Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Environ Pollut. 2020 May;260:114033. doi: 10.1016/j.envpol.2020.114033. Epub 2020 Jan 22.
Poyang Lake is the largest freshwater lake in China and a globally important wetland with various functions. Exploring the multidecadal trend of water quality and hydroclimatic conditions is important for understanding the adaption of the lake system under the pressure from multiple anthropogenic and meteorological stressors. The present study applied the Mann-Kendall trend analysis and Pettitt test to detect the trend and breakpoints of hydroclimatic, and water quality parameters (from the 1980s to 2018) and the trend of monthly-seasonal ammonia (NH-N) and total phosphorus (TP)concentrations (from 2002 to 2018) in Poyang Lake. Results showed that Poyang Lake had undergone a highly significant warming trend from 1980 to 2018, with a warming rate of 0.44 °C/decade in terms of annual daily mean air temperature. The wind speed and water level of the lake presented a highly significant decreasing trend, whereas no notable trend was detected for precipitation variations. The annual mean total nitrogen (TN), NH-N, TP, and permanganate index (COD) concentrations showed significant upward trends from the 1980s to 2018. Remarkable abrupt shifts were detected for TN, NH-N, and COD in around 2003. They were in accordance with the water level breakpoint of the lake, thus implying the important role of hydrological conditions in water quality variations in floodplain lakes. A significant increasing trend has been detected for Chl-a variations during wet season from 2008 to 2018, which could be attributed to the increasing trend of nutrient concentration during the nutrient-limited phase of Poyang Lake. These hydroclimatic and water quality trends suggest a high risk of increasing phytoplankton growth in Poyang Lake. This study thus emphasizes the need for adaptive lake eutrophication management for floodplain lakes, particularly the consideration of the strong trade-off and synergies between hydroclimatic conditions and water quality variations.
鄱阳湖是中国最大的淡水湖，也是具有多种功能的全球重要湿地。探索水质和水文气候条件的数十年趋势，对于了解在多种人为和气象胁迫下湖泊系统的适应具有重要意义。本研究应用 Mann-Kendall 趋势分析和 Pettitt 检验，检测了 1980 年代至 2018 年期间的水文气候和水质参数（1980 年代至 2018 年）以及 2002 年至 2018 年期间的氨氮（NH-N）和总磷（TP）月-季浓度的趋势，并发现了变化的趋势和突变点。结果表明，鄱阳湖自 1980 年以来经历了一个显著的变暖趋势，年平均日气温的升温率为 0.44°C/十年。风速和湖泊水位呈显著下降趋势，而降水变化则没有明显的趋势。总氮（TN）、NH-N、TP 和高锰酸盐指数（COD）的年平均浓度自 1980 年代以来呈显著上升趋势。TN、NH-N 和 COD 于 2003 年左右出现显著突变。它们与湖泊水位的突变点一致，这表明水文条件对洪泛区湖泊水质变化的重要作用。2008 年至 2018 年期间，湿季 Chl-a 的变化呈显著上升趋势，这可能归因于鄱阳湖营养限制阶段期间营养浓度的增加趋势。这些水文气候和水质趋势表明，鄱阳湖浮游植物生长增加的风险很高。因此，本研究强调了需要对洪泛区湖泊进行适应性富营养化管理，特别是需要考虑到水文气候条件和水质变化之间的强烈权衡和协同作用。
