Farías, Laura; Faúndez, Juan (2020): Nitrous oxide distribution in the continental shelf off Central Chile (2005-2009) [dataset]. PANGAEA, https://doi.org/10.1594/PANGAEA.916020
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Abstract:
Continental shelves tend to have high standing stocks of organic carbon and high rates of primary production relative to the open ocean and serve as important link between land and the ocean interior and between the sediment and the water column, playing a key role in the N and C balance, and accounting for up to 50% of the total N loss. One of the widest continental shelves in the eastern South Pacific (ESP) is present off central Chile (36°S). This is an important geographic feature in terms of physical and biological interactions owing to the large area available for coupling between the benthic and pelagic systems. In addition, this area is subjected to a strong coastal upwelling during austral spring and summer; when winds shift to a predominantly northward direction, stressing the sea surface layer and producing an intense cross-shelf transport and uplift of Equatorial Subsurface waters (ESSW) over the shelf. The ESSW, characterized by high NO3- and low O2 content, promotes surface fertilization and, subsequently, intense organic matter respiration and remineralization at depth, along with an efflux of subsurface-accumulated N2O (Farías et al. 2009, Cornejo & Farías, 2012). Thus, periods of maximum productivity and intense suboxia, or even anoxia, when diverse electron donors (e.g., organic matter, NH4+, NO2-, H2S) are present, represent a potential hotspot for fixed N removal processes.
We present a data set that has been obtained during different FIP cruises (Fondo de Investigaciones Pesqueras) (2005-2009) which consisted of several transects perpendicular to the coast between 35° and 40°S and from the coast to 77.8° W (central Chile). Data collected include classical oceanographic variables including N2O and important greenhouse gas.
Keyword(s):
Related to:
Cornejo, Marcela; Farías, Laura (2012): Meridional variability of the vertical structure and air–sea fluxes of N2O off central Chile (30–40°S). Progress in Oceanography, 92-95, 33-42, https://doi.org/10.1016/j.pocean.2011.07.016
Cornejo, Marcela; Murillo, Alejandro A; Farías, Laura (2015): An unaccounted for N2O sink in the surface water of the eastern subtropical South Pacific: Physical versus biological mechanisms. Progress in Oceanography, 137, 12-23, https://doi.org/10.1016/j.pocean.2014.12.016
Farías, Laura; Carrasco, Cristina; Faúndez, Juan (2019): Nitrous oxide and biogeochemical variables related to Intermediate Waters into Eastern South Pacific Ocean. Departamento de Oceanografia, Universidad de Concepción, PANGAEA, https://doi.org/10.1594/PANGAEA.906231
Coverage:
Median Latitude: -36.972339 * Median Longitude: -74.187399 * South-bound Latitude: -40.000000 * West-bound Longitude: -77.805000 * North-bound Latitude: -35.483000 * East-bound Longitude: -72.633300
Date/Time Start: 2005-12-07T01:30:00 * Date/Time End: 2009-01-12T21:50:00
Minimum DEPTH, water: 0 m * Maximum DEPTH, water: 500 m
Event(s):
MOBIO-2005-1 * Latitude: -35.500000 * Longitude: -72.633300 * Date/Time: 2005-12-07T01:30:00 * Method/Device: CTD/Rosette (CTD-RO)
MOBIO-2005-3 * Latitude: -35.500000 * Longitude: -72.951600 * Date/Time: 2005-12-07T04:20:00 * Method/Device: CTD/Rosette (CTD-RO)
MOBIO-2005-5 * Latitude: -35.487000 * Longitude: -73.548300 * Date/Time: 2005-12-07T10:45:00 * Method/Device: CTD/Rosette (CTD-RO)
Comment:
Continuously sampled variables:
Temperature, salinity and disolved oxygen were obtained unsing a CTD-O probe (SeaBird)
Discretely sampled variables:
Water samples were collected using Niskin bottles attached to rosette sampler, in order to obtain discrete measurements
of dissolver oxygen (O2) and nutrients (NO3, NO2, SiO4 and PO43). Discrete samples of DO (in triplicate) were analyzed using the AULOX measurement system, an automatic Winkler method. Samples for all nutrients (15 mL in triplicate) were filtered (using a 0.45 μm GF/F glass filter) and stored (frozen) until analysis, using standard colorimetric techniques (Grasshoff, 1983). N2O samples were taken in triplicate in 20 mL vials and carefully sealed to avoid air bubbles. They were then preserved with 50 μL of saturated HgCl2 and stored in darkness until analysis. N2O was analyzed by creating a 5 mL headspace of ultrapure Helium (He) and then equilibrated within the vial, and measured by gas chromatography (Shimadzu 17A) using an electron capture detector (ECD). The calibration curves were made previous to each measurement with five points using pure He, 0.1, 0.5, and 1 of N2O standards and dry air. The ECD detector linearly responded to this concentration range and the analytical error for N2O measurements was ~3%. The uncertainty of the measurements was calculated from the standard deviation of the triplicate measurements by depth. Samples with a variation coefficient above 10% were not considered in the N2O database.
Parameter(s):
| # | Name | Short Name | Unit | Principal Investigator | Method/Device | Comment |
|---|---|---|---|---|---|---|
| 1 | Event label | Event | Faúndez, Juan | |||
| 2 | Cruise/expedition | Expedition | Faúndez, Juan | |||
| 3 | Cruise/expedition | Expedition | Faúndez, Juan | Research vessel | ||
| 4 | Station label | Station | Faúndez, Juan | |||
| 5 | Latitude of event | Latitude | Faúndez, Juan | |||
| 6 | Longitude of event | Longitude | Faúndez, Juan | |||
| 7 | Date/Time of event | Date/Time | Faúndez, Juan | |||
| 8 | DEPTH, water | Depth water | m | Faúndez, Juan | Geocode | |
| 9 | Temperature, water | Temp | °C | Faúndez, Juan | CTD-O probe | |
| 10 | Salinity | Sal | Faúndez, Juan | CTD-O probe | ||
| 11 | Oxygen, dissolved | DO | ml/l | Faúndez, Juan | CTD-O probe | |
| 12 | Oxygen, dissolved | DO | ml/l | Faúndez, Juan | Automated WInkler method (AULOX) | |
| 13 | Nitrous oxide, dissolved | N2O | nmol/l | Faúndez, Juan | Gas chromatograph (Shimadzu 17A) with an electron capture detector (ECD) | |
| 14 | Silicate | Si(OH)4 | µmol/l | Faúndez, Juan | Colorimetry, flow-segmented (Grasshoff et al. 1983) | |
| 15 | Nitrate | [NO3]- | µmol/l | Faúndez, Juan | Colorimetry, flow-segmented (Grasshoff et al. 1983) | |
| 16 | Nitrite | [NO2]- | µmol/l | Faúndez, Juan | Colorimetry, flow-segmented (Grasshoff et al. 1983) | |
| 17 | Phosphate | [PO4]3- | µmol/l | Faúndez, Juan | Colorimetry, flow-segmented (Grasshoff et al. 1983) |
Change history:
2020-05-07T13:57:18 – Dataset was overwritten with events. in the initial upload there were no events
2020-05-25T19:49:54 – Events were updated to the same as other dataset
License:
Creative Commons Attribution 4.0 International (CC-BY-4.0)
Size:
9902 data points
Download Data
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