Environmental behaviors of PAHs in Ordovician limestone water of Fengfeng coal mining area in China

In this study, we collected a total of 15 Ordovician limestone (OL) water, 4 shallow groundwater, 3 mine water, 2 surface water, and 2 coal bedrock water samples, aiming to analyze the characteristics of distributions and sources of polycyclic aromatic hydrocarbons (PAHs) in OL water in a typical exploited coal mine named as Fengfeng mining area. Firstly, the PAHs behaviors and characteristics in different types of water of the mining area were investigated and summarized. And then, the hydrogen and oxygen isotopes were combined with isomer ratio method to determine the characteristics, sources, and behaviors of PAHs in OL water, respectively. Results showed that the concentration of PAHs ranged from 0.06 to 0.56 ng/L in OL water of Fengfeng Mine. Among them, the dominant 2–4 cyclic PAHs, including Nap, Phe, Flt, and Flu, were detected at a low concentration level with high detection rate. Characteristic compound ratios Ant/(Ant + Phe) and Flt/(Flt + Pyr) showed that the PAHs were derived from the combustion of the coal and biomass. The results of δD/δ18O and δD/Phe testing showed that the PAHs in most OL water came from rainfall infiltration recharge with coal and biomass combustion products in exposed bedrock area at high altitude. The PAHs of some polluted areas were derived from leakage recharge of shallow groundwater, mine water, and coal bedrock water.