Tempo-spatial variation of non-point source pollutants in a complex landscape]

The occurrence of non-point source pollution, is not only related to its sources, landscape pattern, but also dependents on the factors such as soil erosion, rainfall, irrigation, surface and underground run-off. Thus non-point source pollution is characterized by in nature tempo-spatial variation. In this paper, the tempo-spatial variation of non-point source pollution due to nutrient salts in a complex landscape was studied by field water sampling and analysis. The results were as follow: 1. Spatial variability of all nutrient concentration in rainfall-deficit year was generally smaller than that in normal rainfall year with different level for different pollutants in a single period. 2. Spatial variability of solid particles in surface water was much marked than the other pollutants studied both in the rainfall-deficit year and in the normal rainfall year, while the smaller variation in different water periods of a year in the normal rainfall year. 3. Apparently, those areas with stable run-off had a small seasonal variation of non-point source pollution. However, large seasonal change occurred mainly in the upper reach of river where run-off changed seasonally, and/or where farmland dominated, as well as where point-source pollution occurred.