Yates, CA, Johnes, PJ, Owen, AT, Brailsford, FL, Glanville, HC, Evans, CD, Marshall, MR, Jones, DL, Lloyd, CEM, Jickells, T and Evershed, RP (2019) Variation in dissolved organic matter (DOM) stoichiometry in UK freshwaters: Assessing the influence of land cover and soil C:N ratio on DOM composition. Limnology and Oceanography, 64 (6). 2328 - 2340. ISSN 0024-3590

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Dissolved organic matter (DOM) plays an important role in freshwater biogeochemistry. To investigate the influence of catchment character on the quality and quantity of DOM in freshwaters, 45 sampling sites draining subcatchments of contrasting soil type, hydrology, and land cover within one large upland‐dominated and one large lowland‐dominated catchment were sampled over a 1‐yr period. Dominant land cover in each subcatchment included: arable and horticultural, blanket peatland, coniferous woodland, and improved, unimproved, acid, and calcareous grasslands. The composition of the C, N, and P pool was determined as a function of the inorganic nutrient species (NO3−, NO2−, NH4+, and PO43−) and dissolved organic nutrient (dissolved organic carbon [DOC], dissolved organic nitrogen [DON], and dissolved organic phosphorus [DOP]) concentrations. DOM quality was assessed by calculation of the molar DOC : DON and DOC : DOP ratios and specific ultraviolet absorbance (SUVA254). In catchments with little anthropogenic nutrient inputs, DON and DOP typically composed > 80% of the total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) concentrations. By contrast, in heavily impacted agricultural catchments DON and DOP typically comprised 5–15% of TDN and 10–25% of TDP concentrations. Significant differences in DOC : DON and DOC : DOP ratios were observed between land cover class with significant correlations observed between both the DOC : DON and DOC : DOP molar ratios and SUVA254 (rs = 0.88 and 0.84, respectively). Analysis also demonstrated a significant correlation between soil C : N ratio and instream DOC : DON/DOP (rs = 0.79 and 0.71, respectively). We infer from this that soil properties, specifically the C : N ratio of the soil organic matter pool, has a significant influence on the composition of DOM in streams draining through these landscapes.

Item Type: Article
Additional Information: This is the final published version of the article (version of record). It first appeared online via Wiley at http://doi.org/10.1002/lno.11186 - please refer to any applicable terms of use of the publisher.
Divisions: Faculty of Natural Sciences > School of Geography, Geology and the Environment
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Depositing User: Symplectic
Date Deposited: 09 Dec 2019 12:21
Last Modified: 03 Mar 2021 10:13
URI: https://eprints.keele.ac.uk/id/eprint/7354

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