用同位素稀释法研究土壤-植物系统镉的迁移

STUDY ON TRANSFER OF CADMIUM IN SOIL-PLANT SYSTEMS WITH THE ISOTOPIC DILUTION METHOD

本试验用^(109)Cd标记土壤,在盆栽试验条件下研究以水溶性盐和以污泥形式进入土壤的镉,以及土壤原有镉在土壤-植物系统的实际迁移率,并用同位素放射性比度比较的方法分析了0.1MCaCl_2、DTPA和0.1N HCl浸提镉与植物吸收镉的关系。结果表明,以水溶性镉盐处理的土壤,大大提高了黑麦草植株的镉浓度。在加镉处理的土壤中,植物主要吸收外加镉,外加镉向植物地上部的实际迁移率大子土壤原有的镉。以水溶性盐进入土壤的镉的迁移率。为污泥镉的2～3倍。0.1M CaCl_2浸提镉与植物吸收镉的放射性比度较为接近,0.1N HCl则浸提出了一部分植物难以吸收的镉。

Experiments were conducted to determine the transfer rate from endogenous and exogenous cadmium in soil to plants.Soils were labelled with 109Cd and amended with soluble cadmium salt or Cd containing sewage sludge.Ryegrass (Lolium perenne L.) were grown in pots and the effective transfer of cadmium from different sources to shoot of the plant were measured.The soils were also extracted with 0.1 M CaCl2 DTPA and 0.1N HC1.The results showed that the addition of soluble cadmium salt substantially increassed the plant cadmium content.Plant absorbed mainly the cadmium from exogenous sources in the soils treated with cadmium.The effective transfer rate of exogenous cadmium was higher than that of endogenous ones,and the soluble salt form was 2 to 3 times higher than that in the sewage sludge.0.1 M CaCl2 extracted Cd was significantly correlated with the plant cadmium content.The specific radioactivity of cadmium extracted by this reagent was nearer to the plant cadmium than that extracted by others.0.1 N HCl extracted cadmium could not be absorbed by plants.