|Abstract Title:||Unexpected microbial methylmercury production in flooded and warmed upland soils|
|Presenter Name:||Yu-Rong Liu|
|Company/Institution:||Huazhong Agricultural University|
|Session:||Impacts of climate change on global Hg cycling|
Abstract Information :
Mercury (Hg) can be converted to neurotoxic methylmercury (MeHg) by certain microbes typically in anaerobic environments, threatening human health due to its bioaccumulation in food webs. However, it is unclear whether microbial Hg methylation can occur in oxic upland soils when the micro-environment is affected by flooding and warming. Here, we conducted a series of incubation experiments to investigate the effects of increased water content and temperature on MeHg production in two typical upland soils. Results showed that flooding significantly facilitated MeHg production in both types of upland soils (i.e., long-term and short-term use) with Hg spiking, while no MeHg production was observed in the soils with 25% water. Further, we found a significant correlation between the MeHg concentration and the proportion of Geobacter, which dominated in Hg methylating communities. In addition, elevated temperature enhanced MeHg production in the flooded upland soils, where the proportions of some Hg methylators (i.e., Clostridium, Acetonema and Geobacter) were higher than those in the control. Our analyses further revealed that MeHg production in the upland soils was also correlated with non-Hg methylators, which could influence the activity of Hg methylating communities via potential microbial syntrophy. Taken together, our work suggests that oxic uplands after flooding and warming can turn into a potential MeHg reservoir in response to ongoing climate changes.