Historical mining activities often lead to continuing wide spread contaminants in both groundwater and surface water in previously operational mine site areas. The contamination may continue for many years after closi...Historical mining activities often lead to continuing wide spread contaminants in both groundwater and surface water in previously operational mine site areas. The contamination may continue for many years after closing down the mining activities. The essential first step for sustainable management of groundwater and development of remediation strategies is the unknown contaminant source characterization. In a mining site, there are multiple species of contaminants involving complex geochemical processes. It is difficult to identify the potential sources and pathways incorporating the chemically reactive multiple species of contaminants making the source characterization process more challenging. To address this issue, a reactive transport simulation model PHT3D is linked to a Simulated Annealing based the optimum decision model. The numerical simulation model PHT3D is utilized for numerically simulating the reactive transport process involving multiple species in the former mine site area. The simulation results from the calibrated PHT3D model are illustrated, with and without incorporating the chemical reactions. These comparisons show the utility of using a reactive, geochemical transport process’ simulation model. Performance evaluation of the linked simulation optimization methodology is evaluated for a contamination scenario in a former mine site in Queensland, Australia. These performance evaluation results illustrate the applicability of linked simulation optimization model to identify the source characteristics while using PHT3D as a numerical reactive chemical species’ transport simulation model for the hydro-geochemically complex aquifer study area.展开更多
One of the most serious and important environmental issues related to the mining sector in Central Queensland is the contamination of abandoned mine sites. Representative of this issue is the abandoned Mount Morgan go...One of the most serious and important environmental issues related to the mining sector in Central Queensland is the contamination of abandoned mine sites. Representative of this issue is the abandoned Mount Morgan gold mine. The potential dispersal of acid mine drainage (AMD), a product of more than 100 million tons of sulphide-rich waste rock, into the surrounding environment, is the most challenging environmental problem currently facing this abandoned mine site. The abandoned Mount Morgan gold mine has multiple pollutant species that involve complex geochemical processes. The present study simulated the flow and transport processes founded on hydrological and geochemical conditions of the real-life field at the mine site. To assess the groundwater contamination risk and detect unknown pollution sources, few chemical species such as Iron and Sulphur were considered as the contaminants. The flow model was simulated using the computer code MODFLOW, and PHT3D was used for the simulation of advection, dispersion and chemical reactions of constituents dissolved in this groundwater system, and to mimic the reactive chemical transport processes in the polluted groundwater. To improve on results from other studies (Datta et al., 2017;Scotney, 2016;Doyle, 2016), a calibrated model was a main focus for this study. Field concentration measurements were matched with the flow simulation outcomes to calibrate the model. The results obtained showed a great potential to model transport of contaminants in the groundwater system using a real-world situation.展开更多
Permeable reactive barrier（PRB） filled with zero valent iron（ZVI, Fe0） can be an effective option to remove nitrate from contaminated groundwater. The long-term performance of such PRBs, however, might be compromi...Permeable reactive barrier（PRB） filled with zero valent iron（ZVI, Fe0） can be an effective option to remove nitrate from contaminated groundwater. The long-term performance of such PRBs, however, might be compromised by the problem of declining reactivity and permeability, which could cause a decrease in the nitrate removal efficiency. In this study we explored suitable model formulations that allow for a process-based quantification of the passivation effect on denitrification rates and tested the model for a 40 years long operation scenario. The conceptual model underlying our selected formulation assumes the declining reactivity of the ZVI material through the progressing passivation caused by the precipitation of secondary minerals and the successive depletion of the ZVI material. Two model scenarios, i.e., the base model scenario which neglects the explicit consideration of the passivation effect and one performed with the model in which the impact of the passivation effect on denitrification was considered, were compared. The modeling results illustrate that nitrate removal in the model of considered passivation started to be incomplete after 10 years, and the effluent nitrate concentration of PRB rose up to 86% of the injected water concentration after 40 years, in contrast to the base scenario, corresponding well with the field observations of successively declining nitrate removal efficiencies. The model results also showed that the porosity of the PRB increased in both models. In order to improve and recover the reactivity of ZVI, pyrite was added to the PRB, resulting in completely nitrate removal and lower consumption of ZVI.展开更多
文摘Historical mining activities often lead to continuing wide spread contaminants in both groundwater and surface water in previously operational mine site areas. The contamination may continue for many years after closing down the mining activities. The essential first step for sustainable management of groundwater and development of remediation strategies is the unknown contaminant source characterization. In a mining site, there are multiple species of contaminants involving complex geochemical processes. It is difficult to identify the potential sources and pathways incorporating the chemically reactive multiple species of contaminants making the source characterization process more challenging. To address this issue, a reactive transport simulation model PHT3D is linked to a Simulated Annealing based the optimum decision model. The numerical simulation model PHT3D is utilized for numerically simulating the reactive transport process involving multiple species in the former mine site area. The simulation results from the calibrated PHT3D model are illustrated, with and without incorporating the chemical reactions. These comparisons show the utility of using a reactive, geochemical transport process’ simulation model. Performance evaluation of the linked simulation optimization methodology is evaluated for a contamination scenario in a former mine site in Queensland, Australia. These performance evaluation results illustrate the applicability of linked simulation optimization model to identify the source characteristics while using PHT3D as a numerical reactive chemical species’ transport simulation model for the hydro-geochemically complex aquifer study area.
文摘One of the most serious and important environmental issues related to the mining sector in Central Queensland is the contamination of abandoned mine sites. Representative of this issue is the abandoned Mount Morgan gold mine. The potential dispersal of acid mine drainage (AMD), a product of more than 100 million tons of sulphide-rich waste rock, into the surrounding environment, is the most challenging environmental problem currently facing this abandoned mine site. The abandoned Mount Morgan gold mine has multiple pollutant species that involve complex geochemical processes. The present study simulated the flow and transport processes founded on hydrological and geochemical conditions of the real-life field at the mine site. To assess the groundwater contamination risk and detect unknown pollution sources, few chemical species such as Iron and Sulphur were considered as the contaminants. The flow model was simulated using the computer code MODFLOW, and PHT3D was used for the simulation of advection, dispersion and chemical reactions of constituents dissolved in this groundwater system, and to mimic the reactive chemical transport processes in the polluted groundwater. To improve on results from other studies (Datta et al., 2017;Scotney, 2016;Doyle, 2016), a calibrated model was a main focus for this study. Field concentration measurements were matched with the flow simulation outcomes to calibrate the model. The results obtained showed a great potential to model transport of contaminants in the groundwater system using a real-world situation.
基金supported by the National Natural Science Foundation of China(Nos.41402213 and 51279016)the Open Fund of Three Gorges Research Center for Geo-hazard,Ministry of Education,China University of Geosciences(No.TGRC201403)+2 种基金the Open Fund of the Key Laboratory of Groundwater Contamination and Remediation,China Geological Survey(CGS)and Hebei Province(No.KF201508)the Foundation of Central Public Welfare Scientific Institute Basic Scientific Research(No.CKSF2016021/YT)the Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Personnel of China(2014)
文摘Permeable reactive barrier（PRB） filled with zero valent iron（ZVI, Fe0） can be an effective option to remove nitrate from contaminated groundwater. The long-term performance of such PRBs, however, might be compromised by the problem of declining reactivity and permeability, which could cause a decrease in the nitrate removal efficiency. In this study we explored suitable model formulations that allow for a process-based quantification of the passivation effect on denitrification rates and tested the model for a 40 years long operation scenario. The conceptual model underlying our selected formulation assumes the declining reactivity of the ZVI material through the progressing passivation caused by the precipitation of secondary minerals and the successive depletion of the ZVI material. Two model scenarios, i.e., the base model scenario which neglects the explicit consideration of the passivation effect and one performed with the model in which the impact of the passivation effect on denitrification was considered, were compared. The modeling results illustrate that nitrate removal in the model of considered passivation started to be incomplete after 10 years, and the effluent nitrate concentration of PRB rose up to 86% of the injected water concentration after 40 years, in contrast to the base scenario, corresponding well with the field observations of successively declining nitrate removal efficiencies. The model results also showed that the porosity of the PRB increased in both models. In order to improve and recover the reactivity of ZVI, pyrite was added to the PRB, resulting in completely nitrate removal and lower consumption of ZVI.
