Organic-N loss by efflux and burial associated with a low efflux of inorganic N and with nitrate assimilation in Arctic sediments (Svalbard, Norway)

Blackburn, T H; Hall, Per; Hulth, Stefan; Landén, Angela

doi:10.3354/meps141283

Cited by 67 publications

(62 citation statements)

References 21 publications

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“…Lomstein et al 1998). The same variability has been found in deeper estuaries, where in some cases DON was an important component of the TDN efflux (Lomstein et al 1989;Blackburn et al 1996) and in others it was small or insig- Comparison between light and dark (A) sediment fluxes and (B) macroalgal uptake/release of dissolved nitrogen. Error bars ϭ SE; n ϭ 72 each for light and dark for all measurements except amino acids, where n ϭ 60.…”

Section: Discussionmentioning

confidence: 74%

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Tyler

McGlathery

Anderson

2003

Limnology & Oceanography

145

101

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Coastal lagoons are a common land-margin feature worldwide and function as an important filter for nutrients entering from the watershed. The shallow nature of lagoons leads to dominance by benthic autotrophs, which can regulate benthic-pelagic coupling. Here we demonstrate that both microalgae and macroalgae are important in controlling dissolved inorganic as well as organic nitrogen (DIN and DON) fluxes between the sediments and the water column. Fluxes of nitrogen (NH , NO , DON, urea, and dissolved free and combined amino acids [DFAA,DCAA]) and O 2 were measured from October 1998 through August 1999 in sediment cores collected from Hog Island Bay, Virginia. Cores were collected from four sites representing the range of environmental conditions across this shallow lagoon: muddy, high-nutrient and sandy, low-nutrient sites that were both dominated by benthic microalgae, and a mid-lagoon site with fine sands covered by dense macroalgal mats. Sediment-water column DON fluxes were highly variable and comparable in magnitude to DIN fluxes; fluxes of individual compounds (urea, DFAA, DCAA) often proceeded simultaneously in different directions. Where sediment metabolism was net autotrophic because of microalgal activity, TDN (total dissolved nitrogen) fluxes, mostly comprised of DIN, urea, and DFAA, were directed into the sediments. Heterotrophic sediments, including those underlying macroalgal mats, were a net source of TDN, mostly as DIN. Macroalgae intercepted sediment-water column fluxes of DIN, urea, and DFAA, which accounted for 27-75% of calculated N demand. DON uptake was important in satisfying macroalgal N demand seasonally and where DIN concentrations were low. Up to 22% of total N uptake was released to the water column as DCAA. Overall, macroalgae assimilated, transformed, and rereleased to the water column both organic and inorganic N on short (minutes-hours) and long (months) time scales. Microalgae and macroalgae clearly regulate benthic-pelagic coupling and thereby influence transformations and retention of N moving across the land-sea interface.

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Section: Discussionmentioning

confidence: 74%

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Tyler

McGlathery

Anderson

2003

Limnology & Oceanography

145

101

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“…Numerous studies from a wide variety of marine environments have shown that DOC and DON concentrations in sediment porewater may be manyfold higher than in the overlying water (e.g. Martin and McCorkle, 1993;Blackburn et al, 1996;Burdige and Zheng, 1998;Alperin et al, 1999;Holcombe et al, 2001). We have summarized the published sedimentary fluxes of DON and DOC from different marine systems in Table 3.…”

Section: Doc and Don Fluxesmentioning

confidence: 99%

“…The rate-determining step for both aerobic and anaerobic microbial degradation of POM and production of DOM is the hydrolysis by extracellular enzymes (Wilczek et al, 2005). Higher POM reactivity induces the production and activity of bacterial hydrolytic enzymes (Boetius and Lochte, 1994;Wilczek et al, 2005), and hydrolysis proceeds under both oxic and anoxic conditions, although not necessarily always at the same rates (Hansen and Blackburn 1991;Kristensen and Holmer, 2001). In this regard, Thibodeau et al (2010) recently reported that OM remineralization rates along the LC are highest in the lower estuary and decrease eastwards.…”

Section: Doc and Don Fluxesmentioning

confidence: 99%

“…5). Initial hydrolysis of freshly deposited POM in surface sediments generally produces DOM with a C / N ratio that is lower than that of the deposited POM (Blackburn et al, 1996;Burdige and Zheng, 1998;Weston et al, 2006). We observed that the difference between C / N ratios of sediment POM and porewater DOM ( C / N = C / N POM -C / N DOM ) decreases along the LC from ∼ 6 at the head of the LC to ∼ 1 at station 18, while the difference was negative (about −3) at station 16 and in the Anticosti Channel sediments (Fig.…”

Section: Versus N Partitioning During Dom Production and Remineralimentioning

confidence: 99%

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Benthic fluxes of dissolved organic nitrogen in the lower St. Lawrence estuary and implications for selective organic matter degradation

et al. 2013

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Abstract. The distribution of dissolved organic nitrogen (DON) and carbon (DOC) in sediment porewaters was determined at nine locations along the St. Lawrence estuary and in the gulf of St. Lawrence. In a previous manuscript (Alkhatib et al., 2012a), we have shown that this study area is characterized by gradients in the sedimentary particulate organic matter (POM) reactivity, bottom water oxygen concentrations, and benthic respiration rates. Based on the porewater profiles, we estimated the benthic diffusive fluxes of DON and DOC in the same area. Our results show that DON fluxed out of the sediments at significant rates (110 to 430 µmol m −2 d −1 ). DON fluxes were positively correlated with sedimentary POM reactivity and varied inversely with sediment oxygen exposure time (OET), suggesting direct links between POM quality, aerobic remineralization and the release of DON to the water column. DON fluxes were on the order of 30 to 64 % of the total benthic inorganic fixed N loss due to denitrification, and often exceeded the diffusive nitrate fluxes into the sediments. Hence they represented a large fraction of the total benthic N exchange, a result that is particularly important in light of the fact that DON fluxes are usually not accounted for in estuarine and coastal zone nutrient budgets. In contrast to DON, DOC fluxes out of the sediments did not show any significant spatial variation along the Laurentian Channel (LC) between the estuary and the gulf (2100 ± 100 µmol m −2 d −1 ). The molar C / N ratio of dissolved organic matter (DOM) in porewater and the overlying bottom water varied significantly along the transect, with lowest C / N in the lower estuary (5-6) and highest C / N (> 10) in the gulf. Large differences between the C / N ratios of porewater DOM and POM are mainly attributed to a combination of selective POM hydrolysis and elemental fractionation during subsequent DOM mineralization, but selective adsorption of DOM to mineral phases could not be excluded as a potential C / N fractionating process. The extent of this C-versus N-element partitioning seems to be linked to POM reactivity and redox conditions in the sediment porewaters. Our results thus highlight the variable effects selective organic matter (OM) preservation can have on bulk sedimentary C / N ratios, decoupling the primary source C / N signatures from those in sedimentary paleoenvironmental archives. Our study further underscores that the role of estuarine sediments as efficient sinks of bioavailable nitrogen is strongly influenced by the release of DON during early diagenetic reactions, and that DON fluxes from continental margin sediments represent an important internal source of N to the ocean.

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“…The sources of organic matter to these sediments are benthic and pelagic primary producers and terrestrial organic matter. The quantity and quality of organic matter introduced into the sediment has been found to have an overall determining effect on benthic mineralization (e.g., Blackburn and Henriksen 1983;Lomstein et al 1989;Therkildsen and Lomstein 1994;Sloth et al 1995).…”

mentioning

confidence: 99%

The effect of eelgrass decomposition on sediment carbon and nitrogen cycling: A controlled laboratory experiment

Pedersen

Berntsen

Lomstein

1999

Limnology & Oceanography

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The initial benthic degradation of senescent Zostera marina leaves was studied in controlled flowthrough microcosm chambers for 33 d. Sediment chambers without added eelgrass leaves served as control chambers. The inflowing artificial seawater and ouflowing seawater were analyzed for dissolved organic carbon and nitrogen (DOC and DON), total acid-hydrolyzable amino acids (THAA), dissolved free amino acids (DFAA), urea, NH , NO , incubation, 24.3% of the DON efflux was identified as acid-hydrolyzable amino acids, dissolved free amino acids, and urea in the chambers with eelgrass addition, whereas these compounds accounted for 33.8% of the DON efflux in the control chambers. There were indications of a stimulated bacterial growth on the eelgrass leaves during the first 7 d after leaf addition that was measured as an increase in acid-hydrolyzable amino acids. Further, there was a gradual increase in acid-hydrolyzable amino acids in the sediment throughout the incubation that could only be explained as bacterial growth (and/or protein synthesis). Most of the nitrogen for microbial growth was mobilized from the indigenous particulate organic nitrogen pool, whereas it could be inferred that the energy source for bacterial growth was mainly supplied from the added eelgrass leaves. Most of the nitrogen mineralized within the sediment was incorporated into the microbial biomass with a resultant low efflux of inorganic nitrogen from the sediment to the water column.

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Organic-N loss by efflux and burial associated with a low efflux of inorganic N and with nitrate assimilation in Arctic sediments (Svalbard, Norway)

Cited by 67 publications

References 21 publications

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Benthic fluxes of dissolved organic nitrogen in the lower St. Lawrence estuary and implications for selective organic matter degradation

The effect of eelgrass decomposition on sediment carbon and nitrogen cycling: A controlled laboratory experiment

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