北京市不同土地利用方式下土壤铬和镍的积累

Chromium and Nickel Accumulations in Soils under Different Land Uses in Beijing Municipality

通过对北京市菜地、稻田、果园、绿化地、麦地以及自然土壤的调查分析,探讨了不同土地利用方式对土壤中铬、镍积累的影响。结果表明,在6种土地利用类型中,按从高到低的顺序土壤铬浓度依次为:菜地>稻田>麦地>绿化地>果园>自然土壤,土壤镍浓度依次为:菜地>稻田>绿化地>麦地>自然土壤>果园。与北京市土壤背景值比较,土壤中铬、镍的浓度并没有普遍增加,仅在菜地以及稻田中存在一定的积累趋势。不同土地利用类型中土壤铬、镍浓度的分布趋势较为一致,二者在土壤中的浓度仍主要受到成土母质的影响,受人类活动的影响仍不太大。

Soil pollution from heavy metals has been concerned by scientists for decades. The mobilization of heavy metals into the biosphere by human activity has become an important process in the geochemical cycling of these metals. Since the human activities vary greatly with the different land use type, it is important to assess the soil environmental quality under the different land use type. Beijing, a city developing with high speed, is suffering the huge changes in land use. Unfortunately, the effects of such changes on the environment still remain unknown. Through the investigation on 6 land-use types, which include the vegetable field, paddy field, orchard, greenbelt, cornfield and natural soil, 607 concentrations for Cr and Ni were obtained. Using background concentration as criterion, the concentrations of Cr and Ni in the soils from vegetable field and paddy field showed obvious increase, especially the concentrations of Cr in the soils. In addition, the concentrations of Cr in the vegetable field soils were significantly higher than those in other land use type soils except paddy field. So it could be concluded that land use showed great effects on the accumulation of Cr and Ni in the soils of vegetable field. In general, Cr and Ni showed the similar distribution in the soil, which might indicate that two elements had the similar source, i.e., parent material. But in greenbelt the concentrations of Cr and Ni were not consistent since the tail gas of automobile affected the concentrations of Ni. So parent rock played quite important roles on the concentrations of Cr and Ni in the soils.