摘要
为了解地质低背景区农田土壤-作物系统中重金属的富集及迁移特征,采集了广西钦北区878 km^(2)酸性火成岩出露区的30套水稻籽实及根系土样品作为研究对象,研究酸性火成岩地质低背景区土壤和水稻中重金属(As、Cd、Cr、Cu、Hg、Ni、Pb和Zn)分布特征、土壤Cd等重金属的赋存状态及其生物有效性。结果显示:研究区土壤呈酸性,pH值为4.66~5.36;Cd、As、Cr等重金属元素含量较低,均低于或远低于我国土壤环境质量标准规定的风险筛选值,水稻籽实中As、Cr、Hg和Pb均未超标,但Cd超标率为16.7%。土壤中As和Pb主要以残渣态存在,Hg主要以残渣态和强有机结合态存在,而Cd的生物富集系数和生物有效性最高,水溶态、离子交换态和碳酸盐结合态的比例总和为32%。水稻籽实吸收Cd等重金属主要与土壤pH值、Fe、Mn和土壤质地有关。酸性火成岩地质低背景区农田酸性、强酸性土壤Cd等重金属元素含量低,但生物有效性高,其生态风险值得关注。
In order to understand the transfer characteristics of heavy metals in farmland soil-crop system with low geochemical background,30 paired rice grain and soil samples from 878 km^(2) acid magmatic rock area outcropped in Qinbei district of Guangxi were collected.Specifically,the distribution of heavy metals(As,Cd,Cr,Cu,Hg,Ni,Pb and Zn)in the soils and rice grains,the fractionations and influencing factors on bioavailability of Cd and other metals in the soils were studied.The results showed that soil pH values in studied area ranged from 4.66 to 5.36,which was acidic.The concentrations of Cd,As,Cr and other heavy metals were all lower than or far below the risk screening values specified in Chinese soil environmental quality standard(GB15618—2018).In rice grains from the studied area,As,Cr,Hg and Pb did not exceed the standard;but for Cd an exceedance rate of 16.7%was observed.In soils,As and Pb mainly existed in the residual fraction,Hg mainly existed in the residual and strong organic binding fractions.Moreover,the bioconcentration factor(BCF)and bioavailability of Cd were the highest with 32%being the water soluble,ion exchangeable and carbonate binding fractions.The transfer of heavy metals from soil to rice grains is mainly related to soil pH value,Fe,Mn,and soil texture.Therefore,the ecological risk of heavy metals in farmland in acid magmatic rock area with low geochemical background is worthy of attention due to its acidic/strongly acidic soil with heavy metals being of low levels but high bioavailability.
作者
杨琼
杨忠芳
刘旭
余涛
王磊
吴天生
张起钻
季峻峰
YANG Qiong;YANG Zhongfang;LIU Xu;YU Tao;WANG Lei;WU Tiansheng;ZHANG Qizuan;JI Junfeng(School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;School of Agricultural Sciences, Zhengzhou University, Zhengzhou 450001, Henan, China;School of Science, China University of Geosciences, Beijing 100083, China;Guangxi Bureau of Geology & Mineral Prospecting & Exploitation, Nanning 530023, Guangxi, China;Geology Team No.4 of Guangxi Zhuang Autonomic Region, Nanning 530031, Guangxi, China;Guangxi Institute of Geological Survey, Nanning 530023, Guangxi, China;Tianjin Center, China Geological Survey, Tianjin 300170, China;Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, Jiangsu, China)
出处
《华东地质》
2022年第1期49-60,共12页
East China Geology
基金
中国地质大学(北京)地调成果转化基金(编号:202001)
国家重点研发计划项目(编号:2017YFD0800300)
“广西中东部地区土壤硒元素和重金属元素地球化学研究(编号:桂国土资函[2015]44号)”
“广西土壤Se、Ge、Cd等元素异常成因与生态效应研究(编号:桂国土资函[2017]2676号)”
“广西典型土壤重金属生态地球化学研究(编号:桂环函[2018]275号)”
《全国土壤污染状况详查示范》委托业务“广西土壤重金属地质高背景区污染识别与生态风险评价(编号:IGGEW2018005)”项目联合资助。
关键词
酸性火成岩区
地质低背景
土壤
水稻籽实
重金属
生态风险
acid magmatic rock area
low geochemical background
soil
rice grain
heavy metals
ecological risk
