巢湖流域河湖系统水环境因子分布特征及营养状态评价

Distribution of Water Environmental Factors and Evaluation of Trophic State in the River-Lake System of Chaohu Lake Basin

分析秋季巢湖流域河湖系统水环境因子空间分布特征,对水质状况开展评价,为流域水环境综合治理和生态环境保护提供科学依据。2019年10月在巢湖和7条入湖河流分别设置8个和25个采样点,监测水环境因子,并采用水质指数(WQI)对其营养状态进行评价。结果表明:(1)巢湖流域河湖水系之间所有水质参数(除水温外)和WQI指数均存在显著性差异,巢湖流域河湖系统水环境在营养梯度上呈现明显的空间格局,东巢湖水质优于西巢湖;杭埠河、柘皋河、裕溪河水质优于兆河、白石山河、派河、南淝河;依据WQI指数,东巢湖、西巢湖、杭埠河、柘皋河、裕溪河水质为较好,兆河、白石山河、派河、南淝河水质为中等;(2)相较以往研究,本研究中西巢湖水质无明显变化,东巢湖水质略有下降,白石山河和兆河由原来的清水型河流转变为污染严重型河流,污染程度加重,其余环湖河流水质无明显变化;(3)应加强巢湖入湖河流氮源的管理和控制,并加强对小型流域的持续监测,深入了解小型支流在整个营养物质输送中所起的作用。

Chaohu Lake, located in central Anhui Province, is a typical eutrophic lake with 33 rivers surrounding the lake in radial pattern. In this study, we analyzed the spatial distribution of water environmental factors in the Chaohu Lake basin and the trophic state of the lake was assessed using the water quality index(WQI). Our aim was to provide scientific evidence for managing water quality and conserving the ecology of Chaohu Lake basin. During October 11-17, 2019, water environmental factors were determined on water collected at 33 sampling stations in Chaohu Lake and 7 tributaries, including East and West Chaohu Lake(ECH and WCH), Nanfei River(NFH), Hangbu River(HBH), Zhaohe River(ZH),Yuxi River(YXH), Paihe River(PH), Baishishan River(BSSH) and Zhegao River(ZGH). Results were as follows:(1) Except for water temperature, there were significant spatial differences in water quality parameters and the WQI in the Chaohu Lake basin. The water environment of the basin presented an obvious spatial nutrient gradient:the water quality of East Chaohu Lake was better than that of West Chaohu Lake,the water quality of Hangbu River,Zhegao River and Yuxi River were better than that of Zhaohe River,Baishishan River,Paihe River and Nanfei River. The WQI of East and West Chaohu Lake were79.69 and 76.88, and the WQI of the seven investigated rivers were in the order: Hangbu River(84.90)>Zhegao River(80.14)>Yuxi River(78.96)>Zhaohe River(67.60)>Baishishan River(65.14) = Paihe River(65.14) >Nanfei River(64.58). According to WQI, the water quality conditions in East Chaohu Lake,West Chaohu Lake,Hangbu River,Zhegao River and Yuxi River were at the good level,while Zhaohe River,Baishishan River,Paihe River and Nanfei River were at the moderate level.(2) Compared with previous studies, there was no significant change in the water quality of West Chaohu Lake and water quality in East Chaohu Lake decreased slightly, pollution levels in Zhaohe River and Baishishan River increased dramatically, from clean to seriously polluted, and water quality in the other rivers remained about the same.(3) The management and control of nitrogen sources in tributaries of Chaohu Lake should be strengthened, and continuous monitoring of water quality in small watersheds should be strengthened to better understand the role of small tributaries in the nutrient transport of the entire basin.