Seasonal variability of sediment controls of carbon cycling in an agricultural stream

Research output: Contribution to journalArticle

Authors

External organisations

  • School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. Electronic address: sxc469@alumni.bham.ac.uk.
  • British Geological Survey (BGS), Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK.
  • School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; School of Geography, Geology and the Environment, University of Keele, Keele, Newcastle ST5 5BG, UK.
  • School of Geography, Geology and the Environment, University of Keele, Keele, Newcastle ST5 5BG, UK.
  • School of Geography, Geology and the Environment, University of Keele, Keele, Newcastle ST5 5BG, UK; School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin Street, Dublin D08 X622, Ireland.
  • School of Geography Earth, and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

Abstract

Streams and rivers are 'active pipelines' where high rates of carbon (C) turnover can lead to globally important emissions of carbon dioxide (CO2) and methane (CH4) from surface waters to the atmosphere. Streambed sediments are particularly important in affecting stream chemistry, with rates of biogeochemical activity, and CO2 and CH4 concentrations far exceeding those in surface waters. Despite an increase in research on CO2 and CH4 in streambed sediments there is a lack of knowledge and insight on seasonal dynamics. In this study the seasonally variable effect of sediment type (sand-dominated versus gravel-dominated) on porewater C cycling, including CO2 and CH4 concentrations, was investigated. We found high concentrations of CO2 and CH4 in the streambed of a small agricultural stream. Sand-dominated sediments were characterised by higher microbial activity and CO2 and CH4 concentrations than gravel-dominated sediments, with CH4:CO2 ratios higher in sand-dominated sediments but rates of recalcitrant C uptake highest in gravel-dominated sediments. CO2 and CH4 concentrations were unexpectedly high year-round, with little variation in concentrations among seasons. Our results indicate that small, agricultural streams, which generally receive large amounts of fine sediment and organic matter (OM), may contribute greatly to annual C cycling in freshwater systems. These results should be considered in future stream management plans where the removal of sandy sediments may perform valuable ecosystem services, reducing C turnover, CO2 and CH4 concentrations, and mitigating greenhouse gas (GHG) production.

Details

Original languageEnglish
Pages (from-to)732-741
Number of pages10
JournalScience of the Total Environment
Volume688
Early online date23 Jun 2019
Publication statusPublished - 20 Oct 2019

Keywords

  • Carbon cycling, Gravel, Greenhouse gas, Sand, Sediment, Streambed