昆山农地砷分布及成因探讨

Arsenic Distribution in Agricultural Land of Kunshan and Investigation of Its Contributing Factors

土壤中的砷会经作物和径流等途径转移,甚至进入食物链而对人产生危害。为了解影响农用地土壤中砷含量的因素,选择江苏昆山农地为研究对象,探讨地理区位、土地利用方式、土壤特性与农用地土壤砷含量的关系,并用逐步回归法建立了昆山农地土壤砷含量与土壤理化参数关系的回归方程。研究表明:地形和农田的氧化还原环境会改变土壤砷含量,因此,地势高处的土壤砷含量高于地势低处,旱地高水田低。不同利用方式的旱地土壤的砷含量也不同,林地>抛荒地>菜地>玉米-西瓜田>苗圃。此外,土壤砷含量还与化肥施用量正相关,并与土壤黏粒呈正相关,却与土壤pH、有机质、全氮和细砂粒含量呈负相关。

Arsenic （As） in agricultural soil will be transferred into food chain through plants and runoff so that human health is threatened by contaminated food or water. In order to determine the factors impacting the As concentration in agricultural soil, the agricultural lands in Kunshan were chosen as the study sites. The relationship between As concentration in soil and the geographical districts, land use types, soil chemical-physical properties were discussed. The regression equations about As concentration in soil and soil chemical-physical properties were set up by step regression. It is indicated that the topography and the environment of the oxidation and reduction can change the As concentration in soil. Therefore, the As concentration in upper of terrain was higher than that in lower of terrain and the As concentration in the dry land was higher than that in paddy field. Even in the dry land the As concentrations in the different use types were also different. The As concentration order from large to small in dry land soil was forest soil, uncultivated land and wasteland, vegetable garden, maize and watermelon fields, nursery of young stocks and flowers. In addition, the As concentration has positive correlation with the percent of clay and has negative correlation with pH, the organic matter, the total nitrogen and the percent of silt.