Several studies have suggested the pivotal roles of eutrophic lakes in carbon(C)cycling at regional and global scales.However,how the co-metabolism effect on lake sediment organic carbon(OC)mineralization changes in response to integrated inputs of labile OC and nutrients is poorly understood.This knowledge gap hinders our ability to predict the carbon sequestration potential in eutrophic lakes.Therefore,a 45-day microcosm experiment was conducted to examine the dominant mechanisms that underpin the co-metabolism response to the inputs of labile C and nutrients in lacustrine sediments.Results indicate that the labile C addition caused a rapid increase in the positive co-metabolism effect during the initial stage of incubation,and the co-metabolism effect was positively correlated with the C input level.The positive co-metabolism effect was consistently higher under high C input,which was 152％higher than that under low C input.The higher β-glucosidase activity after nutrient addition,which,in turn,promoted the OC mineralization in sediments.In addition,different impacts of nutrients on the co-metabolism effect under different C inputs were observed.Compared with the low nutrient treatments,the largest co-metabolism effect under high C with high nutrient treatment was observed by the end of the incubation.In the high C treatment,the intensity of the co-metabolism effect(CE)under high nitrogen treatment was 1.88 times higher than that under low nitrogen condition.However,in the low C treatment,the amount of nitrogen had limited impact on co-metabolism effect.Our study thus proved that the microorganisms obviously regulate sediment OC turnover via stoichiometric flexibility to maintain a balance between resources and microbial requirements,which is meaningful for evaluating the OC budget and lake eutrophication management in lacustrine sediments.

Jie MA;Fei HE;Xingcheng YAN;Ruijie SHI;Ming JI;Bin XU;Xiaodong WU;Zhichun LI;Xiaoguang XU;Guoxiang WANG

Nanjing Institute of Environment Sciences,Ministry of Ecology and Environment,Nanjing 210042,China;Sorbonne University,Paris,UMR 7619,METIS,Paris 75005,France;School of Environment,Nanjing Normal University,Nanjing 210023,China;College of Urban and Environmental Sciences,Hubei Normal University,Huangshi 435002,China;School of Environment and Surveying Engineering,Soochow University,Suzhou 234000,China

海洋湖沼学报（英文版）

[1]Jie MA;Fei HE;Xingcheng YAN;Ruijie SHI;Ming JI;Bin XU;Xiaodong WU;Zhichun LI;Xiaoguang XU;Guoxiang WANG-.Stoichiometric flexibility regulates the co-metabolism effect during organic carbon mineralization in eutrophic lacustrine sediments)[J].海洋湖沼学报（英文版）,2022(05):1974-1984

Stoichiometric,flexibility,regulates,metabolism,effect,during,organic,carbon,mineralization,lacustrine,sediments,Several,studies,have,suggested,pivotal,roles,lakes,cycling,regional,global,scales,However,how,OC,changes,response,integrated,inputs,labile,nutrients,poorly,understood,This,knowledge,gap,hinders,ability,predict,sequestration,potential,Therefore,day,microcosm,experiment,was,conducted,examine,dominant,mechanisms,that,underpin,Results,indicate,addition,caused,rapid,increase,initial,stage,incubation,positively,correlated,level,consistently,higher,which,than,low,glucosidase,activity,after,promoted,In,different,impacts,were,observed,Compared,treatments,largest,by,end,intensity,CE,nitrogen,times,condition,amount,had,limited,Our,study,thus,proved,microorganisms,obviously,turnover,via,stoichiometric,maintain,balance,between,resources,microbial,requirements,meaningful,evaluating,budget,eutrophication,management

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