北京平原区元素的大气干湿沉降通量

Dry and wet atmospheric deposition fluxes of elements in the Plain area of Beijing Municipality,China

从2005年11月到2006年11月,采用被动方式同时采集了北京市平原区10个地点的大气干、湿沉降样品共计39件。分析干、湿沉降样品中K、Na、Ca、Mg、Cd、Hg、Pb、As、B、Mo、Mn、Zn、Cu、Cr、Ni元素的含量,分别计算出各元素的年沉降通量。其中,有害金属元素Cd、Hg、Pb、As的年沉降通量的平均值分别为2.36、0.24、219.95、29.00(g/hm2·a)。对比后发现,研究区大气中Cd和Hg的年输入通量远远低于四川成都经济区,Cd和Hg的大气污染状况相对南方地区较轻,As和Pb的年输入通量相对成都经济区差异较小。研究区元素的大气沉降通量与同点位的土壤元素的相关分析表明,元素的沉降通量并不是农田生态系统中土壤元素的主要输入途径,大气沉降中的元素主要来自远源。

From November 2005 to November 2006, 39 samples of dry and wet atmospheric deposition were collected from ten sites in the Plain area of Beijing Municipality, The samples were filtered and divided into soluble and insoluble fractions and analyzed for K, Na,Ca, Mg, Cd, Hg, Pb, As, B, Mo, Mn, Zn, Cu, Cr and Ni contents. The annual deposition fluxes of the 15 elements were calculated respectively. Of these elements, the average deposition fluxes of the harmful heavy metal elements Cd, Hg, Pb and As are 2.36, 0.24, 219,95 and 29.00 g/hm^2.a respectively, Comparison of the deposition fluxes of the heavy metal elements shows that： the annual loadings of Cd and Hg in the atmosphere in the study area are far lower than those in the Chengdu economic area, Sichuan; the Cd and Hg pollution in the atmosphere is weaker than in southern China; and the annual loadings of As and Pb have little difference as compared with the Chengdu economic area. Correlation analysis of the deposition flux of elements in the atmosphere and that in softs at the same site in the study area shows that the element deposition fluxes are not the main input way of the elements in soils in the farmland ecosystem, and the elements in atmospheric fallouts came mainly from distal sources.