Mobilisation of N and P from Agricultural land and Its Impact on Stream Water Quality in Karst Hilly Areas, Southwestern China

摘要

In order to evaluate the impacts of N and P mobility from agricultural soils on surface water quality, the dissolved N and P concentrations in the runoff, the drainage and stream waters nearby agricultural lands were investigated at the karst hilly regions in central Guizhou Province. The results shown that the concentrations of (NO_3)~-, (NH_4)~+ and (PO_4)~(3-) in the runoff from upland soils were 9.8～22.1 mg L~(-1), 0.429～0.818 mg L~(-1) and 0.025～0.052 mg L~(-1), respectively, and higher concentrations of NO_3- (14.5～25.3 mg L~(-1)) in the drainage waters from paddy soils. In karst areas, the concentrations of NO_3 - in the stream waters nearby agricultural lands was 14.9～28.5 mg L~(-1), as indicated by high concentration of NO_3- compared with the Grade III of Surface Water Quality Standard of China, suggesting a eutrophication problem for surface water nearby agricultural lands with intensive cultivation.