title: Dissolved organic carbon content and characteristics in relation to carbon dioxide partial pressure across Poyang Lake wetlands and adjacent aquatic systems in the Changjiang basin.
abstract: Dissolved organic carbon (DOC) plays diverse roles in carbon biogeochemical cycles. Here, we explored the link between DOC and pCO2using high-performance size-exclusion chromatography (HPSEC) with UV254detection and excitation emission matrix (EEM) fluorescence spectroscopy to determine the molecular weight distribution (MW) and the spectral characteristics of DOC, respectively. The relationship between DOC and pCO2was investigated in the Poyang Lake wetlands and their adjacent aquatic systems. The results indicated significant spatial variation in the DOC concentrations, MW distributions, and pCO2. The DOC concentration was higher in the wetlands than in the rivers and lakes. pCO2was high in wetlands in which the dominant vegetation was Phragmites australis, whereas it was low in wetlands in which Carex tristachya was the dominant species. DOC was divided into five fractions according to MW, as follows: super-low MW (SLMW, <1 kDa); low MW (LMW, 1-2.5 kDa); intermediate MW (IMW, 2.5-3.5 kDa); high MW (HMW, 3.5-6 kDa); and super-high MW (SMW, > 40 kDa). Rivers contained high proportions of HMW and extremely low amounts of SLMW, whereas wetlands had relatively high proportions of SLMW. The proportion of SMW (SMWp) was particularly high in wetlands. We found that pCO2significantly positively correlated with the proportion of IMW, and significantly negatively correlated with SMWp. These data improve our understanding of the MW of bioavailable DOC and its conversion to CO2. The present results demonstrate that both the content and characteristics of DOC significantly affect pCO2. pCO2and DOC must be studied further to help understanding the role of the wetland on the regional CO2budget.
authors.affiliation: Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Huaxin
authors.initials: H
authors.lastname: Wang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100087, China.
authors.forename: Ruyuan
authors.initials: R
authors.lastname: Jiao
authors.affiliation: Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Wang
authors.affiliation: Key Laboratory of Lake and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: yanwj@igsnrr.ac.cn.
authors.forename: Weijin
authors.initials: W
authors.lastname: Yan
mesh_terms: D002244:Carbon / Q000032:analysis*; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000032:analysis*; D002681:China; D004784:Environmental Monitoring; D060106:Lakes / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis*; D010313:Partial Pressure; D012995:Solubility; D053833:Wetlands
chemical_list: D009930:Organic Chemicals; D002245:Carbon Dioxide; D002244:Carbon
keywords: Carbon dioxide partial pressure; Dissolved organic carbon; High-performance size-exclusion chromatography; Molecular weight; Poyang Lake wetland