Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China.
Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, PR China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, PR China.
Sci Total Environ. 2017 Jan 1;575:996-1004. doi: 10.1016/j.scitotenv.2016.09.170. Epub 2016 Oct 5.
Due to global warming, some regions of Earth may face frequent and severe droughts in the future, leading to the deterioration of surface water quality. In this study, we investigated the effects of drought-induced drawdown on the water quality of the Zhoucun Reservoir, Shandong Province, East China, during the fall overturn. Field surveys were conducted during stratification (April-November) over three standard years 2012, 2013, and 2014, and over the El Niño event of 2015. Temporal and vertical variations of the physical and chemical indexes were investigated during monitoring. Results show that after the formation of stratification, the hypolimnion rapidly shifted to anaerobic conditions, with the accumulation of pollutants such as manganese (Mn) and total phosphorous (TP). Due to the extreme El Niño event in 2015, both the upper and lower metalimnion limits moved down along with the water level in summer, which resulted in the transfer of hypolimnion water to the metalimnion. In summer 2015, large amounts of pollutants were measured in the metalimnion: a phenomenon that did not occur at the same period of the standard years. At the beginning of the overturn in 2015, the water quality of the whole reservoir deteriorated when the metalimnion water shifted to the epilimnion. Mn and TP concentrations in the epilimnion reached 0.202mg/L and 0.086mg/L, respectively, which are significantly higher than those in the standard years. Although the tributary rivers entered the epilimnion of the reservoir during the overturn, Mn and TP concentrations of the inflow were only of 0.049-0.072mg/L and 0.033-0.047mg/L, respectively, indicating that these rivers were not the source of the high TP and high Mn concentrations in the epilimnion. Hence, we conclude that more attention should be paid to the metalimnion position and the vertical distribution of pollutants when studying lakes and reservoirs experiencing droughts.
由于全球变暖，地球的一些地区未来可能会频繁遭遇严重干旱，导致地表水质恶化。在本研究中，我们调查了 2012 年、2013 年和 2014 年三个标准年以及 2015 年厄尔尼诺年秋季翻转期间，干旱引起的水位下降对中国华东山东省周村水库水质的影响。在分层期（4 月至 11 月）进行了现场调查，监测期间调查了理化指标的时间和垂直变化。结果表明，分层形成后，下湖迅速转为厌氧条件，污染物如锰（Mn）和总磷（TP）积累。由于 2015 年厄尔尼诺事件极端，上下金属层限制在夏季随水位一起向下移动，导致下湖水体转移到金属层。2015 年夏季，金属层中测量到大量污染物：这一现象在标准年同期并未发生。2015 年翻转开始时，当金属层水转移到表水层时，整个水库水质恶化。表水层 Mn 和 TP 浓度分别达到 0.202mg/L 和 0.086mg/L，明显高于标准年。尽管在翻转期间支流进入了水库的表水层，但流入的 Mn 和 TP 浓度仅为 0.049-0.072mg/L 和 0.033-0.047mg/L，表明这些河流不是表水层高 TP 和高 Mn 浓度的来源。因此，我们得出结论，在研究经历干旱的湖泊和水库时，应更加关注金属层位置和污染物的垂直分布。
