摘要
本文讨论瑞典大气铅污染史、以往大气铅沉积物的地理分布以及北方森林土壤中铅污染物的迁移转化。本文以瑞典的湖泊沉积物、泥炭和土壤剖面中^(206)Pb/^(207)Pb同位素比和铅含量分析为基础。最早的大气铅污染现象始于3500～4000年前。大约在公元元年希腊-罗马时期污染出现了一次小规模却十分明显的高峰。在大约公元1000年,一次较大的不可逆转的污染增长出现了;在大约公元1200年和1530年湖泊纹泥沉积物表现了污染高峰,这与欧洲的冶金高峰有着密不可分的关系。伴随着工业革命大气铅污染有所增长,但并不像人们想象的那样多,其增长也根本不是从所谓的"背景值"开始。第二次世界大战后,铅污染增长显著,大约在1970年达到顶峰,按照目前的趋势,污染程度将很快倒退到中世纪的水平。工业化以前的污染分布和当代的污染分布很相似,都是很明显的由南向北渐变,这是由于从欧洲大陆和英国群岛北上的大气作用的结果。在瑞典铅污染的累积负荷为2～3g/m^2,其中至少有50%是在公元1800年以前沉降的。在北部森林土壤中,大部分造成污染的铅都聚集在B层。现在粗腐殖质层中的铅含量比污染前的原始森林土壤中的含量高1000倍。
This paper discusses the history of atmospheric lead pollution, the past geographic distribution of atmospheric lead deposition in Sweden, and the fate of the pollution lead in boreal forest soils. The paper is based on analyses of 206Pb/207Pb isotope ratios and lead concentrations in lake sediments, peat deposits and soil profiles from Sweden. The first signs of atmospheric lead pollution date back to 3500 to 4000 years ago. There was a small, but clear peak during the Greek-Roman period around 0 AD. About 1000 AD a major and unreversed increase occurred; varved lake sediments disclose pollution peaks at about 1200 AD and 1530 AD, which match peaks in metallurgy in Europe. With the Industrial Revolution atmospheric lead pollution increased, however, not as much as usually suggested, and not at all from what can be called background values. Lead pollution increased markedly after World War II, peaked about 1970, and will, if the present trend continues, soon be back to Medieval levels. The distribution of pre-industrial pollution was similar to the contemporary pattern with a strong south to north gradient, as a result of northward atmospheric transport from continental Europe and the British Isles. The cumulative load of pollution lead through time is 2 to 3 g m-2 in S Sweden, and of this load at (east 50% was deposited prior to 1800 AD. In boreal forest soils, the main part of this pollution lead has accumulated in the B horizon. Present-day concentrations in the mor layer are up to 1000 times higher than in the pristine forest prior to pollution.Ambio, Vol. 29, No. 3, pp. 150-156, 2000
