Technical Note: Reactivity of C1 and C2 organohalogens formation – from plant litter to bacteria

[摘要] C1/C2 organohalogens (organohalogens with one or two carbon atoms) can havesignificant environmental toxicity and ecological impact, such ascarcinogenesis, ozone depletion and global warming. Natural halogenationprocesses have been identified for a wide range of natural organic matter,including soils, plant and animal debris, algae, and fungi. Yet, few haveconsidered these organohalogens generated from the ubiquitous bacteria, oneof the largest biomass pools on earth. Here, we report and confirm theformation of chloroform (CHCl₃) dichloro-acetonitrile (CHCl₂CN),chloral hydrate (CCl₃CH(OH)₂) and their brominated analogues bydirect halogenation of seven strains of common bacteria and nine cellularmonomers. Comparing different major C stocks during litter decompositionstages in terrestrial ecosystems, from plant litter, decomposed litter, tobacteria, we found increasing reactivity for nitrogenous organohalogen yieldwith decreasing C/N ratio. Our results raise the possibility that naturalhalogenation of bacteria represents a significant and overlookedcontribution to global organohalogen burdens. As bacteria are decomposersthat alter the C quality by transforming organic matter pools from high tolow C/N ratio and constitute a large organic N pool, the bacterial activityis expected to affect the C, N, and halogen cycling through naturalhalogenation reactions.

[学科分类] 地球化学与岩石