Nitrogen cycling in the German Bight (SE North Sea) — Clues from modelling stable nitrogen isotopes

Pätsch, Johannes; Serna, Alexandra; Dähnke, Kirstin; Schlarbaum, Tim; Johannsen, Astrid; Emeis, Kay–Christian

doi:10.1016/j.csr.2009.11.003

Cited by 28 publications

(28 citation statements)

References 43 publications

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“…Accordingly, the δ 15 N values in the complete German Bight were high, which is known from other human impacted coastal regions (Sherwood and Rose, 2005) and reflects the known high δ 15 N values in surface sediments in the German Bight. This has been attributed to the large riverine input of reactive nitrogen in the German Bight (Pätsch et al, 2010).…”

Section: Discussion Carbon Sources and The δ 15 N-baselinesmentioning

confidence: 99%

Food-Web Structure in Four Locations Along the European Shelf Indicates Spatial Differences in Ecosystem Functioning

et al. 2018

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Section: Discussion Carbon Sources and The δ 15 N-baselinesmentioning

confidence: 99%

Food-Web Structure in Four Locations Along the European Shelf Indicates Spatial Differences in Ecosystem Functioning

et al. 2018

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“…There could be many reasons for this gradual decrease: on-going construction has changed the sediment and hydromorphology to conditions that are much less favourable for denitrification, and one of the main controlling factors -nitrate concentration -has decreased (Radach & Pätsch 2007, Pätsch & Lenhart 2011. However, this nitrate decrease has not kept pace with diminishing denitrification capacity, so that current nitrate loads are discharged almost undiminished into the outer estuary.…”

Section: Estimate Of Denitrification In the Estuarymentioning

confidence: 99%

“…This means that coastal sediments remove significant amounts of N r only as long as NO 3 − substrate is available; whereas this denitrification ceases when the river nitrate load is low during the summer months. In the summer, the sediments further away from the river plume do not receive significant amounts of nitrate, as water column nitrate concentration is already depleted due to phytoplankton assimilation (see also Sørensen et al 1979, Pätsch et al 2010, Deek et al 2011.…”

Section: Influences On Denitrification Rates Of Sediments In the Elbementioning

confidence: 99%

“…Between 2000 and 2010, the river had an average fresh water discharge of 731 m 3 s −1 and delivered an average annual dissolved N r load of 82 ± 24 kt (of which 3.9 ± 0.9 was ammonium) (Pätsch & Lenhart 2011) into the Elbe Estuary and SE North Sea. The nitrate discharge of the Elbe River is higher in winter than in summer.…”

Section: Study Sitementioning

confidence: 99%

“…While the overall trend of riverine N-loads shows a gradual decrease over time (Pätsch & Lenhart 2011), this trend may be reversed in light of the expected increase in river-borne loads of N r due to increased biofuel production in the catchment. Furthermore, riverine N loads can be modified in the estuary, where nitrate can either be removed via denitrification or produced by remineralisation and nitrification of sediment organic matter.…”

Section: Introductionmentioning

confidence: 99%

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N2 fluxes in sediments of the Elbe Estuary and adjacent coastal zones

Deek¹,

Dähnke²,

Beusekom³

et al. 2013

Mar. Ecol. Prog. Ser.

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The conversion of reactive nitrogen species to N 2 during denitrification in sediments may be one of the most valuable ecosystem services provided by estuarine and intertidal environments near river discharge areas. To quantify the rates and limiting factors of denitrification in the estuary of the Elbe River and adjacent Wadden Sea (SE North Sea), we measured sediment N 2 fluxes across subtidal and intertidal sediments, and along gradients in nitrate and organic matter concentrations. We conducted 2 sampling campaigns, in . In September, nitrate concentration in bottom water and organic matter content in sediments limited N 2 production; such limitations were not observed in March. We extrapolated the estuarine sediment nitrogen removal of March and September to the present-day area of intertidal and subtidal sediments in the Elbe Estuary between the port of Hamburg and the transition to the North Sea. Our estimate suggests that 3.3 ± 1.2 kt nitrate-N are removed in sediments in this region in spring and summer. This implies that reactive nitrogen removal in the inner Elbe Estuary reduces the spring/summer load of the Elbe River (47 kt N) by around 7%, a reduction that is much lower than commonly assumed for estuaries, and significantly lower than nitrate removal in the Elbe was in historical times.

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Coupled nitrification–denitrification leads to extensive N loss in subtidal permeable sediments

Marchant

Holtappels

Lavik

et al. 2016

Limnology & Oceanography

101

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We investigated microbial pathways of nitrogen transformation in highly permeable sediments from the German Bight (South-East North Sea) by incubating sediment cores percolated with 15 N-labeled substrates under near in situ conditions. In incubations with added 15 NH 3 revealed high denitrification rates within the sediment under oxic and anoxic conditions. Denitrification rates were strongly and positively correlated with oxygen consumption rates, suggesting that denitrification is controlled by organic matter availability. Nitrification and denitrification rates were of the same magnitude and the rapid production N-labeling experiments show that these subtidal permeable sediments are, in sharp contrast to common belief, a substantial source of N 2 O. Our combined results show that nitrification fuels denitrification by providing an additional source of nitrate, and as such masks true N-losses from these highly eutrophic sediments. Given the widespread occurrence of anthropogenically influenced permeable sediments, coupled benthic nitrification-denitrification might have an important but so far neglected role in N-loss from shelf sediments.

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Nitrogen cycling in the German Bight (SE North Sea) — Clues from modelling stable nitrogen isotopes

Cited by 28 publications

References 43 publications

Food-Web Structure in Four Locations Along the European Shelf Indicates Spatial Differences in Ecosystem Functioning

Food-Web Structure in Four Locations Along the European Shelf Indicates Spatial Differences in Ecosystem Functioning

N2 fluxes in sediments of the Elbe Estuary and adjacent coastal zones

Coupled nitrification–denitrification leads to extensive N loss in subtidal permeable sediments

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