复杂景观中营养型非点源污染物时空变异特征分析

非点源污染的形成不仅受到地表物质来源、景观格局的影响,同时还受到土壤侵蚀过程、降雨过程、灌溉过程、地表和地下水文过程的影响.由于影响非点源污染的因子复杂多样,从而导致它的时空变化较大.正确认识非点源污染的时空变异特征对于科学布设监测点和研究它的变化规律具有重要意义.本文通过野外定点监测,研究了非点源污染的时空变异.结果发现:①干旱年份各种污染物空间变异小于降雨正常年份.②对于不同污染物,无论在干旱年份还是正常年份,地表水中固体悬浮颗粒物的空间变异均较大,其他污染物的空间变异相对较小.③对于固体悬浮颗粒物,干旱年份不同水文期之间的空间变异比较接近,而正常年份的空间变异不同水文期之间差异较大.④非点源污染季节变异较小的监测点主要出现在具有稳定水源和地表径流季节变化较小的地区;而非点源污染空间变异较大的监测点主要出现在山区河流上游地表径流季节变化明显、农业用地面积较大且地表径流季节变化较大和明显受到点源污染影响的地区.

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.