川中丘陵区自然沟渠水体氮磷污染状况评价

An Evaluation of Nitrogen and Phosphorus Pollution in a Natural Ditch in the Hilly Area of Central Sichuan Basin

通过对川中丘陵区72条自然沟渠水体氮磷含量特征进行野外调查,并结合综合污染指数法对该区自然沟渠水体氮磷污染状况进行分析评价。结果表明,该区自然沟渠水体TN含量范围在2.09~46.90 mg/L,平均值为5.39 mg/L;TP含量范围在0.04~0.72 mg/L,平均值为0.18 mg/L。居民区沟渠水体氮磷含量明显高于水田沟渠和旱地沟渠。不同类型自然沟渠水体氮磷含量季节变化趋势不同,居民区沟渠旱季（11月）水体氮磷含量均高于雨季（6月）,但水田和旱地沟渠旱季水体氮磷含量均低于雨季。综合污染指数分析结果显示,川中丘陵区不同地区自然沟渠水体氮磷综合污染基本处于重度污染的状况。

Surveys of Nitrogen and Phosphorus content were combined with a composite index evaluation of a ral ditch in the hilly area of Central Sichuan Basin, China. The total nitrogen levels in the ditch water ranged natu- from 2. 09 mg,/L to 46.90 mg/L with an average of 5.39 rag/L, and the total phosphorus content ranged from 0.04 mg/ L to 0.72 mg/L with an average of 0.18 mg,/L. Levels of nitrogen and phosphorus in the ditch water varied accord- ing to the surrounding land uses. In residential areas, nitrogen and phosphorus levels were higher than those in ag- ricultural areas of sloping cropland and paddy fields. Seasonal changes in nitrogen and phosphorus content also de- pended on the surrounding land use. In residential areas, nitrogen and phosphorus levels were higher in the dry season （November） than in the wet season （June）. Conversely, in agricultural areas of paddy fields and sloping croplands, nitrogen and phosphorus levels were lower in November than in June. The result of this pollution assess- ment shows that nitrogen and phosphorus levels in the ditch water of the hilly area of Central Sichuan Basin consti- tute high pollution.