成都平原土壤铅污染及其评价

采用随机布点方法在成都平原采集了0~20cm耕层土样及20~40cm的底层土样共98个。分析了成都平原土壤铅含量状况，同时用地质累积指数法进行了污染程度评价，并对污染土壤的分布规律以及铅在土壤中的迁移进行了探讨。结果表明：成都平原大多数农田土壤已经受到不同程度的铅污染。在86个耕层土样中，只有20个样点没有受到铅污染。受铅污染的样点中，污染级别为1~4级，以1、2级为主，属无污染到中污染的过渡状态和中度污染。其中1级污染有33个样点（占总样点数的38.4 %），2级污染有30个样点（占总样点数的34.9 %）。个别样点已接近或达到了强度污染的水平。污染土壤的分布与污染源的位置关系密切，与土壤的理化性质也有一定的关系；铅主要累积在0~20cm的耕层土壤，同时也发生了一定的迁移，其数量与土壤理化性质有关。

POLLUTION AND EVALUATION OF Pb IN SOIL IN CHENGDU PLAIN

Ninety eight soil samples of 0~20 cm topsoil and 20~40 cm bottom-soil were taken from Chengdu Plain by random method. The contents of Pb in these samples were detected. The Geoaccumulation Index was used to evaluate heavy metal contamination degree. The distributions of polluted soil and the mobility of Pb were discussed. The results show that most of the cropland soil was polluted. Only 20 samples were not polluted among the 86 samples of 0~20 cm topsoil. Among the polluted soil samples, the contamination grade is from 1 to 4, the grade of 1 and 2 is the major one, and they belong to the state of low-medium and medium contamination grade. Each of the two major grades has 30 soil samples (accounting for 38.4% of the total soil samples) . Few samples has reached intense contamination degree. The distribution of the polluted soil was tightly contacted with the pollution source, and closed to the physical and chemical characters of soil in some degree; Pb was mostly accumulated in 0~20cm topsoil, and mobilized in the soil. The quantity was closed to the physical and chemical characters of the soil.