Source Identification and Degradation Pathway of Multiple Persistent Organic Pollutants in Groundwater at an Abandoned Chemical Site in Hebei, China

The difficulty of defining the sources of pollution limits the effectiveness of water pollution control measures. This study focused on the Guangrong Canal, a contaminated canal that has been subjected to multiple recovery efforts with unsatisfactory results. Groundwater was first investigated upstream of Guangrong Canal. In Aug 2014, the organic pollutants detected in a sample of groundwater were O-toluidine, aniline, phenol, 2,4-dichlorophenol, phthalate (2-ethylhexyl) ester (DEHP), and 4-nitrotoluene. In Jan 2015, benzene, aniline, O-toluidine, phthalate (2-ethylhexyl) ester (DEHP), and naphthalene were detected in groundwater as well. Additional organic pollutants such as C15-C28, C29-C36, O-toluidine, 4-nitrotoluene, and so on were detected in the soil. The distribution of the organic pollutants indicated that a sewage pit was the pollutant source. The organic pollutants were consistent with the production of organic acids at this abandoned site. We investigated the area around the site to identify the degradation pathway and pollutant source. Based on the results, a pump-and-treat method was adopted at the abandoned site. We then sampled the groundwater 6 months later to evaluate the recovery method. To address pollution of surface waters such as the Guangrong Canal, an investigation of the groundwater and soil from upstream should be performed; the results of the present study indicate that the pump-and-treat method can be most effective for recovering a chemical site.