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Nutrient enrichment induces a shift in dissolved organic carbon (DOC) metabolism in oligotrophic freshwater sediments.

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)1131-1139
Number of pages9
JournalScience of The Total Environment
Volume690
Early online date4 Jul 2019
DOIs
DateAccepted/In press - 4 Jul 2019
DateE-pub ahead of print - 4 Jul 2019
DatePublished (current) - 10 Nov 2019

Abstract

Dissolved organic carbon (DOC) turnover in aquatic environments is modulated by the presence of other key macronutrients, including nitrogen (N) and phosphorus (P). The ratio of these nutrients directly affects the rates of microbial growth and nutrient processing in the natural environment. The aim of this study was to investigate how labile DOC metabolism responds to changes in nutrient stoichiometry using 14C tracers in conjunction with untargeted analysis of the primary metabolome in upland peat river sediments. N addition led to an increase in 14C-glucose uptake, indicating that the sediments were likely to be primarily N limited. The mineralisation of glucose to 14CO2 reduced following N addition, indicating that nutrient addition induced shifts in internal carbon (C) partitioning and microbial C use efficiency (CUE). This is directly supported by the metabolomic profile data which identified significant differences in 22 known metabolites (34% of the total) and 30 unknown metabolites (16% of the total) upon the addition of either N or P. 14C-glucose addition increased the production of organic acids known to be involved in mineral P dissolution (e.g. gluconic acid, malic acid). Conversely, when N was not added, the addition of glucose led to the production of the sugar alcohols, mannitol and sorbitol, which are well known microbial C storage compounds. P addition resulted in increased levels of several amino acids (e.g. alanine, glycine) which may reflect greater rates of microbial growth or the P requirement for coenzymes required for amino acid synthesis. We conclude that inorganic nutrient enrichment in addition to labile C inputs has the potential to substantially alter in-stream biogeochemical cycling in oligotrophic freshwaters.

    Research areas

  • Dissolved organic matter, DOM processing, Metabolic profiling, Nutrient availability, Stoichiometry

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  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://doi.org/10.1016/j.scitotenv.2019.07.054 . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 791 KB, PDF document

    Embargo ends: 4/07/20

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    Licence: CC BY-NC-ND

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