Introduction to tetrachlorethylene

Tetrachloroethene (PCE) is a chlorinated solvent that has been widely used as a degreaser and dry cleaning agent. PCE is also a common groundwater contaminant that poses serious health risks to humans and the environment. PCE can migrate through fractured bedrock aquifers, where it can undergo various physical, chemical, and biological processes that affect its transport and fate. Understanding the flow and transport of PCE in fractured bedrock is essential for developing effective remediation strategies and protecting groundwater resources.

Methods

In this study, we investigated the flow and transport of perchloroethylene in a fractured bedrock aquifer at a former industrial site in Ontario, Canada. We used a combination of field measurements, laboratory experiments, and numerical modeling to characterize the hydrogeological and geochemical conditions of the site, and to simulate the PCE plume evolution over time. We focused on the effects of fracture network geometry, matrix diffusion, biodegradation, and sorption on the PCE distribution and attenuation.

Results

The results showed that the PCE plume was mainly controlled by the fracture network structure, which created preferential flow paths and heterogeneous hydraulic conductivity. The PCE concentration varied significantly along the flow direction and across the fracture zones. The PCE(CAS 127-18-4) plume also exhibited a complex temporal behavior, with fluctuations in concentration due to seasonal variations in groundwater recharge and discharge. The PCE mass balance analysis indicated that matrix diffusion was the dominant attenuation mechanism, accounting for about 80% of the total mass loss. Biodegradation and sorption were minor processes, contributing to less than 10% of the mass loss each.

Discussion

The study demonstrated that Tetrachloroethene flow and transport in fractured bedrock is a complex phenomenon that requires a multidisciplinary approach to understand and predict. The numerical model was able to capture the main features of the PCE plume, but also revealed some limitations and uncertainties in the model parameters and assumptions. The model results suggested that the PCE plume was relatively stable and would not pose a significant threat to the downgradient receptors. However, the long-term fate of the PCE stored in the rock matrix remains uncertain, and may depend on future changes in hydrological or geochemical conditions.

Conclusion

Tetrachloroethene(CAS 127-18-4) is a persistent groundwater contaminant that can migrate through fractured bedrock aquifers. This study provided a comprehensive analysis of the PCE flow and transport at a contaminated site in Ontario, Canada, using field, laboratory, and modeling methods. The study highlighted the importance of fracture network geometry, matrix diffusion, biodegradation, and sorption on the PCE(CAS 127-18-4) distribution and attenuation. The study also identified some knowledge gaps and challenges for future research on PCE remediation in fractured bedrock systems.