Effects of humic susbstances on adsorption of diledrin in soil

狄氏剂是一种持久性有机污染物（POPs）和有机氯农药。尽管狄氏剂的使用已经被限制或禁止了三十多年，但这种化学物质仍然在一些作物中被检测到，特别是在葫芦科作物中。具有高疏水性的有机化学物质紧密地吸附在土壤颗粒上，因此通常这些化学物质很难被植物从土壤中吸收。土壤中狄氏剂的残留已转化为结合态残留，大部分不能被植物吸收。然而，包括狄氏剂在内的一些持久性有机污染物已经存在了三十多年，但以某种方式被葫芦吸收，这表明这些土壤中仍然存在生物可利用的持久性有机污染物。研究了土壤中狄氏剂的存在形式，认为土壤有机质是持久性有机污染物在土壤中的主要吸附部位。因此，从土壤中提取腐殖酸、腐植酸和胡敏素，用批处理法研究了狄氏剂在这些腐殖酸上的吸附，结果表明，去除腐殖酸和腐植酸的土壤对狄氏剂的吸附量低于未处理的土壤。结果表明，腐殖酸和富里酸影响土壤对狄氏剂的吸附。

Dieldrin is one of persistent organic pollutants (POPs) and organochlorine pesticides. Although the use of dieldrin has been restricted or banned for more than three decades, the chemical is still detected in some crops, especially in cucurbits. Organic chemicals with high hydrophobicity tightly adsorb on soil particles, and thus usually these chemicals are hardly taken up by plants from soil. Furthermore, the residual dieldrin in soil must have changed to bound residue, and most of it cannot be taken up by plants. However, some POPs including dieldrin, which have existed over three decades, are somehow taken up by cucurbits, which suggests that bioavailable POPs still exist in those soils. In the present study, the existence form of dieldrin in soil was examined.It has been suggested that the main adsorption sites of POPs on soil are soil organic matters. Therefore, both humic and fluvic acids and humin were extracted from soil, and the adsorptions of dieldrin on these humic substances were examined by batch method.The adsorption amounts of dieldrin on soil removed humic and fluvic acids were lower than those on the soil without treatment. These results suggest that humic acid and fulvic acids affected on the adsorption of dieldrin on soil.