利用放射性同位素115+115mCd对两种污灌土壤中不同形态镉的研究

重金属镉对作物的危害,除了与植物的种、属特性有关之外,还与镉在土壤中的形态密切相关.因此,深入研究镉在土壤中的形态,对镉污染的防治有一定的指导作用. 对于镉在土壤中形态的研究,目前的状况一是研究得还不够多,二是有关形态的分类提法不一.日本园田把镉在土壤中的形态分为全量、交换态、可给态和碱溶态,并认为污染土壤中,交换态占大部分.美国的Silvera等则把它分为水溶态、交换态、可给态和不溶态.我们把这两种提法结合起来,根据我国土壤的特点,将其分为全量、交换态、可给态、碱溶态和水溶态来研究。

STUDY ON CADMIUM FORMS IN WASTEW ATER-IRRIGATED SOIL WITH 115+115mCd

Experimental results were obtained by using tracer of 115+115mCd after the method of Yoji Sonoda and Silvera, D. J., Soil samples were collected at two wastewater-irrigated areas, one being acid meadow brown soil in Shenyang, and the other solonized light meadow soil in Tianjin.Experimental results are summarized as follows:1. 54-72% of Cd exists in exchangeable form in these soils.2. The rate of alkali-soluble form is increasing and the rate of exchangeable form is decreasing with increase of pH, This is in accord with results of Yoji Sonoda.3. For extraction of available form of Cd in alkaline soil, a 0.005M solution of DTPA is preferred, because extraction is not complete with 0.1N HCl by Yoji Sonoda's.