Soil macroinvertebrates as ecosystem engineers play significant,but largely ignored,roles in affecting mercury(Hg)cycle by altering soil physical-chemical properties.Ant is likely ex-panded into boreal mires with climate warming,however,its impacts on Hg cycle remained poorly understood.We compared total Hg(THg)and methylmercury(MeHg)contents in soils from antmounds(Lasius flavus)and the nearby ambient in a boreal mire in Northeast China.The present work seeks to unravel factors that controlling MeHg levels in case of ant appearance or absence.The average THg was 179 μg/kg in the ant mound and was 106.1μg/kg in nearby soils,respectively.The average MeHg was 10.9 μg/kg in the ant mound and was 12.9 μg/kg in nearby soils,respectively.The ratios of MeHg to THg(％MeHg)were 7.61％in ant mounds and 16.75％in nearby soils,respectively.Ant colonization caused THg en-richment and MeHg depletion,and this change was obvious in the 10-20 cm depth soil layer where ants mainly inhabited.Spectrometry characteristics of soil dissolved organic matter(DOM)exert a stronger control than microorganisms on MeHg variation in soils.A structural equation model revealed that the molecular weight of DOM inhibited MeHg irrespective of ant presence or absence,while humification conducive to MeHg significantly in ant mound soils.Microorganisms mainly affected Hg methylation by altering the molecular weight and humification of DOM.We propose that the effects of ant colonization on MeHg rested on DOM feature variations caused by microorganisms in boreal mires.

Zhongsheng Zhang;Xuehui Zhang;Yuan Xin;Haitao Wu

Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences,Changchun 130012,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shengyang University,Shenyang 110044,China

环境科学学报（英文版）

[1]Zhongsheng Zhang;Xuehui Zhang;Yuan Xin;Haitao Wu-.Ant colonization increased total mercury but reduced methylmercury contents in boreal mires,Northeast China)[J].环境科学学报（英文版）,2022(09):50-58

mires,macroinvertebrates,panded,antmounds,Lasius,mire,rested

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