滇西保山-临沧地区土壤元素背景值特征及成因分析

Characteristics and Genesis of Soil Element Background Baoshan-Lincang Area in Western Yunnan Province

基于滇西保山-临沧地区土地质量地球化学调查数据资料,采用具有稳健特性的中位数表征表层土壤53种元素的地球化学背景值,对比了不同成土母质和不同用地类型元素分布特征和富集贫化规律,在此基础上采用因子分析从元素组合特征角度剖析了地球化学背景值的成因机制.结果表明,研究区土壤中As、Hg、Cr、Mn、Sn等9种元素含量明显高于全国和云南省背景值;W、Mo、Sb、U含量高于全国水平但低于云南省背景值;CaO、MgO、Na_(2)O含量低于全国水平但高于云南省背景值;Be、Ba、Cd含量与全国水平相当但高于云南省背景值;Cu、Ni、Pb、Zn、I等19种元素含量高于全国水平但与云南省背景值相当.成土母质是表层土壤元素地球化学背景值的主要控制因素,用地类型对背景值亦有一定的影响.因子分析表明风化作用、淋滤作用、生物富集作用、黏土物理化学吸附作用和人类生产活动共同影响着研究区表层土壤的背景值特征,其中母岩的风化作用起着重要作用.研究成果为区域资源环境评价提供了基础地球化学信息.

Based on the geochemical survey data of land quality Baoshan-Lincang area in western Yunnan Province,the geochemical background of 53 elements in surface soil were characterized by the median with robust characteristics.Their distribution and enrichment or dilution features of elements in different parent materials and land use types were compared.On this basis,factor analysis was used to analyze the genetic mechanism of geochemical background from the perspective of element combination characteristics.The results showed that the contents of As,Hg,Cr,Mn,Sn and other 9 elements were significantly higher than the national and Yunnan background.The contents of W,Mo,Sb and U were higher than the national level but lower than the background of Yunnan Province.The contents of CaO,MgO and Na_(2)O were lower than the national level but higher than the background of Yunnan Province.The contents of Be,Ba and Cd were similar to the national level but higher than the background of Yunnan Province.Nineteen elements,such as Cu,Ni,Pb,Zn,I,were higher than the national level,but similar to the background of Yunnan Province.Soil forming parent material is the main controlling factor of geochemical background of surface soil elements.Land use types also has certain influence on background.Factor analysis shows that weathering,leaching,bioaccumulation,clay physicochemical adsorption and human activities jointly affect the background value characteristics of surface soil in the study area,and the weathering of parent rock plays an important role.The research results provide basic geochemical information for regional resource environment assessment.