福建省长汀县重点水土流失区土壤元素地球化学特征及其指示意义

Geochemical characteristics and its indicative significance of soil elements in key soil erosive areas of Changting County, Fujian Province

针对水土流失演化过程中元素地球化学迁移规律这一重要科学问题,对福建省长汀县重点水土流失区开展了土地质量地球化学调查,查明了水土流失区土壤元素地球化学特征,对土壤养分丰缺以及土壤环境生态风险进行了评价。长汀县重点水土流失区土壤养分相对福建省背景值偏低,表现为土壤养分缺乏,土壤重金属含量普遍较低,无土壤环境质量风险。由不同成土母岩形成土壤的元素含量差异明显:侏罗纪碎屑岩发育的土壤表现为元素贫化,而变质岩发育的土壤表现为元素富集。对比不同程度水土流失区土壤元素含量的差异,发现随着水土流失程度的加剧,土壤中N、P、有机质等营养元素发生流失显著,As、Cd、Hg等重金属元素随水土流失的演变而发生扩散。

In view of element geochemical migration law during soil erosion, a geochemical investigation of land quality was carried out to ascertain the geochemical characteristics of soil elements and evaluate the abundance and deficiency of soil nutrients and the ecological risk of soil environment in the key soil erosive areas of Changting County, Fujian Province. Compared with the related background values of Fujian Province, the soil nutrients and contents of soil heavy metals in the key soil erosive areas of Changting County are relatively low, indicating risk-free soil environmental quality. The element contents of soils originated from different parent rocks show visible differences: the soil developed from the Lower and Middle Jurassic clastic rocks are characterized with element depletion, while the soil from metamorphic rocks are rich in elements. By comparing the differences of soil element contents in various degrees of soil erosive areas, it is found that with the aggravation of soil erosion, the nutrient elements including nitrogen, phosphorus and organic matter in the soil are significantly lost, and the heavy metal elements such as arsenic, cadmium and mercury are diffused with the evolution of erosion.