Technical Note: Reactivity of C1 and C2 organohalogens formation – from plant litter to bacteria
- 1Baruch Institute of Coastal Ecology & Forest Science, Clemson University, Georgetown, South Carolina, USA
- 2School of Life Sciences, The Chinese University of Hong Kong, Shatin N.T., Hong Kong SAR, China
- 3Department of Environmental Science & Engineering, South China University of Technology, Guangzhou, Guangdong, China
- 4Vocational and Technological School of Guangdong Environmental Protection, Guangdong, China
- 5Department of Land, Air and Water Resources, University of California – Davis, California, USA
Abstract. C1/C2 organohalogens (organohalogens with one or two carbon atoms) can have significant environmental toxicity and ecological impact, such as carcinogenesis, ozone depletion and global warming. Natural halogenation processes have been identified for a wide range of natural organic matter, including soils, plant and animal debris, algae, and fungi. Yet, few have considered these organohalogens generated from the ubiquitous bacteria, one of the largest biomass pools on earth. Here, we report and confirm the formation of chloroform (CHCl3) dichloro-acetonitrile (CHCl2CN), chloral hydrate (CCl3CH(OH)2) and their brominated analogues by direct halogenation of seven strains of common bacteria and nine cellular monomers. Comparing different major C stocks during litter decomposition stages in terrestrial ecosystems, from plant litter, decomposed litter, to bacteria, we found increasing reactivity for nitrogenous organohalogen yield with decreasing C/N ratio. Our results raise the possibility that natural halogenation of bacteria represents a significant and overlooked contribution to global organohalogen burdens. As bacteria are decomposers that alter the C quality by transforming organic matter pools from high to low C/N ratio and constitute a large organic N pool, the bacterial activity is expected to affect the C, N, and halogen cycling through natural halogenation reactions.