新疆巴里坤东部几类主要土壤的地球化学特征

Geochemical characteristics of soils in Barkol Region, Xinjiang

分析巴里坤盆地东部主要的及具代表性的几类土壤,如栗钙土、淡栗钙土、淡棕钙土和石灰性草甸土常量化学成分和某些微量元素含量,并与周边山地基岩及湖积物化学成分对比,发现这些土壤经历了由山地基岩→坡积、冲洪积物/湖积物→土壤的演化过程。在较干旱的环境及生物、化学作用影响下,土壤对基岩/母质在化学成分上既表现出一定的继承性,又有一定变异性。该地区栗钙土常量元素含量最接近山地基岩平均值。淡栗钙土和淡棕钙土则和基岩有较大差异,并分别以富含CaCO3和SiO2为特征。石灰性草甸土与其它土壤显著不同,其富CaCO3,贫TFe,并且Fe3+/Fe2+<<1。土壤中某些微量元素与中国/世界土壤平均水平相比,有益元素P、Cr、zn大致持平,有害元素As、Pb明显偏高。这种成分特征是在基岩化学成分背景上相关元素贫化或富集作用的结果。

Based on field investigation and references, it is known that the typical soils in BarkolBasin went through composition changes from bedrocks to talus accumulation, proluvium and alluvium, or lacustrine sediments, finally to soils. In arid environment and effects of biology and chemistry, the soils presented certain inheritance and variations to chemical Compositions of bedrock/parent material. For example, major element contents of the chestnut soil were much similar to mean contents of major elements of bedrocks. The light Chestnut soil and the light brown calcic sol varied from bedrocks in major element contents, specially, the light chestnut soils contained abundant CaCO3, and the light brown calcic soil had highest amount of SiO2. The calcareous meadow soil had the highest amount of CaCO3, the lowest amount of TFe, and Fe^3＋/Fe^2＋ 〈〈 1. In contrast with soils in Chine/world, P, Cr and Zn, the beneficial microelements had moderate contents in the soils in Barkol region, but the amounts of As and Pb, the harmful microelements in the oils were higher. That is the result from the background of bedrock composition and the secondary concentration.