Key Laboratory of Virtual Geographic Environment, Ministry of Education, College of Geographic Science, Nanjing Normal University, Nanjing, 210023, China.
Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China.
Environ Sci Pollut Res Int. 2017 Dec;24(36):28079-28101. doi: 10.1007/s11356-017-0305-7. Epub 2017 Oct 9.
Knowledge of tempo-spatial dynamics of water quality and its response to river flow is important for the management of lake water quality because river discharge associated with rainstorms can be an important source of pollutants to the estuary. Total phosphorus (TP), chlorophyll a (Chl-a), and total suspended matter (TSM) are important indexes of water quality and important factors influencing eutrophication and algal blooms. In this study, remote sensing was used to monitor these indexes to investigate the effects of river discharge on the estuary of Taihu Lake by the largest inflow river which is Chendong River using a total of 136 Geostationary Ocean Color Images (GOCI). In situ datasets collected during the four cruise experiments on Taihu Lake between 2011 and 2015 were used to develop the TP, Chl-a, and TSM inversion models based on simple empirical algorithms: 154 points for TP (mg/L), 114 for Chl-a (μg/L), and 181 for TSM (mg/L). The spatial and temporal changes of the concentration of the three parameters in the Chendong River estuary were analyzed by combining the GOCI data, the flow of the Chendong River, and meteorological data throughout the year in 2014. The several key findings are as follows: (1) In summer and autumn, TP, Chl-a, and TSM contents were significantly higher than in winter and spring. TP and Chl-a have a few similar distribution characteristics. And organic suspended matter in summer was the main reason for the increase of the TSM concentration. (2) The severe surface erosion in the rivers cannot be ignored; the high erodibility is an important factor in the increase of TP and TSM concentrations in the estuary. The concentration of the water quality parameter showed exponential decay with distance from the shore. The concentration decreased slowly after 12 km and then remained essentially constant. (3) TP content in the Chendong River estuary decreased under steady flow inputs and dramatically increased when the flow became large. The increase in Chl-a content was linked to higher levels of TP and good weather conditions after the rain event. Higher flow rates mainly play a dilution role for the Chl-a concentration. Erosion of the surface soil via rainfall is a major source of TSM to the estuary. This paper firstly analyzes tempo-spatial dynamics of water quality and its response to river flow in estuary of Taihu Lake, helps to further understand the impact of river input on lake water quality, and is important for lake eutrophication.
水质时空动态及其对河流流量的响应知识对于湖泊水质管理非常重要，因为暴雨引起的河流排放可能是河口污染物的重要来源。总磷（TP）、叶绿素 a（Chl-a）和总悬浮物（TSM）是水质的重要指标，也是影响富营养化和藻类水华的重要因素。本研究利用总共 136 景静止轨道海洋水色卫星（GOCI），通过遥感监测这些指标，探讨了最大入湖河流——滆湖河入湖口水质时空动态及其对河流流量的响应。本研究利用 2011 年至 2015 年期间在太湖进行的四次巡航实验收集的现场数据集，基于简单的经验算法，分别建立了 TP（mg/L）、Chl-a（μg/L）和 TSM（mg/L）的 154 个点、114 个点和 181 个点的反演模型。结合 GOCI 数据、2014 年全年的滆湖河流量和气象数据，分析了 2014 年整个年度该河口的三个参数浓度的时空变化。主要研究结果如下：（1）夏季和秋季，TP、Chl-a 和 TSM 含量明显高于冬季和春季。TP 和 Chl-a 具有一些相似的分布特征。夏季有机悬浮物是 TSM 浓度增加的主要原因。（2）河流的严重表层侵蚀不容忽视；高可蚀性是河口 TP 和 TSM 浓度增加的一个重要因素。水质参数的浓度随距岸距离呈指数衰减。在距离海岸 12 公里后，浓度下降缓慢，然后基本保持不变。（3）在稳定流量输入下，滆湖河口的 TP 含量下降，而流量增大时则显著增加。Chl-a 含量的增加与雨后较高的 TP 水平和良好的天气条件有关。较高的流速主要对 Chl-a 浓度起稀释作用。降雨导致的表层土壤侵蚀是 TSM 进入河口的主要来源。本研究首次分析了太湖河口水质时空动态及其对河流流量的响应，有助于进一步了解河流输入对湖泊水质的影响，对湖泊富营养化具有重要意义。
