[Seasonal Variation Characteristics of Pollution Risk in a Riverside Source Area Based on Source Apportionment]

Riverbank filtration is internationally accepted as a safe new method for extracting drinking water. This paper describes the structure and characteristics of pollution sources in the Hulan water source area of Harbin during wet and dry seasons, based on groundwater pollution sources apportionment technology. Pollution risk of the water source area was also assessed using the pollution sources-pathway-receptor model. Impacts on water quality safety under the collective effects of seasonal changes and human activities were then analyzed. Results showed that groundwater pollution sources have different spatial distribution characteristics based on pollution source apportionment during wet and dry seasons, with four principal influencing factors:①water-rock interaction caused by exploitation of water sources, ② natural geological processes resulting from dissolution of iron manganese minerals, and pollution by ③ nitrogen and ④ organics in response to human activities. Pollution risk assessment showed that water sources were at low risk during both wet and dry seasons. However, the south area of the water source area showed high groundwater pollution risk during the wet season, while other high-risk areas were mainly distributed around the riverbanks and densely populated areas during the dry season. These findings indicate that human activities greatly influence groundwater pollution risk during the dry season; accordingly, this season should be the focus of integrated water quality management and control for the water source area.