Department of Bioscience and Biotechnology, Chungnam National University, Daejeon 34134, Korea.
Int J Environ Res Public Health. 2021 Mar 11;18(6):2871. doi: 10.3390/ijerph18062871.
Long-term variations in reservoir water chemistry could provide essential data in making sustainable water quality management decisions. Here, we analyzed the spatiotemporal variabilities of nutrients, sestonic chlorophyll-a (CHL-a), nutrient enrichment, dominant algal species, and overall chemical water health of the third-largest drinking water reservoir in South Korea during 2000-2020. Our results distinctly explained the strong influence of monsoon rainfall on spatial and annual water chemistry variations. We observed a consistent increase in the chemical oxygen demand alluding to organic matter pollutants, while a steady declining trend in the sestonic CHL-a. The long-term total phosphorus (TP) level showed a steady reduction from the riverine zone to the lacustrine area. However, a higher total coliform bacteria (TCB) was observed at the water intake tower sites. TP displayed a strong link to algal CHL-a and ambient nitrogen phosphorus ratios, suggesting a robust phosphorus-limitation state. The severe phosphorus-limitation was also corroborated by the findings of trophic state index deviation. The high and low flow dynamics exhibited the strong influence of intensive rainfall carrying many nutrients and sediments and flushing out the sestonic CHL-a. Successive eutrophic conditions prevailed along with dominating blue-green algae species (Microcystis and Anabaena). We observed a strong positive correlation (r = 0.62) between water temperature and CHL-a and between total suspended solids and TP (r = 0.65). The multi-metric water pollution index characterized the overall water quality as 'good' at all the study sites. In conclusion, the long-term spatiotemporal variabilities of the ecological functions based on the nutrient-CHL-a empirical models are regulated mainly by the intensive monsoon precipitation. The drinking water could become hazardous under the recurrent eutrophication events and chemical degradations due to uncontrolled and untreated inflow of sewage and wastewater treatment plant effluents. Therefore, we strongly advocate stringent criteria to mitigate phosphorus and organic pollutant influx for sustainable management of Daecheong Reservoir.
长期的水库水化学变化可以为制定可持续的水质管理决策提供重要数据。在这里，我们分析了 2000-2020 年期间韩国第三大饮用水库的养分、悬浮叶绿素-a（CHL-a）、营养富化、优势藻类物种和整体化学水质的时空变化。我们的结果清楚地解释了季风降雨对空间和年度水化学变化的强烈影响。我们观察到化学需氧量持续增加，这暗示着有机污染物的存在，而悬浮 CHL-a 则呈稳定下降趋势。长期总磷（TP）水平显示出从河流区到湖泊区的稳定减少。然而，在取水塔站点观察到更高的总大肠菌群（TCB）。TP 与藻类 CHL-a 和环境氮磷比之间存在很强的联系，表明存在强烈的磷限制状态。营养状态指数偏差的发现也证实了这种严重的磷限制状态。高、低流量动态显示了密集降雨携带大量养分和沉积物的强烈影响，并冲刷了悬浮 CHL-a。富营养化条件连续占主导地位，同时存在蓝藻（微囊藻和鱼腥藻）等优势物种。我们观察到水温与 CHL-a 之间存在强烈的正相关（r = 0.62），以及总悬浮固体与 TP 之间存在强烈的正相关（r = 0.65）。多指标水污染指数表明，所有研究点的水质总体良好。总之，基于养分-CHL-a 经验模型的生态功能的长期时空变化主要受强烈的季风降水调节。由于未受控制和未经处理的污水和污水处理厂废水的流入，饮用水可能会在反复发生的富营养化事件和化学降解下变得危险。因此，我们强烈主张严格的标准来减轻磷和有机污染物的流入，以实现对大坝水库的可持续管理。
