重庆市土壤-蔬菜系统中重金属的分布特征及其化学调控研究

Distribution and Control of Heavy Metals by Additives in Soil-Vegetable System in Chongqing

采用现场采样及盆栽试验方法,研究了重庆市土壤-蔬菜系统中重金属的分布特征及其化学调控。调查表明,重庆市蔬菜重金属总体上尚未达到污染水平,但其污染危险有随时间推延而升高的趋势。叶菜类蔬菜除砷外,镉、汞、铅等进入临界级。蔬菜中的镉、砷主要来自于土壤,汞、铅则来自于大气。不同类型蔬菜的富集能力为叶菜类>茄果类>豆类>块茎类>瓜类,不同重金属的富集顺序为镉>汞>铅>砷。盆栽试验表明,在高污染背景条件下,添加石灰、腐植酸、硫化钠、亚硒酸钠都能够抑制土壤汞、镉进入蔬菜,但选用腐植酸既能增产,又能降低蔬菜汞、镉含量。汞镉在莴笋各器官的分配仅与重金属元素有关,而与添加的化学物质及其添加量无关,汞主要积累于根部,镉则积累于可食茎叶部分。

The present investigation showed t hat heavy metals in vegetables in Chongqing,have not generally exceeded to official level nowadays,but got more and more serious with times' going.The cadmium,mercury and lead in leaf vegetables accessed to the critical level except arsenic.The c admium and arsenic maybe derived fro m soils while mercury and lead from atmosphere.The concentrations of the heavy metals i n vegetables were in an order:leaf vegetables>eggplant and fruit vegeta bles>bean>root tu-ber>melon,while the concentration s of the heavy metals as cadmium>merc ury>lead>arsenic.Pot experiments showed that mercury and cadmium could be prevent ed from pollution on vegetables by ad ding lime,humic acid,sodium sulfid e and sodium se-lenite under the background of the se rious soil pollution.The humic acid should be applied as first priority s electively because that,it could not only increase the vegeta bles' yield by 8.29%,but also decrease the content of mercury and cadmium in vegetables by32.35%and 18.65%respectively,com pared with the controls.The mercury and cadmiumwere mostly accumulated in the root and cadmium in the edible such as stem and leaf of vegetables.