Eutrophication of Lake Ulansuhai in 2006-2017 and its main impact factors

为探明草型湖泊乌梁素海水体营养状态及演变趋势，明确水体富营养化的关键影响因子，本文采用2006-2017年每年7月份湖泊水质监测数据，利用综合营养指数法评价了湖泊不同区域监测点的水体营养状态，模拟分析了湖泊水体营养状态的演变过程及趋势特征，定性分析了湖泊富营养的关键影响因子.研究结果表明：乌梁素海湖区北部、西部和南部监测点处于轻度富营养状态的极限概率分别为0.588、0.633和0.329，而湖泊的中部和东部监测点处于中营养状态的极限概率分别为0.810和0.536，说明乌梁素海湖区北部、西部和南部区域夏季水体营养状态将呈现向轻度富营养化演变的趋势，而湖区中部和东部区域则呈现向中营养化演变的趋势.水环境因子中水体理化指标对湖泊富营养化起决定性作用，且盐度指标响应概率高达55%，是水体理化指标中第1位影响因子，同时pH值与水深指标也是影响乌梁素海水体富营养化程度的重要因子.;In order to ascertain the eutrophication status, evolution trend, and its main impact factors in Lake Ulansuhai, the water quality monitoring data in July between 2006 and 2017 were applied to evaluate the eutrophication status at different monitoring sites by which could represent the typical regions of the lake. The evolution process and trend characteristics of the eutrophication of lake water nutrient status were simulated and analyzed. The key influencing factors of lake eutrophication were qualitatively analyzed. The results showed that the limit probability of slight eutrophication at the northern, western and southern monitoring sites was 0.588, 0.633 and 0.329, respectively, while that in the central and eastern monitoring sites was 0.810 and 0.536, respectively. This indicated that the water eutrophication in the northern, western and southern regions of the lake would present a slight eutrophication evolution trend. Meanwhile the central and eastern regions of the lake present a moderate eutrophication evolution trend. The physical and chemical indexes of water body played a decisive role in the lake eutrophication, among which the response probability of salinity index was as high as 55%, meaning that salinity index was the most important impact factor to the lake eutrophication. pH and water depth also played a quite important role in influencing the lake eutrophication.