厦门某旱地土壤垂直剖面中重金属迁移规律及来源解析

采用ICP-MS和TIMS分析测定厦门市农业区某旱地土壤垂直剖面中8种重金属元素(V、Cr、Co、Ni、Cu、Zn、Sr和Pb)含量及铅锶同位素组成,重点分析土壤剖面金属的纵向分层和淋失迁移特征.结果表明,除Sr外,其余重金属在大部分剖面深度中均未超过背景值,表明受外来源的影响较小. Sr在整个剖面的迁移系数均大于0,表明存在不同程度的富集; Zn和Co在近地表处富集; Cr、Ni和Cu在整个剖面中以亏损为主; V和Pb受外来活动的干扰小.淋洗迁移特征分析表明,Sr和Pb淋洗下移较活跃,其下移深度较大,但Pb下移深度低于Sr下移深度.因子分析表明,重金属主要为自然因子的输入,其次为农业活动和交通运输等复杂人为活动的输入.富集因子分析表明,Sr受外源不同程度影响.铅锶同位素组成分析表明,垂直剖面土壤中Pb主要来源于母质层,而Sr除来源于母质层外,还受到复杂人为源的影响,并已有向底层(30～70 cm)迁移的趋势.

Migration and Source Analysis of Heavy Metals in Vertical Soil Profiles of the Drylands of Xiamen City

The concentrations of eight heavy metal elements (V, Cr, Co, Ni, Cu, Zn, Sr, and Pb) and the isotopic composition of Pb and Sr were determined in vertical soil profiles of the drylands of Xiamen City using ICP-MS and TIMS. The vertical distributions and leaching migration patterns of the heavy metals were also analyzed. The results showed that most of the heavy metals (except for Sr) were not enriched relative background values at most profile depths, which indicated that heavy metal content is less affected by exogenous sources. The migration coefficients of Sr were greater than 0 throughout the entire soil profile; Zn and Co were enriched in the surface soil; and Cr, Ni, and Cu were depleted throughout the profile. V and Pb were less influenced by external activities. Sr and Pb showed clear vertical migration characteristics, and the migration depth of Sr was greater than that of Pb. Factor analysis showed that the heavy metals mainly originated from natural sources, followed by agricultural activities, transportation, and other complex anthropogenic activities. Enrichment factor analysis showed that Sr was affected by exogenous sources to varying extents. The isotopic composition analysis of Pb and Sr showed that Pb was mainly derived from the parent material, whereas Sr was interpreted as deriving from both the parent material and anthropogenic activities, and tended to migrate to the subsurface soil horizons (30-70 cm).