Evaluation of Water Quality in Middle and Lower Yangtze River of China

The water resource is the basic natural resource and one of the controlling factors of the ecological environment. However, for China with extensive economic growth and high population pressure, deterioration of water quality has been a very serious problem. This research will focus on five main provinces along the Yangtze River, one of the richest and most economically developed areas in China. The data of lakes in five provinces is mainly from China Lake Scientific Database and the study chooses and analyzes four elements of the lake: nitrogen content, phosphorus content, dissolved oxygen content,and pH value. These four elements represent water quality or reflect the source of pollution. By R studio, both the ANOVA test and regression equation are used to indicate four elements' relationship among each other in the whole five provinces and each province's water quality and use condition. Jiangsu's average dissolved oxygen content is the highest among the five provinces and is supposed to have the highest water quality because of the strong self-purification ability of water. However, since it also owns the most developed industry seen from data of the number of industrial enterprise and industrial wastewater, lakes in Jiangsu have the highest average nitrogen and phosphorus content. Anhui has low dissolved oxygen content which can harm the production in the fishery. The pH value of lakes in Jiangxi is much lower than that of lakes in other provinces. Jiangxi province suffers from acid rain all year- round, which causes the acidification of groundwater and surface lakes.