汉江上游水体氮素污染特征

2011年对汉江上游干流进行了6次采样,分析了水体氮素的污染特征。结果表明,汉江上游水体NH₃-N,NO₃-N和NO₂-N的年平均值分别为:1.037,1.751和0.044 mg/L。氮素时间分布曲线表现为:NH₃-N浓度的周年变化趋势为双峰型,呈现:丰水期 >枯水期 >平水期的规律。NO₃-N,NO₂-N浓度的周年变化趋势为单峰型曲线,NO₃-N呈现:丰水期 >枯水期 >平水期的规律,NO₂-N丰水期最高,枯水期和平水期相差不大。汉江上游水体氮素空间分布表现为:NH₃-N,NO₃-N浓度自源头向下游呈现出"低值-升高-降低"的趋势。NH₃-N污染主要来自农村生活污水和畜禽养殖排放物,NO₃-N污染主要来自水土流失。

Nitrogen Pollution Characteristics in Upstream of Hanjiang River

To discover the characteristics of nitrogen pollution, the authors collected and studied water samples from the upstream of Hanjiang River for six times in 2011. A careful examination of the samples revealed that the average nitrogen concentration in the forms of ammonia nitrogen(NH₃-N), nitrate nitrogen(NO₃-N) and nitrite nitrogen(NO₂-N) was 1.037 mg/L, 1.751 mg/L, and 0.044 mg/L, respectively. The annual distribution curve of NH₃-N concentration fell into the double-peak pattern with the highest concentration in flood season, relatively low concentration in dry season, and the lowest in normal water period. The annual distribution of NO₃-N concentration fell into the single-peak pattern curve with the highest concentration in flood season, relatively low concentration in dry season, and the lowest in normal water period. The annual distribution of NO₂-N also fell into the single-peak pattern curve with the highest concentration in flood season, relatively low concentration in the dry season and common water period with little difference. The spatial distribution of nitrogen pollution demonstrated increasing in concentration of NH₃-N and NO₃-N at first, and then decreasing in these two types of pollutants all the way from the source to the downstream part of Hanjiang River. The source of the NH₃-N pollution mainly comes from rural domestic waste water, and livestock and poultry breeding. NO₃-N pollution is mainly due to soil erosion.