Data-driven approach to identify field-scale biogeochemical transitions using geochemical and geophysical data and hidden Markov models: Development and application at a uranium-contaminated aquifer

Abstract

[1] Although mechanistic reaction networks have been developed to quantify the biogeochemical evolution of subsurface systems associated with bioremediation, it is difficult in practice to quantify the onset and distribution of these transitions at the field scale using commonly collected wellbore datasets. As an alternative approach to the mechanistic methods, we develop a data-driven, statistical model to identify biogeochemical transitions using various time-lapse aqueous geochemical data (e.g., Fe(II), sulfate, sulfide, acetate, and uranium concentrations) and induced polarization (IP) data. We assume that the biogeochemical transitions can be classified as several dominant states that correspond to redox transitions and test the method at a uranium-contaminated site. The relationships between the geophysical observations and geochemical time series vary depending upon the unknown underlying redox status, which is modeled as a hidden Markov random field. We estimate unknown parameters by maximizing the joint likelihood function using the maximization-expectation algorithm. The case study results show that when considered together aqueous geochemical data and IP imaginary conductivity provide a key diagnostic signature of biogeochemical stages. The developed method provides useful information for evaluating the effectiveness of bioremediation, such as the probability of being in specific redox stages following biostimulation where desirable pathways (e.g., uranium removal) are more highly favored. The use of geophysical data in the approach advances the possibility of using noninvasive methods to monitor critical biogeochemical system stages and transitions remotely and over field relevant scales (e.g., from square meters to several hectares).Citation: Chen, J., S. S. Hubbard, and K. H. Williams (2013), Data-driven approach to identify field-scale biogeochemical transitions using geochemical and geophysical data and hidden Markov models: Development and application at a uranium-contaminated aquifer, Water Resour. Res., 49,[6412][6413][6414][6415][6416][6417][6418][6419][6420][6421][6422][6423][6424]

Complex conductivity of soils

“…Induced polarization has many applications in hydrogeophysics including inference of hydraulic properties (Binley et al [2005]; Weller et al [2010], Joseph et al [2015]; Nordsiek et al [2015]), facies discrimination , the detection of contaminants in soils (e.g., Sogade et al [2006], Flores Orozco et al [2012], Schwartz and Furman [2012], Schmutz et al [2012], Chen et al [2013]), and the detection of cracks (e.g., Okay et al [2013]). Induced polarization has shown also a unique capability to monitor non-intrusively sorption processes in the electrical double layer (Vaudelet et al [2011a, b], Hao et al [2016]) and precipitation of metallic particles during redox-controlled reactions (e.g., Mewafy et al 4 [2013], Abdulsamad [2017]).…”

“…The amplitude of resistivity and the phase can be recasted into a complex conductivity. Under an applied (primary) electrical field, its in-phase (real) component characterizes the electromigration of the charge carriers while its quadrature (out-of-phase, imaginary) component is used to describe local accumulations of electrical charge Induced polarization has many applications in hydrogeophysics including inference of hydraulic properties [Binley et al, 2005;Weller et al, 2010;Joseph et al, 2015;Nordsiek et al, 2015], facies discrimination , the detection of contaminants in soils [e.g., Sogade et al, 2006;Flores Orozco et al, 2012;Schwartz and Furman, 2012;Schmutz et al, 2012;Chen et al, 2013], and the detection of cracks [e.g., Okay et al, 2013]. Induced polarization has shown also a unique capability to monitor nonintrusively sorption processes in the electrical double layer [Vaudelet et al, 2011a[Vaudelet et al, , 2011bHao et al, 2016] and precipitation of metallic particles during redox-controlled reactions [e.g., Mewafy et al, 2013;Abdulsamad, 2017].…”

Quantifying shallow subsurface water and heat dynamics using coupled hydrological-thermal-geophysical inversion

“…Yabusaki et al (2011) developed a three-dimensional hydro-biogeochemical reactive transport model of Rifle to improve understanding of the uranium variability, hydrological conditions and soil properties under the pulsed acetate amendment. Chen et al (2013) developed a data-driven biogeophysical approach to quantify redoxdriven biogeochemical transformations using geochemical measurements and induced polarization data. Wainwright et al (2015) used induced polarization data and stochastic methods to estimate the spatial distribution of naturally reduced zones in the subsurface, which served as biogeochemical hot spots; the geophysical information was used to constrain simulations of biogeochemical cycles across the Rifle floodplain.…”

The Relative Importance of Saturated Silica Sand Interfacial and Pore Fluid Geochemistry on the Spectral Induced Polarization Response

“…Geophysical data sets can also be acquired in a time‐lapse sense, which permits monitoring of changes in subsurface systems (Binley et al, ; Vereecken et al, ). Several recent studies indicate the potential of geophysical methods for characterizing and monitoring geochemical reactions and biogeochemical processes (Chen et al, , ; Hubbard et al, ; Revil et al, ). In particular, interest has grown in the use of induced polarization (IP) methods for the investigation of geochemical and biogeochemical properties (Revil & Skold, ; Vaudelet et al, ; Weller & Slater, ; Wu et al, ).…”