黄土性土壤对砷的净化作用及迁移规律研究

Purification and migration characteristics of arsenic in loessial soil

通过土柱淋滤试验,从动态角度研究了黄土性土壤对砷的净化作用及迁移规律。研究结果表明,黄土性土壤对砷是一次性的吸附净化并达到饱和状态。土壤对砷净化吸附分为3个阶段:全吸附段、部分吸附段和吸附饱和段。受土壤粘粒和钙影响,黄土性土壤中砷运移的速度不同,其顺序为v(粘化层)<v(犁底层+老耕层)<v(耕层)<v(钙积层)。在淋入液质量浓度一定的条件下,土层越厚,淋出液中砷的零值延时越长,饱和吸附时间也越长。当淋入液砷质量浓度为10.0mg/L时,黄土地区土层1.5m深度可作为对砷的净化深度。当一定厚度的土壤层达到砷吸附饱和状态时,如果持续增加污水淋入量,则砷在土层内达到吸附饱和的界限下移。

By leaching experiment in soil columns, the purification and migration characteristics of arsenic in loessial soil were stud-ied. Results showed the arsenic can be quickly absorbed onto loessial soil and reach adsorption saturation. The adsorption and puri-fication of arsenic in loessial soil can be divided into three stages, which were complete adsorption, partial adsorption and saturation adsorption. The migration velocities of arsenic in the columns were decided by the contents of clay and calcium in soil, and were in the following sequence: argillic horizon<plow pan + original topsoil<top soil = calcic horizon. For a constant arsenic concentration, the thicker the soil layer, the longer the time for the arsenic to reach breakthrough and saturation. If the concentration of arsenic were less than 10.0 mg/L, 1.5 meters can be regarded as purification depth. When a certain depth soil layer reached saturated, the limit of saturated absorption would move deeper if the leaching continues.