Source analysis of dissolved heavy metals in the Shaying River Basin, China

Over the years, the Shaying River Basin has experienced frequent instances of river pollution. The presence of numerous critical pollutant discharge enterprises and sewage-treatment plants in the vicinity of the Shaying River has transformed it a major tributary with relatively serious pollution challenge within the upper reaches of Huaihe River Basin. To study the sources of manganese (Mn), chromium (Cr), nickel (Ni), arsenic (As), cadmium (Cd) and lead (Pb) in Shaying River water, 123 sets of surface water samples were collected from 41 sampling points across the entire basin during three distinct phases from 2019 to 2020, encompassing normal water period, dry season and wet season. The primary origins of heavy metals in river water were determined by analyzing the heavy metal contents in urban sewage wastewater, industrial sewage wastewater, groundwater, mine water, and the heavy metal contributions from agricultural non-point source pollution. The analytical findings reveal that Mn primarily originates from shallow groundwater used for agricultural irrigation, While Cr mainly is primarily sourced from urban sewage treatment plant effluents, coal washing wastewater, tannery wastewater, and industrial discharge related to metal processing and manufacturing. Ni is mainly contributed by urban sewage treatment plant effluents and industrial wastewater streams associated with machinery manufacturing and metal processing. Cd primarily linked to industrial wastewater, particularly from machinery manufacturing and metal processing facilities, while Pb is predominantly associated with urban sewage treatment plant effluents and wastewater generated in Pb processing and recycling wastewater. These research provides a crucial foundation for addressing the prevention and control of dissolved heavy metals at their sources in the Shaying River.