Microbially-Mediated Methyl Iodide Production in Water Samples from an Estuarine System
The dynamics of aquatic systems are known to facilitate the formation of aggregates of nutrient-rich particulate matter which provide suitable substrate for microbial colonization. Although bacteria-aggregate associations often result in the degradation of Particulate Organic Matter (POM) in aquatic systems, little is known about their contribution to the production of methyl iodide (CH3I), an environmentally important biogas that has a potential impact on atmospheric chemistry. This study investigated the role of microbial communities in the production of CH3I and its facilitation by particle aggregation in the Tamar estuary in the South-West of England. Macroaggregates were generated through a laboratory simulated aggregation process. Assessment of bacterial abundance, production and elevated concentration of CH3I indicated that microbial activity in the experimental setups resulted in the production of CH3I. A statistical test of significance between aggregated and non-aggregated setups also indicated that the presence of bacterial aggregates significantly enhanced CH3I production by about 32 % of the concentration attributed to microbial activity. This suggests that estuarine systems are potentially ideal environments for microbially-mediated CH3I production.