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Octachlorostyrene could be identified and quantified in fish, water and sediment of the North Sea and adjacent estuaries by high resolution gas chromatography and mass spectrometry. Lipid related octachlorostyrene levels in livers of various fish ranged from 20 to 3700 ng/g lipid. Comparing levels from 1972 and 1983 no remarkable differences could be observed among the samples investigated. In fish livers originating from the Mediterranaen, North Atlantic and the Red Sea octachlorostyrene was not detectable. 相似文献
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J. Gan S. R. Yates M. A. Anderson W. F. Spencer F. F. Ernst M. V. Yates 《Chemosphere》1994,29(12):2685-2700
Methyl bromide (CH3Br) is currently the most widely used soil fumigant, and its emission into the atmosphere after application reportedly contributes to ozone depletion in the stratosphere. Irreversible degradation and partially reversible sorption reactions affect the quantity of this furnigant reaching the soil surface and escaping into the atmosphere. Incubation studies in closed headspace vials under controlled conditions showed that degradation of CH3Br was highly dependent on soil organic matter content, and to a lesser extent, on the moisture level in the soil. Methylation of CH3Br on organic matter was suggested to be the major reaction that CH3Br undergoes in the soil environment. Other soil constituents such as clay did not contribute to the degradation under moist or air-dried conditions, though enhanced degradation was observed on oven-dried montmorillonite and kaolinite clays. Within soil profiles, degradation of CH3Br decreased with soil depth mainly due to the reduction of soil organic matter content with depth. In both Greenfield and Wasco sandy loams, the degradation rate of CH3Br in soil layers from 0 to 270 cm could be estimated from soil organic matter content. Sorption of CH3Br on moist soils was generally limited, and varied with soil depth. The degree of sorption could be predicted from soil moisture alone or soil moisture and organic matter content. 相似文献
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Common soles Solea solea (L.) are extremely suitable for studying the fate of pesticides in marine fish by means of laboratory experiments involving small-sized, accurately controlled, closed aquarium systems. In 5 different experiments, a total of 16 fishes of Age Group I were maintained in water of 10°C and 20‰ S continuously filtered through charcoal, and given oral doses of 0.85 μg DDT-14C up to 5 times/week. A total application of 1.7, 17 or 35 μg DDT-14C, corresponding to 3, 28, or 57 experimental days, resulted in 72, 60 or 43% DDT-14C accumulation. After feeding with 17 μg unlabelled DDT over a period of 4 weeks and final feeding with 1.7 μg 14C-labelled DDT for 2 days, S. solea displayed the same percentage (74%) of accumulated DDT-14C as after feeding with 1.7 μg DDT-14C without prior feeding. Therefore, the decreasing accumulation percentages with inereasing doses, i.e., with longer application periods, are due to elimination during the application period. During a period of 2 months in pesticide-free water, S. solea eliminated 62% of the DDT-14C which it had accumulated after feeding with 17 μg DDT-14C over a period of 4 weeks. The gastro-intestinal tract is assumed to be a major route of DDT elimination. Independent of dosage, there was a characteristic distribution pattern of accumulated DDT: brain, liver and gastro-intestinal tract ranked highest, while the concentration in skeletal muscle was lowest. Even during the elimination period the pattern appeared unchanged. DDE, DDD and a polar component occurred as metabolites, but in all organs more than 80% of the accumulated DDT remained unchanged. Percentages of metabolites were higher in liver and gastro-intestinal tract than in skeletal muscle. Prolonged exposure to DDT in the diet induced DDT transformation in the gastro-intestinal contents, most probably in the bacterial flora of the gut. 相似文献
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Jeffrey H. Gove Ernst Linder Walter M. Tzilkowski 《Environmental and Ecological Statistics》1996,3(1):65-80
The possibility of a bimodal log-likelihood function arises with certain data when the combined removal and signs-of-activities estimator is used. Bimodal log-likelihoods may, in turn, yield disjoint confidence intervals for certain confidence levels. The hypothesis that bimodality is caused by the violation of the equal catchability assumption of the removal model, leading to the combination of contradictory data/models in the combined estimator is set forth. Simulations exploring the effect of the violation of removal model assumptions on estimation and inference showed that the assumption of unequal capture probability influenced the frequency of bimodal likelihoods; similarly, extreme parameter values for probability of capture influenced the number of excessively large confidence intervals produced. A sex-specific combined estimator is developed as a remedial model tailored to the problem. The simulations suggest that both the signs-of-activities estimator and the sex-specific estimator perform equally well over the range of simulations presented, though the signs-of-activities estimator is easier to implement. 相似文献
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W. H. O. Ernst J. A. C. Verkleij R. Vooijs 《Environmental monitoring and assessment》1983,3(3-4):297-305
A survey of the methods of boindication of heavy metals in terrestrial ecosystems and their effectiveness for predicting the consequences of environmental stress on organisms is presented. Two main inputs of heavy metals for terrestrial ecosystems have been considered: airborne and soil-borne. Airborne metals can be monitored due to physical adsorption on plant surfaces or due to chemical exchange processes in cell walls. Active biomonitoring widely uses both aspects, however, without predictive values. Meaningful bioindication of soilborne heavy metals can only be achieved by passive monitoring. Due to the different functions of heavy metals in organisms-micronutrients and trace elements-the knowledge of natural background values is important, considering the qualitative aspects of metals in the soil. In exceptional situations morphological and anatomical changes of plant organs will facilitate bioindication; in every case chemical analysis of the concentration of heavy metals is an essential part of the monitoring program. A long-term exposure of organisms to heavy metals will influence the genetic structure of populations. Therefore measurement of heavy metal tolerance of plants has to be a standard procedure in monitoring programs. 相似文献
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