城市环境土壤污染的原因【外文翻译】.doc

原文:
Causes of Soil Contamination in the Urban Environment
Dust Deposition
Extensive dust deposition is mainly caused by industrial emission. It is deposited in dry conditions and as suspended particulate matter. The size of particulate matter varies. The fraction of less than 10 μm designated as respirable particulate matter is most dangerous for human health. A portion of cement dust and fly ash may exceed that value, but there are some kinds of particulate matter with a general size distribution of less than 10 μm like asbestos dust and smoke derived from oil-fired power stations. It should be borne in mind that the smaller the suspended matter is the higher the contaminant concentration is due to the enhanced sorption capacity.
Contaminated particulate matter can be transported from outdoors into rooms. There, a dust accumulation occurs, particularly if windows remain opened during daytime. Of interest is parison between garden soil and house dust concentration. In England it has been found that the Cd, Cu, Pb and Zn values were larger in house dust than in the associated gardens (Thornton 1991).
Dust formation in urban areas may play an important role, in particular in arid and semi-arid regions, where dry conditions dominates, but also in humid climates dust is of importance for soil formation. For instance, in the city of Hanover (Germany) with a population of 520