Pollution Characteristics and Risks of Polycyclic Aromatic Hydrocarbons in Underground and Surface Drinking Water Sources in Northeast Inner Mongolia

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are hazardous and ubiquitous pollutants in the aquatic environment, and understanding the pollution characteristics and risk levels of PAHs is of great significance to the sustainable development of drinking water sources and drinking water safety. Hence, PAHs residues were measured qualitatively and quantitatively with solid-phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS) in 33 water samples (including 22 groundwater and 11 surface water samples) of the drinking water sources in the Manzhouli and Xinyouqi areas of northeast Inner Mongolia, and assessments of the pollution level of PAHs and the health and ecological risks were carried out. The results showed that PAHs were detected in all 33 sampling points of Manzhouli drinking water sources, except for benzo[k] fluoranthene, benzo[a] pyrene, and dibenzo[a,h] anthracene, with detection rates ranging from 36.36% to 95.45%; the detection rates of the other 13 PAHs monomers were 100%. The detection range of ρ（ΣPAHs） was 42.76-164.50 ng·L-1, and the mean value was 90.82 ng·L-1. The detection ranges of ρ（ΣPAHs） in surface water and groundwater were 66.39-164.50 ng·L-1 and 42.76-147.70 ng·L-1, respectively. The concentration of the detected naphthalene was the highest, with a mean value of 36.91 ng·L-1, and the concentration of anthracene was the lowest, with a mean value of 0.81 ng·L-1; there were no significant differences among the concentrations of all the PAHs monomers of the surface and groundwater (P>0.05). The pollution of PAHs was at a median level in China and abroad, mainly in the middle and low loops (3-4 loops). The analysis of the sources of PAHs in groundwater and surface water in Manzhouli using the ratio feature method and principal component analysis showed that the PAHs in the drinking water source water bodies in the Manzhouli area were mainly affected by the combustion of coal and biomass and oil, and some surface water sources were affected by the oil source. The human health and ecological risk assessment results showed that the water body of drinking water would not cause health risks to the human body, and the ecological risk was at a medium level; however, the high risk of benzo[b] fluoranthene (BbF) monomer production should be continuous cause for concern. From the perspective of the sustainable development of drinking water sources and drinking water safety, the necessary supervision and protection measures should be considered to prevent further pollution. The results of this research provide a scientific basis for the pollution control and prevention and control of PAHs in drinking water sources.