A quantitative methodology to assess the risks to human health from CO2 leakage into groundwater

Leakage of CO2 and associated gases into overlying aquifers as a result of geologic carbon capture and sequestration may have adverse impacts on aquifer drinking-water quality. Gas or aqueous-phase leakage may occur due to transport via faults and fractures, through faulty well bores, or through leaky confining materials. Contaminants of concern include aqueous salts and dissolved solids, gaseous or aqueous-phase organic contaminants, and acidic gas or aqueous-phase fluids that can liberate metals from aquifer minerals. Here we present a quantitative risk assessment framework to predict potential human health risk from CO2 leakage into drinking water aquifers. This framework incorporates the potential release of CO2 into the drinking water aquifer; mobilization of metals due to a decrease in pH; transport of these metals down gradient to municipal receptors; distributions of contaminated groundwater to multiple households; and exposure and health risk to individuals using this water for household purposes. Additionally, this framework is stochastic, incorporates detailed variations in geological and geostatistical parameters and discriminates between uncertain and variable parameters using a two-stage, or nested, Monte Carlo approach. This approach is demonstrated using example simulations with hypothetical, yet realistic, aquifer characteristics and leakage scenarios. These example simulations show a greater risk for arsenic than for lead for both cancer and non-cancer endpoints, an unexpected finding. Higher background groundwater gradients also yield higher risk. The overall risk and the associated uncertainty are sensitive to the extent of aquifer stratification and the degree of local-scale dispersion. These results all highlight the importance of hydrologic modeling in risk assessment. A linear relationship between carcinogenic and noncarcinogenic risk was found for arsenic and suggests action levels for carcinogenic risk will be exceeded in exposure situations before noncarcinogenic action levels, a reflection of the ratio of cancer and non-cancer toxicity values. Finally, implications for ranking aquifer vulnerability due to geologic configuration, aquifer mineralogy, and leakage scenarios are discussed.

[1]  J. Nicot,et al.  Investigation of water displacement following large CO2 sequestration operations , 2009 .

[2]  Jiemin Lu,et al.  Potential risks to freshwater resources as a result of leakage from CO2 geological storage: a batch-reaction experiment , 2010 .

[3]  Jan M. Nordbotten,et al.  Injection and Storage of CO2 in Deep Saline Aquifers: Analytical Solution for CO2 Plume Evolution During Injection , 2005 .

[4]  K. Ahmed,et al.  Arsenic poisoning of Bangladesh groundwater , 1998, Nature.

[5]  Liange Zheng,et al.  Evaluation of Potential Changes in Groundwater Quality in Response to CO2 Leakage from Deep Geologic Storage , 2010 .

[6]  Matteo Loizzo,et al.  Building CO2 Storage Risk Profiles With The Help Of Quantitative Simulations , 2009 .

[7]  Andrew F. B. Tompson,et al.  Numerical simulation of chemical migration in physically and chemically heterogeneous porous media , 1993 .

[8]  Yue Hao,et al.  Geochemical detection of carbon dioxide in dilute aquifers , 2009, Geochemical transactions.

[9]  Jens Birkholzer,et al.  On mobilization of lead and arsenic in groundwater in response to CO2 leakage from deep geological storage , 2009 .

[10]  Rainer Helmig,et al.  A contribution to risk analysis for leakage through abandoned wells in geological CO2 storage , 2010 .

[12]  C. W. Gardiner,et al.  Handbook of stochastic methods - for physics, chemistry and the natural sciences, Second Edition , 1986, Springer series in synergetics.

[13]  William E. Kastenberg,et al.  A model for assessing and managing the risks of environmental lead emissions , 1999 .

[14]  W. H. Carter,et al.  Toxicological interactions among arsenic, cadmium, chromium, and lead in human keratinocytes. , 2001, Toxicological sciences : an official journal of the Society of Toxicology.

[15]  David W Keith,et al.  Regulating the ultimate sink: managing the risks of geologic CO2 storage. , 2003, Environmental science & technology.

[16]  C. A. Hoppert,et al.  Absorption and distribution of Cr51 in the albino rat , 1959 .

[17]  Michael A. Celia,et al.  Spatial characterization of the location of potentially leaky wells penetrating a deep saline aquifer in a mature sedimentary basin , 2004 .

[18]  A. Lasaga.  Kinetic theory in the earth sciences , 1998 .

[19]  Curtis M. Oldenburg,et al.  The consequences of failure should be considered in siting geologic carbon sequestration projects , 2009 .

[20]  R. L. Dodge,et al.  Carbon Dioxide Sequestration in Geological Media State of the Science , 2010 .

[21]  A. Rinaldo,et al.  Simulation of dispersion in heterogeneous porous formations: Statistics, first‐order theories, convergence of computations , 1992 .

[22]  L. Grant,et al.  The comparative developmental neurotoxicity of lead in humans and animals. , 1990, Neurotoxicology and teratology.

[23]  Jonny Rutqvist,et al.  A comparative review of hydrologic issues involved in geologic storage of CO2 and injection disposal of liquid waste , 2008 .

[24]  Stefan Finsterle,et al.  Percolation-theory and fuzzy rule-based probability estimation of fault leakage at geologic carbon sequestration sites , 2010 .

[25]  Daniel M. Tartakovsky,et al.  Probabilistic risk analysis of groundwater remediation strategies , 2009 .

[26]  Macrodispersivity and Large-scale Hydrogeologic Variability , 2001 .

[27]  Liange Zheng,et al.  Changes in the chemistry of shallow groundwater related to the 2008 injection of CO2 at the ZERT field site, Bozeman, Montana , 2010 .

[28]  C. Steefel,et al.  A coupled model for transport of multiple chemical species and kinetic precipitation/dissolution rea , 1994 .

[29]  Karsten Pruess,et al.  TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive geochemical Transport in Variable Saturated Geologic Media , 2004 .

[30]  W. M. Haynes.  CRC Handbook of Chemistry and Physics , 1990 .

[31]  Rebecca C. Smyth,et al.  Assessing risk to fresh water resources from long term CO2 injection- laboratory and field studies , 2009 .

[32]  L. Barraj,et al.  Low-level arsenic exposure in drinking water and bladder cancer: a review and meta-analysis. , 2008, Regulatory toxicology and pharmacology : RTP.

[33]  W. Kinzelbach,et al.  The Random Walk Method in Pollutant Transport Simulation , 1988 .

[34]  Sookyun Wang,et al.  Dissolution of a mineral phase in potable aquifers due to CO2 releases from deep formations; effect of dissolution kinetics , 2004 .

[35]  Andrew F. B. Tompson,et al.  Numerical simulation of solute transport in three-dimensional, randomly heterogeneous porous media , 1990 .

[36]  Paul J. Lioy,et al.  Assessing total human exposure to contaminants. A multidisciplinary approach , 1990 .

[37]  Yoram Rubin,et al.  The concept of comparative information yield curves and its application to risk‐based site characterization , 2009 .

[38]  Susan D. Pelmulder,et al.  Regional scale framework for modeling water resources and health risk problems , 1996 .

[39]  R. Jackson,et al.  Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers. , 2010, Environmental science & technology.

[40]  C. Appelo,et al.  Geochemistry, groundwater and pollution , 1993 .

[41]  R. Ababou,et al.  Numerical simulation of three-dimensional saturated flow in randomly heterogeneous porous media , 1989 .

[42]  Y. Rubin.  Stochastic modeling of macrodispersion in heterogeneous porous media , 1990 .

[43]  L. Gold,et al.  Trichloroethylene cancer risk: simplified calculation of PBPK-based MCLs for cytotoxic end points. , 1997, Regulatory toxicology and pharmacology : RTP.

[44]  J. O'Shea,et al.  The absorption of arsenic and its relation to carcinoma , 1975, The British journal of dermatology.

[45]  H. Guess,et al.  Uncertainty estimates for low-dose-rate extrapolations of animal carcinogenicity data. , 1977, Cancer research.

[46]  F. O. Hoffman,et al.  Propagation of uncertainty in risk assessments: the need to distinguish between uncertainty due to lack of knowledge and uncertainty due to variability. , 1994, Risk analysis : an official publication of the Society for Risk Analysis.

[47]  C P Weisel,et al.  Ingestion, inhalation, and dermal exposures to chloroform and trichloroethene from tap water. , 1996, Environmental health perspectives.

[48]  Karsten Pruess,et al.  Reactive geochemical transport simulation to study mineral trapping for CO2 disposal in deep arenaceous formations , 2003 .

[49]  H. Christopher Frey,et al.  Characterization and Simulation of Uncertain Frequency Distributions: Effects of Distribution Choice, Variability, Uncertainty, and Parameter Dependence , 1998 .

[50]  Steven F. Carle,et al.  Contamination, risk, and heterogeneity: on the effectiveness of aquifer remediation , 2008 .

[51]  G. Pinder,et al.  Non-Probabilistic Uncertainty in Subsurface Hydrology and Its Applications: an Overview , 2006 .

[52]  C. R. Cothern,et al.  Development of quantitative estimates of uncertainty in environmental risk assessments when the scientific data base is inadequate , 1986 .

[53]  Susan D. Pelmulder,et al.  On the development of a new methodology for groundwater‐Driven health risk assessment , 1998 .

[54]  Sam Huang,et al.  Miscible Displacement In the Weyburn Reservoir: A Laboratory Study , 1993 .

[55]  R. Andricevic,et al.  Radionuclide migration using a travel time transport approach and its application in risk analysis , 1994 .

[56]  Melisa F. Pollak,et al.  Research for deployment: incorporating risk, regulation, and liability for carbon capture and sequestration. , 2007, Environmental science & technology.

[57]  E. Dubé,et al.  Arsenic toxicity at low doses: epidemiological and mode of action considerations. , 2004, Toxicology and applied pharmacology.

[58]  D. Barnes,et al.  Reference dose (RfD): description and use in health risk assessments. , 1988, Regulatory toxicology and pharmacology : RTP.

[59]  David N. Lerner,et al.  Organic contamination of the Birmingham aquifer, U.K. , 1990 .

[60]  X. Jianming,et al.  Paleoclimatic interpretation of the past 30 ka from isotopic studies of the deep confined aquifer of the North China plain , 2003 .

[61]  T. McKone,et al.  PREDICTING THE UNCERTAINTIES IN RISK ASSESSMENT , 1991 .

[62]  J. Allison,et al.  MINTEQA2/PRODEFA2, a geochemical assessment model for environmental systems: Version 3. 0 user's manual , 1991 .

[63]  G. Fogg,et al.  Diffusive fractionation of 3H and 3He in groundwater and its impact on groundwater age estimates , 2006 .

[64]  Furchner Je,et al.  Comparative metabolism of radionuclides in mammals-IV. Retention of silver-110m in the mouse, rat, monkey, and dog. , 1968 .

[65]  A. Shraim,et al.  A global health problem caused by arsenic from natural sources. , 2003, Chemosphere.

[66]  David R. Cole,et al.  Gas-water-rock interactions in Frio Formation following CO2 injection: Implications for the storage of greenhouse gases in sedimentary basins , 2006 .

[67]  Graham E. Fogg,et al.  Random-Walk Simulation of Transport in Heterogeneous Porous Media: Local Mass-Conservation Problem and Implementation Methods , 1996 .

[68]  R. Maxwell,et al.  Stochastic environmental risk analysis: an integrated methodology for predicting cancer risk from contaminated groundwater , 1999 .

[69]  V. Cvetkovic,et al.  Evaluation of Risk from Contaminants Migrating by Groundwater , 1996 .

[70]  Glenn E. Hammond,et al.  Field‐scale model for the natural attenuation of uranium at the Hanford 300 Area using high‐performance computing , 2010 .

[71]  Claire Welty,et al.  Revisiting the Cape Cod bacteria injection experiment using a stochastic modeling approach. , 2005, Environmental science & technology.

[72]  Lars Jarup,et al.  Hazards of heavy metal contamination. , 2003 .

[73]  B. Metz.  IPCC special report on carbon dioxide capture and storage , 2005 .

[74]  Yoram Rubin,et al.  A risk‐driven approach for subsurface site characterization , 2008 .

[75]  Y. Rubin,et al.  A methodology to integrate site characterization information into groundwater‐driven health risk assessment , 1999 .

[76]  Gordon H. Huang,et al.  An integrated fuzzy-stochastic modeling approach for risk assessment of groundwater contamination. , 2007, Journal of environmental management.

[77]  D. M. LeNeveu,et al.  CQUESTRA, a risk and performance assessment code for geological sequestration of carbon dioxide , 2008 .

[78]  Daniel M. Tartakovsky,et al.  Probabilistic risk analysis in subsurface hydrology , 2007 .

[79]  Jens Birkholzer,et al.  Identification of thermodynamic controls defining the concentrations of hazardous elements in potable ground waters and the potential impact of increasing carbon dioxide partial pressure , 2009 .

[80]  Y. Kharaka.  Reactive transport modeling to study changes in water chemistry induced by CO2 injection at the Frio-I brine pilot , 2010 .

[81]  Joel Massmann,et al.  Groundwater contamination from waste management sites: The interaction between risk‐based engineering design and regulatory policy: 1. Methodology , 1987 .

[82]  Jennifer L. Lewicki,et al.  Natural and industrial analogues for leakage of CO2 from storage reservoirs: identification of features, events, and processes and lessons learned , 2007 .

[83]  R. Spear,et al.  Integrating uncertainty and interindividual variability in environmental risk assessment. , 1987, Risk analysis : an official publication of the Society for Risk Analysis.

[84]  David R. Cole,et al.  Gas-water-rock interactions in sedimentary basins: CO2 sequestration in the Frio Formation, Texas, USA , 2006 .

[85]  Jason S. Ogola,et al.  Impact of Gold mining on the Environment and Human Health: A Case Study in the Migori Gold Belt, Kenya , 2002 .

[86]  R. Ababou,et al.  Implementation of the three‐dimensional turning bands random field generator , 1989 .

[87]  T E McKone,et al.  Uncertainties in health-risk assessment: an integrated case study based on tetrachloroethylene in California groundwater. , 1992, Regulatory toxicology and pharmacology : RTP.

[88]  Raffaele Giordano,et al.  A fuzzy knowledge-based decision support system for groundwater pollution risk evaluation. , 2004, Journal of environmental management.

[89]  Rajesh J. Pawar,et al.  The impact of CO2 on shallow groundwater chemistry: observations at a natural analog site and implications for carbon sequestration , 2010 .

[90]  Thomas E. McKone,et al.  Human exposure to volatile organic compounds in household tap water: the indoor inhalation pathway , 1987 .

[91]  O. Malm.  Gold mining as a source of mercury exposure in the Brazilian Amazon. , 1998, Environmental research.

[92]  G. Fogg,et al.  Role of Molecular Diffusion in Contaminant Migration and Recovery in an Alluvial Aquifer System , 2001 .

[93]  W. Giger,et al.  Arsenic contamination of groundwater and drinking water in Vietnam: a human health threat. , 2001, Environmental science & technology.

[94]  G. Dagan.  Flow and transport in porous formations , 1989 .

[95]  Stefan Bachu,et al.  Semianalytical solution for CO2 leakage through an abandoned well. , 2005, Environmental science & technology.

[96]  Y. Rubin.  Applied Stochastic Hydrogeology , 2003 .

[97]  S. Ashby,et al.  A parallel multigrid preconditioned conjugate gradient algorithm for groundwater flow simulations , 1996 .

[98]  Natalie W. Harrington,et al.  Recommended distributions for exposure factors frequently used in health risk assessment. , 1994, Risk analysis : an official publication of the Society for Risk Analysis.

[99]  R. Maxwell,et al.  Integrated surface-groundwater flow modeling: A free-surface overland flow boundary condition in a parallel groundwater flow model , 2006 .

[100]  Franklin W. Schwartz,et al.  Macroscopic dispersion in porous media: The controlling factors , 1977 .

[101]  Thomas E. McKone,et al.  Measured and estimated air concentrations of chloroform in showers: Effects of water temperature and aerosols , 1997 .

[102]  John L. Wilson,et al.  Efficient and accurate front tracking for two‐dimensional groundwater flow models , 1991 .

[103]  Joel Massmann,et al.  Hydrogeological Decision Analysis: 1. A Framework , 1990 .

[104]  Max Henrion,et al.  Uncertainty: A Guide to Dealing with Uncertainty in Quantitative Risk and Policy Analysis , 1990 .

[105]  E. Eric Adams,et al.  Field study of dispersion in a heterogeneous aquifer , 1992 .

[106]  Reed M. Maxwell,et al.  Quantifying the effects of three-dimensional subsurface heterogeneity on Hortonian runoff processes using a coupled numerical, stochastic approach , 2008 .

[107]  Jan M Nordbotten,et al.  Practical Modeling Approaches for Geological Storage of Carbon Dioxide , 2009, Ground water.

[108]  Jim E. Jones,et al.  Newton–Krylov-multigrid solvers for large-scale, highly heterogeneous, variably saturated flow problems , 2001 .