Brase, Lisa; Bange, Hermann Werner; Lendt, Ralf; Sanders, Tina; Dähnke, Kirstin (2017): Nitrous oxide (N2O) measurements in the surface water of the Elbe Estuary in 2015 [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.882348, Supplement to: Brase, L et al. (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
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Abstract:
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.
Project(s):
Coverage:
Median Latitude: 53.750165 * Median Longitude: 9.253049 * South-bound Latitude: 53.454906 * West-bound Longitude: 8.528573 * North-bound Latitude: 53.964870 * East-bound Longitude: 10.078645
Date/Time Start: 2015-04-28T10:02:00 * Date/Time End: 2015-06-11T17:21:00
Minimum DEPTH, water: 2 m * Maximum DEPTH, water: 2 m
Event(s):
LP201504_Stat_1_1 * Latitude: 53.964292 * Longitude: 8.528573 * Date/Time: 2015-04-28T10:02:00 * Location: Elbe Estuary * Campaign: LP201504 * Basis: Ludwig Prandtl * Method/Device: Membrane pump (MP)
LP201504_Stat_1_2 * Latitude: 53.964529 * Longitude: 8.532631 * Date/Time: 2015-04-28T10:03:00 * Location: Elbe Estuary * Campaign: LP201504 * Basis: Ludwig Prandtl * Method/Device: Membrane pump (MP)
LP201504_Stat_1_3 * Latitude: 53.964789 * Longitude: 8.536769 * Date/Time: 2015-04-28T10:04:00 * Location: Elbe Estuary * Campaign: LP201504 * Basis: Ludwig Prandtl * Method/Device: Membrane pump (MP)
Parameter(s):
# | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
---|---|---|---|---|---|---|
1 | Event label | Event | Brase, Lisa | |||
2 | Latitude of event | Latitude | Brase, Lisa | |||
3 | Longitude of event | Longitude | Brase, Lisa | |||
4 | DEPTH, water | Depth water | m | Brase, Lisa | Geocode | |
5 | Date/Time of event | Date/Time | Brase, Lisa | |||
6 | Nitrous oxide | N2O | µg/kg | Brase, Lisa | N2O analyzer (Los Gatos Research, Model 914-0022, LGR) | An N2O analyzer (Los Gatos Research, Model 914-0022, LGR) was used to measure gas-phase mole fractions of N2O as well as water vapor (H2O) using off-axis integrated cavity output spectroscopy (ICOS) (Baer et al., 2002). |
7 | Nitrous oxide, dissolved | N2O | nmol/l | Brase, Lisa | N2O analyzer (Los Gatos Research, Model 914-0022, LGR) | An N2O analyzer (Los Gatos Research, Model 914-0022, LGR) was used to measure gas-phase mole fractions of N2O as well as water vapor (H2O) using off-axis integrated cavity output spectroscopy (ICOS) (Baer, Paul et al. 2002). |
8 | Nitrous oxide saturation | N2O sat | % | Brase, Lisa | N2O analyzer (Los Gatos Research, Model 914-0022, LGR) | An N2O analyzer (Los Gatos Research, Model 914-0022, LGR) was used to measure gas-phase mole fractions of N2O as well as water vapor (H2O) using off-axis integrated cavity output spectroscopy (ICOS) (Baer, Paul et al. 2002) |
9 | Ammonium | [NH4]+ | µmol/l | Brase, Lisa | Continuous flow analyser, Seal, AA3 | 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. Average of the measurement of 2 replicates. |
10 | Nitrite | [NO2]- | µmol/l | Brase, Lisa | Continuous flow analyser, Seal, AA3 | 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. Average of the measurement of 2 replicates. |
11 | Nitrate | [NO3]- | µmol/l | Brase, Lisa | Continuous flow analyser, Seal, AA3 | 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. Average of the measurement of 2 replicates. |
12 | Oxygen | O2 | µmol/l | Brase, Lisa | FerryBox system |
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