The Occurrence, Distribution and Risk Assessment of Typical Perfluorinated Compounds in Groundwater from a Reclaimed Wastewater Irrigation Area in Beijing

Perfluorinated compounds (PFCs) have been extensively studied in recent years due to their persistence, bioaccumulation and toxicity. However, most of the studies are concentrated in surface water with high concentration of PFCs in rivers, sewage and lakes, while few studies explore the status of PFCs pollution in groundwater.

To investigate the content, distribution and ecological risk of typical PFCs compounds in groundwater in the reclaimed water irrigation area of Beijing.

52 groundwater samples were collected from the reclaimed water irrigation area in May to June 2020 and were analyzed by solid phase extraction and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS).

The results showed that 10 target PFCs including perfluorocarboxylic acid (PFCAs) and perfluorosulfonic acid (PFSAs) were detected in groundwater in Beijing, with a concentration of 1.07-24.19ng/L. Among them, the highest detected concentration of perfluorobutanoic acid (PFBA), perfluorooctanoic acid (PFOA), and perfluorobutane sulfonate (PFBS) averaged 2.94ng/L, 2.88ng/L and 1.15ng/L, respectively. The concentration of ∑PFCs in this study was relatively low compared to the groundwater from the fluorochemical industrial park, which was related to the mostly farmland location of the observation wells in the study area. After observing the performance of PFCs in shallow wells (< 50m) and deep wells (>50m), it was found that the concentration of PFCs decreased significantly with increasing well depth. In addition, in view of the spatial distribution of groundwater PFCs in the whole region, the concentration of groundwater PFCs around the landfill was significantly high and decreased with increasing distance from the landfill, indicating that the landfill had a certain contribution to the pollution of surrounding groundwater PFCs.

By calculating the risk quotient of PFOA, perfluorooctane sulfonate (PFOS) and PFBA, the landfill has not posed an ecological risk to the surrounding environment. However, in view of the concealment and persistence of groundwater PFCs, it is recommended to carry out continuous regular monitoring and evaluation.