Dissolved organic matter (DOM) export to a temperate estuary: seasonal variations and implications of land use

Stedmon, Colin A.; Markager, Stiig; Søndergaard, Morten; Vang, Torben; Laubel, A.; Borch, Niels Henrik; Windelin, Anders

doi:10.1007/bf02784988

Cited by 99 publications

(57 citation statements)

References 32 publications

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“…Inputs of organic matter, nitrogen and phosphorus to coastal ecosystems have increased greatly (Nixon 1995;Howarth et al 1996;Conley 2000;Stedmon et al 2006;Sharp 2010). Although eutrophication is the major concern related to these inputs, the pH of coastal waters is also influenced through the enhanced CO 2 uptake from primary production and CO 2 release from respiration associated with increased nutrient inputs.…”

Section: Impacts Of Anthropogenic Watershed Perturbations On Seawater Phmentioning

confidence: 99%

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Duarte

Hendriks

Moore

et al. 2013

Estuaries and Coasts

609

452

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Ocean acidification due to anthropogenic CO 2 emissions is a dominant driver of long-term changes in pH in the open ocean, raising concern for the future of calcifying organisms, many of which are present in coastal habitats. However, changes in pH in coastal ecosystems result from a multitude of drivers, including impacts from watershed processes, nutrient inputs, and changes in ecosystem structure and metabolism. Interaction between ocean acidification due to anthropogenic CO 2 emissions and the dynamic regional to local drivers of coastal ecosystems have resulted in complex regulation of pH in coastal waters. Changes in the watershed can, for example, lead to changes in alkalinity and CO 2 fluxes that, together with metabolic processes and oceanic dynamics, yield high-magnitude decadal changes of up to 0.5 units in coastal pH. Metabolism results in strong diel to seasonal fluctuations in pH, with characteristic ranges of 0.3 pH units, with metabolically intense habitats exceeding this range on a daily basis. The intense variability and multiple, complex controls on pH implies that the concept of ocean acidification due to anthropogenic CO 2 emissions cannot be transposed to coastal ecosystems directly. Furthermore, in coastal ecosystems, the detection of trends towards acidification is not trivial and the attribution of these changes to anthropogenic CO 2 emissions is even more problematic. Coastal ecosystems may show acidification or basification, depending on the balance between the invasion of coastal waters by anthropogenic CO 2 , watershed export of alkalinity, organic matter and CO 2 , and changes in the balance between primary production, respiration and calcification rates in response to changes in nutrient inputs and losses of ecosystem components. Hence, we contend that ocean acidification from anthropogenic CO 2 is largely an open-ocean syndrome and that a concept of anthropogenic impacts on marine pH, which is applicable across the entire ocean, from coastal to open-ocean environments, provides a superior framework to consider the multiple components of the anthropogenic perturbation of marine pH trajectories. The concept of anthropogenic impacts on seawater pH acknowledges that a regional focus is necessary to predict future trajectories in the pH of coastal waters and points at opportunities to manage these trajectories locally to conserve coastal organisms vulnerable to ocean acidification.

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Section: Impacts Of Anthropogenic Watershed Perturbations On Seawater Phmentioning

confidence: 99%

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Duarte

Hendriks

Moore

et al. 2013

Estuaries and Coasts

609

452

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“…Since FDOM does not usually contribute to a major portion of DOC, a positive correlation between FDOM and DOC has only been observed in specific areas, such as river estuarine systems (Del Vecchio and Blough, 2004;Coble, 2007). Stedmon et al (2006) demonstrated that stronger correlations were observed between DOC and FDOM as humic substances derived from terrestrial DOM are more colored than DOM produced in situ. In general, terrestrial DOM occurring in rivers originates mainly from plant decomposition and leaf litter in the form of humic substances (Huang and Chen, 2009).…”

Section: Behaviors and Sources Of Fdom In The Estuarine Mixing Zonementioning

confidence: 99%

“…It is well known that a single sampling event is not enough to capture the full range of natural variability in DOM abundance over all seasons (Stedmon et al, 2006;Huang and Chen, 2009;Markager et al, 2011;Dai et al, 2012;Moyer et al, 2015). Overall, our results show that monthly variations are significant.…”

Section: Fluxes Of Doc and Fdom In The Estuarine Mixing Zonementioning

confidence: 99%

Sources, fluxes, and behaviors of fluorescent dissolved organic matter (FDOM) in the Nakdong River Estuary, Korea

Lee¹,

Kim²

2018

Biogeosciences

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Abstract. We monitored seasonal variations in dissolved organic carbon (DOC), the stable carbon isotope of DOC (δ 13 C-DOC), and fluorescent dissolved organic matter (FDOM) in water samples from a fixed station in the Nakdong River Estuary, Korea. Sampling was performed every hour during spring tide once a month from October 2014 to August 2015. The concentrations of DOC and humic-like FDOM showed significant negative correlations against salinity (r 2 = 0.42-0.98, p < 0.0001), indicating that the river-originated DOM components were the major source and behave conservatively in the estuarine mixing zone. The extrapolated δ 13 C-DOC values (−27.5 to −24.5 ‰) in fresh water confirm that both components are mainly of terrestrial origin. The slopes of humic-like FDOM against salinity were 60-80 % higher in the summer and fall due to higher terrestrial production of humic-like FDOM. The slopes of proteinlike FDOM against salinity, however, were 70-80 % higher in spring due to higher biological production in river water. Our results suggest that there are large seasonal changes in riverine fluxes of humic-and protein-like FDOM to the ocean.

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“…The Horsens estuary is a shallow estuary with a mean depth of 2.9 m and a surface area of 77.5 km 2 (Stedmon et al, 2006;Markager et al, 2011). Tidal range is low and mixing is mainly wind driven (Gustafsson and Bendtsen, 2007).…”

Section: The Estuarymentioning

confidence: 99%

“…The concentrations of both inorganic and organic N and P are determinated by loadings, biological processes and mixing with the marine end member. On an annual scale the estuary is a reactor transforming DIN (approximately 80 % of the loadings) to DON (Stedmon et al, 2006;Markager et al, 2011). …”

Section: Maximum Acceptable N and P Loadsmentioning

confidence: 99%

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

Hinsby

Markager

Kronvang

et al. 2012

Hydrol. Earth Syst. Sci.

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Abstract.Intensive farming has severe impacts on the chemical status of groundwater and streams and consequently on the ecological status of dependent ecosystems. Eutrophication is a widespread problem in lakes and marine waters. Common problems are hypoxia, algal blooms, fish kills, and loss of water clarity, underwater vegetation, biodiversity and recreational value. In this paper we evaluate the nitrogen (N) and phosphorus (P) concentrations of groundwater and surface water in a coastal catchment, the loadings and sources of N and P, and their effect on the ecological status of an estuary. We calculate the necessary reductions in N and P loadings to the estuary for obtaining a good ecological status, which we define based on the number of days with N and P limitation, and the corresponding stream and groundwater threshold values assuming two different management options. The calculations are performed by the combined use of empirical models and a physically based 3-D integrated hydrological model of the whole catchment. The assessment of the ecological status indicates that the N and P loads to the investigated estuary should be reduced to levels corresponding to 52 and 56 % of the current loads, respectively, to restore good ecological status. Model estimates show that threshold total N (TN) concentrations should be in the range of 2.9 to 3.1 mg l −1 in inlet freshwater (streams) to Horsens estuary and 6.0 to 9.3 mg l −1 in shallow aerobic groundwater (∼ 27-41 mg l −1 of nitrate), depending on the management measures implemented in the catchment. The situation for total P (TP) is more complex, but data indicate that groundwater threshold values are not needed. The stream threshold value for TP to Horsens estuary for the selected management options is 0.084 mg l −1 . Regional climate models project increasing winter precipitation and runoff in the investigated region resulting in increasing runoff and nutrient loads to the Horsens estuary and many other coastal waters if present land use and farming practices continue. Hence, lower threshold values are required in many coastal catchments in the future to ensure good status of water bodies and ecosystems.

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Dissolved organic matter (DOM) export to a temperate estuary: seasonal variations and implications of land use

Cited by 99 publications

References 32 publications

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Is Ocean Acidification an Open-Ocean Syndrome? Understanding Anthropogenic Impacts on Seawater pH

Sources, fluxes, and behaviors of fluorescent dissolved organic matter (FDOM) in the Nakdong River Estuary, Korea

Threshold values and management options for nutrients in a catchment of a temperate estuary with poor ecological status

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