盐龙湖表面流人工湿地底泥氧化层对污染物释放的影响

Effect of oxide layer of sediment on contaminant release in surface flow constructed wetland of Yanlong Lake

为了解盐城市盐龙湖表面流人工湿地底泥氧化层理化性质,探讨其对底泥氮、磷及有机物释放过程的影响,在测定底泥理化性质的基础上进行了室内静态柱状试验.结果表明:盐龙湖表面流人工湿地长期运行后在底泥表层形成了厚度为1 cm、呈棕黄色、无明显臭味、含水率低、TP含量高、TOC和TN含量低的氧化层;氧化层对于底泥中污染物的释放特征影响显著(P<0.05),对内源污染的控制具有一定的正面作用;无氧化层试验组上覆水中TN、NH3-N和COD的平均质量浓度分别比有氧化层试验组高9.5%、30.8%和3.5%;在湿地的实际管理中,不宜对湿地进行疏浚,如疏浚则疏浚深度应达到健康层.

In order to understand the physical and chemical properties of sediment oxide layer in surface flow constructed wetland of Yanlong Lake, Yancheng City, and to explore its influence on the release process of nitrogen, phosphorus and organic matter from sediment, indoor static columnar tests were carried out on the basis of determining the physical and chemical properties of sediment. The results showed that after long-term operation, the surface flow constructed wetland of Yanlong Lake formed oxidized layer with thickness of 1cm, brown-yellow, no obvious odor, low water content, high TP content, low TOC and TN contents on the surface of sediment. The oxidation layer has a significant effect on the release characteristics of pollutants in sediment (P <0. 05), and has a positive effect on the control of endogenous pollution. The average concentration of TN, NH3 -N and COD in the overlying water of the non-oxidized layer test group was 9. 5%, 30. 8% and 3. 5% higher than that of the oxidized layer test group, respectively. In the actual management of wetlands, it is not appropriate to dredge wetlands. If dredging, the dredging depth should reach the healthy layer.