Qiu Xiao-Peng, Huang Ting-Lin, Zeng Ming-Zheng, Shi Jian-Chao, Cao Zhan-Hui
School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
Huan Jing Ke Xue. 2017 Feb 8;38(2):547-554. doi: 10.13227/j.hjkx.201608001.
Global warming can intensify the El Niño phenomenon that recurs every 2-7 years, which will lead to a great interannual variability of climate and may induce the deterioration of the water quality of reservoirs. To study the influence of the extreme El Niño events on the water quality of stratified reservoirs during summer, field surveys were conducted in Zhoucun Reservoir and its inflow rivers from May to August in a normal year (2012) and a strong El Niño year (2015). Temporal variations of physical and chemical index were investigated during monitoring. The results showed that the Zhoucun Reservoir was stratified during the study period. The precipitation in the summer of the normal year was significantly higher than that in the El Niño year at the same period. In the summer of the normal year, the water level increased from 124.26 m to 127.14 m and the hypolimnion thickness increased by 3.1 m. However, in 2015, the rapid decrease of the water level from May to August (from 121.65 m to 119.46 m) led to the decrease of the hypolimnion thickness (by 3.2 m). The inflow rivers belonged to surface current and its nutrients concentrations were obviously higher than those in the epilimnion. The inflow nutrients loads increased significantly in the summer of the normal year, as a result, total nitrogen increased from 1.00 mg·L to 2.06 mg·L, nitrate increased from 0.19 mg·L to 1.28 mg·L, and total phosphorus increased from 0.023 mg·L to 0.088 mg·L in the lacustrine zone of the reservoir. In contrast, the nutrients concentrations changed little in the summer of the El Niño year due to the decrease in runoff. Nonetheless, the reducing pollutants concentrations of the hypolimnion in the El Niño year were significantly higher than those in the normal year, which may be due to the temporal variations of hypolimnion thicknesses. The maximum concentrations of iron, manganese, ammonium and sulfide in the summer of the El Niño year were 0.38, 1.36, 2.36 and 1.67 mg·L, respectively. All these index exceeded the standards for surface water Class Ⅲ. We conclude that the extreme El Niño event has an apparent influence on the nutrients concentrations in the epilimnion and the pollutants concentrations in the hypolimnion in Zhoucun Reservoir.
全球变暖会加剧每2至7年出现一次的厄尔尼诺现象，这将导致气候的年际变化很大，并可能引发水库水质恶化。为研究极端厄尔尼诺事件对夏季分层水库水质的影响，于正常年份（2012年）和强厄尔尼诺年份（2015年）的5月至8月，在周村水库及其入库河流进行了实地调查。监测期间调查了物理和化学指标的时间变化。结果表明，研究期间周村水库处于分层状态。正常年份夏季的降水量明显高于同期厄尔尼诺年份的降水量。正常年份夏季，水位从124.26米上升到127.14米，温跃层厚度增加了3.1米。然而，2015年5月至8月水位迅速下降（从121.65米降至119.46米）导致温跃层厚度减小（减小了3.2米）。入库河流属于表层流，其营养物质浓度明显高于表层水。正常年份夏季入库营养物质负荷显著增加，结果水库湖口区总氮从1.00毫克·升增加到2.06毫克·升，硝酸盐从0.19毫克·升增加到1.28毫克·升，总磷从0.023毫克·升增加到0.088毫克·升。相比之下，由于径流量减少，厄尔尼诺年份夏季营养物质浓度变化不大。尽管如此，厄尔尼诺年份温跃层中污染物浓度的降低幅度明显高于正常年份，这可能是由于温跃层厚度的时间变化所致。厄尔尼诺年份夏季铁、锰、铵和硫化物的最大浓度分别为0.38、1.36、2.36和1.67毫克·升。所有这些指标均超过地表水Ⅲ类标准。我们得出结论，极端厄尔尼诺事件对周村水库表层水的营养物质浓度和温跃层中的污染物浓度有明显影响。
