农田沟渠挺水植物对N、P的吸收及二次污染防治

生长在农田沟渠湿地中的芦苇和茭草对 N、有很好的吸收能力,芦苇茎叶的 N、含量分别为15.0,1.9g/kg,相当于每年吸收 818kg/hm² 的 N 和 103.6kg/hm²的 P,茭草地上部分的N、P 含量分别为 17.2,3.8g/kg,相当于每年吸收 131kg/hm²的 N 和 28.9kg/hm²的 P.对比实验发现,收割区 0～20cm 深度底泥中的有机质、总氮(TN)、总磷(TP)含量明显低于未收割区,但 NH₄ ⁺-N 和 NO₃^- -N 含量增高.植物收割改善了湿地 -的透光、透气条件,促进污染物分解转化,造成无机氮含量上升.茭白对氮磷的吸收能力也较高,每年收获后可带走200kg/hm² N,21.1kg/hm² P.以人为种植取代野生的芦苇和茭草,可获得很好的净化效果,解决植物的二次污染问题.

Absorption and prevention of secondary pollution of N and P by emergent plants in farmland ditch

Reed (Phragmites communis) and wild rice (Zizania latifolia) grown in ditch wetland have a high ability to absorb N and P. Determined assimilation amount of N are 15.0g/kg equal to 818kg/(hm2?a)] by reed and 17.2g/kg equal to 131kg/(hm2?a)] by wild rice. The absorbed amount of P by reed and wild rice are 1.9g/kg equal to 103.6kg/(hm2?a)] and 3.8g/kgequal to 28.9kg/(hm2?a)] respectively. The contents of organic matters, TN and TP in sediment of harvested plot in the depth of 0~20cm were lower than that in non-harvested plot. But the contents of NH4 -N and NO3 -N increased. The - harvest of plant led to the amelioration of transparency and aeration of wetland and accelerated the decomposition and transformation of organic matters and TN. A commercial crop- Zizania caduciflora Turez Hand-mazt also has good assimilation ability of nutrients. The harvest of it would remove 200kg/hm2 of N and 21.1kg/hm2 of P every year. Thus, from the view of water quality improvement, the cultivation of Z. caduciflora instead of wild plants could be a good suggestion to resolve the secondary pollution problem of N and P.