鄱阳湖富营养化现状及成因分析

Eutrophic Status and Causing Factors for Poyang Lake,China

鄱阳湖为中国第一大淡水湖,也是江西省重要湿地,具备“丰水一片、枯水一线”的特性。按照“丰水期、平水期、枯水期”进行富营养化评价可科学反应鄱阳湖富营养水平,为多支流、水位季节变化的大型湖泊蓝藻水华研究提供科学参考。采用综合分析法和相关性分析法从2018年枯水期(2月份)至2020年丰水期(7月份)对鄱阳湖13个点监测,研究鄱阳湖富营养化,并进行成因分析,结果表明,鄱阳湖富营养水平为中富-富营养水平,没有明显加重趋势。水位对湖泊富营养化的影响较大,枯水期、平水期、丰水期富营养化水平呈下降趋势;而从监测点的变化看,枯水期至平水期的变化更具有波动性,说明平水期受枯水期、丰水期的双重影响。入湖口处营养物质累积作用和及湖泊的自净作用,导致鄱阳湖富营养化程度湖区要低于入湖口,在入湖河流中,赣江南支、饶河入湖口的富营养化程度最高,其次为赣江北支、赣江中支、信江入湖口,修河、抚河入湖口的富营养化水平最低;而在湖区监测点中,都昌、星子、康山、柳树湾、西源、金溪咀刘家的富营养化程度依次递减。下一步应加强入湖河流营养盐管控及增加湖区水环境容量,从而降低鄱阳湖富营养化水平和蓝藻水华风险。

Poyang lake is the largest freshwater lake in China and an important wetland in Jiangxi province,It has the characteristics of"the water surface is very large in the flood season and linear in the dry season".Assessment of eutrophication according to"high-water period,normal-water period and low-water period"can scientifically reflect Poyang lake's eutrophication level.Comprehensive analysis and correlation analysis were used,A total of 13 sites were monitored from 2018 low-water period(February)to 2020 high-water period(July)to study the eutrophication in Poyang lake and analyze the cause of eutrophication.The results show that Poyang lake is at the level of middle eutrophication to eutrophi-cation and didn't have the apparent deepening trend.Water level affects eutrophication of lake.Eutrophication of high-water period,normal-water period and low-water period is in the downward variation.From the change of monitoring point,the change from low water period to normal water period is more fluctuant,which shows that normal water period is influenced by both low water period and high water period.The accumulation of nutrients at the lake mouth and the self-purification of the lake lead to a lower eutrophication in the Poyang lake area than at the lake mouth.The eutrophication level in lake mouth of Ganjiang River south branch and Raohe River is the highest,followed by the lake mouth of Ganjiang River north branch and Ganjiang River middle branch and Xinjiang river.The eutrophication level in the lake mouth of Xiuhe river and Fuhe River is the lowest.The eutrophication levels of Duchang,Xingzi,Kangshan,Liushuwang,Xiyuan,JInxi Lake decreased in turn.In order to reduce the eutrophication level and the risk of cyanobacteria bloom,it is necessary to strengthen the control of nutrients and to increase the water environmental capacity of the Poyang lake.