鄱阳湖氮、磷营养盐的滞留效应研究

Study on the retention effect of nitrogen and phosphate nutrients in Poyang Lake

通过对鄱阳湖2010、2011年氮、磷输入与输出量的监测,分析鄱阳湖对氮、磷的滞留效应,探讨了影响氮、磷滞留的主要因素。结果表明,2010、2011年鄱阳湖输入、输出的TP,总溶解性无机氮(DIN)浓度存在显著差异,输入浓度均明显高于输出浓度,表明鄱阳湖对氮、磷具有显著的滞留作用;TP浓度滞留效率普遍高于DIN浓度滞留效率,丰水期和枯水期TP、DIN浓度的年平均滞留效率分别为92.5%、87.5%和81.7%、80.4%,枯水期两者的差异较小;氮的实际滞留效率要高于磷的实际滞留效率,DIN的年平均实际滞留效率是TP的1.5倍,从季节分布上来看,丰水期氮、磷的实际滞留效率均高于枯水期,且TP、DIN的实际滞留效率随季节变化呈现出较一致的周期波动性;TP、DIN滞留的主要影响因素为径流输入、非点源污染输入以及经湖口的输出,降雨、降尘、底泥释放、生物滞留对其影响相对较小;鄱阳湖氮、磷收支估算结果表明,氮的实际滞留效率稍高于磷的实际滞留效率,这是由于人类活动导致的氮输入量大于磷输入量,以及氮、磷的滞留机制存在差异。

The concentration of nitrogen and phosphate in inflow and outflow of Poyang Lake was monitored from 2010 to 2011. The retention capacity of Poyang Lake to nitrogen and phosphate was analyzed and the factors that influencing the nutrients retention were investigated. The results showed that there was a significant difference between input and output nutrients, the concentration of TP and dissolvable inorganic nitrogen （DIN） in inflow of Poyang Lake was obvious higher than that in outflow,which revealed the high retention capacity of Poyang Lake to nutrients. The TP retention efficiency was gen- erally higher than DIN retention efficiency, the annual average TP retention efficiency in dry seasons and wet seasons was 92.5 %, 87.5 % and annual average DIN retention efficiency was 81.7 ~/~0,80.4 % respectively, their difference in dry seasons was relatively small. The actual annual average DIN retention efficiency was 1.5 times of actual annual average TP retention efficiency, they were higher in wet season than in dry season and they presented similar periodic fluctuation. The main factors that influencing the nutrients retention were surface run-off and non-point source pollution, rainfall, dust, sediment release and biological retention had relative small effect on nutrient retention. In Poyang Lake, the retention rate of nitrogen was slightly higher than phosphorus, because the human activities bring more nitrogen to the lake, and retention mechanism of nitrogen and phosphorus was different.