Base on the measurement data of water level and water quality at four typical hydrological stations of Poyang Lake in 2008,the proportion of non-point source pollution for nitrogen and organics were analyzed,the variation of water quality with the water level and water cycle was also discussed. The results showed that: (1) for the whole basin, the proportion of ammonia load from point sources and non-point sources were 34 ％ and 66 ％ respectively, while permanganate index load from non-point sources was account for 80 ％ of the total, anther 20％ was contributed by point sources load. (2) During the flood season,the ammonia and permanganate index at hydrological stations presented the same variation tendency, they both increased first and then decreased with the raising water level. (3)Mean ammonia nitrogen concentration in dry season and wet season were 0.49 and 0.28 mg/L respectively, ammonia pollution in dry season were higher than that in wet season; mean permanganate index in dry season and wet season were 2. 33 and 2.66 mg/L respectively, which indicated that the organic pollution in wet season were slightly serious than in wet season. (4) The concentration of pollutant at hydrological stations was increased with raising water cycle.If the water cycle remain unchanged, the concentration of pollutant in outflow was negative related with lake storage capacity, the greater of lake storage capacity, the less of pollution was.%根据2008年鄱阳湖4个典型监测站(星子站、蛤蟆石站、都昌站、康山站)的水位、水质实测数据,分析了鄱阳湖氨氮、高锰酸盐指数年非点源负荷比例,初步探讨了水质对水位变化、换水周期的响应.结果表明:(1)全流域平均氨氮年点源负荷比例为34%,非点源负荷比例为66%;高锰酸盐指数年点源负荷比例为20%,非点源负荷比例为80%.(2)在汛期,各监测站点氨氮和高基酸锰酸盐指数随水位的增高总体呈现先增大后减小的趋势.(3)各监测站点枯水、丰水期氨氮均值分别为0.49、0.28 mg/L,枯水期氨氮均值大于丰水期;各监测站点枯水、丰水期高锰酸盐指数均值分别为2.33、2.66 mg/L,枯水期高锰酸盐指数均值略小于丰水期.(4)当换水周期变长时,出流污染物浓度变大.如果换水周期不变,当湖库容越大(即水位越高),出流污染物浓度越小; 反之,出流污染物浓度就越大.
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