Assessment of Spatial-Temporal Patterns of Surface Water Quality in the Min River (China) and Implications for Management

This paper investigated the spatial-temporal variations and pollution source of surface water quality by analyzing the data from 8 water quality monitoring stations along the middle and lower reaches of the Min River between 2003 and 2008. The results showed that surface water quality was worse in the middle reaches of the Min River than that in the lower reaches and its tributary. Seasonal and spatial differences were found for TEMP, PH, DO, BOD₅, COD_mn and NH₃-N, whereas for TN and TP the differences were mainly due to the water quality station. The level of organics (BOD5 and COD_mn) was higher in summer (high flow period), and the level of nutrients (NH₃-N) was higher in winter (low flow period). In the middle reaches of the Min River, point sources (from wastewater treatment plants and industrial effluents) were the dominant inputs of organics (COD_mn) and nutrients (NH₃-N, TN and TP) to river. In the lower reaches of the Min River, diffuse sources (from agricultural fertilizer, soil erosion, etc.) were the dominant contributor of organics and TP to river, point sources were the dominant input of NH3-N, whilst many different potential sources for TN transportation. In tributary, diffuse sources were the dominant organics and TP input, both point and diffuse sources were dominant NH₃-N and TN input. Overall, these results reinforced the notion that pollution control by periods and regions was important for effective water management in the middle and lower reaches of the Min River.