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  • 1
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    Unknown
    High Resolution Measurements of Nitrous Oxide (N2O) in the Elbe Estuary (2017)
    Frontiers
    In:  Frontiers in Marine Science, 4 . Art.Nr. 162.
    Details
    Publication Date: 2020-02-06
    Description: Nitrous oxide (N2O) is one of the most important greenhouse gases and a major sink for stratospheric ozone. Estuaries are sites of intense biological production and N2O emissions. We aimed to identify hot spots of N2O production and potential pathways contributing to N2O concentrations in the surface water of the tidal Elbe estuary. During two research cruises in April and June 2015, surface water N2O concentrations were measured along the salinity gradient of the Elbe estuary by using a laser-based on-line analyzer coupled to an equilibrator. Based on these high-resolution N2O profiles, N2O saturations, and fluxes across the surface water/atmosphere interface were calculated. Additional measurements of DIN concentrations, oxygen concentration, and salinity were performed. Highest N2O concentrations were determined in the Hamburg port region reaching maximum values of 32.3 nM in April 2015 and 52.2 nM in June 2015. These results identify the Hamburg port region as a significant hot spot of N2O production, where linear correlations of AOU-N2Oxs indicate nitrification as an important contributor to N2O production in the freshwater part. However, in the region with lowest oxygen saturation, sediment denitrification obviously affected water column N2O saturation. The average N2O saturation over the entire estuary was 201% (SD: ±94%), with an average estuarine N2O flux density of 48 μmol m−2 d−1 and an overall emission of 0.18 Gg N2O y−1. In comparison to previous studies, our data indicate that N2O production pathways over the whole estuarine freshwater part have changed from predominant denitrification in the 1980s toward significant production from nitrification in the present estuary. Despite a significant reduction in N2O saturation compared to the 1980s, N2O concentrations nowadays remain on a high level, comparable to the mid-90s, although a steady decrease of DIN inputs occurred over the last decades. Hence, the Elbe estuary still remains an important source of N2O to the atmosphere.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3389/fmars.2017.00162
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Unknown
    Oxidation kinetics and inverse isotope effect of marine nitrite-oxidizing isolates (2017)
    Inter Research
    In:  Aquatic Microbial Ecology, 80 (3). pp. 289-300.
    Details
    Publication Date: 2020-02-06
    Description: Nitrification, the step-wise oxidation of ammonium to nitrite and nitrate, is important in the marine environment because it produces nitrate, the most abundant marine dissolved inorganic nitrogen (DIN) component and N-source for phytoplankton and microbes. This study focused on the second step of nitrification, which is carried out by a distinct group of organisms, nitrite-oxidizing bacteria (NOB). The growth of NOB is characterized by nitrite oxidation kinetics, which we investigated for 4 pure cultures of marine NOB (Nitrospina watsonii 347, Nitrospira sp. Ecomares 2.1, Nitrococcus mobilis 231, and Nitrobacter sp. 311). We further compared the kinetics to those of non-marine species because substrate concentrations in marine environments are comparatively low, which likely influences kinetics and highlights the importance of this study. We also determined the isotope effect during nitrite oxidation of a pure culture of Nitrospina (Nitrospina watsonii 347) belonging to one of the most abundant marine NOB genera, and for a Nitrospira strain (Nitrospira sp. Ecomares 2.1). The enzyme kinetics of nitrite oxidation, described by Michaelis-Menten kinetics, of 4 marine genera are rather narrow and fall in the low end of half-saturation constant (Km) values reported so far, which span over 3 orders of magnitude between 9 and 〉1000 µM NO2-. Nitrospina has the lowest Km (19 µM NO2-), followed by Nitrobacter (28 µM NO2-), Nitrospira (54 µM NO2-), and Nitrococcus (120 µM NO2-). The isotope effects during nitrite oxidation by Nitrospina watsonii 347 and Nitrospira sp. Ecomares 2.1 were 9.7 ± 0.8 and 10.2 ± 0.9‰, respectively. This confirms the inverse isotope effect of NOB described in other studies; however, it is at the lower end of reported isotope effects. We speculate that differences in isotope effects reflect distinct nitrite oxidoreductase (NXR) enzyme orientations.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.3354/ame01859
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Nitrogen cycling in sediments on the NW African margin inferred from N and O isotopes in benthic chambers (2022)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Benthic nitrogen cycling in the Mauritanian upwelling region (NW Africa) was studied in June 2014 from the shelf to the upper slope where minimum bottom water O 2 concentrations of 25 µM were recorded. Benthic incubation chambers were deployed at 9 stations to measure fluxes of O 2 , dissolved inorganic carbon (DIC) and nutrients (NO 3 - , NO 2 - , NH 4 + , PO 4 3- , H 4 SiO 4 ) along with the N and O isotopic composition of nitrate (δ 15 N-NO 3 - and δ 18 O-NO 3 - ) and ammonium (δ 15 N-NH 4 + ). O 2 and DIC fluxes were similar to those measured during a previous campaign in 2011 whereas NH 4 + and PO 4 3- fluxes on the shelf were 2 – 3 times higher and possibly linked to a long-term decline in bottom water O 2 concentrations. The mean isotopic fractionation of NO 3 - uptake on the margin, inferred from the loss of NO 3 - inside the chambers, was 1.5 ± 0.4 ‰ for 15/14 N ( 15 ϵ app ) and 2.0 ± 0.5 ‰ for 18/16 O ( 18 ϵ app ). The mean 18 ϵ app : 15 ϵ app ratio on the shelf (〈 100 m) was 2.1 ± 0.3, and higher than the value of 1 expected for microbial NO 3 - reduction. The 15 ϵ app are similar to previously reported isotope effects for NO 3 - respiration in marine sediments but lower than determined in 2011 at a same site on the shelf. The sediments were also a source of 15 N-enriched NH 4 + (9.0 ± 0.7 ‰). A numerical model tuned to the benthic flux data and that specifically accounts for the efflux of 15 N-enriched NH 4 + from the seafloor, predicted a net benthic isotope effect of N loss ( 15 ϵ sed ) of 3.6 ‰; far above the more widely considered value of ~0‰. This result is further evidence that the assumption of a universally low or negligible benthic N isotope effect is not applicable to oxygen-deficient settings. The model further suggests that 18 ϵ app : 15 ϵ app trajectories > 1 in the benthic chambers are most likely due to aerobic ammonium oxidation and nitrite oxidation in surface sediments rather than anammox, in agreement with published observations in the water column of oxygen deficient regions.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Seasonal variability of nitrous oxide concentrations and emissions in a temperate estuary (2023)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2024-02-07
    Description: Nitrous oxide (N2O) is a greenhouse gas, with a global warming potential 298 times that of carbon dioxide. Estuaries can be sources of N2O, but their emission estimates have significant uncertainties due to limited data availability and high spatiotemporal variability. We investigated the spatial and seasonal variability of dissolved N2O and its emissions along the Elbe Estuary (Germany), a well-mixed temperate estuary with high nutrient loading from agriculture. During nine research cruises performed between 2017 and 2022, we measured dissolved N2O concentrations, as well as dissolved nutrient and oxygen concentrations along the estuary, and calculated N2O saturations, flux densities, and emissions. We found that the estuary was a year-round source of N2O, with the highest emissions in winter when dissolved inorganic nitrogen (DIN) loads and wind speeds are high. However, in spring and summer, N2O saturations and emissions did not decrease alongside lower riverine nitrogen loads, suggesting that estuarine in situ N2O production is an important source of N2O. We identified two hotspot areas of N2O production: the Port of Hamburg, a major port region, and the mesohaline estuary near the maximum turbidity zone (MTZ). N2O production was fueled by the decomposition of riverine organic matter in the Hamburg Port and by marine organic matter in the MTZ. A comparison with previous measurements in the Elbe Estuary revealed that N2O saturation did not decrease alongside the decrease in DIN concentrations after a significant improvement of water quality in the 1990s that allowed for phytoplankton growth to re-establish in the river and estuary. The overarching control of phytoplankton growth on organic matter and, subsequently, on N2O production highlights the fact that eutrophication and elevated agricultural nutrient input can increase N2O emissions in estuaries.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 5
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    Physical oceanography, nutrients, and nitrogen and oxygen isotopic composition of nitrate measured on water bottle samples during SONNE cruise SO259 (2019)
    PANGAEA
    Details
    Publication Date: 2023-07-06
    Description: The University of Hamburg is part of environmental studies in the INDEX Program, which was establishes by the BGR (Federal Institute of Geosciences and Natural Resources) in Hanover to explore Massive Sulphides with regard to a potential future deep sea mining. The INDEX license area is located in the oligotrophic subtropical gyre of the South Indian Ocean. The water samples were collected with a CTD water rosette during two ship cruises with R/V Merian in 2016 (MSM 59/2 "INDEX 2016-2"; November−December 2016) and R/V Sonne in 2017 (SO 259 "INDEX 2017"; August−October 2017) and were analysed for nutrients and stable isotopes of nitrate.
    Keywords: CTD/Rosette; CTD-RO; DATE/TIME; Density, sigma-theta (0); DEPTH, water; ELEVATION; Event label; INDEX2017; Indian Ocean; LATITUDE; LONGITUDE; Nitrate; Original value; Oxygen; Phosphate; Recalculated from ml/l by using (ml/l)*44.66; Salinity; SEAL AutoAnalyzer 3 HR (AA3 HR); SO259; SO259_100-1; SO259_1-1; SO259_15-1; SO259_16-1; SO259_2-1; SO259_3-1; SO259_4-1; SO259_45-1; SO259_49-1; SO259_50-1; SO259_5-1; SO259_60-1; SO259_6-1; SO259_61-1; SO259_99-1; Sonne_2; Station label; Temperature, water; δ15N, nitrate; δ18O, nitrate
    Type: Dataset
    Format: text/tab-separated-values, 1672 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 6
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    Unknown
    Nitrous oxide (N2O) measurements in the surface water of the Elbe Estuary in 2015 (2017)
    PANGAEA
    In:  Supplement to: Brase, Lisa; Bange, Hermann Werner; Lendt, Ralf; Sanders, Tina; Dähnke, Kirstin (2017): High Resolution Measurements of Nitrous Oxide (N2O) in the Elbe Estuary. Frontiers in Marine Science, 4, https://doi.org/10.3389/fmars.2017.00162
    Details
    Publication Date: 2023-07-06
    Description: Nitrous oxide (N2O) is one of the most important greenhouse gases and a major sink for stratospheric ozone. Estuaries are sites of intense biological production and N2O emissions. We aimed to identify hot spots of N2O production and potential pathways contributing to N2O concentrations in the surface water of the tidal Elbe estuary. During two research cruises in April and June 2015, surface water N2O concentrations were measured along the salinity gradient of the Elbe estuary by using a laser-based on-line analyzer coupled to an equilibrator. Based on these high-resolution N2O profiles, N2O saturations, and fluxes across the surface water/atmosphere interface were calculated. Additional measurements of DIN concentrations, oxygen concentration, and salinity were performed. Highest N2O concentrations were determined in the Hamburg port region reaching maximum values of 32.3 nM in April 2015 and 52.2 nM in June 2015. These results identify the Hamburg port region as a significant hot spot of N2O production, where linear correlations of AOU-N2Oxs indicate nitrification as an important contributor to N2O production in the freshwater part. However, in the region with lowest oxygen saturation, sediment denitrification obviously affected water column N2O saturation. The average N2O saturation over the entire estuary was 201% (SD: ±94%), with an average estuarine N2O flux density of 48 ?mol m-2 d-1 and an overall emission of 0.18 Gg N2O y-1. In comparison to previous studies, our data indicate that N2O production pathways over the whole estuarine freshwater part have changed from predominant denitrification in the 1980s toward significant production from nitrification in the present estuary. Despite a significant reduction in N2O saturation compared to the 1980s, N2O concentrations nowadays remain on a high level, comparable to the mid-90s, although a steady decrease of DIN inputs occurred over the last decades. Hence, the Elbe estuary still remains an important source of N2O to the atmosphere.
    Keywords: Ammonium; Continuous flow analyser (AA3, Seal Analytics, Germany); Date/Time of event; DEPTH, water; Elbe Estuary; Event label; FerryBox system; Helmholtz-Zentrum Geesthacht, Institute of Coastal Research; HZG; Latitude of event; Longitude of event; LP201504; LP201504_Stat_1_1; LP201504_Stat_1_10; LP201504_Stat_1_11; LP201504_Stat_1_12; LP201504_Stat_1_13; LP201504_Stat_1_14; LP201504_Stat_1_15; LP201504_Stat_1_16; LP201504_Stat_1_17; LP201504_Stat_1_18; LP201504_Stat_1_19; LP201504_Stat_1_2; LP201504_Stat_1_3; LP201504_Stat_1_4; LP201504_Stat_1_5; LP201504_Stat_1_6; LP201504_Stat_1_7; LP201504_Stat_1_8; LP201504_Stat_1_9; LP201504_Stat_10_1; LP201504_Stat_10_10; LP201504_Stat_10_11; LP201504_Stat_10_12; LP201504_Stat_10_13; LP201504_Stat_10_14; LP201504_Stat_10_15; LP201504_Stat_10_16; LP201504_Stat_10_17; LP201504_Stat_10_18; LP201504_Stat_10_19; LP201504_Stat_10_2; LP201504_Stat_10_20; LP201504_Stat_10_3; LP201504_Stat_10_4; LP201504_Stat_10_5; LP201504_Stat_10_6; LP201504_Stat_10_7; LP201504_Stat_10_8; LP201504_Stat_10_9; LP201504_Stat_11_1; LP201504_Stat_11_10; LP201504_Stat_11_11; LP201504_Stat_11_12; LP201504_Stat_11_13; LP201504_Stat_11_14; LP201504_Stat_11_15; LP201504_Stat_11_16; LP201504_Stat_11_17; LP201504_Stat_11_18; LP201504_Stat_11_19; LP201504_Stat_11_2; LP201504_Stat_11_20; LP201504_Stat_11_3; LP201504_Stat_11_4; LP201504_Stat_11_5; LP201504_Stat_11_6; LP201504_Stat_11_7; LP201504_Stat_11_8; LP201504_Stat_11_9; LP201504_Stat_12_1; LP201504_Stat_12_10; LP201504_Stat_12_2; LP201504_Stat_12_3; LP201504_Stat_12_4; LP201504_Stat_12_5; LP201504_Stat_12_6; LP201504_Stat_12_7; LP201504_Stat_12_8; LP201504_Stat_12_9; LP201504_Stat_13_1; LP201504_Stat_13_10; LP201504_Stat_13_11; LP201504_Stat_13_12; LP201504_Stat_13_13; LP201504_Stat_13_14; LP201504_Stat_13_15; LP201504_Stat_13_2; LP201504_Stat_13_3; LP201504_Stat_13_4; LP201504_Stat_13_5; LP201504_Stat_13_6; LP201504_Stat_13_7; LP201504_Stat_13_8; LP201504_Stat_13_9; LP201504_Stat_14_1; LP201504_Stat_14_2; LP201504_Stat_14_3; LP201504_Stat_14_4; LP201504_Stat_14_5; LP201504_Stat_14_6; LP201504_Stat_15_1; LP201504_Stat_15_2; LP201504_Stat_15_3; LP201504_Stat_15_4; LP201504_Stat_17_1; LP201504_Stat_17_10; LP201504_Stat_17_11; LP201504_Stat_17_12; LP201504_Stat_17_13; LP201504_Stat_17_14; LP201504_Stat_17_15; LP201504_Stat_17_16; LP201504_Stat_17_17; LP201504_Stat_17_2; LP201504_Stat_17_3; LP201504_Stat_17_4; LP201504_Stat_17_5; LP201504_Stat_17_6; LP201504_Stat_17_7; LP201504_Stat_17_8; LP201504_Stat_17_9; LP201504_Stat_18_1; LP201504_Stat_18_2; LP201504_Stat_18_3; LP201504_Stat_19_1; LP201504_Stat_19_10; LP201504_Stat_19_11; LP201504_Stat_19_12; LP201504_Stat_19_13; LP201504_Stat_19_14; LP201504_Stat_19_15; LP201504_Stat_19_16; LP201504_Stat_19_2; LP201504_Stat_19_3; LP201504_Stat_19_4; LP201504_Stat_19_5; LP201504_Stat_19_6; LP201504_Stat_19_7; LP201504_Stat_19_8; LP201504_Stat_19_9; LP201504_Stat_2_1; LP201504_Stat_2_10; LP201504_Stat_2_11; LP201504_Stat_2_12; LP201504_Stat_2_13; LP201504_Stat_2_14; LP201504_Stat_2_15; LP201504_Stat_2_16; LP201504_Stat_2_17; LP201504_Stat_2_18; LP201504_Stat_2_19; LP201504_Stat_2_2; LP201504_Stat_2_3; LP201504_Stat_2_4; LP201504_Stat_2_5; LP201504_Stat_2_6; LP201504_Stat_2_7; LP201504_Stat_2_8; LP201504_Stat_2_9; LP201504_Stat_20_1; LP201504_Stat_20_10; LP201504_Stat_20_11; LP201504_Stat_20_12; LP201504_Stat_20_13; LP201504_Stat_20_14; LP201504_Stat_20_15; LP201504_Stat_20_16; LP201504_Stat_20_17; LP201504_Stat_20_18; LP201504_Stat_20_2; LP201504_Stat_20_3; LP201504_Stat_20_4; LP201504_Stat_20_5; LP201504_Stat_20_6; LP201504_Stat_20_7; LP201504_Stat_20_8; LP201504_Stat_20_9; LP201504_Stat_21_1; LP201504_Stat_21_10; LP201504_Stat_21_11; LP201504_Stat_21_12; LP201504_Stat_21_13; LP201504_Stat_21_14; LP201504_Stat_21_15; LP201504_Stat_21_16; LP201504_Stat_21_17; LP201504_Stat_21_18; LP201504_Stat_21_19; LP201504_Stat_21_2; LP201504_Stat_21_20; LP201504_Stat_21_21; LP201504_Stat_21_22; LP201504_Stat_21_23; LP201504_Stat_21_24; LP201504_Stat_21_25; LP201504_Stat_21_26; LP201504_Stat_21_27; LP201504_Stat_21_28; LP201504_Stat_21_29; LP201504_Stat_21_3; LP201504_Stat_21_30; LP201504_Stat_21_31; LP201504_Stat_21_32; LP201504_Stat_21_33; LP201504_Stat_21_34; LP201504_Stat_21_4; LP201504_Stat_21_5; LP201504_Stat_21_6; LP201504_Stat_21_7; LP201504_Stat_21_8; LP201504_Stat_21_9; LP201504_Stat_22_1; LP201504_Stat_22_10; LP201504_Stat_22_11; LP201504_Stat_22_12; LP201504_Stat_22_13; LP201504_Stat_22_14; LP201504_Stat_22_15; LP201504_Stat_22_16; LP201504_Stat_22_17; LP201504_Stat_22_18; LP201504_Stat_22_2; LP201504_Stat_22_3; LP201504_Stat_22_4; LP201504_Stat_22_5; LP201504_Stat_22_6; LP201504_Stat_22_7; LP201504_Stat_22_8; LP201504_Stat_22_9; LP201504_Stat_23_1; LP201504_Stat_23_10; LP201504_Stat_23_11; LP201504_Stat_23_12; LP201504_Stat_23_13; LP201504_Stat_23_14; LP201504_Stat_23_15; LP201504_Stat_23_16; LP201504_Stat_23_2; LP201504_Stat_23_3; LP201504_Stat_23_4; LP201504_Stat_23_5; LP201504_Stat_23_6; LP201504_Stat_23_7; LP201504_Stat_23_8; LP201504_Stat_23_9; LP201504_Stat_24_1; LP201504_Stat_24_10; LP201504_Stat_24_11; LP201504_Stat_24_12; LP201504_Stat_24_13; LP201504_Stat_24_14; LP201504_Stat_24_15; LP201504_Stat_24_16; LP201504_Stat_24_17; LP201504_Stat_24_18; LP201504_Stat_24_19; LP201504_Stat_24_2; LP201504_Stat_24_3; LP201504_Stat_24_4; LP201504_Stat_24_5; LP201504_Stat_24_6; LP201504_Stat_24_7; LP201504_Stat_24_8; LP201504_Stat_24_9; LP201504_Stat_3_1; LP201504_Stat_3_10; LP201504_Stat_3_11; LP201504_Stat_3_12; LP201504_Stat_3_13; LP201504_Stat_3_14; LP201504_Stat_3_15; LP201504_Stat_3_16; LP201504_Stat_3_17; LP201504_Stat_3_18; LP201504_Stat_3_19; LP201504_Stat_3_2; LP201504_Stat_3_20; LP201504_Stat_3_3; LP201504_Stat_3_4; LP201504_Stat_3_5; LP201504_Stat_3_6; LP201504_Stat_3_7; LP201504_Stat_3_8; LP201504_Stat_3_9; LP201504_Stat_4_1; LP201504_Stat_4_10; LP201504_Stat_4_11; LP201504_Stat_4_12; LP201504_Stat_4_13; LP201504_Stat_4_14; LP201504_Stat_4_15; LP201504_Stat_4_16; LP201504_Stat_4_17; LP201504_Stat_4_18; LP201504_Stat_4_19; LP201504_Stat_4_2; LP201504_Stat_4_20; LP201504_Stat_4_3; LP201504_Stat_4_4; LP201504_Stat_4_5; LP201504_Stat_4_6; LP201504_Stat_4_7; LP201504_Stat_4_8; LP201504_Stat_4_9; LP201504_Stat_5_1; LP201504_Stat_5_10; LP201504_Stat_5_11; LP201504_Stat_5_12; LP201504_Stat_5_13; LP201504_Stat_5_14; LP201504_Stat_5_15; LP201504_Stat_5_16; LP201504_Stat_5_17; LP201504_Stat_5_18; LP201504_Stat_5_19; LP201504_Stat_5_2; LP201504_Stat_5_20; LP201504_Stat_5_3; LP201504_Stat_5_4; LP201504_Stat_5_5; LP201504_Stat_5_6; LP201504_Stat_5_7; LP201504_Stat_5_8; LP201504_Stat_5_9; LP201504_Stat_6_1; LP201504_Stat_6_10; LP201504_Stat_6_11; LP201504_Stat_6_12; LP201504_Stat_6_13; LP201504_Stat_6_14; LP201504_Stat_6_15; LP201504_Stat_6_16; LP201504_Stat_6_17; LP201504_Stat_6_18; LP201504_Stat_6_19; LP201504_Stat_6_2; LP201504_Stat_6_20; LP201504_Stat_6_3; LP201504_Stat_6_4; LP201504_Stat_6_5; LP201504_Stat_6_6; LP201504_Stat_6_7; LP201504_Stat_6_8; LP201504_Stat_6_9; LP201504_Stat_7_1; LP201504_Stat_7_10; LP201504_Stat_7_11; LP201504_Stat_7_12; LP201504_Stat_7_13; LP201504_Stat_7_14; LP201504_Stat_7_15; LP201504_Stat_7_16; LP201504_Stat_7_17; LP201504_Stat_7_18; LP201504_Stat_7_19; LP201504_Stat_7_2; LP201504_Stat_7_20; LP201504_Stat_7_3; LP201504_Stat_7_4; LP201504_Stat_7_5; LP201504_Stat_7_6; LP201504_Stat_7_7; LP201504_Stat_7_8; LP201504_Stat_7_9; LP201504_Stat_8_1; LP201504_Stat_8_2; LP201504_Stat_8_3; LP201504_Stat_9_1; LP201504_Stat_9_10; LP201504_Stat_9_11; LP201504_Stat_9_12; LP201504_Stat_9_13; LP201504_Stat_9_14; LP201504_Stat_9_15; LP201504_Stat_9_2; LP201504_Stat_9_3; LP201504_Stat_9_4; LP201504_Stat_9_5; LP201504_Stat_9_6; LP201504_Stat_9_7; LP201504_Stat_9_8; LP201504_Stat_9_9; LP201506; LP201506_Stat_25_1; LP201506_Stat_25_10; LP201506_Stat_25_11; LP201506_Stat_25_12; LP201506_Stat_25_13; LP201506_Stat_25_14; LP201506_Stat_25_15; LP201506_Stat_25_16; LP201506_Stat_25_2; LP201506_Stat_25_3; LP201506_Stat_25_4; LP201506_Stat_25_5;
    Type: Dataset
    Format: text/tab-separated-values, 3585 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 7
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    Nitrite consumption and associated isotope changes during a river flood event in the Elbe river (2016)
    PANGAEA
    In:  Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research | Supplement to: Jacob, Juliane; Sanders, Tina; Dähnke, Kirstin (2016): Nitrification and Nitrite Isotope Fractionation as a Case Study in a major European River. Biogeosciences, 13(19), 5649-5659, https://doi.org/10.5194/bg-13-5649-2016
    Details
    Publication Date: 2023-07-11
    Description: In oceans, estuaries, and rivers, nitrification is an important nitrate source, and stable isotopes of nitrate are often used to investigate recycling processes (e.g. remineralisation, nitrification) in the water column. Nitrification is a two-step process, where ammonia is oxidised via nitrite to nitrate. Nitrite usually does not accumulate in natural environments, which makes it difficult to study the single isotope effect of ammonia oxidation or nitrite oxidation in natural systems. However, during an exceptional flood in the Elbe River in June 2013, we found a unique co-occurrence of ammonium, nitrite, and nitrate in the water column, returning towards normal summer conditions within 1 week. Over the course of the flood, we analysed the evolution of d15N-[NH4]+ and d15N-[NO2]- in the Elbe River. In concert with changes in suspended particulate matter (SPM) and d15N SPM, as well as nitrate concentration, d15N-NO3 - and d18O-[NO3] -, we calculated apparent isotope effects during net nitrite and nitrate consumption. During the flood event, 〉 97 % of total reactive nitrogen was nitrate, which was leached from the catchment area and appeared to be subject to assimilation. Ammonium and nitrite concentrations increased to 3.4 and 4.4 µmol/l, respectively, likely due to remineralisation, nitrification, and denitrification in the water column. d15N-[NH4]+ values increased up to 12 per mil, and d15N-[NO2]- ranged from -8.0 to -14.2 per mil. Based on this, we calculated an apparent isotope effect 15-epsilon of -10.0 ± 0.1 per mil during net nitrite consumption, as well as an isotope effect 15-epsilon of -4.0 ± 0.1 per mil and 18-epsilon of -5.3 ± 0.1 per mil during net nitrate consumption. On the basis of the observed nitrite isotope changes, we evaluated different nitrite uptake processes in a simple box model. We found that a regime of combined riparian denitrification and 22 to 36 % nitrification fits best with measured data for the nitrite concentration decrease and isotope increase.
    Keywords: Ammonium; Carbon, total, particulate; Carbon/Nitrogen ratio; Colorimetric; DATE/TIME; DEPTH, water; Element analyser, Thermo Finnigan flash EA 1112; FerryBox system; Fluorescence determination; Geesthacht weir, Germany; Gravimetric analysis (GF/F filtered); GW2011-2016_Stat_1; Mass spectrometer Finnigan MAT 252; Mass spectrometer ThermoFisher Delta V; Nitrate; Nitrite; Nitrogen, inorganic, dissolved; Nitrogen, total, particulate; Oxygen; pH; Phosphate; Salinity; Sample ID; Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM; Silicate; Suspended particulate matter; Temperature, water; Water sample; WS; δ15N, ammonium; δ15N, nitrate; δ15N, nitrite; δ15N, total particulate nitrogen; δ18O, nitrate
    Type: Dataset
    Format: text/tab-separated-values, 443 data points
    Location Call Number Limitation Availability
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  • 8
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    A decade of nitrate dual stable isotope measurements in the Elbe River (Germany) (2023)
    PANGAEA
    Details
    Publication Date: 2023-08-09
    Description: We investigated nutrient input and retention in the Elbe River (Germany) at the river/estuarine transition with high agricultural loads of nitrogen. Surface water samples were taken at the weir Geesthacht (stream kilometre 585, 53°25'31''N, 10°20'10''E) from 2011 to 2021. In these samples, we analyzed nutrient concentrations, nitrate dual stable isotopes and suspended particulate matter composition. Usually, samples were taken once or twice per month. Aims of the study were to investigate 1) nitrate retention in the Elbe River and catchment, 2) seasonal dynamic of nitrate stable isotopes and 3) key nitrogen turnover processes and their respective controls over a ten year period.
    Keywords: Carbon, total; Carbon/Nitrogen ratio; Continuous flow analyser (AA3, Seal Analytics, Germany); DATE/TIME; DEPTH, water; Elemental analyzer (EA), Thermo Scientific, FlashEA 1112; Element analyser, Carlo Erba NA2500, coupled with an isotope ratio mass spectrometerFinnigan MAT 252; Fluorescence measurement (OPA), with auto-analyser; Geesthacht weir, Germany; GF/F WHA1825047, Whatman, UK; GW2011-2016_Stat_1; Helmholtz-Zentrum Hereon; Hereon; Measurement as N2O using isotope-ratio mass spectrometry (IRMS). Bacterial conversion to N2O, so called Denitrifier-method (according to Sigman et al. 2001; Casciotti et al. 2002). Average of the measurement of 2 replicates; Nitrogen, total; Nitrogen in ammonium; Nitrogen in nitrate; Nitrogen in nitrite; Phosphorus in orthophosphate; Sample ID; Silicate, dissolved; Suspended particulate matter; Water sample; WS; δ15N, nitrate; δ15N, total nitrogen; δ18O, nitrate
    Type: Dataset
    Format: text/tab-separated-values, 2723 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 9
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    Compilation of nitrate δ15N in the ocean (2021)
    PANGAEA
    Details
    Publication Date: 2024-02-03
    Description: The database for nitrate concentrations and nitrate δ15N includes new data and most of the measurements that have been published to date. This database also includes most of the nitrate δ15N measurements in the database of Rafter et al. (2019; Biogeosciences 16, 2617-2633; https://doi.org/10.5194/bg-16-2617-2019). It consists of 944 stations with 15300 measurements of nitrate δ15N. All data are uploaded, except the GOSHIP P2 and P6 sections for which we report average profiles vs. depth. Full data sets for these sections will be included upon publication in a follow-up version.
    Keywords: Comment; Cruise/expedition; DEPTH, water; Identification; LATITUDE; LONGITUDE; nitrate; Nitrate; nitrogen isotopes; ocean; Reference/source; Time Stamp; Vessel; δ15N, nitrate
    Type: Dataset
    Format: text/tab-separated-values, 100052 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 10
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    Nutrients and nutrient isotope data in South Equatorial Atlantic Ocean water samples collected during the Meteor cruise M131 in 2016 (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-08
    Description: R/V Meteor cruise M131 carried out a physical oceanography research program with a biogeochemical sampling component in the South Equatorial Atlantic Ocean and eastern boundary upwelling region off Angola and Namibia. The program was part of the EU collaborative project PREFACE (“Enhancing prediction of tropical Atlantic climate and its impacts”) and the sampling for and analysis of nutrient data were linked to BMBF collaborative project GENUS (“Geochemistry and Ecology of the Namibian Upwelling System”). CTD data of the expedition M131 are archived under doi:10.1594/PANGAEA.910994. The bottle files corresponding to water samples analysed for nutrient concentrations and nitrate isotopic composition were provided by Gerd Krahmann (GEOMAR). Depths and data for temperature, salinity, oxygen concentrations labeled “CTD“ in the table are values from calibrated CTD sensors at closure of the bottles, numbers for fluorescence are uncalibrated. Water samples were taken by Maria-Elena Vorrath during M131 and were analyzed after shipment in the laboratory of Kirstin Dähnke at Helmholtz-Zentrum Geesthacht. Nutrient concentrations were measured with an AutoAnalyzer 3 system (Seal Analytics) using standard colorimetric methods by Markus Ankele. Nitrate was determined after reduction to nitrite, followed by a reaction with sulfanilamide to form a red azo dye (Grasshoff and Anderson 1999). Phosphate was measured after formation of a blue antimony-phosphorous colour complex, according to Murphy and Riley (1962). Ammonium was measured fluorometrically based on Holmes et al. (1999). The relative errors of duplicate sample measurements were below 1.5% for NOx and phosphate concentrations, and below 0.3% for ammonium and silicate. The detection limit was 〈0.5 µmol kg−1 for NOx, 〉 0.1 µmol kg−1 for phosphate, 〉0.013 µmol kg−1 for ammonium and 〉0.016 µmol kg−1 for silicate. Delta15N_NO3 and Delta18O_NO3 were determined in the laboratory at Helmholtz-Zentrum Geesthacht (Kirstin Dähnke) with the denitrifier method (Sigman et al. 2001; Casciotti et al. 2002). The isotopic composition was determined with a GasBench II coupled to a Delta Plus XP mass spectrometer (ThermoFinnigan). Replicate measurements were performed, and two international standards (IAEA-N3, Delta15N = 4.7‰, Delta18O=25.6‰ and USGS 34 (Delta15N=-1.8‰, Delta18O=-27.9‰; Böhlke et al. 2003), were measured with each batch of samples. To correct for exchange with oxygen atoms from water, a bracketing correction was applied (Sigman et al. 2009). The standard deviation for standards and samples was 0.2‰ for Delta15N and 0.4‰ for Delta18O.
    Keywords: Ammonium; Ammonium, standard deviation; CTD; CTD/Rosette; CTD-RO; DATE/TIME; DEPTH, water; Event label; Helmholtz-Zentrum Geesthacht, Institute of Coastal Research; HZG; LATITUDE; LONGITUDE; M131; M131_1188-1; M131_1190-1; M131_1193-1; M131_1205-1; M131_1208-1; M131_1220-1; M131_1232-1; M131_1275-1; M131_1287-1; M131_1301-1; Measurement as N2O using isotope-ratio mass spectrometry (IRMS). Bacterial conversion to N2O, so called Denitrifier-method (according to Sigman et al. 2001; Casciotti et al. 2002). Average of the measurement of 2 replicates; Meteor (1986); Nitrate; Nitrate and Nitrite; Nitrate and Nitrite, standard deviation; Nitrite; Nitrite, standard deviation; Oxygen; Phosphate; Phosphate, standard deviation; Pressure, water; Salinity; Sample code/label; Silicate; Silicate, standard deviation; Standard-calorimetric method (according to Grasshoff et al. 1999), with auto-analyser. Average of the measurement of 2 replicates.; Station label; Temperature, water; δ15N, nitrate; δ15N, nitrate, standard deviation; δ18O, nitrate; δ18O, nitrate, standard deviation
    Type: Dataset
    Format: text/tab-separated-values, 2107 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
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