Humus is often used as an organic modifier to reduce the bioaccumulation of heavy metals in plants,but the effects of different humus components from different sources on the fate of mercury(Hg)in paddy fields are still unclear.Here,fulvic acid(FA)and humic acid(HA)extracted from composted straw(CS),composted cow dung(CCD),peat soil(PM)and lignite coal(LC)were used to understand their effects on the methylation and bioaccumulation of Hg in paddy soil by pot experiments.Amendments of both FA and HA largely increased the abundance of Hg-methylating microbes and low-molecular-weight organic matters(e.g,cysteine)in paddy soil.They were also found to change the aromaticity,molecular size and Chromophoric DOM concentration of DOM,and resulted in heterogeneous effects on migra-tion and transformation of Hg.All the FA-amended treatments increased the mobility and methylation of Hg in soil and its absorption in roots.Nevertheless,FA from different sources have heterogeneous effects on transport of Hg between rice tissues.FA-CCD and FA-PM pro-moted the translocation of MeHg from roots to rice grains by 32.95％and 41.12％,while FA-CS and FA-LC significantly inhibited the translocation of inorganic Hg(IHg)by 52.65％and 66.06％and of MeHg by 46.65％and 36.23％,respectively.In contrast,all HA-amended treatments reduced the mobility of soil Hg,but promoted Hg methylation in soil.Among which,HA-CCD and HA-PM promoted the translocation of MeHg in rice tissues by 88.95％and 64.10％,while its accumulation in rice grains by 28.43％and 28.69％,respectively.In gen-eral,the application of some FA and HA as organic modifiers to reduce Hg bioaccumulation in rice is not feasible.

Shu Ran;Tianrong He;Xian Zhou;Deliang Yin

Key Laboratory of Karst Georesources and Environment(Guizhou University),Ministry of Education,Guiyang 550025,China;College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China;Guizhou Karst Environmental Ecosystems Observation and Research Station,Ministry of Education,Guiyang 550025,China

环境科学学报（英文版）

[1]Shu Ran;Tianrong He;Xian Zhou;Deliang Yin-.Effects of fulvic acid and humic acid from different sources on Hg methylation in soil and accumulation in rice)[J].环境科学学报（英文版）,2022(09):93-105

composted,Amendments,methylating,Chromophoric,IHg

Effects,fulvic,acid,humic,from,different,sources,methylation,soil,rice,Humus,often,used,bioaccumulation,heavy,metals,plants,but,effects,humus,components,fate,mercury,paddy,fields,are,still,unclear,Here,FA,HA,extracted,straw,CS,cow,dung,CCD,peat,PM,lignite,coal,LC,were,understand,their,by,pot,experiments,both,largely,increased,abundance,microbes,low,molecular,weight,matters,cysteine,They,also,found,change,aromaticity,size,DOM,concentration,resulted,heterogeneous,migra,transformation,All,amended,treatments,mobility,its,absorption,roots,Nevertheless,have,transport,between,tissues,translocation,MeHg,grains,while,significantly,inhibited,inorganic,respectively,In,contrast,all,reduced,promoted,Among,which,eral,application,some,modifiers,not,feasible

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