非点源污染物在沟渠湿地中的累积和植物吸收净化

对有机质和总氮在沟渠湿地底泥中的垂直分布和水平分布的研究表明，40 cm以下深度的芦苇(Phragmites communis)和茭草(Zizania latifolia)湿地底泥对有机质和总氮有显著的持留和累积作用；但表层底泥中含量随季节变化大，最高与最低值相差近2倍以上.有机质和总氮之间有极显著的相关关系，在芦苇和茭草湿地底泥中的相关系数分别为0.9876和0.9335.水体中总氮与NH₄⁺-N和NO₃-N也显著相关，表明总氮的主要成分是有机氮，其矿化作用是无机氮的重要来源.每年秋季芦苇收割以后，可带走氮818 kg·hm^-2和磷103.6 kg·hm^-2，茭草可带走氮131 kg·hm^-2和磷28.9 kg·hm^-2.茭白对氮的吸收能力高，试验表明，利用茭白取代野生植物，既能取得很好的净化效果，又可被农民主动回收，解决植物的二次污染问题.

Accumulation of non?point source pollutants in ditch wetland and their uptake and purification by plants

The study on the vertical and horizontal distribution of organic matters and total nitrogen (TN) in the sediment of ditch wetland naturally grown with reed (Phragmites communis) and wild rice (Zizania latifolia) showed that the sediment below 40 cm depth had a significant effectiveness in retaining and accumulating organic matters and TN, but in its surface layer, this effectiveness varied largely with seasons, and the maximum was more than twofold of the minimum. TN was highly correlated with organic matters, the correlation coefficient being 0.9876 in reed wetland and 0.9335 in wild rice wetland, and in water phase, it was positively related to NH4+ -N and NO3-N, indicating that the main composition of TN was organic N, and the mineralization of organic N was the sources of inorganic N. The harvest of reed in each autumn could take away 818 kg x hm(-2) of N and 103.6 kg x hm(-2) of P, and that of wild rice could take away 131 kg x hm(-2) of N and 28.9 kg x hm(-2) of P. Zizania caduci flora had a high assimilation ability of nutrients. Its cultivation in ditch wetland to replace wild helophytes would be a good approach to attain higher absorbing ability of N and P, and to resolve the secondary pollution problem of emerged plants, because farmers could harvest it voluntarily.