Biomarker-indicated extent of oxidation of plant-derived organic carbon (OC) in relation to geomorphology in an arsenic contaminated Holocene aquifer, Cambodia

Magnone, Daniel and Richards, Laura A. and Polya, David A. and Bryant, Charlotte and Jones, Merren and van Dongen, Bart E. (2017) Biomarker-indicated extent of oxidation of plant-derived organic carbon (OC) in relation to geomorphology in an arsenic contaminated Holocene aquifer, Cambodia. Scientific Reports, 7 (1). p. 13093. ISSN 2045-2322

Full content URL: https://doi.org/10.1038/s41598-017-13354-8

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Abstract

The poisoning of rural populations in South and Southeast Asia due to high groundwater arsenic concentrations is one of the world’s largest ongoing natural disasters. It is important to consider environmental processes related to the release of geogenic arsenic, including geomorphological and organic geochemical processes. Arsenic is released from sediments when iron-oxide minerals, onto which arsenic is adsorbed or incorporated, react with organic carbon (OC) and the OC is oxidised. In this study we build a new geomorphological framework for Kandal Province, a highly studied arsenic affected region of Cambodia, and tie this into wider regional environmental change throughout the Holocene. Analyses shows that the concentration of OC in the sediments is strongly inversely correlated to grainsize. Furthermore, the type of OC is also related to grain size with the clay containing mostly (immature) plant derived OC and sand containing mostly thermally mature derived OC. Finally, analyses indicate that within the plant derived OC relative oxidation is strongly grouped by stratigraphy with the older bound OC more oxidised than younger OC.

Keywords:arsenic, geomorphology, sedimentary organic material, Cambodia
Subjects:F Physical Sciences > F140 Environmental Chemistry
F Physical Sciences > F160 Organic Chemistry
F Physical Sciences > F850 Environmental Sciences
F Physical Sciences > F820 Geomorphology
Divisions:College of Science > School of Geography
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ID Code:29212
Deposited On:30 Oct 2017 09:46

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