Pollutants in the Estuary of Xiaoqing River: Analysis and Water Quality Assessment

【Objective】 The Xiaoqing River is located in Shandong province. In this paper, we analyze the contaminants in its estuary and assess its water quality. 【Method】 We selected the section from Shicun to Yangjiaogou for analysis. Water quality was evaluated based on data measured from 2019 to 2021 from four water sampling locations in the section. The main pollutants in the locations were analyzed using the principal component analysis method; we also analyzed the origin of these pollutants. 【Result】 Water quality in sampling locations in the section had improved from 2019 to 2021, with the water quality level changing to Class IV in 2021. The pollutants that exceeded the standard at these locations are total nitrogen (TN), of which nitrate (NO3-) is the main pollutant. NO3- at Shicun was affected by both non-point pollution and domestic sewage, while the origin of NO3- at Houxinzhuang was sewage and manure. Meteorological factors such as temperature and rainfall had indirect affect in water quality in the estuary. 【Conclusion】 The comprehensive water quality identification index combined with the combinatorial integration method is accurate for assessing water quality. The main pollutants in the estuary of Xiaoqing River are total nitrogen, especially nitrate.