抑制土壤汞进入陆生食物链

DEPRESSION OF SOIL MERCURY ENTERING TERRESTRIAL FOOD CHAIN

土壤对Ｈｇ￣（２＋）有自净力，其作用实质是Ｈｇ的形态转化．本研究试验了膨润土、腐殖质、碳酸钙对汞形态转化的影响．结果表明，膨润土是使Ｈｇ￣（２＋）迅速向残留态转化而降低作物对汞的吸收，其效果在用量为０─４５０ｇ／ｋｇ范围呈线性增长；腐殖质使Ｈｇ￣（２＋）迅速向腐殖质态汞转化，且有与矿质粘粒争夺Ｈｇ￣（２＋）之势，故最适用量因土壤粘粒含量而异；碳酸钙也使Ｈｇ￣（２＋）向残留态转化，对酸性土的最佳用量，以使土壤的钙饱和度达到５０％—８５％为好。

The influences of bentonite,humus and CaCO_3 on transformation of mercury in soilwere investigated. The results showed that bentonite, humus, and CaCO_3 are able to stimu-late the transformation of Hg from ion to other bonding forms and consequently depress ad-sorption of Hg by plant. Bentonite depressed the Hg adsorption linearly correlated with itscontent within a range of 0─450 g/kg.Humus competed with soil clay for Hg￣(2+) and the re-lation of content-response correlated with clay content of the sample. CaCO_3 was effective todepress plant Hg uptake from soil under certain conditions.The mechanism of CaCO_3 issomewhat similar to that of bentonite.