摘要
本研究以广西桂林市毛村岩溶区为研究对象,针对棕色、黑色和红色石灰土中重金属(Cu、Pb、Zn、Cr、Cd)的富集特征及环境风险展开分析。通过测试土壤理化性质、重金属含量与形态,结合风险评价指数(RAC),评估土壤重金属的富集特征和环境风险。结果表明:(1)石灰土重金属背景值普遍较高,其中Zn含量超过土壤环境质量二级标准,Cd含量显著高于三级标准,生态环境风险突出;黑色石灰土因脱钙不完全导致重金属残留量最高,红色石灰土中Zn富集程度最高(545.02 mg·kg^(-1)),这应与其高粘组分强烈的外源聚集能力有关。(2)形态分析显示,Cr、Cu、Zn和Pb以残余态为主(48.21%~96%),体现自然源属性;而Cd非残余态占比高达80%,表明其强人为输入特征。石灰土中可交换态含量极低(<1%),但可还原和可氧化态占比高,这与其高有机质和矿物质的特性一致。(3)RAC评价表明,仅有黑色石灰土的RAC值普遍低于10%,不存在风险,而对于棕色石灰土来说,其Cd、Cu和Zn的RAC值均超过15%,存在中等风险,因此,需要警惕棕色石灰土用作耕地,并建议优先强化棕色石灰土的污染治理和管控。
This study investigated the enrichment characteristics and environmental risks of heavy metals(Cu,Pb,Zn,Cr,Cd)in three types of limestone soils(brown,black,and red)in the karst area of Maocun Village,Guilin,Guangxi.By analyzing soil physicochemical properties,heavy metal concentrations,and speciation,combined with the Risk Assessment Code(RAC),the enrichment characteristics and environmental risks of heavy metals in the soil were evaluated.The results showed that:(1)The background values of heavy metals in limestone soils were generally high.The concentration of Zn exceeded the Grade II soil environmental quality standard,while the concentration of Cd significantly surpassed the Grade III standard,indicating high ecological risks.Black limestone soil exhibited the highest residual heavy metal content due to incomplete decalcification,while red limestone soil showed the highest Zn enrichment(545.02 mg·kg^(-1)),likely linked to cornfield cultivation and external inputs.(2)Speciation analysis revealed that Cr,Cu,Zn,and Pb were predominantly in residual forms(48.21%~96%),reflecting natural sources.In contrast,Cd was dominated by non-residual forms(80%,mainly iron-manganese oxide-bound),indicating strong anthropogenic inputs.Exchangeable fractions were extremely low(<1%),but iron-manganese oxide and organic-bound fractions were prominent,associated with high organic matter and iron content.(3)RAC assessment indicated moderate risks(RAC>10%)for Cd,Cu,and Zn in brown limestone soil,and for Cr in red limestone soil;other metals posed low risks.Cd’s high bioavailability necessitates attention to its food chain migration risks.The study proposes prioritizing Cd and Zn control by reducing agricultural and mining inputs,optimizing land use,and implementing organic amendments and long-term monitoring.This research provides a scientific basis for heavy metal pollution management in karst areas.
作者
郝玉培
赵茜倩
刘昆鑫
Hao Yupei;Zhao Xiqian;Liu Kunxin(Department of Modern Engineering,Anshun Technical College,Anshun 561000,China;School of Geography and Environmental Science,Guizhou Normal University,Guiyang 550025,China;111 Geological Party,Guizhou Bureau of Geology and Mineral Exploration&Development,Guiyang 550081,China)
出处
《广东化工》
2025年第17期98-100,105,共4页
Guangdong Chemical Industry
基金
安顺职业技术学院院级基金项目重点课题(安职院重点基金合X202302号)
云南省地质矿产勘查开发局科技创新项目(云地实[2025]2号)。
关键词
岩溶区
石灰土
重金属
环境风险
RAC
karst area
limestone soil
heavy metals
environmental risk
RAC
