Jacob, Juliane; Sanders, Tina; Dähnke, Kirstin (2016): Nitrite consumption and associated isotope changes during a river flood event in the Elbe river [dataset]. Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research, PANGAEA, https://doi.org/10.1594/PANGAEA.865348, Supplement to: Jacob, J et al. (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
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Abstract:
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.
Coverage:
Latitude: 53.425270 * Longitude: 10.336110
Date/Time Start: 2013-06-06T10:08:00 * Date/Time End: 2013-06-20T09:25:00
Minimum DEPTH, water: 0 m * Maximum DEPTH, water: 0 m
Event(s):
Comment:
The objectives of this project were to identify the key processes in the nitrogen cycle in the estuarine and coastal waters using stable N isotopes and to quantify these processes. As parameter the nutrient loads and stable isotopes values of nitrogen were measured.
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Sample ID | Sample ID | Jacob, Juliane | |||
| 2 | DATE/TIME | Date/Time | Jacob, Juliane | Geocode | ||
| 3 | DEPTH, water | Depth water | m | Jacob, Juliane | Geocode | |
| 4 | Salinity | Sal | Jacob, Juliane | FerryBox system | PSU. Measurement by on-line-in-situ FerryBox-System (Pertersen et al. 2001) | |
| 5 | Temperature, water | Temp | °C | Jacob, Juliane | FerryBox system | Measurement by on-line-in-situ FerryBox-System (Pertersen et al. 2001) |
| 6 | pH | pH | Jacob, Juliane | FerryBox system | Original given in mg/l, multiplied by 31.25. Measurement by on-line-in-situ FerryBox-System (Pertersen et al. 2001) | |
| 7 | Oxygen | O2 | µmol/l | Jacob, Juliane | FerryBox system | Measurement by on-line-in-situ FerryBox-System (Pertersen et al. 2001) |
| 8 | Silicate | Si(OH)4 | µmol/l | Jacob, Juliane | Colorimetric | Standard-colorimetric method (according to Grasshoff), with auto-analyser |
| 9 | Phosphate | [PO4]3- | µmol/l | Jacob, Juliane | Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM | Nutrient concentrations were analysed with a continuous flow analyser (AA3, Seal Analytics, Germany). For nitrite and nitrate analyses, standard photometric techniques were used (Grasshoff et al., 2009) with detection limits of 0.1 and 1.0 micromol per liter. Ammonium was measured fluorometrically with a detection limit of 0.5 micromol per liter based on (Holmes et al., 1999). Detection limits: nitrite (NO2) 0.1 micromol per liter, nitrate (NO3) 1.0 micromol per liter, amonnium (NH4) 0.5 micromol per liter. |
| 10 | Ammonium | [NH4]+ | µmol/l | Jacob, Juliane | Fluorescence determination | Fluorescence measurement (OPA), with auto-analyser |
| 11 | Nitrite | [NO2]- | µmol/l | Jacob, Juliane | Seal QuAAtro SFA Analyzer, Seal Analytical, 800 TM | Nutrient concentrations were analysed with a continuous flow analyser (AA3, Seal Analytics, Germany). For nitrite and nitrate analyses, standard photometric techniques were used (Grasshoff et al., 2009) with detection limits of 0.1 and 1.0 micromol per liter. Ammonium was measured fluorometrically with a detection limit of 0.5 micromol per liter based on (Holmes et al., 1999). Detection limits: nitrite (NO2) 0.1 micromol per liter, nitrate (NO3) 1.0 micromol per liter, amonnium (NH4) 0.5 micromol per liter. |
| 12 | Nitrate | [NO3]- | µmol/l | Jacob, Juliane | Nutrient concentrations were analysed with a continuous flow analyser (AA3, Seal Analytics, Germany). For nitrite and nitrate analyses, standard photometric techniques were used (Grasshoff et al., 2009) with detection limits of 0.1 and 1.0 micromol per liter. Ammonium was measured fluorometrically with a detection limit of 0.5 micromol per liter based on (Holmes et al., 1999). <br> Detection limits: nitrite (NO2) 0.1 micromol per liter, nitrate (NO3) 1.0 micromol per liter, amonnium (NH4) 0.5 micromol per liter. | |
| 13 | δ15N, nitrate | δ15N NO3 | ‰ air | Jacob, Juliane | Mass spectrometer ThermoFisher Delta V | Dual nitrate isotopes (including nitrite) were analysed using the denitrifier method (Sigman et al., 2001, doi:10.1021/ac010088e; Casciotti et al., 2002, doi:10.1021/ac020113w). In brief, water samples were injected into a concentrated Pseudomonas aureofaciens (ATCC#13985) suspension to analyse nitrate. Bacteria denitrify the substrate to N2O gas, which was then analysed on a GasBench II, coupled to a Delta V isotope ratio mass spectrometer (Thermo Fisher Scientific). The sample volume was always adjusted to achieve the same gas amount in the samples (final gas amount of 10 nmol in case of nitrate). International isotope standards with known d-values were used for calibration. IAEA N3 and USGS 34 were used for nitrate isotope calibration. All samples were analysed in replicate. Standard deviation of standards and samples was <0.2 permille for d15N-NO3-. |
| 14 | δ18O, nitrate | δ18O NO3 | ‰ | Jacob, Juliane | Mass spectrometer ThermoFisher Delta V | Dual nitrate isotopes (including nitrite) were analysed using the denitrifier method (Sigman et al., 2001, doi:10.1021/ac010088e; Casciotti et al., 2002, doi:10.1021/ac020113w). In brief, water samples were injected into a concentrated Pseudomonas aureofaciens (ATCC#13985) suspension to analyse nitrate. Bacteria denitrify the substrate to N2O gas, which was then analysed on a GasBench II, coupled to a Delta V isotope ratio mass spectrometer (Thermo Fisher Scientific). The sample volume was always adjusted to achieve the same gas amount in the samples (final gas amount of 10 nmol in case of nitrate). International isotope standards with known d-values were used for calibration. IAEA N3 and USGS 34 were used for nitrate isotope calibration. All samples were analysed in replicate. Standard deviation of standards and samples was <0.5 permille for d18O-NO3-. |
| 15 | δ15N, ammonium | δ15N [NH4]+ | ‰ air | Jacob, Juliane | For analysis of the ammonium isotopic composition, nitrite was removed by reduction with sulfamic acid (Granger and Sigman, 2009, doi:10.1002/rcm.4307). Afterwards, ammonium was chemically converted to nitrite with hypobromite and ammonium then was reduced to N2O using sodium azide (Zhang et al., 2007, doi:10.1021/ac070106d). Ammonium isotopes were analysed in all samples with [NH4+] >1 µmol/L. Sample gas extraction and purification was equivalent to nitrite and nitrate isotope samples. <br>USGS 26 were used to calibrate ammonium isotope values. All samples were analysed in replicate. Standard deviation of standards and samples was <0.5 permille. | |
| 16 | δ15N, nitrite | δ15N NO2 | ‰ air | Jacob, Juliane | Mass spectrometer ThermoFisher Delta V | For analysis of the nitrogen isotopic signature of nitrite, Stenotrophomonas nitrireducens bacteria were used to selectively reduce nitrite (Böhlke et al., doi:10.1021/ac070176k). Bacteria denitrify the substrate to N2O gas, which was then analysed on a GasBench II, coupled to a Delta V isotope ratio mass spectrometer (Thermo Fisher Scientific). The sample volume was always adjusted to achieve the same gas amount in the samples (final gas amount of 5 nmol in case of nitrite). International isotope standards with known d-values were used for calibration. For nitrite isotope analysis, we used in-house potassium nitrite and sodium nitrite standards with known d15N values of -81.5 permille and -27.5 permille, determined via IRMS analysis. All samples were analysed in replicate. Standard deviation of standards and samples <0.3 permille. |
| 17 | Nitrogen, inorganic, dissolved | DIN | µmol/l | Jacob, Juliane | sum of Ammonium, Nitrite and Nitrate | |
| 18 | Suspended particulate matter | SPM | mg/l | Jacob, Juliane | Gravimetric analysis (GF/F filtered) | Milligram SPM on GF/F Filter |
| 19 | Nitrogen, total, particulate | TPN | % | Jacob, Juliane | In suspended matter, mass fraction. Measurement after flash combustion by EA | |
| 20 | Carbon, total, particulate | TPC | % | Jacob, Juliane | Element analyser, Thermo Finnigan flash EA 1112 | In suspended matter, mass fraction. Total carbon (TC) in suspended matter was determined with an Elemental Analyser (Thermo Flash EA 1112) calibrated against a certified acetanilide standard (IVA Analysentechnik, Germany). The standard deviation of C/N analysis was 0.05% for carbon. |
| 21 | Carbon/Nitrogen ratio | C/N | Jacob, Juliane | Element analyser, Thermo Finnigan flash EA 1112 | Calibrated against a certified acetanilide standard (IVA Analysentechnik, Germany). The standard deviation of C/N analysis was 0.05% for carbon and 0.005% for nitrogen | |
| 22 | Nitrogen, total, particulate | TPN | µmol/l | Jacob, Juliane | In suspended matter. Measurement after flash combustion by EA (calculated in Micromol per liter) | |
| 23 | δ15N, total particulate nitrogen | δ15N TPN | ‰ air | Jacob, Juliane | Mass spectrometer Finnigan MAT 252 | d15N-SPM (suspended matter) was analysed with an element analyser (Carlo Erba NA 2500) coupled with an isotope ratio mass spectrometer (Finnigan MAT 252). All samples were analysed in replicate. Standards for d15N-SPM are IAEA N1, IAEA N2, and a certified sediment standard (IVA Analysentechnik, Germany). Standard deviation of standards and samples was <0.1 permille. |
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Creative Commons Attribution 3.0 Unported (CC-BY-3.0)
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443 data points