Land use and hydrological factors control concentrations and diffusive fluxes of riverine dissolved carbon dioxide and methane in low-order streams

Wei Tang; Y Jun Xu; Maofei Ni; Siyue Li

doi:10.1016/j.watres.2023.119615

Land use and hydrological factors control concentrations and diffusive fluxes of riverine dissolved carbon dioxide and methane in low-order streams

Water Res. 2023 Mar 1:231:119615. doi: 10.1016/j.watres.2023.119615. Epub 2023 Jan 15.

Authors

Wei Tang¹, Y Jun Xu², Maofei Ni³, Siyue Li⁴

Affiliations

¹ Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, China.
² School of Renewable Natural Resources, Coastal Studies Institute, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
³ College of Eco-Environmental Engineering, The karst environmental geological hazard prevention laboratory of Guizhou Minzu University, Guizhou Minzu University, Guiyang 550025, China.
⁴ Institute of Changjiang Water Environment and Ecological Security, School of Environmental Ecology and Biological Engineering, Key Laboratory for Green Chemical Process of Ministry of Education, Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education, Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan 430205, China. Electronic address: syli2006@163.com.

PMID: 36682236
DOI: 10.1016/j.watres.2023.119615

Abstract

We analyzed the impacts of land use/land cover types on carbon dioxide (CO₂) and methane (CH₄) concentration and diffusion in 1^st to 4^th Strahler order tributaries of the Longchuan River to the upper Yangtze River in China by using headspace equilibration method and CO₂SYS program. Field sampling and measurements were conducted during the dry and wet seasons from 2017 to 2019. The average of calculated CO₂ partial pressure (pCO₂, mean ± SD: 2389 ± 3220 μatm) by CO₂SYS program was 1.9-fold higher than the value (mean ± SD: 1230 ± 1440 μatm) 10 years ago in the Longchuan River basin, where the urban land area increased by a factor of 7 times. Further analysis showed that corrected pCO₂ by headspace method and dissolved CH₄ (dCH₄) decrease as the stream order and flow velocity increase. The pCO₂ and dCH₄ in the wet season was lower than that in the dry season. The explanatory ability of land use types on the variation of corrected pCO₂ and dCH₄ was stronger at the reach scale than at the riparian and catchment scales in two seasons. Urban land at reach scale further showed much higher explanation on corrected pCO₂ and dCH₄ than cropland, grassland and forest land in the wet season. The Longchuan River emits approximately 112.5 kt CO₂-C and 1.0 kt CH₄-C per year, being 1.7-fold of the total lateral export of dissolved inorganic and dissolved organic carbon (68.3 kt C y^-1). The findings highlight the scale effects of land use on the observed seasonality in dissolved carbon gases in low-order streams.

Keywords: CO(2) partial pressure (pCO(2)); Diffusive fluxes; Dissolved CH(4) (dCH(4)); Hydrological control; Low-order streams; Scale effects of land use/land cover types.

MeSH terms

Carbon Dioxide*
China
Forests
Methane* / analysis
Rivers
Seasons

Substances

Carbon Dioxide
Methane