改性粘土辅助沉水植物修复技术维持清水稳态的原位研究

在富营养湖泊治理实践中,修复沉水植被被认为是改善水质的长效措施,而壳聚糖改性粘土是短期快速改善水质的有效手段.本研究利用改性粘土辅助沉水植被修复,旨在探索改善水质的长效方案.2011年5-11月在太湖梅梁湾开展了四组不同处理(对照、水草、水草+粘土、粘土)围隔实验,在水草(盖度13.0%)和水草+粘土(盖度52.3%)围隔中不同程度重建了苦草群落.实验期内每3 d一次的水质监测表明,粘土处理可显著改善水质,水体总氮(TN)、总磷(TP)、正磷酸盐(PO34--P)和叶绿素a(Chl.a)含量分别比对照下降了20.7%、74.6%、31.0%和80.4%,透明度(SD)升高了90.4%;粘土辅助植被修复改善水质效果最长稳,水体TN、TP、PO34--P和Chl.a含量分别比对照下降了36.2%、64.0%、28.6%和71.1%,SD升高了76.4%;低盖度苦草群落单独处理对水质改善效果不显著.在三种处理中,粘土辅助植被修复改善底质效果最好,使间隙水的TN、TP、PO34--P、NH4+-N分别比实验前下降了15.6%、61.7%、55.8%和82.8%.本研究表明改性粘土辅助沉水植被修复可作为重富营养水体中水质改善的整合技术,但其长期生态效应仍需谨慎评估.

In situ study on the maintenance of clear water by restoration of submersed macrophytes with the aid of modified soils

Restoration of submersed vegetation is generally considered as an effective long-term approach to improve the water quality of eutrophic lakes,and chitosan-modified soil has been used to rapidly improve the water quality in the recent years.In this study,an experiment with four treatments(the control,submersed macrophyte,submersed marcophyte+soil,and soil) was carried out in the hypereutrophic water(Meiliang Bay) in Lake Taihu during May to December in 2011,with the aim to develop a macrophyte-mediated approach to improve water quality.During the period of the experiment,submersed vegetation had a final coverage of 13.0% and 52.3% in the submersed macrophyte and the submersed macrophyte+soil treatments,respectively.The indices of water quality were measured in 3-day intervals.The results showed that the soil was effective to improve the water quality,with a decrease in the contents of TP by 74.6%,TN by 20.7%,PO₄^3--P by 31.0%,Chl.a by 80.4% and an increased SD by 90.4% as compared to the control;the submersed marcophyte+soil treatment was the most effective way to decrease the contents of TP (64.0%),TN(36.2%),PO₄^3--P(28.6%) and Chl.a(71.1%),and increased the SD(76.4%).The submersed marcophyte restoration alone did not improve the water quality.The submersed marcophyte+soil treatment was also the most effective one among the three treatments to decrease the contents of TN(15.6%),TP(61.7%),PO₄^3--P(55.8%) and NH₄⁺-N(82.8%) in the sediment interstitial water.The study implies that restoration of submersed vegetation with the aid of chitosan-modified soil be an effective technology to improve the water quality,although the effectiveness needs to be further evaluated on a long-term basis.