武汉东湖水生植被重建及水质改善试验研究

普遍存在的水体富营养化及水生植被衰退引起水生态系统崩溃和水质恶化,受损湖泊进行水生植被(特别是沉水植被)的修复/重建被认为是改善湖泊水质和湖泊生态恢复的重要手段。研究在严重富营养化的东湖水果湖边建立的围隔中开展,采用多种措施对围隔的底质和水质进行适当改善,依据自然湖泊中水生植被分布和植物种类组成的特点,选用14种常见的土著水生植物在该区进行移栽与群落构建。经过水生植被的重建,所移栽的14种水生植物全部存活,并建立起相对稳定的植被群落,而且经过随后4个月的水质监测,发现植被重建后围隔内的水质得到显著改善,尤其是水的色度、透明度和叶绿素含量改善最为明显,与围隔外(即东湖I站)相比,围隔内除NO3-外湖水中的各种营养盐含量以及底泥中TP的含量都不同程度的降低,其中以TPW降幅最大;PCA分析发现构建的植物群落结构主要受水体的TPW、氨氮浓度、电导率、水下消光系数以及底泥的TPS影响;pH、COND、ORP、TPs、DO、碱度、Kd、PO43-、NO3-、TPW和DIC这些主要的环境梯度对构建的水生植物群落中各层片上的各种优势物种体内TN、TP含量影响最大。总而言之,本研究实现了水体从"浊水态"向"清水态"的快速转换。这一结果表明在富营养湖泊中通过建立围隔,采用"化整为零"的策略逐步恢复水生植被是一个可行方案。此外,增加水生植物物种多样性可以增加植被恢复的成效。

Restoration of Constructed Hydrophytes Community in East Lake of Wuhan and Experilnental Study on Water Quality Improvement

Worldwide water eutrophication and hydrophytes declines render the collapse of water ecosystem and the deterioration of water quality. Restoration/reconstruction of aquatic macrophytes vegetation, especially submersed macrophytes vegetation is considered as an important tool for improvement of water quality and ecological restoration of the lakes. Taking enclosure of heavily eutrophic Shuiguohu of East Lake, Wuhan as a case, several steps were applied to evenly improving sediment and water quality in enclosures, and 14 autochthonic species of aquatic plants, according to respective distribution and construction in natural lakes, were chosen to replant in the Lake and construct macrophytes community. Through half a year restoration of hydrophytes vegetation, all of 14 macrophytes replanted survived and relatively steady community was established. Water quality, in particular water chroma, SD and Chl a contents in enclosures was improved after vegetation reconstruction. Compared with outside, all of nutrients other than NO3- from water and TP of sediment in enclosures decreased at different degrees, with TPw decreasing at the largest. Through PCA analysis, TPW, NH4-N, conductivity, Kd and TPS were found to affect structure of community. Main environmental gradients such as pH, COND, ORP, TPS, DO, alkalinity, Kd, PO43-, NO3-, TPW and DIC could affect dominant species in different synusia structures of constructed macrohytes community at largest. The study made the rapid shift of the Lake water from turbid state to clear state, indicating it was a feasible scheme to take a policy of turning integer to integrant parts to restore vegetation gradually through building enclosures in entrophic lakes. Enlarging the species biodiversity of aquatic plants could heighten the success rate of hydrophytes restoration.