三峡库区小流域水体硝态氮含量及与土地利用的关系

Nitrate Concentration in Water in Small Watersheds of Three Gorges Reservoir Area and Its Relationship with Land-use

通过对三峡库区宝塔河与曲溪两小流域内土地利用结构和施肥状况的调查，以及对流域水体中硝态氮含量连续3年的监测，探讨了土地利用结构和施肥状况等对水体中硝态氮含量的影响。结果表明：①不同流域水体中硝态氮含量存在很大差异，曲溪流域变化范围是0．4—14．6mg／1，平均为6．96mg／l；宝塔河流域变化范围是0．2～6．8mg／1，平均为2．41mg／l，耕地和林地面积所占的比例对流域水体中硝态氮含量有很重要的影响；②曲溪流域水体硝态氮含量的季节性变化表现为春季〈夏季〈秋季〈冬季，这一变化与降雨量的大小有一定关系，也与季节性的农事活动有关；宝塔河流域受居民非农业活动影响显著，其水体硝态氮含量的季节性变化规律不明显，年度变化表现为2005年略高于2004年，但2006年却略为下降，农业耕作对水体硝酸盐的含量影响比曲溪弱。

This article mainly discusses the influence of land-use structure and fertilizer tion on the nitrate concentration in water body in two small watersheds in Three Gorges consumpReservoir Area. By investigating the structure of land-use and the consumption of fertilizer and nitrate variability in three consecutive years, some conclusions are drawn that： （1） Distinguished discrepancies exist in nitrate concentration between the two watersheds. In Quxi Watershed, it fluctuates between 0. 4 and 14. 6 mg/l, and the average is 6. 96mol/l; in Baotahe Watershed, it is between 0. 2 and 6. 8mol/l, and the average is 2. 41mol/l. The ratio of arable land and forest land plays an important role on the nitrate concentration in water bodies of the watersheds. （2） Seasonal change of the nitrate concentration in Quxi Watershed is higher in winter, then autumn and summer, lower in spring, which may relate to the rainfall and seasonal agricultural activities. Due to the significant effect of the residents＇non-agricultural activities, the nitrate concentration in Baotahe Watershed shows no seasonal change rule, the annual change is that it increased in 2005 and then decreased in 2006;and the effect of cultivation on the nitrate in Baotahe is weaker than that in Quxi.