Abstract:
BACKGROUNDIn recent years, reports of the detection of PAHs in groundwater have gradually increased, but research on PAHs in groundwater of major hydrogeological units in China is not being conducted.
OBJECTIVESTo study and compare the distribution characteristics of PAHs in groundwater under different hydrogeological conditions, using a total of 82 samples of shallow pore water and Karst groundwater samples collected in the Huabei plain, the Pearl River Delta plain, and the Southwestern Karst area.
METHODSGas Chromatography-Mass Spectrometry (GC-MS) was used to test PAHs in groundwater samples, and statistical methods were used to compare the detection frequency, concentration and composition of PAHs in the three different areas.
RESULTS16 PAHs were detected and each PAH was detected in at least one sample. The highest detection rate of PAHs was chrysene (6.10%). The PAH with the highest concentration was naphthalene (5.41 μg/L). Only the concentration of benzo(a)pyrene exceeded the Class Ⅲ limit in the standard for groundwater quality, and the over-standard rate was 2.44%. The PAHs in groundwater are mainly 2-4 rings, but the composition of PAHs in the three regions was different. The relative proportion of 4-rings PAHs in the northern pore water was high, accounting for 52.48%, whereas the pore water in the South and the Karst water in the Southwest were dominated by 3-rings (56.60%) and 2-rings (95.66%), respectively.
CONCLUSIONSThe main cause of contamination of PAHs in Northern pore water was by combustion. The PAHs contamination in the Southern pore water was related to the industrial layout of the Pearl River Delta, whereas the PAHs of Qujing Karst water were mainly affected by atmospheric precipitation. The detection differences of PAHs in different districts were related to their physicochemical properties, hydrogeological conditions, pollution sources, meteorological and hydrological factors. The results provide basic data support for groundwater PAHs pollution monitoring and the formulation of a groundwater related standard in China.