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排序方式: 共有223条查询结果,搜索用时 62 毫秒
91.
Wienold J Recknagel S Scharf H Hoppe M Michaelis M 《Waste management (New York, N.Y.)》2011,31(3):530-535
The EU RoHS Directive (2002/95/EC of the European Parliament and of the Council) bans the placing of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants on the EU market. It necessitates methods for the evaluation of RoHS compliance of assembled electronic equipment. In this study mounted printed circuit boards from personal computers were analyzed on their content of the three elements Cd, Pb and Hg which were limited by the EU RoHS directive. Main focus of the investigations was the influence of sample pre-treatment on the precision and reproducibility of the results. The sample preparation steps used were based on the guidelines given in EN 62321. Five different types of dissolution procedures were tested on different subsequent steps of sample treatment like cutting and milling. Elemental analysis was carried out using ICP-OES, XRF and CV-AFS (Hg). The results obtained showed that for decision-making with respect to RoHS compliance a size reduction of the material to be analyzed to particles ?1.5 mm can already be sufficient. However, to ensure analytical results with relative standard deviations of less than 20%, as recommended by the EN 62321, a much larger effort for sample processing towards smaller particle sizes might be required which strongly depends on the mass fraction of the element under investigation. 相似文献
92.
Sebastian Borowski Marcin Kucner 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1354-1364
Sugar beet pulp residues (SBPR) from hydrolysis and dewatering of beet pulp were co-digested with municipal sewage sludge (MSS). The highest biogas yields of nearly 512 dm3/kg VSfed (volatile solids fed) were achieved for SBPR, treated both as the monosubstrate and as a mixture with MSS (1 : 1 by weight). Simultaneously, the highest methane production of 348 dm3 CH4/kg VSfed was determined when the sewage sludge was co-digested with 35% SBPR. The analysis of digestate showed that neither ammonia nor volatile fatty acids destabilized the biogas production.Implications:?Processing of sugar beet pulp into bioethanol via enzymatic hydrolysis and microbial fermentation has become increasingly attractive. However, in this process, only the liquid fraction derived from hydrolysis is subjected into alcoholic fermentation, whereas the remaining solid fraction needs to be utilized. This study demonstrated that sugar beet pulp residues after bioethanol production can successfully be co-digested with sewage sludge to increase biogas productivity of anaerobic digesters located at wastewater treatment plants. 相似文献
93.
94.
Sebastian Stehle Anja Knäbel Ralf Schulz 《Environmental monitoring and assessment》2013,185(8):6295-6310
Due to the specific modes of action and application patterns of agricultural insecticides, the insecticide exposure of agricultural surface waters is characterized by infrequent and short-term insecticide concentration peaks of high ecotoxicological relevance with implications for both monitoring and risk assessment. Here, we apply several fixed-interval strategies and an event-based sampling strategy to two generalized and two realistic insecticide exposure patterns for typical agricultural streams derived from FOCUS exposure modeling using Monte Carlo simulations. Sampling based on regular intervals was found to be inadequate for the detection of transient insecticide concentrations, whereas event-triggered sampling successfully detected all exposure incidences at substantially lower analytical costs. Our study proves that probabilistic risk assessment (PRA) concepts in their present forms are not appropriate for a thorough evaluation of insecticide exposure. Despite claims that the PRA approach uses all available data to assess exposure and enhances risk assessment realism, we demonstrate that this concept is severely biased by the amount of insecticide concentrations below detection limits and therefore by the sampling designs. Moreover, actual insecticide exposure is of almost no relevance for PRA threshold level exceedance frequencies and consequential risk assessment outcomes. Therefore, we propose a concept that features a field-relevant ecological risk analysis of agricultural insecticide surface water exposure. Our study quantifies for the first time the environmental and economic consequences of inappropriate monitoring and risk assessment concepts used for the evaluation of short-term peak surface water pollutants such as insecticides. 相似文献
95.
96.
97.
Almut Gerhardt Stefanie Schmidt Sebastian Hss 《Environmental pollution (Barking, Essex : 1987)》2002,120(3)
The nematode Caenorhabditis elegans receives increasing attention in sediment ecotoxicology and new toxicity tests with sensitive test parameters are under development. In this study, the motility of C. elegans could be measured for the first time online in sediment, using the Multispecies Freshwater Biomonitor. Whereas single nematodes could not be recorded, groups of 10 nematodes gave typical locomotive signals in different media (water, agar, sediment) with comparable precision and accuracy. The results of this study encourage to develop a new rapid online whole-sediment toxicity test with behaviour as sensitive test parameter. 相似文献
98.
Sebastian Gayler Stefan Trapp Michael Matthies Reiner Schroll Herwart Behrendt 《Environmental science and pollution research international》1995,2(2):98-103
The uptake of terbuthylazine and its medium polar metabolites into maize plants under outdoor conditions is investigated.
For this purpose, a dynamical fate model consisting of soil, plant and air is developed. The model calculations are compared
with experimental results of outdoor lysimeter tests, carried out with14C-labelled herbicide applied to sandy agricultural soil at a single application rate of 890 g/ha. Approximately 0.3 % of the
applied activity remains in all the plants after the vegetation period. The model predicts that about three times that amount
is volatilized from the plants into the air. Activity uptaken from soil and volatilized from plant surface into air is predominately
associated with metabolites. During the whole vegetation period the fraction of unchanged terbuthylazine in the plants is
very small (less than 1 % of the extractable activity). 相似文献
99.
Sebastian U. Senger und Dietrich J. G. Werner 《Umweltwissenschaften und Schadstoff-Forschung》1999,11(5):253-259
Zusammenfassung Eine Zusammenstellung der Ozon-Me?werte der Luftme?stationnetze in Hessen und NRW ergab für die Jahresmittelwerte von 1990–1998
im Durchschnitt eine schwache Abnahme der Ozonkonzentrationen. Dabei lagen die Jahresmittelwerte der Ozonkonzentrationen über
Waldstationen doppelt so hoch wie über Stadtstationen. Die Ozonkonzentrationen verhalten sich im regionalen Vergleich umgekehrt
proportional zur Verkehrsdichte. In der Zahl der überschreitungen der gesetzlich festgelegten Grenzwerte von ≥180 μg Ozon/m3 pro Jahr lagen die Waldstationen mit dem 2–3 fachen Wert über den Stadtstationen. Lediglich die j?hrlichen Maximalwerte der
stündlich gemessenen Ozonwerte n?hern sich einander.
Die hohen Ozonwerte über den Waldstationen stehen im Zusammenhang mit den niedrigen Konzentrationen von NOx. Nachts reduziert
sich das Ozon über den Waldstationen durch Rückreaktion mit vergleichsweise geringen Konzentrationen von NO nur bis ca. 50%,
w?hrend der Ozongehalt über Stadtstationen bis nahe Null absinkt. Dieser Vorgang über den Stadtstationen wird auch durch Photolyse
des in hohen Konzentrationen vorliegenden NO2 und die dadurch erfolgende erh?hte Bildung von Ozon w?hrend des Tages nicht wieder kompensiert.
Für die hier dargestellten Ergebnisse gibt es prinzipiell keine Unterschiede zwischen den Ozonverh?ltnissen in Hessen und
NRW.
相似文献
100.
Dowdall M Gerland S Karcher M Gwynn JP Rudjord AL Kolstad AK 《Journal of environmental radioactivity》2005,84(1):111-130
Monitoring of the marine environment for radioactivity, for both radiological protection and oceanographic purposes, remains an expensive and labour intensive activity due to the large sample volumes needed and the complex and lengthy analytical procedures required to measure low levels of contamination. Because of this, some consideration must be given to the design of sampling plans to ensure effective and efficient sampling that can be defended on the basis of scientific rationale. This article tests the hypothesis that geostatistical techniques may prove of use in the optimisation and design of sampling regimes for the monitoring of temporal fluctuations in the levels of technetium at a location in the Norwegian Arctic marine environment. The level of temporal correlation exhibited by two relevant time series was investigated and the information used to observe the effect of sampling frequency on the production of monthly estimates of activity of technetium in both seawater and seaweed. The results indicate that reduced sampling frequency allows production of estimates that acceptably replicate the actual data and that use of geostatistical procedures may offer advantages in the planning of monitoring systems for marine radioactivity. The use of an oceanographic model was also investigated as a means of assessing the temporal correlation prior to actual sampling, an approach that may offer significant advantages by reducing the need to have lengthy time series prior to designing sampling regimes. 相似文献