排序方式: 共有27条查询结果,搜索用时 359 毫秒
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Marianna Siegmund-Schultze Maria do Carmo Sobral Márcia M. G. Alcoforado de Moraes Jarcilene S. Almeida-Cortez J. Roberto G. Azevedo Ana Lúcia Candeias Arne Cierjacks Edvânia T. A. Gomes Günter Gunkel Volkmar Hartje Fred F. Hattermann Martin Kaupenjohann Hagen Koch Johann Köppel 《Regional Environmental Change》2018,18(7):1883-1888
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Jörg Matschullat Tim Scharnweber Dieter Garbe-Schönberg Annette Walther Volkmar Wirth 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1201-1211
ABSTRACT Epilithic lichen (Xanthoria elegans in Canada, Lecanora muralis in Germany) were gathered from 17 locations in Ontario, Canada (from Lake Ontario to James Bay) and 43 locations in Germany (from the Alps to the North Sea and from the Baltic Sea to the Erzgebirge). Sample aliquots were digested in nitric acid and trace elements were analyzed by inductively coupled plasma-mass spectrom-etry techniques. The organohalogens were determined as absorbable organic halogens (AOXs) by coulometry. Concentration ranges from Germany for trace element samples and AOXs were determined. The lichen showed high spatial resolution in their element enrichment patterns. This allowed for differentiation between natural and anthropogenic dominance in ambient air concentrations. This biomonitoring method has proven to be very sensitive, fast, and reliable. No clear relationship could be found between trace element and AOX concentrations. The AOX values may reflect individual metabolic rates of the fungal partner in lichen symbionts. 相似文献
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William A. Duvel Robert D. Volkmar Winona L. Specht Fred W. Johnson 《Journal of the American Water Resources Association》1976,12(4):799-812
ABSTRACT Geologic, engineering, and biological investigations of six Pennsylvania coldwater streams were undertaken to determine the impact of channel modifications instituted both prior to and following Hurricane Agnes. The primary focus of the study was on the ecological changes brought about by stream channelization. No long-term deleterious effects on water quality, attached algae, benthic fauna, or forage fish populations were found. Trout, however, were found to be greater in numbers and weight in natural than in channelized stream reaches. Lack of suitable physical habitat appears to be the primary cause of reduced trout populations in stream reaches which have been channelized. 相似文献
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