Spatial distribution, risk assessment, and seasonal variations of 4-nonylphenol in China’s Yinma River Basin

In recent decades the Yinma River Basin has been receiving increasing pollution from industrial and domestic wastewater, agriculture, and livestock production – which are all potential 4-NP pollution sources. Thus, this work investigated spatial-seasonal distribution, risks, and seasonal variations of 4-nonylphenol in the aquatic environment of the Yinma River Basin. The results indicated that the highest concentrations in water and sediment occurred in livestock-production, industrial, and domestic-wastewater areas, and the lowest occurred in agricultural areas; a seasonal variation in 4-NP concentrations in water was observed, with the highest concentrations occurring in the dry season and the lowest concentrations in the wet season. The results for risk quotient indicated that in three water seasons, low ecological risks of 4-NP in water primarily occurred in agricultural areas, and high ecological risks occurred downstream of domestic-wastewater drainage; the ecological risks of 4-NP in sediment from all the sampling sites were exposed to moderate or high ecological risks. Based on the results for hazard quotient, a seasonal variation in human health risks of 4-NP in water was observed; except for a sampling site located downstream of domestic wastewater drainage, human health risks of 4-NP in water were low