中国南方喀斯特集中分布区土壤Cd污染特征及来源

Pollution characteristics and sources of cadmium in soils of the karst area in South China

土壤重金属污染问题已成为我国广泛关注的生态环境问题,开展喀斯特地区土壤中Cd污染分布规律及来源研究,可为土壤环境质量评价与管理提供依据。本文收集了近年来南方八省206个市(区)土壤Cd的相关研究文献数据,采用单因子污染指数法对土壤Cd污染状况进行评价、Pearson相关分析研究喀斯特出露面积比与土壤Cd含量相关关系,并对来源进行探讨。结果表明:(1)中国南方喀斯特地区土壤具有较高的Cd含量,几何平均含量为0.36 mg·kg^(-1),高于全国土壤平均值、世界平均值及区域非喀斯特地区平均值;(2)不同省份污染程度趋势为广西>湖南>四川>广东>贵州>重庆>云南>湖北;(3)人为活动,无论矿业开发、城镇化、农业活动均不是中国南方喀斯特地区土壤Cd含量高的主要因素;碳酸盐岩Cd背景值高及碳酸盐岩风化成土Cd的相对富集,是中国南方喀斯特地区土壤Cd含量高的主要自然因素。

Heavy metal pollution in soils has become an extensive concern of the ecological environment problems in China. Understanding of distribution and source of Cd pollution in soil in karst areas could provide a basis for the assessment and management of soil environmental quality. Here,we collected the soil Cd related research literature,which covers 206 cities（ counties）from eight provinces of southern China. We used the single factor pollution index method to evaluate Cd pollution levels and used the Pearson＇s correlation analysis to reveal the linkage between the Cd concentrations and the area of exposed carbonate rock,and discussed the source of pollution. The results showed that：（ 1） The soil in karst areas of southern China had high Cd concentration,with a geometric mean value of 0.36 mg·kg^-1,which was higher than the national average,the world average and the regional average of non-karst areas.（ 2） The pollution degree in different provinces was in order of Guangxi 〉Hunan 〉Sichuan 〉Guangdong〉 Guizhou 〉Chongqing 〉Yunnan Hubei.（ 3） Anthropogenic activities including mining,urbanization,and agricultural activities were not the main reasons for high soil Cd concentrations in karst areas of southern China. The high background value of Cd in carbonate rocks and the relative enrichment of Cd in weathered carbonate rocks were the main natural factors for high Cd concentrations in karst areas of southern China.