Methylmercury(MeHg)is a potent neurotoxin and bioaccumulates in food webs.Microbial transformation of inorganic mercury(Hg)produces most of the MeHg in the marine environment.The gene pair hgcAB encodes for Hg methyla...Methylmercury(MeHg)is a potent neurotoxin and bioaccumulates in food webs.Microbial transformation of inorganic mercury(Hg)produces most of the MeHg in the marine environment.The gene pair hgcAB encodes for Hg methylation,a process predominantly attributed to anaerobic bacteria.However,recent studies indicate the formation of methylmercury in low-oxygen zones within marine water columns,although the mechanisms remain poorly understood.“Blue holes”are marine sinkholes containing redox gradients stratified with depth and high microbial diversity across a range of biogeochemical cycles.Here,we present the first metagenomic analysis focused on the potential for Hg methylation in a blue hole ecosystem.Yongle Blue Hole(YBH),currently the world’s deepest known blue hole,was selected as a representative site to investigate the genetic potential for Hg methylation and to explore the functional capabilities of putative Hg-methylators within this unique environment.Metagenomic analysis showed that the anoxic sulfidic deep water was likely to be a hotspot for Hg methylation,driven by abundant and diverse Deltaproteobacteria.In the suboxic intermediate layer,Nitrospina and Myxococcota dominated the Hg-methylating community.Furthermore,Hg methylators were found to have different lifestyles(free-living or particle-associated)and to occupy distinct ecological niches within the YBH.In addition,the contribution of sinking particles to Hg methylation,especially in the deep anoxic water column,was highlighted.Our study unveils the biodiversity and survival strategies of Hg methylators across distinct environments.The findings suggest that blue holes could serve as model stratified ecosystems for studying Hg methylation processes across different habitats.展开更多
Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic ...Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic hydrocarbons(PAHs)are susceptible to the influences of meteorological conditions,emissions,and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path.The daily concentrations of total PM_(2.5)-bound PAHs ranged from 0.65 to 80.76 ng/m^(3),with an annual mean of 11.94 ng/m^(3).Here,we found that the concentration of PM_(2.5)-bound PAHs in winter was significantly higher than that in summer,which was mainly due to source and meteorology influence.The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs,while precipitation and low temperature exacerbated this difference.According to the concentration variation trend of PM_(2.5)-bound PAHs and their relationship with meteorological conditions,a new grouping of PAHs is applied,which suggested that PAHs have different environmental fates and migration paths.A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle,but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting.Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_(2.5)-bound PAHs than that in other regions,and the risk in winter was three times than in summer.展开更多
基金supported by The University of Melbourne’s Research Computing Services and the Petascale Campus Initiative.
文摘Methylmercury(MeHg)is a potent neurotoxin and bioaccumulates in food webs.Microbial transformation of inorganic mercury(Hg)produces most of the MeHg in the marine environment.The gene pair hgcAB encodes for Hg methylation,a process predominantly attributed to anaerobic bacteria.However,recent studies indicate the formation of methylmercury in low-oxygen zones within marine water columns,although the mechanisms remain poorly understood.“Blue holes”are marine sinkholes containing redox gradients stratified with depth and high microbial diversity across a range of biogeochemical cycles.Here,we present the first metagenomic analysis focused on the potential for Hg methylation in a blue hole ecosystem.Yongle Blue Hole(YBH),currently the world’s deepest known blue hole,was selected as a representative site to investigate the genetic potential for Hg methylation and to explore the functional capabilities of putative Hg-methylators within this unique environment.Metagenomic analysis showed that the anoxic sulfidic deep water was likely to be a hotspot for Hg methylation,driven by abundant and diverse Deltaproteobacteria.In the suboxic intermediate layer,Nitrospina and Myxococcota dominated the Hg-methylating community.Furthermore,Hg methylators were found to have different lifestyles(free-living or particle-associated)and to occupy distinct ecological niches within the YBH.In addition,the contribution of sinking particles to Hg methylation,especially in the deep anoxic water column,was highlighted.Our study unveils the biodiversity and survival strategies of Hg methylators across distinct environments.The findings suggest that blue holes could serve as model stratified ecosystems for studying Hg methylation processes across different habitats.
基金supported by the National Key R&D Projects of China(No.2019YFC0214405)the National Natural Science Foundation of China(Nos.21966016,21667014).
文摘Monthly particle-phase ambient samples collected at six sampling locations in Yuxi,a high-altitude city on the edge of Southeast Asia,were measured for particle-associated PAHs.As trace substances,polycyclic aromatic hydrocarbons(PAHs)are susceptible to the influences of meteorological conditions,emissions,and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path.The daily concentrations of total PM_(2.5)-bound PAHs ranged from 0.65 to 80.76 ng/m^(3),with an annual mean of 11.94 ng/m^(3).Here,we found that the concentration of PM_(2.5)-bound PAHs in winter was significantly higher than that in summer,which was mainly due to source and meteorology influence.The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs,while precipitation and low temperature exacerbated this difference.According to the concentration variation trend of PM_(2.5)-bound PAHs and their relationship with meteorological conditions,a new grouping of PAHs is applied,which suggested that PAHs have different environmental fates and migration paths.A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle,but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting.Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_(2.5)-bound PAHs than that in other regions,and the risk in winter was three times than in summer.
