水土流失区土壤硒、锌地球化学特征及其生物有效性——以福建省长汀县为例

Geochemical characteristics and bioavailability of selenium and zinc in soils in an area subjected to water and soil erosion:A case study of Changting County,Fujian Province

水土流失影响着土壤中元素的分布与分配,土壤中硒、锌等微量有益元素在水土流失区的分布、分配规律及其生物有效性是衡量水土流失生态效应的重要因素。针对水土流失区硒、锌的地球化学特征及生物有效性,以福建省长汀县水土流失区为例开展了土壤及农作物地球化学调查,获取了水土流失区土壤及农作物Se、Zn的关键地球化学参数。结果发现:水土流失区土壤Se含量中位值为0.43×10^(-6),Zn含量中位值为46×10^(-6);Se富集于变质岩发育的土壤中,Zn富集于变质岩和花岗岩发育的土壤中;土壤Se、Zn在竹林地中含量相对其他土地利用类型更高;随着水土流失程度的增加,土壤Se含量呈递减趋势;Se、Zn的生物富集系数与土壤w(Si)/w(Al)值呈显著正相关,与土壤Se、Zn以及有机质等指标含量呈显著负相关。结果表明:长汀县水土流失区土壤Se、Zn的分布、分配主要受变质岩和花岗岩的控制;水土流失过程存在显著的土壤Se流失;土壤Se、Zn生物有效性受黏土矿物及有机质吸附的影响而呈现降低,水土流失区土壤中非活性态的Se、Zn可能存在较大比例。

Water and soil erosion affects the distribution and partitioning of elements in soils.The distribution and partitioning patterns and bioavailability of trace beneficial elements such as selenium(Se)and zinc(Zn)in water and soil erosion areas serve as significant factors for measuring the ecological effects of water and soil erosion.Through the geochemical survey of soil and crops,this study investigated the geochemical characteristics and bioavailability of Se and Zn in the water and soil erosion area of Changting County,Fujian Province,obtaining the critical geochemical parameters of Se and Zn in soil and crops in the study area.The results are as follows:(1)The soil Se and Zn contents in the study area show median values of 0.43×10^(-6)and 46×10^(-6),respectively;(2)Se is enriched in the soil developed from metamorphic rocks,whereas Zn is enriched in the soil developed from metamorphic rocks and granites;(3)The soil Se and Zn contents are higher in bamboo forests compared to other land-use types;(4)The soil Se content shows a decreasing trend as the water and soil erosion intensifies;(5)The bio-concentration factors of Se and Zn are significantly positively correlated with w(Si)/w(Al)ratios,and negatively correlated with Se,Zn,and organic matter.As indicated by the results above,the distribution and partitioning of soil trace beneficial elements like Se and Zn in the study area are primarily subjected to metamorphic rocks and granites.The water and soil erosion is accompanied by a significant soil Se loss.The bioavailability of soil Se and Zn is reduced by the adsorption of clay minerals and organic matter.Additionally,there may be a large proportion of inactive Se and Zn in the soil of the water and soil erosion area.