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Title: Arsenic mobilization in shallow aquifers due to CO 2 intrusion from storage reservoirs

We developed an integrated framework of combined batch experiments and reactive transport simulations to quantify water-rock-CO 2 interactions and arsenic (As) mobilization responses to CO 2 and/or saline water leakage into USDWs. Experimental and simulation results suggest that when CO 2 is introduced, pH drops immediately that initiates release of As from clay minerals. Calcite dissolution can increase pH slightly and cause As re-adsorption. Thus, the mineralogy of the USDW is ultimately a determining factor of arsenic fate and transport. Salient results suggest that: (1) As desorption/adsorption from/onto clay minerals is the major reaction controlling its mobilization, and clay minerals could mitigate As mobilization with surface complexation reactions; (2) dissolution of available calcite plays a critical role in buffering pH; (3) high salinity in general hinders As release from minerals; and (4) the magnitude and quantitative uncertainty of As mobilization are predicated on the values of reaction rates and surface area of calcite, adsorption surface areas and equilibrium constants of clay minerals, and cation exchange capacity. Results of this study are intended to improve ability to quantify risks associated with potential leakage of reservoir fluids into shallow aquifers, in particular the possible environmental impacts of As mobilization at carbon sequestrationmore » sites.« less
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)
  3. New Mexico Inst. of Mining and Technology, Socorro, NM (United States)
  4. Univ. of Utah, Salt Lake City, UT (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 2045-2322
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Earth Sciences; Arsenic mobilization, adsorption/desorption, clay mineral, surface complexation, integrated framework, batch experiment.
OSTI Identifier: