Analysis of Surface Water pH and Ammonia Nitrogen Seasonal Variation Characteristics in Harbin, China

The national requirements for surface water environmental quality are becoming increasingly strict. It is quite necessary for local governments to conduct water quality supervision by analyzing the seasonal variation characteristics of pollutants exceeding the standard in surface water. In recent years, the mainstream of the Songhua River in Harbin has met the Class III value of the “Environmental Quality Standards for Surface Water” (GB3838-2002, China), but the pH and ammonia nitrogen data exceeded the standard in certain months. In order to study the seasonal variation characteristics of pH and ammonia nitrogen in each section, this article selects monitoring data for pH and ammonia nitrogen of representative sections of surface water in Harbin from 2015 to 2019. It then creates time-series graphs, calculates the correlation between pH and water temperature, dissolved oxygen, and total phosphorus using the Pearson and Spearman correlation coefficient method, as well as reviewing the literature to analyze the causes of seasonal variations. The results show that the mainstream and longer tributaries of the Songhua River in Harbin are prone to pH rise in May, primarily due to seasonal natural factors, but this is not as evident in the shorter tributaries. During the winter season (January–February) when the river is covered with ice, the mainstem and tributaries of the Songhua River in Harbin are prone to significantly elevated ammonia concentrations, mainly due to natural and anthropogenic factors, but this is less pronounced in the short tributaries with better water quality.