典型碳酸盐岩区耕地土壤剖面重金属形态迁移转化特征及生态风险评价  

Migration,Transformation Characteristics,and Ecological Risk Evaluation of Heavy Metal Fractions in Cultivated Soil Profiles in a Typical Carbonate-Covered Area

作　　者：唐世琪 刘秀金[1,2,3] 杨柯 郭飞[1,2,3] 杨峥 马宏宏 刘飞[1,2,3] 彭敏 李括 TANG Shi-qi;LIU Xiu-jin;YANG Ke;GUO Fei;YANG Zheng;MA Hong-hong;LIU Fei;PENG Min;LI Kuo(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Sciences,Langfang 065000,China;Research Center of Geochemical Survey and Assessment on Land Quality,China Geological Survey,Langfang 065000,China;Key Laboratory of Geochemical Cycling of Carbon and Mercury in the Earth's Critical Zone,Chinese Academy of Geological Sciences,Langfang 065000,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000 [2]中国地质调查局土地质量地球化学调查评价研究中心,廊坊065000 [3]中国地质科学院地球表层碳-汞地球化学循环重点实验室,廊坊065000

出　　处：《环境科学》2021年第8期3913-3923,共11页Environmental Science

基　　金：中国地质调查局项目(DD20190518)。

摘　　要：碳酸盐岩土壤母质区是我国耕地土壤重金属高含量的主要分布区,且耕地重金属迁移转化受到自然过程与人为活动的交互影响.以广西碳酸盐岩母质水田9条土壤剖面为研究对象,在分析测试土壤Cd、As、Zn、Cr、Cu、Hg、Ni和Pb含量、pH、Corg含量等土壤性质指标以及Cd、As、Zn和Cr赋存形态基础上,重点探讨了研究区耕地土壤重金属形态垂向分布特征、重金属生态风险以及对比在自然成土过程中和人为活动干扰下重金属迁移转化的影响因素.结果表明,研究区土壤剖面中Cd、As、Zn和Cr存在样本超农用地(水田)污染风险筛选值,Cd和As部分超管制值.土壤剖面Cd各形态均有一定比例分布,且随剖面深度由浅至深,Cd生态风险较高的水溶态、离子交换态比例呈显著下降趋势;土壤剖面As、Zn和Cr各深度段均以残渣态为主,随深度加深,水溶态和离子交换态比例变化不大.风险评价编码法(RAC)和次生相与原生相分布比值法(RSP)评价结果显示,研究区土壤Cd污染风险相对较高,总体上As、Zn和Cr处于无污染或无风险状态.研究区自然发育的土壤,黏土矿物含量和土壤发育程度对Cd迁移活动性的影响较为显著,而受人为活动影响的耕作层中,土壤pH与有机质含量则成为其迁移活动性的主控因素;土壤As的迁移能力主要与土壤有机质、Fe_(2)O_(3)含量以及土壤发育程度有关,但在耕作层中,有机质对其控制作用明显增强;土壤中Zn、Cr迁移能力的主控因素均为pH,而在人类活动干扰下,pH对其影响更为强烈.In China,high heavy metal concentrations in cultivated soil are mainly distributed in carbonate-covered areas.The migration and transformation of heavy metals in such soils are influenced by interactions between natural processes and human activities.This study examined the profiles of nine paddy soils,derived from carbonate rocks in Guangxi.The Cd,As,Zn,Cr,Cu,Hg,Ni,and Pb contents we determined,and soil properties such as pH,Corg content,and fractions of Cd,As,Zn,and Cr were tested.Based on the above data,we assessed the vertical distribution of heavy metal fractions,as well as the ecological risks and factors affecting the migration ability of heavy metals,under the influence of human activities and natural soil formation.The results show that compared with the carbonate rocks in Guangxi,the soil profile of the study area is significantly enriched with all eight heavy metals.Among them,Cd,As,Zn,and Cr exceeded China’s agricultural land(paddy field) pollution risk screening values,and Cd and As partially exceed the risk intervention values.All fractions of Cd in the soil profiles are widely distributed.The proportion of water-soluble and ion-exchange Cd fractions with high ecological risk decreased significantly from the surface to greater depths in the soil profile.As,Zn,and Cr in the soil profile were mainly in residual states,and the proportion of water-soluble and ion-exchange fractions did not change considerably with increasing depth.The evaluation results of RAC and RSP show that Cd pollution risk in the study area is relatively high,whereas As,Zn,and Cr are generally pollution-free or risk-free.In naturally developed soil in the study area,the clay mineral content and degree of soil development have significant effects on Cd migration,whereas in the cultivated layer affected by human activities,the soil pH and organic matter content are the main controlling factors.The migration ability of soil As is mainly related to soil organic matter,Fe_(2)O_(3) content,and soil development degree,but organic matte

关 键 词：碳酸盐岩 耕地 土壤剖面 重金属形态 迁移转化 生态风险 

分 类 号：X53[环境科学与工程—环境工程]