城市環(huán)境土壤污染的原因外文翻譯-環(huán)境工程-展示頁
2025-05-27 13:32本頁面
【正文】 om the source. Moreover, it is obvious that there is a dependence on the wind direction, since the concentrations may be enhanced predominantly in the main wind direction. Very high concentrations of heavy metals accumulated especially in the upper portion of the humic topsoils (Penin and Tschernev 1997). The tendencies described associated with the heavy metal gradients are basically applicable to organic pollutants as well. Near the town of Strazske (Slovakia) with 5,000 inhabitants which is dominated by a chemical factory that produced technical Polychlorinated Biphenyls (PCB) mixtures between 1959 and 1984, samples were taken on an adjacent mountain slope influenced by the intensive dust emission and nearby deposition. As shown in Table , the accumulation of PCB (and Polycyclic Aromatic Hydrocarbons) in the organic layer exceeded the resul ts from the mineral subsoil (depth gradient) and higher values tended to be found at the lower position of the neighbouring slope in direct contact with the emission source than at the central and upper position. In contrast to the heavy metals, the distance gradient seemed obviously to be less significant (Wilcke et al. 2020). Industrial and mining processes influence increasingly the inventory of contaminants in the upper parts of the soils in the course of time. Trace elements usually in the earth’s crust in very small quantities reach high concentrations that would never have been found in the absence of industrial development. For instance, in Wyoming and Idaho, USA, dustinducing surface mining of coal and phosphorus led to an increase of selenium in the environment due to the exposure of Se containing overburden (Pierzynski et al. 2020). If soils of an urban environment are pared with heavy metal mining soils, an appreciable difference can be noticed. Thornton (1991) analysed topsoils of special mi ning villages and the British capital London, with a population of 13,200,000, with reference to all locations investigated in England and Wales (Table ). In general, it was stated that the results from London are much higher than from all locations investigated as everybody would expect, but surprisingly, the concentrations of the mining villages exceeded the London results considerably, apart from cadmium. In other words, the urban impact apparently seems to be less significant than the mining impact. With reference to urban environments, in the two Norwegian cities Bergen, with 230,000 inhabitants, and Trondheim, with 160,000 inhabitants, sensitive uses like gardens, parks, kindergartens and playgrounds were checked in order to ascertain the influence of dust deposition. Consequently, the upper 2 cm of the 661 (Bergen) and 631 (Trondheim) soil samples were taken into consideration. Bergen’s most i
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