不同时间尺度下湖泊氮素内源释放强度影响因素的研究

在外源污染得到控制后,氮、磷内源释放成为湖泊持续富营养化的主因。从氮素内源释放机理入手,甄别了影响湖泊氮素释放强度的主要因子,构建了铵态氮和硝态氮释放强度对pH、温度、溶氧量、水动力条件4个因子的对数模型,通过底泥释氮正交模拟实验,对模型进行了回归,结果表明,铵态氮是氮素内源释放的主要形态,其释放强度与pH负相关,与温度正相关,与溶氧量负相关。对于小型浅水型城市湖泊,氮素内源释放强度的影响因素取决于时间尺度：短期水动力条件对释放强度影响较大,但在长期并不显著。溶氧量对氮素内源释放强度的影响长期比短期更明显。本研究可为湖泊氮素内源释放的预测和治理富营养化湖泊工程手段的完善提供参考。

The Factors Affecting the Intensity of Lake Endogenous Nitrogen Release Under the Conditions of Different Time Scales

Endogenous release of nitrogen and phosphorus could continuously pollute lakes after outside pollutions are controlled.To determine the factors affecting endogenous release,this study analyzed the mechanism of endogenous release of nitrogen and found that the pH,temperature,dissolved oxygen,and hydrodynamic condition were the main factors affecting the release process.After then,we established a logarithm model to determine the release intensity of ammonium and nitrate nitrogen by considering these main factors.After verification,results showed that ammonium was the main substance of nitrogen to release,its release density was positively related to temperature and negatively related to pH and aeration status.It was found that,in small-scale shallow lakes,hydrodynamic condition could affect endogenous release of nitrogen significantly in short period,but this was not work in long period.The influence of aeration status on the intensity of endogenous nitrogen release in long period was more significant than that in short period.Our results could provide helpful information for the practices of endogenous release estimation and for the improvement of engineering approach to reduce the release intensity.