Characteristics of carbon concentration and storage in water body of the eutrophic karst lake:A case study from Yilong Lake
To investigate the dynamic changes of carbon concentration and storage in the water body of karst eutrophic lake and their influencing factors,a study was conducted on the spatiotemporal distribution characteristics of water quality and carbon concentration in Yilong Lake from September 2021 to June 2022.The results showed that dissolved carbon dominated the carbon content in the water body of Yilong Lake,with the highest concentration of dissolved inorganic carbon(DIC,(41.26±4.93)mg/L)among the four forms of carbon,followed by dissolved organic carbon(DOC,(16.23±2.23)mg/L).The concentration of particulate carbon was relatively low,with concentrations of particulate organic carbon(POC)and particulate inorganic carbon(PIC)being(10.05±1.81)mg/L and(0.82±0.56)mg/L,respectively.The average annual water carbon storage of Yilong Lake was 5.30 Gg C.The carbon storage of four types accounts for 60.57％(DIC),23.77％(DOC),14.53％(POC)and 1.13％(PIC),respectively.Analysis showed that the concentrations of DOC and POC in Yilong Lake were related to nutrient loading and algae biomass,indicating that they mainly come from algal derived organic carbon.The concentration of DIC was related to DOC,water temperature,ammonia nitrogen and distribution of rivers entering the lake,suggesting that DIC is jointly driven by mineralization,water temperature and dilution of watershed water.PIC was related to chlorophyll-a concentration and pH,indicating that it is mainly affected by the disruption of the acid-base balance caused by algal photosynthesis.Coupling relationship was found among four carbon forms,reflecting the migration and transformation of different carbon forms.Lake eutrophication led to an augmented algal biomass,resulting in concurrently elevated organic carbon levels of POC and DOC.At the same time,the mineralisation of organic matter also caused a synergistic change in inorganic and organic carbon.Compared with other lakes,Yilong Lake exhibited a higher carbon concentration,which may be attributed to factors such as eutrophication,karst geological background,and special geographic location.In terms of carbon storage,water volume was a key factor affecting the carbon storage of lake water bodies,and eutrophication increased the carbon concentration and accumulation rate of water bodies,bolstering the carbon sink effect of lakes.Against the backdrop of increasingly severe global lake eutrophication issues,the role of lake water carbon storage in estimating ecosystem carbon sink is gradually emerging.
carbon concentrationcarbon storagekarst regioneutrophicationYilong Lake
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