ELEMENT GEOCHEMISTRY OF THE TYPICAL BLACK SOIL SECTIONS IN BAIQUAN AREA, HEILONGJIANG PROVINCE: Environmental Implication

The geochemical behavior of elements in earth surface is closely related to natural environment, and the change of element distribution in soil records the environmental characteristics during its formation. Focusing on the typical black soil sections in Baiquan area, the paper studies the distribution rule of major and trace elements and its implied environmental information, and discusses the weathering degree of the soil sections and climatic evolution characteristics during the formation of section. The results show that except SiO₂ and Na₂O, the content of major elements in the soil sections is generally higher than that in Northeast Plain. The average chemical index of alteration (CIA) is 58, with high Saf value, belonging to weak weathering. The trace elements essential for plant growth, such as N, P, S, Mn, B, I, Ge, Se and Mo, accumulate under warm climatic condition, with high content in surface and illuvial layers, and low in eluvial layer and parent material layer; while under cold and dry conditions, they accumulate on the surface. The strong correlation between metal trace elements and Fe indicates that its vertical component is controlled not only by climatic conditions, but also by major elements. The migration rule of major elements reveals the soil in humus layer is of high maturity, mainly formed in a warm and humid climate. The illuvial layer may be at the removal stage of Na and Ca, with soil formed in a relatively cold and dry climate.