Natural attenuation of chlorinated ethenes in hyporheic zones: A review of key biogeochemical processes and in-situ transformation potential. (1st January 2018)

• Record Type: Journal Article
• Authors: Weatherill, John J.; Atashgahi, Siavash; Schneidewind, Uwe; Krause, Stefan; Ullah, Sami; Cassidy, Nigel; Rivett, Michael O.
• Is Part Of: Water research. Volume 128(2018)
• Page Start: 362
• Page End: 382
• Publication Date: 2018-01-01
• Subjects: Chlorinated ethenes -- Hyporheic zone -- Natural attenuation -- Biogeochemistry -- Biotransformation -- Heterogeneity; 1, 1, 1-TCA 1, 1, 1-Trichloroethane -- DCA 1, 2-Dichloroethane -- Ac Acetate -- CA Chlorinated ethane -- cDCE cis-1, 2-dichloroethene -- CE Chlorinated ethene -- DIC Dissolved inorganic carbon -- DNAPL Dense, non-aqueous phase liquid -- DOC Dissolved organic carbon -- DOM Dissolved organic matter -- DON Dissolved organic nitrogen -- HCB hexachlorobenzene -- HCE higher chlorinated ethene -- HFC hyporheic flow cell -- K saturated hydraulic conductivity -- LCE lower chlorinated ethene -- OHR organohalide respiration -- OHRB organohalide-respiring bacteria -- OM organic matter -- PCE tetrachloroethene -- PCR polymerase chain reaction -- POM particulate organic matter -- SCFA short chain fatty acid -- SOM sedimentary organic matter -- TCE trichloroethene -- TCM trichloromethane -- TEA terminal electron acceptor -- TEAP terminal electron accepting process -- VC vinyl chloride; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2017.10.059
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Chlorinated ethenes (CEs) are legacy contaminants whose chemical footprint is expected to persist in aquifers around the world for many decades to come. These organohalides have been reported in river systems with concerning prevalence and are thought to be significant chemical stressors in urban water ecosystems. The aquifer-river interface (known as the hyporheic zone) is a critical pathway for CE discharge to surface water bodies in groundwater baseflow. This pore water system may represent a natural bioreactor where anoxic and oxic biotransformation process act in synergy to reduce or even eliminate contaminant fluxes to surface water. Here, we critically review current process understanding of anaerobic CE respiration in the competitive framework of hyporheic zone biogeochemical cycling fuelled by in-situ fermentation of natural organic matter. We conceptualise anoxic-oxic interface development for metabolic and co-metabolic mineralisation by a range of aerobic bacteria with a focus on vinyl chloride degradation pathways. The superimposition of microbial metabolic processes occurring in sediment biofilms and bulk solute transport delivering reactants produces a scale dependence in contaminant transformation rates. Process interpretation is often confounded by the natural geological heterogeneity typical of most riverbed environments. We discuss insights from recent field experience of CE plumes discharging to surface water and present a range of practical monitoring technologies which address this inherent complexity at different spatial scales. Future research must address key dynamics which link supply of limiting reactants, residence times and microbial ecophysiology to better understand the natural attenuation capacity of hyporheic systems. Graphical abstract: Image Highlights: Conceptual review of hyporheic zones of rivers as natural anoxic-oxic bioreactors. Interactions between organohalide respiration and biogeochemical cycling. Aerobic vinyl chloride mineralisation during hyporheic mixing is conceptualised. Field experience, challenges and characterisation technologies critically reviewed.