The researchers studied water quality in Xiali River which is part of the Dongjiang River. They looked at data from 2003 to 2014 and found that the water quality is good for drinking in some areas, but heavily polluted in others. Key pollutants include ammonia nitrogen, chemical oxygen demand, pH value, arsenic, and total phosphorus. Pollution in the river mainly comes from rare earth smelting, agriculture, and sewage discharge. The findings suggest that different zones along the river have varying pollution levels: the drinking water source area is clean, the reserved area is heavily polluted, and the industrial area is seriously polluted. The study recommends ecological measures to improve the water quality.