Source and quantity of carbon influence its sequestration in Rostherne Mere (UK) sediment: a novel application of steppe
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ORIGINAL PAPER
Source and quantity of carbon influence its sequestration in Rostherne Mere (UK) sediment: a novel application of stepped combustion radiocarbon analysis Evelyn M. Keaveney . Alan D. Radbourne . Suzanne McGowan . David B. Ryves . Paula J. Reimer
Received: 23 September 2019 / Accepted: 23 June 2020 Ó The Author(s) 2020
Abstract We explored the roles of phytoplankton production, carbon source, and human activity on carbon accumulation in a eutrophic lake (Rostherne Mere, UK) to understand how changes in nutrient loading, algal community structure and catchment management can influence carbon sequestration in lake sediments. Water samples (dissolved inorganic, organic and particulate carbon) were analysed to investigate contemporary carbon sources. Multiple variables in a 55-cm sediment core, which represents the last * 90 years of accumulation, were studied to determine historical production rates of algal
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10933-020-00141-1) contains supplementary material, which is available to authorized users. E. M. Keaveney (&) P. J. Reimer School of the Natural and Built Environment, Queen’s University, Belfast BT9 6AX, UK e-mail: [email protected] A. D. Radbourne Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW, UK S. McGowan School of Geography, University of Nottingham, Nottingham NG7 2RD, UK D. B. Ryves Geography and Environment, Loughborough University, Loughborough LE11 3TU, UK
communities and carbon sources. Fluctuations in net primary production, inferred from sedimentary diatom abundance and high-performance liquid chromatography (HPLC) pigment methods, were linked to nutrient input from sewage treatment works (STW) in the catchment. Stepped combustion radiocarbon (SCR) measurements established that lake sediment contains between 11% (* 1929 CE) and 69% (* 1978 CE) recalcitrant carbon, with changes in carbon character coinciding with peaks in accumulation rate and linked to STW inputs. Catchment disturbance was identified by radiocarbon analysis, and included STW construction in the 1930s, determined using SCR analysis, and recent nearby highway construction, determined by measurements on dissolved organic carbon from the lake and outflow river. The quantity of autochthonous carbon buried was related to diatom biovolume accumulation rate (DBAR) and decreased when diatom accumulation rate and valve size declined, despite an overall increase in net carbon production. HPLC pigment analysis indicated that changes in total C deposition and diatom accumulation were related to proliferation of non-siliceous algae. HPLC results also indicated that dominance of recalcitrant carbon in sediment organic carbon was likely caused by increased deposition rather than preservation factors. The total algal accumulation rate controlled the sediment organic carbon accumulation rate, whereas DBAR was correlated to the proportio
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