鄱阳湖双退区受损湿地植被恢复对水质的影响

退化湿地的植被恢复有助于提高湿地生物多样性和净化水体功能。通过监测鄱阳湖双退区（湿地）生态恢复过程中前后水质变化,分析了不同植被覆盖率和植物残体分解对水质的影响。结果表明,在植物生长期间,湿地水体TN质量浓度下降65.4%～71.3%,NO3--N也呈较大幅度下降,并能降低水体TP浓度水平;高植被覆盖增加水体叶绿素质量浓度水平,中低植被覆盖不影响水体叶绿素质量浓度,植被覆盖能有效保持水体较高透明度,但不能降低水体COD质量浓度。在枯水期,高植被覆盖因为植物残体分解使氮素回流水体,导致水体含TN,NH4＋-N,NO3-_N质量浓度显著升高,中低植被覆盖植物残体分解同样显著增加水体氮素,但增加程度小于高植被覆盖;植物残体分解不影响水体TP质量浓度水平;高植被覆盖植物残体分解增加水体叶绿素质量浓度,中低植被覆盖则无影响;高中低植被覆盖区植物残体分解都显著增加水体混浊度,也提高了水体的BOD,对水体COD没有影响。

The effects of vegetation restoration on water quality in the degraded wetlands of Poyang Lake

Wetland vegetation contributes to the maintenance of biodiversity and the improvement of water quality.This paper discusses the monitoring of water quality in the wetland restoration demonstration site of Duobao Town,Poyang Lake and the effects of vegetation on the restoration of water quality.Special focus is placed on the influences of vegetation coverage and plant residue decomposition.The results show that the TN concentration of water in the wetland declines 65.4%-71.3% after one-year of vegetation restoration in summer.It demonstrates that the NO3--N and TP concentrations also decreases.In the same season,high vegetation coverage can significantly increase chlorophyll concentration in the body of water,while the low and medium vegetation coverage does not.In contrast,the vegetation restoration does not induce any change to the COD concentration.In the low water level season,the nitrogen compounds stored in the plants return to the water body through plant residue decomposition.Thus,the concentration of TN,NH4＋-N,NO3--N in the water increases significantly.The concentration of TN,NH4＋-N,NO3--N in water with high plant residue increases much more than those areas with low and medium plant residue.Plant residue decomposition has little effect on the TP concentration in water but the amount of plant residue can affect the chlorophyll concentration.High plant residue decomposition increases the chlorophyll concentration of water significantly,while the water with low and middle residue has almost no effect.The study suggests that cleaning residue from plant material can contribute to water quality maintenance only in the plant＇s growing season.Furthermore,the paper discusses why the BOD concentration of water increases no matter how much the residue decomposes.