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851.
Volk C Wood L Johnson B Robinson J Zhu HW Kaplan L 《Journal of environmental monitoring : JEM》2002,4(1):43-47
The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment. 相似文献
852.
Summary
In part one of this paper (The Environmentalist,1990, pp.301–309) it was shown that conventional economic accounting does not reveal the actual damage to the natural environment, although an ever-increasing share of the Gross National Product is being spent for environmental protection activities. In this, part two of the paper, on the basis of acceptable conventions, the results of an empiric research on defensive expenditures in the GNP are presented, again taking the Federal Republic of Germany as an example. The authors would like to see more research of this type in order to understand better the environmental impacts and the structural deficiencies of modern industrial society.
Dr Christian Leipert and Professor Udo E. Simonis have contributed frequently toThe Environmentalist (see 1989, pp.171–183; 1990, pp.25–38; 1990, pp.301–309). Dr Leipert is research fellow, Dr Simonis is research professor at the environmental policy unit of the Science Center Berlin. 相似文献
853.
The reductive transformation of the 10 most-widely distributed fluorinated volatile compounds and of tetrachloroethene was investigated for up to 177 days under anaerobic conditions in sewage sludge and aquifer sediment slurries. Concentrations of parent compounds and of degradation products were identified by GC-MS. We observed transformation of CFC-11 to HCFC-21 and HCFC-31, of CFC-113 to HCFC-123a, chlorotrifluoroethene and trifluoroethene, of CFC-12 to HCFC-22, of HCFC-141b to HCFC-151b, and of tetrachloroethene to vinyl chloride and ethene. CFC-114, CFC-115, HCFC-142b, HFC-134a and HCFC-22 were not transformed. The results suggest that with both inocula studied here, hydrogenolysis is the primary reductive dechlorination reaction. CFC-113 was the only compound where a dichloro-elimination was observed, leading to the formation of chlorotrifluoroethene as temporal intermediate and to trifluoroethene as end product. The relative reduction rates of chlorofluoromethanes compared reasonably well with theoretical rates calculated based on thermochemical data according to the Marcus theory. Some of the accumulating HCFCs and haloethenes observed in this study are toxic and may be of practical relevance in anaerobic environments. 相似文献
854.
Rainer Brüggemann Christian Steinberg 《Umweltwissenschaften und Schadstoff-Forschung》1995,7(6):323-331
In eine ?kotoxikologische Bewertung von Schadstoffen müssen die Ergebnisse von Wirkungstests einflie?en. Die Qualit?t der
Bewertung im ?kosystemaren Kontext steht und f?llt mit der ?kosystemaren Qualit?t der Tests. In der vorliegenden Arbeit wird
eine Bestandsaufnahme aquatischer Wirkungstests (unabh?ngig von bestehenden legislativen Vorgaben) vorgenommen, und es werden
die Ergebnisse in einer Tabelle zusammengestellt, die Einsatzbereiche, Anwendbarkeit für mathematische Wirkungsmodellierung
und ?kosystemare Relevanz enth?lt. Die hieraus resultierende Tabelle ist schwer zu überblicken und Zusammenh?nge zwischen
bestimmten Wirkungstests sind kaum überschaubar. So ist auch eine Einstufung der aquatischen Wirkungstests ohne zus?tzliche
mathematische Hilfsmittel schwierig. Hier wird gezeigt, wie anhand der Technik derHasse-Diagramme die Einstufung der Wirkungstests nach ihrer Qualit?t erleichtert wird. Es zeigt sich u.a., da? es keinen Test gibt,
der alle Anforderungen gleichzeitig erfüllt. Einerseits gibt es sechs Tests, die — nach ihren Einsatzbereichen und nach ihrer
Umsetzbarkeit für die mathematische Modellierung beurteilt — zwar optimal sind, aber keine ?kosystemare Relevanz aufweisen.
Andererseits gibt es zwei Tests, die besonders ausgezeichnet sind: Einer (Test 8), der drei Einsatzbereiche aufweist und gleichzeitig
sowohl für die mathematische Modellierung geeignet, als auch ?kosystemar relevant ist, und einer, der in zwei anderen Einsatzbereichen
positiv beurteilt wurde und noch ?kosystemar interessant ist (Test 54). Es zeigt sich, da? zwischen Tests mit breitem Einsatzbereich
und solchen, die ?kosystemar relevant sind, eine Lücke klafft.
An evaluation of pollutants depends on the ecotoxicological quality of the effect tests carried out. In this paper a compilation
of aquatic tests is given independently on administration needs. The results are summarized in a table listing fields of application,
importance for mathematical modelling and ecological relevance. The table includes 55 tests and 8 attributes characterizing
each tests The interpretation of the results listed in this table is hardly feasible. An appropriate tool to rank the tests
is the technique ofHasse-diagrams. Using this tool it can be deduced that no test fulfills all demands. There are six tests which are optimal with
respect to applicability and mathematical modelling. However, they have no relevance for ecosystems. Only two tests are optimal
with respect to ecotoxicology, There is still a gap between tests with a wide field of applications and those tests which
are relevant with respect to ecotoxicology. 相似文献
855.
Seigneur C Lohman K Vijayaraghavan K Shia RL 《Environmental pollution (Barking, Essex : 1987)》2003,123(3):365-373
A modeling system that includes a global chemical transport model (CTM) and a nested continental CTM (TEAM) was used to simulate the atmospheric transport, transformations and deposition of mercury (Hg). Three scenarios were used: (1) a nominal scenario, (2) a scenario conducive to local deposition and (3) a scenario conducive to long-range transport. Deposition fluxes of Hg were analyzed at three receptor locations in New York State. For the nominal scenario, the anthropogenic emission sources (including re-emission of deposited Hg) in New York State, the rest of the contiguous United States, Asia, Europe, and Canada contributed 11-1, 25-9, 13-19, 5-7, and 2-5%, respectively to total Hg deposition at these three receptors. Natural sources contributed 16-4%. The results from the local deposition and long-range transport scenarios varied only slightly from these results. However, there are still uncertainties in our understanding of the atmospheric chemistry of Hg that are likely to affect these estimates of local, regional and global contributions. Comparison of model simulation results with data from the Mercury Deposition Network suggests that local and regional contributions may currently be overestimated. 相似文献
856.
Eleven drinking water treatment plants, located downstream of textile plants or pulp and paper mills, have been sampled monthly during a year for the analysis of 17 nonylphenol ethoxylates (NP1-17EO) and two nonylphenoxycarboxylic acids (NP1-2EC). At all but one plant, results in the drinking water, for the sum of these 19 substances, range between below detection levels and 6.7 microg/l. Annual means are between 0.02 and 2.8 microg/l. At the other plant, the yearly average concentration is 10.4 microg/l and the monthly maximum is 43.3 microg/l. In the surface (pre-treatment) water, the annual mean concentrations of the 11 plants range between 0.14 and 17.8 microg/l and the recorded instantaneous maximum is 55.3 microg/l. According to Canadian health authorities, drinking water is a negligible route of human exposure to nonylphenolic compounds, even at the highest concentrations found in this study. After transformation of the data into nonylphenol equivalents, about 20% of the surface water samples exceed the Canadian 1 microg/l nonylphenol water quality guideline for the protection of aquatic life. Some results also exceed Québec's 6 microg/l nonylphenol guideline. The efficiency of the plants in removing nonylphenolic compounds from drinking water is highly variable, ranging from 11% to 99%. 相似文献
857.
The main objective of this study was to examine the relationship between perceived support and affective commitment, and the linkages between these constructs and some of their common antecedents and consequences. More precisely, using a sample of 238 employees, we conducted a longitudinal study to examine the linkages between the favorableness of intrinsically and extrinsically satisfying job conditions, perceived organizational support, perceived supervisor support, affective commitment to the organization and supervisor, and turnover. Affective commitment to the supervisor was found to completely mediate the effect of perceived supervisor support on turnover, whereas neither perceived organizational support nor organizational affective commitment were significantly related to turnover. Perceived organizational support partially mediated the effect of favorable intrinsically satisfying job conditions on organizational affective commitment and fully mediated the effect of extrinsically satisfying job conditions on organizational affective commitment. Finally, perceived supervisor support totally mediated the effect of favorable intrinsically satisfying job conditions on affective commitment to the supervisor. As a whole, findings suggest that exchange relationships between employees and their supervisors should be further investigated in future turnover research. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
858.
859.
E. Menzel Max Schmidt R. Bünsow Gottwalt Christian Hirsch 《Die Naturwissenschaften》1962,49(14):335-336
860.
Anne-Marie Boulay Christian Bouchard Cecile Bulle Louise Deschênes Manuele Margni 《Mitigation and Adaptation Strategies for Global Change》2002,7(4):417-418