不同水葫芦覆盖度对富营养水体氮、磷的去除效果

Effect of water hyacinth coverages on the removal of nitrogen and phosphorus in eutrophic water bodies

为了解不同水葫芦覆盖度对富营养水体氮、磷的去除效果及氮磷物质在净化系统内的流向,在野外采用水流及水面均为静止的净化塘,研究了不同水葫芦覆盖度对水体总氮（TN）、总磷（TP）、铵态氮（NH＋4-N）、硝态氮（NO-3-N）的浓度变化和净化效果及氮磷物质在净化系统中流向影响。结果表明：随着水葫芦覆盖度的增加,TN的净化效果逐渐提高,覆盖度25%、50%、75%、100%处理120 h的TN去除率分别达85.32%、92.35%、95.75%、93.30%;对TP的净化效果,0~8 h内覆盖度100%〉75%〉50%〉25%〉无水葫芦覆盖对照,在24~40 h内覆盖度75%处理净化效果最好,相对而言,TP的去除速度比TN更快。处理32 h的TP去除率分别达92.00%、94.07%、95.56%、94.22%。水葫芦植株对水体氮、磷的直接吸收作用与覆盖度呈正相关,覆盖度100%的水葫芦吸收系统总氮、磷的比例分别占系统总损失氮、磷量的53.26%、56.35%,水葫芦覆盖可促进底泥氮、磷的释放,这对降低内源污染有积极作用。综合考虑水体氮、磷质量浓度下降速度及去除效率,在水葫芦生长旺盛期,以100%覆盖度最好。

An experiment was conducted in outdoor purification ponds with still water covered with different amount of water hyacinth（ Eichhornia crassipes） to study the concentration changes of total nitrogen（ TN）,total phosphorus（ TP）,NH＋4-N,NO-3-N in the water bodies as well as the purification effect,and the N and P flows in the purification system. The results showed that the removal of TN was improved with increased water hyacinth coverage. The removal rates of TN in the treatments of 25%,50%,75%,and 100% coverages after120 h were 85. 32%,92. 35%,95. 75%,and 93. 30%,respectively. The TP removal declined as the water hyacinth coverage decreased from 100%, 75%, 50%,25%,to 0（ CK） during initial 8 h. The treatment of 75%coverage was the most effective in removing TP from the8 th to the 40 th hours. The removal rate of TP was relatively higher than that of TN. The corresponding removal rates of TP after 32 h were 92. 00%,94. 07%,95. 56%,and 94. 22%,respectively,for the four treatments. The absorptions of N and P by water hyacinth plants were positively correlated with the coverages. The amount of N and P removed by water hyacinth of 100% coverage took up 53. 26% and 56. 35% of the total N and P lost from the system. Water hyacinth could stimulate the release of N and P from bottom sediments,which favored the control of inner-sourced pollution.Considering both N and P decrease speeds and N and P removal efficiencies in the water bodies,100% coverage will be the best,especially during the fast-growing period of water hyacinth.