南水北调东线湖群水体营养状态评价及其限制因子研究

Eutrophication Assessment and Limited Factors of Impounded Lakes in the East Route of South-to-North Water Transfer Project

湖泊富营养化问题是我国湖泊保护面临的紧迫问题,开展湖泊营养状态评价及其限制因子研究,对于富营养化湖泊治理和生态系统修复具有重要意义。该研究以南水北调东线工程调蓄湖群-高邮湖、洪泽湖、骆马湖、南四湖、东平湖为研究区域,于2018年4月非调水期和10月调水期对调蓄湖群109个样点开展了系统监测,采用综合营养状态指数法对调蓄湖群营养状态进行了评价,运用多元统计分析方法分析了湖群富营养化特征及其限制因子。结果表明:同一水期内调蓄湖泊间水质指标不尽相同,各调蓄湖泊非调水期水质优于调水期,影响水质达标的主要因子为总氮和总磷。调蓄湖群调水期均处于轻度富营养状态,非调水期均处于中营养状态,非调水期优于调水期。透明度和叶绿素a是决定调蓄湖群富营养化水平的限制性因子。

Eutrophication is an urgent problem faced by lake manager,it is necessary to study lake eutrophication and its limited factors for lake management.In order to assess the eutrophic status and understand its influencing factors,field investigation of water quality was carried out at 109 sampling sites in five impounded lakes(Lake Gaoyou;Lake Hongze;Lake Luoma;Lake Nansi;Lake Dongping)in the east route of South-to-North Water Transfer Project in April 2018(water non-diversion)and October 2018(water diversion)separately.Water samples were collected for determination of permanganate index(CODMn),total nitrogen(TN),total phosphorus(TP)and chlorophyll a(Chl a),and transparency(SD)was measured in situ.The comprehensive trophic level index TLI(∑)was used for eutrophic status assessment,and multivariate statistical analysis was used to analyze the eutrophication characterization and limited factors.The results indicated that water quality parameters were varied among impounded lakes in the same water period,and water quality of impounded lakes in water non-diversion period was better than that in water diversion period,which were mainly affected by total nitrogen and total phosphorus.The comprehensive trophic level index of Lake Gaoyou,Lake Hongze,Lake Luoma,Lake Nansi and Lake Dongping were 54.43 and 49.74、55.00 and 48.50、54.14 and 38.30、53.41 and 40.57、52.86 and 40.77,implying that these lakes were light eutrophication level during water diversion and mesotrophic level during water non-diversion.The correlation coefficients between TLI and SD and Chl a were-0.51 and 0.46 in water diversion period and-0.73 and 0.82 in water non-diversion period,indicating that SD and Chl a were the limited factors for eutrophication of implouded lakes.