摘要
我国岩溶地貌主要分布在广西、贵州、云南等西南地区,全国土壤污染状况调查公报显示这些岩溶区土壤中金属元素通常超标严重,其生物有效性的相关研究仍较缺乏.采集广西典型岩溶重金属地质高背景地区的稻田土壤,分析金属元素As,Cd,Cr,Cu,Ni,Pb和Zn总量,并采用CaCl2和EDTA(Ethylene Diamine Tetraacetic Acid)提取方法分析土壤中金属的生物有效态含量.结果表明,与上部地壳相比,研究区土壤中不同重金属的富集程度顺序为Cd>As>Pb>Zn>Cr>Cu>Ni,与广西灰岩中这些重金属的富集程度顺序基本一致,揭示岩溶区地质高背景土壤重金属的富集具有显著的母岩继承性.土壤Cd的CaCl2提取的平均含量为0.02mg·kg-1,平均提取率为4.37%,远低于人为污染区土壤Cd的CaCl2提取的平均含量和提取率.EDTA提取态Cd的含量平均值为0.84mg·kg-1,平均提取率为52.86%.岩溶区土壤Cd的CaCl2提取态含量与土壤Cd总量没有明显的线性关系,生物有效性和生态风险主要受pH控制:当土壤pH>6.5时,虽然土壤Cd总量较高,但CaCl2提取态Cd含量偏低,生态风险低;而当土壤pH<6.5,土壤Cd总量相对偏低时,CaCl2提取态Cd含量较高,生态风险较高。
China's karst landforms are mainly distributed in Guangxi, Guizhou, Yunnan provinces and other southwest regions. According to the national soil pollution survey bulletin, the concentrations of metal elements in soils of these karst areas usually exceed the national standard, and the relevant research on the metal bioavailability is still lacking. The total concentrations of metals (As,Cd,Cr,Cu,Ni,Pb and Zn) in the paddy soils from typical karst areas in Guangxi were analyzed, and the chemical bioavailable concentrations of these metals in the soils were analyzed by using the chemical extraction methods of CaCl2 and EDTA(Ethylene Diamine Tetraacetic Acid). The Results showed that compared with that in the upper crust,different degree of enrichment of heavy metals in soils from the study area in order for the Cd>As>Pb>Zn>Cr>Cu>Ni, which is basically consistent with the order of concentrations of these heavy metals in Guangxi limestones, it is revealed that heavy metals in the soils from geogenic background karst area has significant inheritance from the parent rock. The average concentration of CaCl2 extracted from soil Cd in the karst areas was 0.02 mg · kg-1,and the average extraction rate was 4.37%,far lower than the average concentration and the average extraction rate for soil Cd in anthropogenic contaminated areas.The average concentration of EDTA extracted Cd was 0.84 mg · kg-1, and the extraction rate was 52.86%. The study found that there was no significant linear relationship between the concentration of CaCl2 extracted Cd and the total concentration of soil Cd in karst areas. The bioavailability and ecological risk were mainly controlled by pH. When the soil pH was higher than 6.5, although the total concentration of soil Cd was high,the concentration of CaCl2 extracted Cd and the ecological risk were low. However, when the soil pH was lower than 6.5 and the total concentration of soil Cd was relatively low,the concentration of CaCl2 extracted Cd and the ecological risk were higher.
作者
郭超
文宇博
杨忠芳
李伟
管冬兴
季峻峰
Guo Chao;Wen Yubo;Yang Zhongfang;Li Wei;Guan Dongxing;Ji Junfeng(Key laboratory of Surficial Geochemistry Ministry of Education,School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing,100083,China)
出处
《南京大学学报（自然科学版）》
CAS
CSCD
北大核心
2019年第4期678-687,共10页
Journal of Nanjing University（Natural Science）
基金
国家重点研发计划(2017YFD0800303)
广西典型土壤重金属生态地球化学调查项目,西南典型岩溶地区多目标地球化学调查(12120114092001)
关键词
地质高背景
岩溶区土壤
镉
CaCl
high geogenic background
karst soil
cadmium
CaCl2 extraction
bioavailability
