地质科技通报 (Jul 2023)

Modelling of groundwater remediation using monitored natural attenuation at a contamination site in Guangzhou

  • Haochen Yuan,
  • Youkuan Zhang,
  • Xiuyu Liang

DOI
https://doi.org/10.19509/j.cnki.dzkq.tb20220434
Journal volume & issue
Vol. 42, no. 4
pp. 268 – 278

Abstract

Read online

Objective Monitoring natural attenuation (MNA), as a low cost remediation method for groundwater pollution that does not produce secondary pollutants and has little impact on the polluted site environment, has high application value and development prospects, and is worth practicing and studying. Methods This paper adopts a groundwater-contaminated site in Baiyun District of Guangzhou to assess the applicability of MNA. Based on the analysis of hydrogeological conditions and pollution status, a groundwater numerical simulation program MODFLOW was used to establish a groundwater flow model for contaminated sites. The pollutant migration numerical simulation program MT3DMS was used to establish a pollutant migration model for the site. The migration processes of groundwater flow, main pollutants total petroleum hydrocarbons (TPH), and heavy metal nickel (Ni) were simulated, respectively. Based on the model, the performances of the MNA alone and the MNA combined with pump and treat methods were compared. Results The results show that TPH and Ni are both sensitive to changes in the Freundlich constant and Freundlich exponent. The TPH shows good natural attenuation effect and can be substantially attenuated by the MNA alone. The concentration of TPH decreased from the initial value of 1.52 mg/L to the target (0.3 mg/L) after 850 days. Ni decay is relatively slow and it is suitable to adopt to a natural attenuation scheme under monitoring combined with the pump & treat method. The concentration of Ni decreased from the initial value of 0.13 mg/L to the target (0.02 mg/L) after 300 days. For a contaminated site with large natural attenuation capacities and/or low groundwater flow velocities, MNA alone is an appropriate remediation strategy. In contrast, for a contaminated site with low natural attenuation capacities and/or high groundwater flow velocities, the MNA combined with pump and treat may be a better remediation strategy. Conclusion This study provides an appropriate reference for the application of MNA to groundwater pollution remediation.

Keywords