Publication Date:
2024-03-22
Description:
Upwelling systems are significant sources of atmospheric nitrous oxide (N₂O). The Benguela Upwelling System is one of the most productive regions worldwide and a temporally variable source of N₂O. Strong O₂ depletions above the shelf are favoring periodically OMZ formations. We aimed to assess underlying N₂O production and consumption processes on different temporal and spatial scales during austral winter in the Benguela Upwelling System, when O₂-deficiency in the water column is relatively low.
The fieldwork took place during the cruise M157 (August 4ᵗʰ – September 16ᵗʰ 2019) onboard the R/V METEOR. This expedition included four close-coastal regions around Walvis Bay at 23°S, which presented the lowest O₂ concentrations near the seafloor and thus may provide hotspots of N₂O production. Seawater was collected in 10 L free-flow bottles by using a rosette system equipped with conductivity-temperature-depth (CTD) sensors (SBE 911plus, Seabird-electronics, USA).
Concentrations of inorganic nutrients (PO₄³⁻, NH₄⁺, NO₃⁻, NO₂⁻, and SiO₂) were measured colorimetrically according to Grasshoff et al. (1999) by means of a continuous segmented flow analyzer (SEAL Analytical, QuAAtro39). To determine the water mass fractions along the sampling transects, vertical profiles were collected using a free-falling microstructure profiler (MSS90L, Sea & Sun Technology). Temperature, dissolved oxygen, and salinity were measured with a CTD system consisting of a SeaBird 911+ probe, mounted on a sampling rosette.
Keywords:
Ammonium; Benguela Upwelling System; BUSUC 1; Continuous Segmented Flow Analyzer, SEAL Analytical, QuAAtro39; CTD, Sea-Bird SBE 911plus; CTD/Rosette; CTD-RO; DATE/TIME; DEPTH, water; Event label; Field observation; LATITUDE; LONGITUDE; M157; M157_10-7; M157_11-4; M157_12-2; M157_14-2; M157_16-25; M157_16-3; M157_16-6; M157_17-16; M157_17-2; M157_24-1; M157_25-1; M157_2-8; M157_28-1; M157_2-9; M157_36-2; M157_41-14; M157_42-2; M157_43-2; M157_43-6; M157_9-2; Meteor (1986); Microstructure profiler, Sea & Sun Technology, MSS90L; Namibia; Nitrate; Nitrite; nutrients; Oxygen; oxygen minimum zone; PCTD-RO; Phosphate; PumpCTD/Rosette; Salinity; Sample code/label; Silicate; Station label; Temperature, water; Water mass; water mass fraction
Type:
Dataset
Format:
text/tab-separated-values, 1660 data points
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