汨罗市白塘镇-桃林寺镇土壤镉元素分布特征及成因分析

Distribution Characteristics and Genesis Analysis of Cadmium in Soil of Baitang Town-Taolin Temple Town,Miluo City

针对汨罗市白塘镇-桃林寺镇土壤镉污染情况,基于网格布点法系统采集1:5万表层土壤和垂向剖面土壤样品,对土壤的As、Cd、Pb、Cu、Zn、Ni、Cr、Hg元素含量及pH进行测定,采取统计学与GIS相结合的方法重点研究镉元素空间分布特征及其变化规律与异常成因。结果表明:区内表层土壤镉元素平均浓度为0.25 mg/kg,变化幅度为0.03~2.55 mg/kg,高于全国背景值,但低于洞庭-江汉平原土壤背景值;研究区表层土壤镉分布特点受土壤p H值、土地利用类型、成土母质影响,且在表层土壤明显富集;垂向剖面指示了研究区西北一带深层土壤还受到湘江重金属污染影响。通过PCA主成分分析表明,区内土壤镉元素主要来源于湘江搬运而来的物质经农田灌溉进入土壤,其次是大气干湿沉降物和成土母质。研究结果可以为研究区农田土壤重金属污染防控对策制定提供科学依据。

According to the soil cadmium pollution in Baitang Town and Taolinsi Town,Miluo City,1:50,000 surface soil and vertical soil samples were collected based on grid distribution method,and the contents of As,Cd,Pb,Cu,Zn,Ni,Cr,Hg and pH of soil were determined.The method of statistics and GIS,the spatial distribution characteristics of cadmium,its changing rules and abnormal genesis were studied.The results showed that the average concentration of cadmium in surface soil was 0.25 mg/kg with a range of 0.03~2.55 mg/kg,higher than the national background value,but lower than the Dongting Jianghan Plain soil background value.The distribution characteristics of cadmium in surface soil in the study area were affected by soil pH value,land use type and parent material,and cadmium was obviously enriched in surface soil.The vertical profile indicates that the deep soil in the northwest of the study area is also affected by heavy metal pollution from Xiangjiang River.The principal component analysis of PCA showed that the cadmium element mainly came from the material transported from Xiangjiang River into the soil through farmland irrigation,