Loreto Brabandere | Vrije Universiteit Brussel (original) (raw)

Papers by Loreto Brabandere

Research paper thumbnail of 15 N dynamics of ammonium and particulate nitrogen in a temperate eutrophic estuary

Biogeochemistry, 2007

We monitored the stable nitrogen isotopic composition (δ15N) of suspended matter and ammonium in ... more We monitored the stable nitrogen isotopic composition (δ15N) of suspended matter and ammonium in the freshwater stretch of the Scheldt estuary (Belgium) over a full year to investigate for seasonal evolution and possible co-variation between isotopic signatures. The δ15N value of ammonium remained rather constant during winter (average = +11.4‰) but increased significantly with the spring and summer bloom, reaching values as high as +70‰. This enrichment of the ammonium pool in 15N coincided with significant ammonium depletion during summer period, suggesting a close causal relationship. Based on a semi-closed system approach we deduced an apparent fractionation factor associated with NH 4+ utilization (i.e. combining effects of uptake and nitrification) of 18.4‰ (SE = 2.0‰), which is similar to values reported in literature. Observed variations of ammonium δ15N could account for about 69% of δ15N variation in suspended matter.

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Research paper thumbnail of Nitrogen processing in a tidal freshwater marsh: a whole ecosystem 15N labeling study

Limnology and Oceanography, 2005

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Research paper thumbnail of Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

Biogeosciences Discussions, 2006

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Research paper thumbnail of Ammonium Transformation in a Nitrogen-Rich Tidal Freshwater Marsh

Biogeochemistry, 2006

The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nut... more The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH 4+ to the flood water entering a 3477 m2 tidal freshwater marsh area, and traced the ammonium processing and retention in four subsequent tide cycles. In this paper we present the results for the water-phase components of the marsh system and compare them to a similar experiment conducted in spring/early summer (May). Changes in concentration and isotopic enrichment of NO 3− + NO 2−, N2O, N2, NH 4+ and suspended particulate nitrogen (SPN) were measured in concert with a mass balance study. All analyzed N-pools were labeled, and 49% of the added 15NH 4+ was retained or transformed. The most important pool for 15N was nitrate, accounting for 17% of 15N-transformation. N2, N2O and SPN accounted for 2.4, 0.02 and 1.4%, respectively. The temporal and spatial patterns of 15N transformation in the water phase component of the system were remarkably similar to those observed in May, indicating good reproducibility of the whole ecosystem labeling approach, but the absolute ammonium transformation rate was 3 times higher in May. While the marsh surface area was crucial for nitrification in May this was less pronounced in September. Denitrification, on the other hand, appeared more important in September compared to May.

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Research paper thumbnail of Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

Biogeosciences, 2007

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Research paper thumbnail of 15N and δ 13C dynamics of suspended organic matter in freshwater and brackish waters of the Scheldt estuary

Journal of Sea Research, 2002

Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the ... more Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the Scheldt river and estuary to investigate the seasonal and spatial patterns of δ13C and δ15N signatures. δ15N of suspended matter showed large seasonal variation. Minimum values ranged from −0.5‰ in the freshwater zone (spring situation) to +2.3‰ in the mesohaline zone (winter situation). Maximum values

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Research paper thumbnail of Denitrification, anammox and fixed nitrogen removal in the water column of a tropical great lake

If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more ... more If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more the case for tropical water bodies. Lake Kivu [2.50° S 1.59° S, 29.37° E 28.83° E] is one of the great lakes of the East African Rift. It is an oligotrophic lake characterized by anoxic deep waters rich in dissolved gases (methane and carbon dioxide) and nutrients, and by well oxygenated and nutrient-depleted surface waters. During the seasonally stratified rainy season (October to May), a nitrogenous zone characterized by the accumulation of nitrite (NO2-) and nitrate (NO3-) is often observed in the lower layer of the mixolimnion. It results from nitrification of ammonium released by decaying organic matter. With the seasonal uplift of the oxygen minimum zone, the nitrogenous zone becomes anoxic and might be the most preferential area for fixed nitrogen (N) removal in Lake Kivu. Our work aimed at identifying and quantifying the processes of N losses by denitrification and/or anammox in ...

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Research paper thumbnail of Methane in a Swedish sill fjord - Benthic fluxes, inventory and atmospheric emission

Methane (CH4) is a potent greenhouse gas, which has the second largest radiative force after carb... more Methane (CH4) is a potent greenhouse gas, which has the second largest radiative force after carbon dioxide. Oceans, including their coastal areas, contribute to the natural CH4 budget in the atmosphere, but measurements are still sparse, and no measurements of CH4 in Swedish fjord systems have been made. For this purpose we measured CH4 concentrations in the water column as well as benthic CH4 fluxes by using in-situ chambers on four occasions during 2009. The study area, the By Fjord, is a sill fjord on the Swedish west coast. Benthic flux measurements were done on a depth transect in the fjord and included both sediments with overlying oxic and anoxic water. The collected data were used to calculate the total fjord integrated net CH4 release from sediments, the transport through the water column, and finally the exchange between water and atmosphere. Moreover, we used modeling to estimate the total CH4 emission to the atmosphere from the By Fjord, which could be used as proxy for...

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Research paper thumbnail of An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord, Western Sweden

AMBIO, 2014

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Research paper thumbnail of Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach

Estuarine Coastal and Shelf Science, 2006

Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)... more Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this, stomach contents were

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Research paper thumbnail of δ 15N and δ 13C dynamics of suspended organic matter in freshwater and brackish waters of the Scheldt estuary

Journal of Sea Research, 2002

Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the ... more Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the Scheldt river and estuary to investigate the seasonal and spatial patterns of δ13C and δ15N signatures. δ15N of suspended matter showed large seasonal variation. Minimum values ranged from −0.5‰ in the freshwater zone (spring situation) to +2.3‰ in the mesohaline zone (winter situation). Maximum values

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Research paper thumbnail of The diet and consumption of dominant fish species in the upper Scheldt estuary, Belgium

Journal of the Marine Biological Association of the UK, 2003

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Research paper thumbnail of Nitrogen losses in anoxic marine sediments driven by Thioploca–anammox bacterial consortia

Nature, 2013

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Research paper thumbnail of A critical assessment of the occurrence and extend of oxygen contamination during anaerobic incubations utilizing commercially available vials

Journal of Microbiological Methods, 2012

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Research paper thumbnail of Stable isotope evidence of ontogenetic changes in the diet of gizzard shad Dorosoma cepedianum

Journal of Fish Biology, 2009

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Research paper thumbnail of Denitrification in the water column of the central Baltic Sea

Geochimica et Cosmochimica Acta, 2013

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Research paper thumbnail of Stable nitrogen isotope ratios of macrophytes and associated periphyton along a nitrate gradient in two subtropical, spring-fed streams

Freshwater Biology, 2007

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Research paper thumbnail of Dissolved organic carbon in the freshwater tidal reaches of the Schelde estuary

Estuarine, Coastal and Shelf Science, 2005

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Research paper thumbnail of Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach

Estuarine, Coastal and Shelf Science, 2006

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Research paper thumbnail of Vertical partitioning of nitrogen-loss processes across the oxic-anoxic interface of an oceanic oxygen minimum zone

Environmental Microbiology, 2013

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Research paper thumbnail of 15 N dynamics of ammonium and particulate nitrogen in a temperate eutrophic estuary

Biogeochemistry, 2007

We monitored the stable nitrogen isotopic composition (δ15N) of suspended matter and ammonium in ... more We monitored the stable nitrogen isotopic composition (δ15N) of suspended matter and ammonium in the freshwater stretch of the Scheldt estuary (Belgium) over a full year to investigate for seasonal evolution and possible co-variation between isotopic signatures. The δ15N value of ammonium remained rather constant during winter (average = +11.4‰) but increased significantly with the spring and summer bloom, reaching values as high as +70‰. This enrichment of the ammonium pool in 15N coincided with significant ammonium depletion during summer period, suggesting a close causal relationship. Based on a semi-closed system approach we deduced an apparent fractionation factor associated with NH 4+ utilization (i.e. combining effects of uptake and nitrification) of 18.4‰ (SE = 2.0‰), which is similar to values reported in literature. Observed variations of ammonium δ15N could account for about 69% of δ15N variation in suspended matter.

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Research paper thumbnail of Nitrogen processing in a tidal freshwater marsh: a whole ecosystem 15N labeling study

Limnology and Oceanography, 2005

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Research paper thumbnail of Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

Biogeosciences Discussions, 2006

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Research paper thumbnail of Ammonium Transformation in a Nitrogen-Rich Tidal Freshwater Marsh

Biogeochemistry, 2006

The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nut... more The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH 4+ to the flood water entering a 3477 m2 tidal freshwater marsh area, and traced the ammonium processing and retention in four subsequent tide cycles. In this paper we present the results for the water-phase components of the marsh system and compare them to a similar experiment conducted in spring/early summer (May). Changes in concentration and isotopic enrichment of NO 3− + NO 2−, N2O, N2, NH 4+ and suspended particulate nitrogen (SPN) were measured in concert with a mass balance study. All analyzed N-pools were labeled, and 49% of the added 15NH 4+ was retained or transformed. The most important pool for 15N was nitrate, accounting for 17% of 15N-transformation. N2, N2O and SPN accounted for 2.4, 0.02 and 1.4%, respectively. The temporal and spatial patterns of 15N transformation in the water phase component of the system were remarkably similar to those observed in May, indicating good reproducibility of the whole ecosystem labeling approach, but the absolute ammonium transformation rate was 3 times higher in May. While the marsh surface area was crucial for nitrification in May this was less pronounced in September. Denitrification, on the other hand, appeared more important in September compared to May.

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Research paper thumbnail of Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

Biogeosciences, 2007

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Research paper thumbnail of 15N and δ 13C dynamics of suspended organic matter in freshwater and brackish waters of the Scheldt estuary

Journal of Sea Research, 2002

Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the ... more Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the Scheldt river and estuary to investigate the seasonal and spatial patterns of δ13C and δ15N signatures. δ15N of suspended matter showed large seasonal variation. Minimum values ranged from −0.5‰ in the freshwater zone (spring situation) to +2.3‰ in the mesohaline zone (winter situation). Maximum values

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Research paper thumbnail of Denitrification, anammox and fixed nitrogen removal in the water column of a tropical great lake

If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more ... more If rates of microbial denitrification in aquatic systems are poorly constrained, it is much more the case for tropical water bodies. Lake Kivu [2.50° S 1.59° S, 29.37° E 28.83° E] is one of the great lakes of the East African Rift. It is an oligotrophic lake characterized by anoxic deep waters rich in dissolved gases (methane and carbon dioxide) and nutrients, and by well oxygenated and nutrient-depleted surface waters. During the seasonally stratified rainy season (October to May), a nitrogenous zone characterized by the accumulation of nitrite (NO2-) and nitrate (NO3-) is often observed in the lower layer of the mixolimnion. It results from nitrification of ammonium released by decaying organic matter. With the seasonal uplift of the oxygen minimum zone, the nitrogenous zone becomes anoxic and might be the most preferential area for fixed nitrogen (N) removal in Lake Kivu. Our work aimed at identifying and quantifying the processes of N losses by denitrification and/or anammox in ...

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Research paper thumbnail of Methane in a Swedish sill fjord - Benthic fluxes, inventory and atmospheric emission

Methane (CH4) is a potent greenhouse gas, which has the second largest radiative force after carb... more Methane (CH4) is a potent greenhouse gas, which has the second largest radiative force after carbon dioxide. Oceans, including their coastal areas, contribute to the natural CH4 budget in the atmosphere, but measurements are still sparse, and no measurements of CH4 in Swedish fjord systems have been made. For this purpose we measured CH4 concentrations in the water column as well as benthic CH4 fluxes by using in-situ chambers on four occasions during 2009. The study area, the By Fjord, is a sill fjord on the Swedish west coast. Benthic flux measurements were done on a depth transect in the fjord and included both sediments with overlying oxic and anoxic water. The collected data were used to calculate the total fjord integrated net CH4 release from sediments, the transport through the water column, and finally the exchange between water and atmosphere. Moreover, we used modeling to estimate the total CH4 emission to the atmosphere from the By Fjord, which could be used as proxy for...

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Research paper thumbnail of An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord, Western Sweden

AMBIO, 2014

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Research paper thumbnail of Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach

Estuarine Coastal and Shelf Science, 2006

Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)... more Large numbers of young of the year herring (Clupea harengus L.) and sprat (Sprattus sprattus (L.)) typically enter and remain within North Sea estuaries during the winter months. The main purpose of this study was to examine their migration dynamics between the North Sea and the Schelde estuary using C and N stable isotopes. Prior to this, stomach contents were

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Research paper thumbnail of δ 15N and δ 13C dynamics of suspended organic matter in freshwater and brackish waters of the Scheldt estuary

Journal of Sea Research, 2002

Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the ... more Suspended particulate organic matter was sampled monthly between June 1999 and April 2000 in the Scheldt river and estuary to investigate the seasonal and spatial patterns of δ13C and δ15N signatures. δ15N of suspended matter showed large seasonal variation. Minimum values ranged from −0.5‰ in the freshwater zone (spring situation) to +2.3‰ in the mesohaline zone (winter situation). Maximum values

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Research paper thumbnail of The diet and consumption of dominant fish species in the upper Scheldt estuary, Belgium

Journal of the Marine Biological Association of the UK, 2003

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Research paper thumbnail of Nitrogen losses in anoxic marine sediments driven by Thioploca–anammox bacterial consortia

Nature, 2013

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Research paper thumbnail of A critical assessment of the occurrence and extend of oxygen contamination during anaerobic incubations utilizing commercially available vials

Journal of Microbiological Methods, 2012

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Research paper thumbnail of Stable isotope evidence of ontogenetic changes in the diet of gizzard shad Dorosoma cepedianum

Journal of Fish Biology, 2009

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Research paper thumbnail of Denitrification in the water column of the central Baltic Sea

Geochimica et Cosmochimica Acta, 2013

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Research paper thumbnail of Stable nitrogen isotope ratios of macrophytes and associated periphyton along a nitrate gradient in two subtropical, spring-fed streams

Freshwater Biology, 2007

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Research paper thumbnail of Dissolved organic carbon in the freshwater tidal reaches of the Schelde estuary

Estuarine, Coastal and Shelf Science, 2005

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Research paper thumbnail of Migration dynamics of clupeoids in the Schelde estuary: A stable isotope approach

Estuarine, Coastal and Shelf Science, 2006

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Research paper thumbnail of Vertical partitioning of nitrogen-loss processes across the oxic-anoxic interface of an oceanic oxygen minimum zone

Environmental Microbiology, 2013

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