Kwon, Man Jae O'Loughlin, Edward J. Antonopoulos, Dionysios A. Finneran, Kevin T. 2024-01-20T16:33:07Z 2024-01-20T16:33:07Z 2021-09-05 2011-08 0045-6535 https://pubs.kist.re.kr/handle/201004/130123 Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a potential human carcinogen, and its contamination of subsurface environments is a significant threat to public health. This study investigated abiotic and biological degradation of RDX in contaminated aquifer material. Anoxic batch systems were started with and without pre-aeration of aquifer material to distinguish initial biological RDX reduction from abiotic RDX reduction. Aerating the sediment eliminated chemical reductants in the native aquifer sediment, primarily Fe(II) sorbed to mineral surfaces. RDX (50 mu M) was completely reduced and transformed to ring cleavage products when excess concentrations (2 mM) of acetate or lactate were provided as the electron donor for aerated sediment. RDX was reduced concurrently with Fe(III) when acetate was provided, while RDX, Fe(III), and sulfate were reduced simultaneously with lactate amendment. Betaproteobacteria were the dominant microorganisms associated with RDX and Fe(III)/sulfate reduction. In particular, Rhodoferax spp. increased from 21% to 35% and from 28% to 60% after biostimulation by acetate and lactate, respectively. Rarefaction analyses demonstrated that microbial diversity decreased in electron-donor-amended systems with active RDX degradation. Although significant amounts of Fe(III) and/or sulfate were reduced after biostimulation, solid-phase reactive minerals such as magnetite or ferrous sulfides were not observed, suggesting that RDX reduction in the aquifer sediment is due to Fe(II) adsorbed to solid surfaces as a result of Fe(III)-reducing microbial activity. These results suggest that both biotic and abiotic processes play an important role in RDX reduction under in situ conditions. (C) 2011 Elsevier Ltd. All rights reserved. English PERGAMON-ELSEVIER SCIENCE LTD SULFATE-REDUCING BACTERIA REDUCTIVE TRANSFORMATION SP-NOV. ANAEROBIC BIODEGRADATION ABIOTIC TRANSFORMATION ELECTRON-DONORS DEGRADATION IRON BIOTRANSFORMATION EXPLOSIVES Geochemical and microbiological processes contributing to the transformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in contaminated aquifer material Article 10.1016/j.chemosphere.2011.05.027 1 CHEMOSPHERE, v.84, no.9, pp.1223 - 1230 CHEMOSPHERE 84 9 1223 1230 scie scopus 000294145400009 2-s2.0-79960836676 Environmental Sciences Environmental Sciences & Ecology Article SULFATE-REDUCING BACTERIA REDUCTIVE TRANSFORMATION SP-NOV. ANAEROBIC BIODEGRADATION ABIOTIC TRANSFORMATION ELECTRON-DONORS DEGRADATION IRON BIOTRANSFORMATION EXPLOSIVES RDX Biodegradation Electron donor Abiotic reduction Iron reduction