Yoko Masue-Slowey
Yoko Masue-Slowey, Ph.D.
Managing Scientist
Environmental & Earth Sciences
New York

Dr. Masue-Slowey has over 17 years of experience analyzing, predicting, interpreting, and synthesizing complex data sets aimed at understanding the distribution, fate, and transport of natural and synthetic chemical compounds in complex natural and engineered systems. For the past 6 years, Dr. Masue-Slowey’s work at Exponent has focused on applying her wide-ranging knowledge of environmental chemistry; chemical source identification; environmental partitioning and forensics; soil science and mineralogy of soil and sediment; and industrial archeology to address and resolve complex environmental questions in a client-oriented fashion. She has applied her geochemical expertise to Natural Resource Damage Assessment (NRDA), international arbitration, Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) cost allocation, insurance cost recovery, and registration of agricultural chemicals.

Dr. Masue-Slowey specializes in metal geochemistry. She evaluates the propensity of metals such as arsenic, mercury, chromium, selenium, zinc, and lead to transform and partition with natural minerals and synthetic solids to quantify and predict the amount of metals that may leach and migrate to groundwater and receptors, such as humans and wildlife. Her holistic approach assesses relevant site-specific conditions to determine the chemical, biological, and physical risk factors driving the fate and transport of metals and other constituents. Yoko works closely with stakeholders to manage risk and reduce uncertainty associated with metals mobility under changing environmental conditions (e.g., temperature and water content).

Dr. Masue-Slowey has supported investigations in a wide variety of industrial settings, including steel mills; coal mines, zinc, and lead mines; coal ash impoundments; coal-fired power plants; landfills; natural gas production facilities; manufactured gas plants; and refineries. As an expert, Dr. Masue-Slowey has provided consultations regarding the fate of organo-metallic compounds in agricultural fields while working closely with industry executives and their legal teams.

Before joining Exponent, Dr. Masue-Slowey was a researcher and instructor at Stanford University. She designed experiments to investigate factors impacting the fate and transport of arsenic in soils and the sequestration of arsenic in wastewater treatment sludge. As a National Science Foundation Postdoctoral Fellow, she investigated the climate implications of organic carbon stability in Hawaiian soils.

Dr. Masue-Slowey is fluent in English and Japanese.

CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Earth System Science, Stanford University, 2009
  • M.S., Soil Science, Texas A&M University, 2004
  • B.S., Plant and Environmental Soil Sciences, Texas A&M University, 2002, magna cum laude
  • NSF Postdoctoral Fellowship in Earth Sciences, 2011–2013

    U.S. Geological Survey, Texas Water Resource Institute research scholarship, 2003–2004

    Outstanding Senior honored by the American Society of Agronomy, 2002

    Distinguished Student, College of Agriculture and Life Sciences (TAMU), 2002

LANGUAGES

  • Japanese

Publications

Bigham GN, Murray KJ, Masue-Slowey Y, Henry EA. Biogeochemical controls on methylmercury in soils and sediments: Implications for site management. Integrated Environmental Assessment and Management 2017; 13(2):249–63.

Masue-Slowey Y, Slowey AJ, Michel FM, Webb SM, Fendorf S. Constraints on precipitation of the ferrous arsenite solid H7Fe4(AsO3)5. Journal of Environmental Quality 2014; 43(3):947–954. doi:10.2134/jeq2013.08.0340

Masue-Slowey Y, Ying SC, Kocar BD, Pallud C and Scott Fendorf. Dependence of arsenic fate and transport on biogeochemical heterogeneity arising from the physical structure of soils and sediments. Journal of Environmental Quality 2013; 42:4:1119–1129.

Ying SC, Masue-Slowey Y, Kocar BD, Griffis SD, Webb SM, Marcus MA, Francis CA, Fendorf S. Distributed microbially- and chemically-mediated redox processes controlling arsenic dynamics within Mn-/Fe-oxide constructed aggregates. Geochimica et Cosmochimica Acta 2012; 96(1):294–303.

Kim E, Masue-Slowey Y, Fendorf S, Luthy RG. Intra-particle migration of mercury(II) in granular polysulfide-rubber-coated activated carbon (PSR-AC). Chemosphere 2012; 86:648–654.

Zhuang Y, Ahn S, Seyfferth AL, Masue-Slowey Y, Fendorf S, Luthy RG. Dehalogenation of polybrominated diphenyl ethers and polychlorinated biphenyl by bimetallic, impregnated, and nanoscale zerovalent iron. Environmental Science and Technology 2011; 45(11):4896–4903.

Masue-Slowey Y, Kocar BD, Jofre S, Mayer KU, Fendorf S. Transport implications resulting from internal redistribution of arsenic and iron within constructed soil aggregates. Environmental Science and Technology 2011; 45(2):582–588.

Masue-Slowey Y, Loeppert RH, Fendorf S. Alteration of ferrihydrite reductive dissolution and transformation by adsorbed As and structural Al: Implications for As retention. Geochimica et Cosmochimica Acta 2011; 75(3):870–886.

Pallud C, Masue-Slowey Y, Fendorf S Aggregate-scale spatial heterogeneity in reductive transformation of ferrihydrite resulting from coupled biogeochemical and physical processes. Geochimica et Cosmochimica Acta 2010; 74(10):2811–2825.

Fendorf S, Nico PS, Kocar BD, Masue Y, Tufano KJ. Arsenic chemistry in soils and sediments. In: Synchrotron-Based Techniques in Soils and Sediments. Balwant S, Gräfe M (eds), Elsevier, Burlington, MA, 34:357–378, 2010.

Masue Y, Loeppert RH, Kramer TA. Arsenate and arsenite adsorption and desorption behavior on coprecipitated aluminum:iron hydroxides. Environmental Science and Technology 2007; 41(3);837–842.

Borch T, Masue Y, Kukkadapu RK, Fendorf S. Phosphate imposed limitations on biological reduction and alteration of ferrihydrite. Environmental Science and Technology 2007; 41(1):166–172.

Presentations and Published Abstracts

Masue-Slowey Y, Chadwick OA, Fendorf S. Soil architecture controls organic carbon turnover in Hawaiian forest soil. Goldschmidt. Boston, MA. 2018.

Masue-Slowey Y, Cook L, Saba T, Boehm PD. Evaluation of site-specific background at refinery site. Battelle Sediments Conference. New Orleans, LA. 2017.

Masue-Slowey Y, Cook L, Saba T, Boehm PD. Evaluation of site-specific background for natural resource damage assessment investigation at refinery sites. Annual International Conference on Soils, Sediments, Water, and Energy. Amherst, MA. 2015.

Masue-Slowey Y. Impacts of soil structure on contaminant and carbon dynamics. Invited, University of Wyoming, Department of Ecosystem Science and Management, 2013.

Masue-Slowey Y. Impacts of physical and chemical complexity on contaminant dynamics. Invited, The University of British Columbia and The University of South Carolina, 2013.

Masue-Slowey Y, Loeppert RH, Fendorf S. Alteration of reductive ferrihydrite dissolution and transformation by adsorbed As and structural Al. Invited, Misasa-IV Solar System Exploration and Few Geosciences Symposium, Tottori, Japan, 2012.

Masue-Slowey Y, Chadwick OA, Fendorf S. Metabolic constrains on organic matter turnover within subsurface soils. The American Geophysical Union fall meeting, San Francisco, CA, 2011.

Masue-Slowey Y, Kocar BD, Jofre SAB, Mayer UK, Pallud C, Fendorf S. Fate and transport of arsenic from constructed soil aggregates. Goldschmidt Conference, Knoxville, TN. 2010.

Sharma R, Masue-Slowey Y, Fendorf S. Role of adsorbed arsenic and structural aluminum on Fe(II) retention and transformation of ferrihydrite. The American Geophysical Union Fall Meeting, San Francisco, CA, 2009 (mentee presentation).

Masue-Slowey Y, Fendorf S. Development of arsenic and iron biogeochemical gradient within constructed aggregate upon redox fluctuation. Goldschmidt Conference, Davos, Switzerland, 2009.

Masue-Slowey Y, Bedore P, Fendorf S. Development of arsenic and iron biogeochemical gradients upon anaerobiosis at soil aggregate scale. The 7th International Symposium for Subsurface Microbiology, Shizuoka, Japan, 2008.

Masue-Slowey Y, Tufano KJ, Loeppert RH, Fendorf S. Alteration in arsenic retention upon reductive transformation of alumino-ferrihydrite. Soil Science Society of America Annual Meeting, New Orleans, LA, 2007.

Masue Y, Borch T, Kocar BD, Fendorf S. Arsenic attenuation upon bioreduction of ferrihydrite. 19th General Meeting of the International Mineralogical Association, Kobe, Japan, 2006.

Masue Y, Borch T, Fendorf S. Factors affecting arsenic retention under anaerobic conditions. Invited, International Symposium 21st Century COE program at Kanazawa University, Japan, 2005.

Masue Y, Kocar BD, Borch T, Fendorf S Arsenic retention on ferrihydrite: Stability under aerobic and anaerobic conditions. 230th American Chemical Society Meeting, Washington D.C. 2005.

Masue Y, Loeppert RH, White GN, Kramer T. Adsorption, desorption, and stabilization behavior of arsenic(V) on Al3+ substituted Fe3+ oxides. 7th International Conference on the Biochemistry of Trace Elements, Uppsala, Sweden, 2003.

Masue Y, Loeppert RH, Kramer T. Influence of counterion on adsorption and desorption behavior of arsenic on ferrihydrite and Al-substituted analogs. American Society of Agronomy Annual Meeting, Denver, CO, 2003.

Project Experience

Area of Project Experience

  • Fate and Transport Assessment of Metals
  • Fate of Chemical Constituents in Coal Ash
  • Chemical Transformation, Partitioning, and Bioaccessibility Assessment
  • Environmental Assessment and Investigations
  • Natural Gas Projects
  • NRDA
  • Contractual Disputes

Specific Project Experience

Fate and Transport Assessment of Metals

Determined key processes controlling the rate and extent of monosodium acid methanearsonate (MSMA) transformation and sequestration in agricultural soils. As a technical expert, provided literature review report to EPA addressing the environmental fate of MSMA.

Managed a team to model transport of arsenic- and lead-containing sediment to a lake from a former paint manufacturing facility and assessed the proposed sediment remedial strategy. Conducted the reconnaissance sampling and analysis of soils and sediments to investigate the fate of arsenic and lead (New Jersey).

Developed an approach to quantify the migration and (re)distribution of arsenic and lead from surface soils impacted by smelter dust (Washington).

Developed a site conceptual model describing the fate of metals in a tundra soil near a mine site. Designed metals speciation analysis and interpreted the results to decipher risks associated with transport of metals in soils.

Determined regional background metals concentrations in soils, and evaluated the risk of metals release from wood ash disposed at a landfill (Ohio).

Supported analysis of the transport and fate of arsenic from a smelter sludge pile and a tailings pond and wind tunnel test to determine the erodibility of smelter sludge (Latin America).

Evaluated methods to locate sources of hexavalent chromium in residential areas near inoperative chromite ore processing facilities (New Jersey).

Analyzed the geochemical conditions of a surface water body and the fate of selenium originating from a coal mine, and assessed geochemical factors critical to selenium exposure by aquatic organisms (West Virginia).

Designed an innovative bi-metal sorbent to remove arsenic from wastewater that was tested for sorption capacity and sludge stability (published).

Uncovered redox processes controlling the fate of arsenic at millimeter resolution in physically complex model soil (published).

Provided literature review and summarized site management-relevant biogeochemical factors controlling methylmercury production in soils and sediments (published).

Fate of Chemical Constituents in Coal Ash

Compared published coal ash leaching methods and explained the merit of each method to an electric power utility client.

Analyzed the chemical composition of groundwater, public and private well water, surface water, soils, and coal ash to delineate the potential impact of coal ash to environmental media. Supported Net Environmental Benefit Analysis of coal ash impoundment closure options.

Determined possible sources of arsenic and factors driving the high concentration of arsenic in groundwater at a coal-fired power plant.

Transformation, Partitioning, and Bioaccessibility Assessment

Identified factors relevant to bioaccessibility and bioavailability of monomethyl arsenic acid (MMA) to soil microorganisms. Illustrated the implication of the resulting MMA transformation to overall mobility of arsenic.

Designed metals speciation analysis and bioaccessibility testing for a tundra soil near a mine site. Provided interpretations of the metals analysis to support assessment of metals’ bioaccessibility to receptors.

Synthesized the geochemical conditions of a surface water body, redox transformation of selenium, and overall the fate of selenium originating from a coal mine to assess aquatic life criteria of selenium (West Virginia).

Performed literature review of thallium chemistry in soils to decipher partitioning in soils and its impact on thallium bioavailability.

Analyzed the impact of heat generated from electrical cables buried in lake sediment on mercury methylation by microorganisms (New York).

Examined microbial transformation of mixed iron and aluminum minerals and its implication for arsenic mobility (published).

Investigated mercury sequestration into polysulfide-rubber-coated activated carbon (published).

Reviewed literature and summarized biogeochemical factors controlling methylmercury production in soils and sediments that are relevant to site management (published).

Analyzed iron mineralogy to evaluate dehalogenation of polybrominated diphenyl ethers (PBDEs) and/or polychlorinated biphenyls (PCBs) by nanoscale zerovalent iron (published).

Environmental Assessment and Investigations

Managed the environmental assessment of a large steel mill. Evaluated temporal changes in operations, waste type and management, effluent discharges, wastewater treatment, and analyzed pathways of chemical constituents to environmental media such as sediment and groundwater. Constituents of interest included PCBs, benzene, metals, and polycyclic aromatic hydrocarbons (PAHs).

Inspected an underground storage tank explosion site. Designed a forensic approach to identify the contents of the tank, which spilled onto surrounding soils (New York).

Performed an onsite inspection of electronic devices and furniture to evaluate possible sources of chemical irritants to office workers. Designed forensic approach to identify the chemical constituents of the irritants, performed a customized experiment, and issued an investigation report (New Jersey).

Evaluated the environmental effectiveness of recycling expanded polystyrene foam.

Supported an assessment of seafood safety and cesium levels resulting from a nuclear power plant’s discharge.

Supported the historical reconstruction of a waterway sediment site in the Northeast involving several parties.

Natural Gas Projects

Performed gas fingerprinting analysis on a natural gas storage field case (Kansas).

Supported analysis to define regional background conditions of groundwater to evaluate the impact from hydraulic fracturing operations to environmental media (Pennsylvania and West Virginia).

NRDA

Litigation support for a substantial NRDA claim at a refinery. Provided real-time support to legal team on contamination reconstruction and chemical forensics during expert’s testimony (New Jersey).

Systematically compared methods of NRDA for sites injured by PCBs across the United States.

Contractual Dispute

As part of a contractual dispute between a wastewater treatment plant designer and a municipality, assessed design criteria for the plant, evolution of regulatory requirements in the region, and communications between parties regarding the design and cost (Pennsylvania).

To resolve a contractual dispute between a utility and a contractor, assessed multiple contracts with subcontractors and change orders to identify savings that the contractor accumulated. Evaluated contracts and communications to develop an event timeline (Illinois).

Additional Information

Peer Reviewer

Environmental Science & Technology

Geochimica et Cosmochimica Acta

Journal of Hazardous Materials

Journal of Asian Earth Sciences

National Science Foundation Low Temperature Geochemistry proposal

Knowledge

News & Events

CREDENTIALS & PROFESSIONAL HONORS

  • Ph.D., Environmental Earth System Science, Stanford University, 2009
  • M.S., Soil Science, Texas A&M University, 2004
  • B.S., Plant and Environmental Soil Sciences, Texas A&M University, 2002, magna cum laude
  • NSF Postdoctoral Fellowship in Earth Sciences, 2011–2013

    U.S. Geological Survey, Texas Water Resource Institute research scholarship, 2003–2004

    Outstanding Senior honored by the American Society of Agronomy, 2002

    Distinguished Student, College of Agriculture and Life Sciences (TAMU), 2002

LANGUAGES

  • Japanese