Comparison between the chemical composition of bedrocks in the upper reaches and that of alluvial plain soils in the lower reaches of a drainage area

Comparative study of chemical compositions between bedrocks of the upper reaches and alluvial plain soils of the lower reaches of the Haihe River and Poyang Lake drainage areas indicates that chemical composition of alluvial plain soils of the lower reaches are remarkably affected by the composition of bedrocks and the process and environment of soil formation. Some characteristic elements in bedrocks of the upper reaches are obviously inherited in the alluvial soils. The examples are CO2, CaO, MgO, FeO and Sr in bedrocks and soils of the Haihe River drainage area and W, Sn, Bi, U, Th, Pb, Rb, Tl, As, Sb, Se, Hg, Nb, Ta, Hf, B, Be, Ge, Pt, Pd and Y in bedrocks and soils of the Poyang Lake drainage area. Affected by the formation process and environment, the alluvial plain soils of the Haihe River drainage area in a semi-wet monsoonal climate of the warm temperate zone are characterized by extreme enrichment in CO2, CaO, Na2O and Cl, marked enrichment in MgO, FeO and Sr and enrichment in P and S. By contrast, the alluvial plain soils of the Poyang lake drainage area in a wet monsoonal climate of the subtropical zone are characterized by marked enrichment in Hg and Se and enrichment in Al2O3, Fe2O3, H2O+, W, Sn, Bi, Mo, U, Th, Pb, Rb, Cs, Tl, Li, Be, B, Ga, Ge, Nb, Ta, Zr, Hf, As, Sb, Co, Cr, Ti, V, Zn, Pt, Pd, REE and Y. The alluvial plain soils of both the Haihe River and Poyang Lake drainage areas are enriched in As, Sb, Hg, B, Cl, W, Sn, Bi, Pb, Se, Ge, Li, Cs, Cu, Au, Fe2O3, V, Cr, Ni, Zr, Hf and Y.