monitoring efforts across jurisdictional boundaries and demonstrated the importance of coordinated monitoring programs, such as the North American Bat Monitoring Program (NABat), for data-driven conservation assessments and planning. 相似文献
80.
Milačič R Zuliani T Oblak T Mladenovič A Ančar JŠ 《Journal of environmental quality》2011,40(4):1153-1161
Electric arc furnace (EAF) steel slag can be used as an alternative high-quality material in road construction. Although asphalts with slag aggregates have been recognized as environmentally acceptable, there is a lack of data concerning the potential leaching of toxic Cr(VI) due to the highly alkaline media of EAF slag. Leaching of selected water extractable metals from slag indicated elevated concentrations of total chromium and Cr(VI). To estimate the environmental impacts of asphalt mixes with slag, leachability tests based on diffusion were performed using pure water and salt water as leaching agents. Compact and ground asphalt composites with natural aggregates, and asphalt composites in which the natural aggregates were completely replaced by slag were prepared. The concentrations of total chromium and Cr(VI) were determined in leachates over a time period of 6 mo. After 1 and 6 mo, the concentrations of some other metals were also determined in the leachates. The results indicated that chromium in leachates from asphalt composites with the addition of slag was present almost solely in its hexavalent form. However, the concentrations were very low (below 25 μg L) and did not represent an environmental burden. The leaching of other metals from asphalt composites with the addition of slag was negligible. Therefore, the investigated EAF slag can be considered as environmentally safe substitute for natural aggregates in asphalt mixes. 相似文献