title: Characterisation of organic matter associated with groundwater arsenic in reducing aquifers of southwestern Taiwan.
abstract: Arsenic (As) in groundwaters extensively used by people across the world constitutes a serious public health threat. The importance of organic matter (OM) as an electron donor in microbially-mediated reduction of As(V) or Fe(III)-bearing As-host minerals leading to mobilisation of solid-phase arsenic is widely recognised. Notwithstanding this, there are few studies characterising OM in such aquifers and, in particular, there is a dearth of data from the classic arsenic bearing aquifers in southwestern Taiwan. Organic geochemical analyses of sediments from a known groundwater arsenic hot-spot in southwestern Taiwan revealed contributions of thermally mature and plant derived origin, consistent with OM sources in all other Asian groundwater aquifer sediments analysed to date, indicating comparable sources and routes of OM transfer. The combined results of amended As(V) reduction assays with the organic geochemical analysis revealed that the microbiological process of dissimilatory As(V) reduction is active in this aquifer, but it is not controlled by a specific source of analysed OM. These indicate that (i) part of the OM that was considered to be less bio-available could still be used as an electron donor or (ii) other electron donors, not analysed in present study, could be controlling the rate of As release.
authors.affiliation: School of Earth, Atmospheric and Environmental Sciences, Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, UK; Higher College of Technology, Ministry of Manpower, Muscat, Oman.
authors.forename: Wafa M
authors.initials: WM
authors.lastname: Al Lawati
authors.forename: Jiin-Shuh
authors.initials: JS
authors.lastname: Jean
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Kulp
authors.forename: Ming-Kuo
authors.initials: MK
authors.lastname: Lee
authors.forename: David A
authors.initials: DA
authors.lastname: Polya
authors.forename: Chia-Chuan
authors.initials: CC
authors.lastname: Liu
authors.forename: Bart E
authors.initials: BE
authors.lastname: van Dongen
mesh_terms: D001151:Arsenic / Q000032:analysis*; D002849:Chromatography, Gas; D002852:Chromatography, Ion Exchange; D004583:Electrons; D004784:Environmental Monitoring / Q000379:methods*; D005290:Ferric Compounds; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis*; D005844:Geology; D060587:Groundwater / Q000737:chemistry*; D006838:Hydrocarbons / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D013058:Mass Spectrometry; D010944:Plants / Q000378:metabolism; D045483:Rivers; D013624:Taiwan; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply
chemical_list: D005290:Ferric Compounds; D006838:Hydrocarbons; D008055:Lipids; D014874:Water Pollutants, Chemical; D001151:Arsenic