Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

Laima, M. C. J.

doi:10.3354/meps082075

Cited by 24 publications

(15 citation statements)

References 20 publications

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“…Since the mat cores did not contain enough extractable liquid for direct centrifugation, 5 ml of synthetic seawater, free of nitrate or nitrite, was added to each tube, homogenized and centrifuged for 10 min at 10 000 × g. Nitrite and nitrate concentrations were analyzed with a Technicon-Auto-Analyser according to Treguer & Le Corre (1975). Ammonium concentration was determined after KCl extraction (Laima 1992) using the phenol/hypochlorite method (Koroleff 1969). These values were corrected for dilution and addition of reagent. )…”

Section: Methodsmentioning

confidence: 99%

Nitrogen budget in a microbial mat in the Camargue (southern France)

Bonin¹,

Michotey²

2006

Mar. Ecol. Prog. Ser.

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The main processes associated with the nitrogen cycle were studied in a microbial mat and in the surrounding water during winter (January), spring (March) and summer (June) in the Camargue (southeastern France). Denitrification, nitrogen fixation, nitrification, dissimilative reduction of nitrate, together with mineralization and ammonium assimilation, were measured under dark and light conditions using inhibitor and nitrogen isotope ( 15 N). All these microbial processes were expressed in the mat. The isotope pairing method allowed the identification of the source of denitrified nitrate. It appeared that a major part of the nitrate formed by nitrification was denitrified and that nitrification was a considerable source of nitrate in spring and summer. From variations in net flux (fixation versus denitrification activities), we conclude that the mat acted as a nitrogen source in summer, but as a sink in winter. KEY WORDS: Nitrogen cycle · Denitrification · Microbial mat Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 322: [75][76][77][78][79][80][81][82][83][84] 2006 The fact that few measurements of denitrification in cyanobacteria-dominated microbial mats have been published may be attributable to technical and interpretational difficulties, which are associated mainly with the commonly used method (acetylene block method; Bonin 1996). Acetylene not only inhibits the terminal step of denitrification but also affects other processes of the nitrogen cycle. Acetylene blocks nitrification, and this interruption in nitrate supply could result in the underestimation of denitrification (Hynes & Knowles 1978, Walter et al. 1979, Hyman & Wood 1985. Furthermore, acetylene can be converted to ethylene by nitrogen-fixing bacteria, leading to a suppression of the inhibition of the nitrous oxide reduction (Van Raalte & Patriquin 1979). Knowledge of the nitrogen cycle in mats could be improved by the application of tracer techniques, especially those using stable isotope ( 15 N). This isotopic technique circumvents the limitation of the acetylene block method and facilitates the determination of the reduction of nitrate originating either from downwards diffusion from the overlying water or from nitrification.Our present level of understanding is not yet sufficient to establish an overview of the interactions of the nitrogen cycle processes realized by micro-organisms, which present very diversified types of metabolism ranging from autotrophy to heterotrophy. However, from a biogeochemical perspective, nitrogen budgets in microbial mats cannot be fully understood without in situ quantification of nitrogen sources (N-fixation) and sinks (denitrification). However, whether mats act as sources or sinks for combined N depends, not only on the balance between N-fixation and denitrification, but also on the rates of other processes producing (nitrification and mineralization, respectively) or consuming nitrate or ammonium (DNRA [dissimilative nitrate reduction to ammoniu...

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Section: Methodsmentioning

confidence: 99%

Nitrogen budget in a microbial mat in the Camargue (southern France)

Bonin¹,

Michotey²

2006

Mar. Ecol. Prog. Ser.

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“…In addition, the production of 29 N 2 continued to the end of the trial (12 h), being sustained by the NO 2 Ϫ pool, which remained largely untouched until after 8 h, when the concentration of NO 3 Ϫ had been reduced to approximately 200 M. The rates of turnover were consistently equal for NO 3 Ϫ and NO 2 Ϫ , being equivalent to 0.11 and 0.12 mol ml of wet sediment Ϫ1 h Ϫ1 , respectively, at a starting concentration of 800 M. Anaerobic ammonium oxidation produced 0. 16 (Fig. 4a).…”

Section: Methodsmentioning

confidence: 99%

Anaerobic Ammonium Oxidation Measured in Sediments along the Thames Estuary, United Kingdom

Trimmer

Nicholls

Deflandre

2003

Appl Environ Microbiol

311

248

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Until recently, denitrification was thought to be the only significant pathway for N 2 formation and, in turn, the removal of nitrogen in aquatic sediments. The discovery of anaerobic ammonium oxidation in the laboratory suggested that alternative metabolisms might be present in the environment. By using a combination of 15 ؊ . We observed a shift in the significance of anaerobic ammonium oxidation to N 2 formation relative to denitrification, from 8% near the head of the estuary to less than 1% at the coast. The relative importance of anaerobic ammonium oxidation was positively correlated (P < 0.05) with sediment organic content. This report of anaerobic ammonium oxidation in organically enriched estuarine sediments, though in contrast to a recent report on continental shelf sediments, confirms the presence of this novel metabolism in another aquatic sediment system.Since the 1970s, substantial research has focused on the ability of estuarine sediments to attenuate riverine nitrogen (N) loads before they affect coastal seas (4,18,19,31,33). Estuarine sediments are essentially anaerobic below a few surface millimeters, and the mineralization of organic matter proceeds via alternate electron acceptors such as NO 3 Ϫ and SO 4 2Ϫ (20,27). In turn, the reduction of NO 3 Ϫ removes NO 3 Ϫ from the overlying waters. Until recently, it was largely thought that NO 3 Ϫ could be either reduced to N 2 gas via denitrification (a facultative metabolism mediated by a variety of bacteria) and lost from the system or reduced to ammonium (NH 4 ϩ ) by fermentative metabolisms and hence conserved within the sediments (dissimilatory nitrate reduction to ammonium [DNRA]) (8,23). It had been demonstrated that changes in sediment organic loadings and estuarine NO 3 Ϫ concentrations may affect the partitioning between these two end products of NO 3 Ϫ reduction (11, 12). The discovery within the laboratory (17) of anaerobic ammonium oxidation revealed a novel metabolism that could short circuit the N cycle, bypassing what was previously thought to be a critical aerobic nitrification phase and potentially providing an alternative pathway for N 2 gas formation in the environment (Fig. 1).Originally, it was thought (17) that anaerobic ammonium oxidation coupled the oxidation of NH 4 ϩ to the reduction of NO 3 Ϫ :Further work, however, showed that the oxidation of ammonium was actually coupled to the reduction of nitrite rather than nitrate (34, 35):The application of this process to the treatment of nitrogenous waste has received a great deal of attention (9, 10), and more recently, the organism responsible has been classified as a new autotrophic planctomycete (28). Anaerobic ammonium oxidation was recently reported to account for as much as 24 and 60% of N 2 formation in continental shelf sediments in relatively deep water (380 and 695 m, respectively) but less than 2% of N 2 formation in eutrophic shallow coastal bay sediments (30). The drop in the significance of anaerobic ammonium oxidation for N 2 formation relative to denitrificatio...

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“…Blackburn (1980) made a seasonal study of ammonium, in a n anoxic marine sediment, which showed th.at ammonium production was closely related to the temperature cycle. Laima (1992) also found in his study of Danish coastal sediments that temperature variations had a pronounced effect on the production rate of ammonium. Otherwise, there seems to be a lack of studies of seasonality in marine sediments and how mineralization rates, adsorption processes and transport processes of amino acids and ammonium are affected by seasonal changes of e.g.…”

Section: Introductionmentioning

confidence: 91%

“…Microbial activity in coastal marine sediments at most sites in the temperate zone is generally regulated by seasonal changes of input of organic matter, bottom water temperature and oxygen concentration. Laima (1992) did a seasonal study of Danish coastal sediments, which were highly influenced by seasonal changes in temperature and organic matter input, and found that even the tightly bound pool of ammonium in the sediment (shaken several times with potassium chloride) varied seasonally.…”

Section: Adsorption Coefficientsmentioning

confidence: 99%

Seasonal variation of dissolved and adsorbed amino acids and ammonium in a near-shore marine sediment

Landén¹,

Hall²

1998

Mar. Ecol. Prog. Ser.

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Dissolved free amino acids (DFAA) and ammonium in the pore water of a coastal sediment at a water depth of 40 m were investigated monthly for more than a year, to improve knowledge on how the concentrations and distributions of these dissolved compounds varied during an annual cycle. Seasonal changes in adsorbed amino acids and ammonium were also studied and adsorption coefficients were calculated. Ammonium distribution in the pore water showed clear seasonal trends. In the warmer period (August and September) there were high concentrations in the pore water, and in winter the lowest concentrations were measured. Pore water concentrations of DFAA were in general low, but showed seasonal trends during the year. At the end of summer when the bottom water temperature reached its maximum (about 14"C), the concentrations of DFAA were also at their maxima However, a response to the input of organlc matter to the sediment was also observed as increased pore water DFAA concentrations. The seasonal response was not strong, which probably was due to several processes (e.g. adsorption, degradation and bacterial assimilation) removing DFAA and thereby preventing large pools of DFAA from being built up in the pore water. Adsorption of ammonium followed the concentration of dissolved ammonium in the pore water and there was neither a relation with input of organic matter nor with temperature in the bottom water. The adsorption coefficient (the dimensionless K) for ammonium was 1.07 * 0.11 and did not vary during the year The adsorption coefficients for amino acids, which were all higher than K for ammonium, did show seasonal trends and the periods with high concentrations of adsorbed amino acids were related not only to high concentrations of DFAA, but also to recent input of organic matter and probably also to the stimulation of bioturbation as a result of high temperature in the bottom water at the end of summer. The results demonstrated a seasonal variation in K of amino acids, but not ammonium, indicating that the processes controlling dissolved concentrations were substantially different for these compounds.

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Extraction and seasonal variation of NH4+pools in differert typos of coastal marine sediments

Cited by 24 publications

References 20 publications

Nitrogen budget in a microbial mat in the Camargue (southern France)

Nitrogen budget in a microbial mat in the Camargue (southern France)

Anaerobic Ammonium Oxidation Measured in Sediments along the Thames Estuary, United Kingdom

Seasonal variation of dissolved and adsorbed amino acids and ammonium in a near-shore marine sediment

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