| 滆湖北部底泥疏浚的生态效应研究 |
| Ecological Effects of Dredging on Aquatic Ecosystem in Northern Gehu Lake |
| 投稿时间：2014-09-19 修订日期：2014-12-17 |
| DOI：10.15928/j.1674-3075.2015.02.006 |
| 中文关键词:底泥疏浚 沉积物 生态效应 滆湖 |
| 英文关键词:dredging sediment ecological effects Gehu Lake |
| 基金项目:江苏省科技计划项目（BM2014041）；江苏省水利科技项目（2013002；2014038；2014042）。 |
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| 中文摘要: |
| 为研究滆湖北部生态系统对底泥疏浚的动态响应，2012年10月至2013年9月在滆湖北部采集沉积物和生物样品，分析疏浚工程对底泥营养盐含量、浮游植物、底栖动物和大型水生植物群落结构的影响。结果表明，滆湖北部疏浚区的总氮、总磷和有机质的平均含量分别为0.65 g/kg、0.63 g/kg和7.73 g/kg，比未疏浚区减少了51.4%、51.2%和72.0%；疏浚区浮游植物的密度为379.6×104～2867.1×104 个/L，比未疏浚区减少了19.8%～28.1%；疏浚区浮游植物的生物量为2.3～10.0 mg/L，比未疏浚区减少了19.5%～50.2%；其中蓝藻的密度下降了28.6%～39.5%，生物量下降了31.8%~66.0%；疏浚区底栖动物中的寡毛类的平均密度和生物量为94.3 个/m2和0.52 g/m2，比未疏浚区减少了57.3%和52.9%；摇蚊类的平均密度和生物量为10.91 个/m2和0.12 g/m2，比未疏浚区减少了91.8%和82.8%；软体动物的平均密度和生物量为0.54 个/m2和0.55 g/m2，比未疏浚区减少了91.8%和91.6%。底泥疏浚区大型水生植物的盖度和生物量分别为50.28%和2.25 kg/m2，与未疏浚区相当。底泥疏浚是削减沉积物内源负荷的有效手段，一定程度上减少了滆湖北部发生蓝藻水华的风险。 |
| 英文摘要: |
| Gehu Lake, with the total area of 164 km2, is the sixth largest fresh water lake in Jiangsu Province and the important component of lake groups in Taihu Lake basin. However, the whole Gehu Lake has degraded from macrophytic lake into algae type lake with frequent occurrence of cyanobacterial bloom in summer and is facing serious ecological crisis because of land reclamation, large-scale reclamation aquaculture and cage culture. In 2011 and 2012, ecological dredging project in northern Gehu Lake was carried out to improve the water quality and ecological environment in Gehu Lake. The aim of our study was to investigate the ecological effects of dredging on aquatic ecosystem in northern Gehu Lake, focusing on the spatial-temporal distribution of nutrients in bottom mud, the spatial-temporal variations of phytoplankton, zoobenthos, and aquatic macrophyte communities including species composition, density and biomass in dredged and un-dredged areas, which will provide scientific evidence for lake eutrophication control and ecological remediation. From October, 2012 to September, 2013, monthly sampling was made at eight sampling sites (site 1- site 3 in the dredged area and site 4- site 8 in the un-dredged area). 1 L surface water sample was collected using water sampler for phytoplankton identification, fixed with Lugos’ solution and settled for 48 h before microscopic examination. Bottom mud samples were collected with a Peterson bottom sampler (1/16 m2), then screened and rinsed for zoobenthos identification, counting and weighing. All the emerged plant in a 1 m2 sampling plot were removed from the root and weighed; submerged plant, floating-leaved plant and floating plant were collected using grass clip, then identified and weighed after water rinsing. Bottom sediments (0-5 cm) were collected with sediment corer, then dried and grinded for nutrients content determination, including the total organic carbon（TOC）, total nitrogen（TN）and total phosphorous（TP）. The results show that the average contents of TN, TP and organic matter in sediments of dredged areas were 0.65 g/kg, 0.63 g/kg and 7.73 g/kg, decreased by 51.4%, 51.2% and 72.0%, respectively, comparing with those in the un-dredged areas, indicating that dredging was an effective approach for nutrients removal in sediments. The phytoplankton density and biomass in dredged areas were 379.6 ×104-2867.1×104 ind./L and 2.3-10.0 mg/L, decreased by 19.8%-28.1% and 19.5%-50.2% comparing with those in the un-dredged areas. Especially, the density and biomass of cyanobacteria were respectively reduced by 28.6%-39.5% and 31.8%-66.0% in dredged areas, which significantly decreased the risk of cyanobacteria bloom in northern Gehu Lake. The average density and biomass of oligochaetas, chironomids and mollusks in dredged areas were 94.3 ind./m2 and 0.52 g/m2, 10.91 ind./m2 and 0.12 g/m2, 0.54 ind./m2 and 0.55 g/m2, decreased respectively by 57.3% and 52.9%, by 91.8% and 82.8%, and by 91.8%-91.6% comparing with those in the un-dredged areas. Dredging project significantly influenced the species diversity and biomass of chironomus and mollusks. The cover and biomass of macrophyte in dredged areas were 50.28% and 2.25 kg/m2, which were basically equivalent to those in un-dredged areas. The results indicate that dredging project is suitable to conduct in eutrophic lakes, which will improve the aquatic ecological environment by removing part proportion of surface sediments and suppressing phytoplankton growth. However, dredging too deep will adversely influence the zoobenthos and aquatic macrophyte communities.
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| 吴沛沛,刘劲松,胡晓东,杨星,翁松干,李志清,郭刘超,吴苏舒.2015.滆湖北部底泥疏浚的生态效应研究[J].水生态学杂志,36(2):32-38. |
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