长春南湖底泥疏淩工程效果研究

【作者】 王小雨；

【导师】 冯江；

【作者基本信息】 东北师范大学 ， 环境科学， 2004， 硕士

【摘要】 本文以长春南湖底泥疏浚工程为研究对象，在南湖底泥疏浚期间，经过2002～2003年连续2年(每年5～10月)水化学、浮游生物、底栖生物和底泥的采样分析，从构成湖泊水生生态系统的三个方面即水化学、水生生物和底泥研究了南湖底泥疏浚的实际效果。分析了南湖底泥疏浚前后水化学、浮游生物和底栖生物的变化，探讨了疏浚后南湖水化因子、浮游生物、底栖生物和底泥演化趋势。疏浚后南湖水质透明度、pH值变化不大；溶解氧和CODCr增加；总氮、氨氮、亚硝酸盐氮、硝酸盐氮、总磷和BOD5比疏浚前降低。水质主因子分析表明：疏浚前，南湖水化学因子中起控制作用的是总磷、CODCr，其次是氨氮和总氮；疏浚后起控制作用的是pH值、BOD5，其次是悬浮物。 疏浚前后水质配对样本t检验结果表明疏浚前后南湖总体的水质状况没有明显的变化(p<0.05)。疏浚后，2002年共鉴定出浮游植物285种及变种，2003年为334种及变种。2002-2003年间南湖浮游植物的优势种相对稳定，为α-中污带到β-中污带指示种。疏浚后浮游植物群落发生了演替，由疏浚前的绿藻—蓝藻—硅藻型演变为目前的绿藻—硅藻—蓝藻型。2002年检出浮游动物134种，2003年117种，浮游动物优势种多为α-中污带到β中污带指示种。底泥疏浚前后南湖浮游动物群落组成发生了变化，疏浚后浮游动物主要是原生动物和轮虫，枝角类和桡足类数量极少，不足1%。疏浚后2000～2003年浮游动物数量上升，生物量下降，表明南湖浮游动物小型化趋势明显。2003年检出底栖动物15种，以寡毛类、摇蚊幼虫和软体动物三个类群为主。南湖底栖动物的种类少，优势种水丝蚓、摇蚊幼虫和羽摇蚊幼虫，为中到重度富营养化的指示种。底泥疏浚对螺、蚌等软体动物干扰较大。疏浚后底栖动物的生物多样性减少，Margalef指数由3.45下降到1.87。南湖底泥疏浚后底泥中有机质含量下降17%，总氮含量下降36%，总磷平均值下降较小，仅为3.33%。总磷含量疏浚后变幅较大，变异系<WP=5>数为95%，I站含量明显偏高导致疏浚后总磷平均值的偏高，影响了底泥疏浚的效果。同疏浚前相比，疏浚后底泥中Cd含量降低；Zn和Cu含量增高，原因是位于南湖大桥西南I站的点源污染引起的。疏浚后底泥中重金属元素积累顺序为：Zn(18.15)>Hg(6.67) >Pb (5.64) >Cd(2.6) >Cu(2.54) >Ni(1.72) >C r(1.02)>As(1)。目前南湖底泥中重金属中C r和As 为土壤环境质量I级标准（GB15618-1995），Cu、Cd、Ni、Pb和Hg介于I级和II级之间，Zn达不到III级。在南湖底泥重金属中Zn污染最为严重。更多还原

【Abstract】 Environmental effects of sediment dredging events have been uncommonly reported for shallow lake in China. A project of bottom sediment dredging has been carried at the Lake Nanhu since 2000 in order to control its eutrophication. During the period from May to October monthly in 2002～2003, the characteristic of the water physical-chemical, the plankton, zoobenthos and the pollutants in sediment had been investigated from 4 sample sites. The objective of this paper was to determine the effects of hydraulic sediment dredging at the Lake Nanhu prior to and after dredging. The effects on surface water pH and Secchi disk depth (SD) were negligible but dissolved oxygen (DO) and chemical oxygen demand by K2Cr2O7 method (CODcr) was increased. While total nitrogen (TN), ammonia nitrogen (NH4-N), nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N), total phosphorus (TP) and biological oxygen demand for five days (BOD5) were decreased. Factor Analysis of water quality indicated that the first factors were TP and CODcr, the second were TN and NH4-N prior to dredging. However, the first factors were pH value and BOD5, the second were suspended solids (SS) after dredging. The result of Paired Sample T test prior to and after dredging showed that the water quality had not been changed significantly.After dredging, the species number of phytoplankton was 285 and 334 respectively, between 2002 and 2003. The dominated species was stable in 2002-2003. The phytoplankton community took succession from chlorophyta-cyanophyta-diatom of prior to dredging to chlorophyta-diatom-cyanophyta of post dredging. The species numbers of zooplankton were 134 and 117 respectively, between 2002 and 2003. The dominated species was stable in 2002-2003. The zooplankton community changed. The zooplankton community was mainly consisted of protozoa and rotifer, and the number of cladocera and copepoda were less than 1 percent. The phenomena, which the number of zooplankton was up and the biomass was down, demonstrated miniaturization trend of the zooplankton was obvious. The sediment dredging had significant impact on mollusca. The Margalef Index of benthic animal community decreased from 3.45 to 1.87. <WP=7> Investigation of the sediment showed that the mean concentrations of organic carbon and the mean total nitrogen decreased 17 percent and 36 percent respectively, compared with prior to sediment dredging. But the concentrations total phosphorus only decreased 3.33 percent. The discrepancy of total phosphorus between different sample sites was significant. The mean concentrations of TP sample site I was significant higher than that of three other’s. The concentrations of the Cd in sediment decreased than that of prior to dredging. While the concentrations of Zn and Cu increased than that of prior to dredging. The cause attributed to the point source situated in sample site I. The heavy metal in sediment contamination factors were very high for Zn (18.15), Hg (6.67), Pb (5.64) and considerable for Cd (2.6), Cu (2.54), Ni (1.72), C r (1.02), As (0.098). C r and As The pollution of Zn was most serious in all eight heavy metals analyzed, its concentration did not meet Soil Environmental Quality Standard（GB15618-1995）.更多还原