Contrasting estuarine processing of dissolved organic matter derived from natural and human‐impacted landscapes

Garcia-Martin, E. Elena ORCID: https://orcid.org/0000-0003-4807-3287; Sanders, Richard ORCID: https://orcid.org/0000-0002-6884-7131; Evans, Chris D. ORCID: https://orcid.org/0000-0002-7052-354X; Kitidis, Vassilis; Lapworth, Dan J. ORCID: https://orcid.org/0000-0001-7838-7960; Rees, Andrew P.; Spears, Bryan M. ORCID: https://orcid.org/0000-0002-0876-0405; Tye, Andy; Williamson, Jennifer L. ORCID: https://orcid.org/0000-0001-8216-5885; Balfour, Chris; Best, Mike; Bowes, Michael; Breimann, Sarah; Brown, Ian J.; Burden, Annette ORCID: https://orcid.org/0000-0002-7694-1638; Callaghan, Nathan ORCID: https://orcid.org/0000-0003-0273-6161; Felgate, Stacey L. ORCID: https://orcid.org/0000-0002-9955-4948; Fishwick, James; Fraser, Mike; Gibb, Stuart W.; Gilbert, Pete J.; Godsell, Nina; Gomez‐Castillo, Africa P.; Hargreaves, Geoff ORCID: https://orcid.org/0000-0002-4361-6134; Jones, Oban; Kennedy, Paul; Lichtschlag, Anna ORCID: https://orcid.org/0000-0001-8281-2165; Martin, Adrian ORCID: https://orcid.org/0000-0002-1202-8612; May, Rebecca; Mawji, Edward; Mounteney, Ian; Nightingale, Philip D.; Olszewska, Justyna P. ORCID: https://orcid.org/0000-0002-4910-2206; Painter, Stuart C.; Pearce, Christopher R. ORCID: https://orcid.org/0000-0002-4382-2341; Pereira, M. Gloria ORCID: https://orcid.org/0000-0003-3740-0019; Peel, Kate; Pickard, Amy ORCID: https://orcid.org/0000-0003-1069-3720; Stephens, John A.; Stinchcombe, Mark; Williams, Peter; Woodward, E. Malcolm S.; Yarrow, Deborah; Mayor, Daniel J. ORCID: https://orcid.org/0000-0002-1295-0041. 2021 Contrasting estuarine processing of dissolved organic matter derived from natural and human‐impacted landscapes. Global Biogeochemical Cycles, 35 (10), e2021GB007023. 17, pp. https://doi.org/10.1029/2021GB007023

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Official URL: http://dx.doi.org/10.1029/2021GB007023

Abstract/Summary

The flux of terrigenous organic carbon through estuaries is an important and changing, yet poorly understood, component of the global carbon cycle. Using dissolved organic carbon (DOC) and fluorescence data from thirteen British estuaries draining catchments with highly variable land uses, we show that land use strongly influences the fate of DOC across the land-ocean transition via its influence on the composition and lability of the constituent dissolved organic matter (DOM). In estuaries draining peatland-dominated catchments, DOC was highly correlated with biologically refractory “humic-like” terrigenous material which tended to be conservatively transported along the salinity gradient. In contrast, there was a weaker correlation between DOC and DOM components within estuaries draining catchments with a high degree of human impact, i.e. relatively larger percentage of arable and (sub-)urban land uses. These arable and (sub-)urban estuaries contain a high fraction of bioavailable “protein-like” material that behaved non-conservatively, with both DOC removals and additions occurring. In general, estuaries draining catchments with a high percentage of peatland (≥18 %) have higher area-specific estuarine exports of DOC (>13 g C m-2 yr-1) compared to those estuaries draining catchments with a high percentage (≥46 %) of arable and (sub-)urban land uses (<2.1 g C m-2 yr-1). Our data indicate that these arable and (sub-)urban estuaries tend to export, on average, ∼50 % more DOC to coastal areas than they receive from rivers, due to net anthropogenic derived organic matter inputs within the estuary.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2021GB007023
UKCEH and CEH Sections/Science Areas:	Pollution (Science Area 2017-) Soils and Land Use (Science Area 2017-) Water Resources (Science Area 2017-)
ISSN:	0886-6236
Additional Keywords:	dissolved organic matter, dissolved organic carbon, land use, land ocean aquatic continuum, estuaries, GroundwaterBGS, Groundwater
NORA Subject Terms:	Marine Sciences
Date made live:	27 Sep 2021 09:49 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531108

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1029/2021GB007023

UKCEH and CEH Sections/Science Areas:

Pollution (Science Area 2017-)
Soils and Land Use (Science Area 2017-)
Water Resources (Science Area 2017-)

ISSN:

0886-6236

Additional Keywords:

dissolved organic matter, dissolved organic carbon, land use, land ocean aquatic continuum, estuaries, GroundwaterBGS, Groundwater

NORA Subject Terms:

Marine Sciences