模拟降雨条件下22种典型土壤镉的淋溶特征及影响因子分析  

Effect of simulated rain on leaching of cadmium from 22 typical soils and key factors identification

作　　者：郑顺安[1,2] 陈春[1,3] 郑向群[1] 刘书田[1] 师荣光[1] 刘潇威[1,3] 沈跃[1] 

机构地区：[1]农业部环境保护科研监测所,农业部产地环境与农产品安全重点开放实验室,天津市农业环境与农产品安全重点开放实验室,天津300191 [2]农业部农业生态与资源保护总站,北京100125 [3]农业部农产品质量安全环境因子风险评估实验室,天津300191

出　　处：《环境化学》2013年第5期867-873,共7页Environmental Chemistry

基　　金：“十二五”农村领域国家科技计划课题(2012AA101404-5);公益性行业(农业)科研专项(200903015);2012年农业行业标准制定和修订项目“叶菜类蔬菜中镉安全性评价研究”资助

摘　　要：搞清模拟降雨条件下重金属在农田土壤中的淋溶特性,有利于阐释重金属的保蓄性能与迁移转化机制.本研究选取了全国22种典型土壤,通过室内土柱试验,探讨雨水作用下土壤镉的淋溶和释放特征,并对影响土壤镉淋溶特性的因子进行分析.结果表明,22种土壤Cd的释放过程大致分为两类,第1类包括吉林黑土、吉林暗棕壤、吉林黑钙土等7种土壤,此类土壤在整个淋溶过程中淋出液Cd2+浓度极低,未超过地下水水质Ⅲ级标准.第2类包括天津潮土、江西红壤、河北褐土等剩余15种土壤,其Cd释放分为两个阶段,淋溶量未超出4 L时,淋出液中Cd2+浓度较高,对地下水及环境威胁较大;超出4 L后,Cd释放速率明显变缓,浓度降低至Ⅲ级标准以下.逐步回归分析的结果显示,土壤中Cd含量、阳离子交换量(CEC)、游离氧化铁含量及pH对降雨作用下土壤Cd释放有重要作用,四者累计的决定系数达到了0.9609,其中土壤中Cd含量所占权重最高,且对累计释放量作用为正,其次为CEC,作用为负.游离铁和pH合计所占权重较低,作用也为负.Leaching characteristics of heavy metals were closely related to their transformation and migration in soils. However, the information on the leach ability of heavy metals in typical Chinese soils was rather limited. This work was conducted to study the leaching characteristics of cadmium （Cd） and their related influence factors in 22 Chinese soils under simulated rain through column experiment. The results indicated that, 22 soils can be divided into two classes. Class 1 included black soil from Jilin, dark brawn soil from Jilin, chernozem from Jilin, loessial soil from Shanxi, paddy soil from Suzhou, felty soil from Tibet and yellow soil from Guizhou. Concentrations of Cd2~ in soil leachates from class 1 during leaching process were inconsistent and very low, less than Groundwater Quality Standard for Class lll. Class 2 included the other 15 soils （fluvo-aquic soil from Tianjin, red soil from Jiangxi, brown soil from Hebei, paddy soil from Hunan, laterite from Hainan, yellow brown soil from Nanjing, lateritic red soil from Nanning, chestnut soil from Inner Mongolia and so on）. The release mechanism of Cd in these soils appears to be consisted of two phases involving the initial rapid process （leachate are less than 4 L） followed by a slow continuous process （leachate exceeds 4 L）. In rapid process, the concentrations of Cd in leachate were comparatively higher. In slow process, the concentrations of Cd in leachate were very low compared with Groundwater Quality Standard for Class 1II. Stepwise multiple regression analysis showed that release of Cd from soils might be related to soil total Cd, CEC, pH and free Fe oxides of soil. These 4 factors could describe 96.09% of the variability in Cd release from soils, which followed by the order： total Cd 〉 CEC 〉 pH plus free Fe oxides. Soil total Cd had positive influence on Cd release, while CEC, pH and free Fe oxides had negative influence.

关 键 词：镉 淋溶 模拟降雨 影响因子 

分 类 号：X144[环境科学与工程—环境科学]