三峡蓄水期间汉丰湖消落区营养状态时间变化

为探明三峡蓄水后汉丰湖消落区水质营养状态的变化特征,于2013年10月至2014年2月对水质进行连续观察,测定了水质物理参数、营养盐与叶绿素(Chl-a)的质量浓度.结果表明,水体中营养盐与Chl-a质量浓度的增加,在淹水后营养程度有升高现象,2014年2月与2013年10月相比,TN、TP、高锰酸盐指数与Chl-a质量浓度分别增加了4.7、1.0、0.2、3.27倍,TN、TP质量浓度均超过藻类生长限值,随滞留时间延长易造成水体富营养化,应引起重视.Chl-a单因子评价反映出水质由贫营养向富营养演变.TN/TP结果表明,TN、TP分别在不同时间内制约着藻类的生长;2013年10~12月与2014年2月,藻类生长受TN限制;2014年1月,藻类生长受TP限制.Chl-a与p H、DO、NH+4-N、NO-3-N、TN、高锰酸盐指数及TP呈显著正相关,而与SD、水温呈显著负相关;蓄水期间,水质受到了同一污染源的影响.因子分析结果表明,汉丰湖消落区水质主要受p H、DO、NO-3-N、TN的影响,同时Chl-a、TP、NH+4-N与好氧性有机物的污染不可忽视;在蓄水稳定初期水体具有自净能力,随蓄水滞留时间的延长,水质污染程度整体上呈现逐步恶化的趋势,应加以控制;三峡蓄水期间,南河、东河营养程度相对较高,应加强治理.

Temporal Variation of Trophic Status in Drawdown Area of Hanfeng Lake in the Storage Period of Three Gorges Reservoir in China

In order to explore the temporal variations of nutrient and biomass in drawdown area of Hanfeng Lake of the Three Gorges Reservoir region, this paper continuously observed the water quality in the storage period of 2013 October to 2014 February. And the concentrations of nutrients,water physical parameters and chlorophyll were determined. The results showed that the concentrations of nutrients and chlorophyll increased, and the nutrition degree increased after the flooding. The concentrations of TN, TP, permanganate index and Chl-a in water in February 2014 were 4.7 times, 1.0 time, 0.2 times and 3.27 times the amount in October 2013. It should be noticed that the concentrations of TN and TP were above the algae growth limit value, which would be easy to cause water eutrophication with prolonged residence time. The single-factor evaluation of Chl-a reflected that the water quality was changed from poor nutrient to eutrophic. The results of N/P showed that TN in Han Feng Lake was a factor limiting the growth of algae in different period. In October to December 2013 and February 2014, TN limited the growth of algae. In January 2014, TP limited the growth of algae. The Chl-a had a significant positive correlation to pH, DO, NH₄⁺-N, NO₃^--N, TN, permanganate index and TP, but significant negative correlations were observed with SD and TEMP. The water quality was influenced by the same source of pollution during the storage period. The result of factor analysis showed that the water quality in riparian zone of Hanfeng Lake was mainly affected by pH, DO, NO₃^--N, TN, while Chl-a, TP, NH₄⁺-N and aerobic organics pollution could not be ignored. The water had self-purification capacity in the early phase of the storage period, the eutrophication aggravated with the increase of retention time, and it should be controlled. During the storage period of the Three Gorges Reservoir, the nutrition levels of south river and east river were relatively high, and the management should be strengthened.