滏阳河衡水市区段沉积物硝酸盐氮的扩散规律

Diffusion of nitrate nitrogen in sediment of stream segment of Fuyang River through Hengshui City

为解决内源负荷污染问题,对滏阳河衡水市区主城区小漕河沉积物和上覆水的性质进行了分析测试,采用实验室静态模拟法研究了硝酸盐氮的释放规律,并计算了其沉积物-水界面的扩散通量.结果表明:垂向沉积物中C、N、P营养盐随着深度的增加,含量逐渐降低.上覆水呈缺氧状态,有机污染严重,营养盐浓度接近甚至超过地表水环境质量标准Ⅴ类限值,富营养化风险高.不同温度下,表层沉积物硝酸盐的释放先上升再下降,且温度越低,越有利于其释放.温度为5℃时,不同深度沉积物硝酸盐的释放先增加后平缓再逐渐下降,且随着深度的增加,释放强度逐渐减弱.硝酸盐氮释放通量为-0.49mg/(m2·d),总体表现为由上覆水向沉积物扩散.研究结果为滏阳河衡水市区段环境综合整治工程以及子牙河流域水污染防治与水质改善提供数据支持.

To solve the internal pollution,sediment and overlying water from xiaocao River were analyzed.Xiaocao River is the stream segment of Fuyang River through Hengshui City.The release of nitrate nitrogen is studied by static simulation in the laboratory.The diffusion flux of nitrate nitrogen on the interface of sediment-water is calculated.The results show that the content of carbon,nitrogen and phosphorus gradually decrease with the increase of the sampling depth.The dissolved oxygen is very lower,which indicates the overlying water is in an anoxic condition.The organic pollution is serious.The nutrient concentrations are close to or even more than the limits ofⅤclass surface water environmental quality standard.The river has high nutritional risk.Under different temperatures,the release of nitrate nitrogen in the surface sediments rises first and then falls,and the lower the temperature,the more serious the release.At the temperature of 5 ℃,the release of nitrate nitrogen in different depths of sediments increases first and then becomes stable and eventually gradually decrease,and when the depth is deeper,the release intensity is weaker.The amount of the NO3--N diffusion flux is-0.49mg/（m^2·d）,and its releasing trend is from the overlying water to the sediment.The results provide data support to the environmental comprehensive renovation project of stream segment of Fuyang River through Hengshui City and to the water pollution control and water quality improvement of Ziya River basin.