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| griddap | Subset | tabledap | Make A Graph | wms | files | Accessible | Title | Summary | FGDC | ISO 19115 | Info | Background Info | RSS | Institution | Dataset ID | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_925782_v1 | https://erddap.bco-dmo.org/erddap/tabledap/bcodmo_dataset_925782_v1.graph | https://erddap.bco-dmo.org/erddap/files/bcodmo_dataset_925782_v1/ | public | [Cr concentration and isotopic composition of Cr(III) and Cr(VI) in the ETNP from RR1804-05 and KM1919-20] - Chromium concentration and isotopic composition of Cr(III) and Cr(VI) in the Eastern Tropical North Pacific from samples collected on R/V Roger Revelle and R/V Kilo Moana in April-May 2018 and Sept-Oct 2019 (Cr Isotope Oceanography of the Eastern Tropical North Pacific Ocean) | Understanding the cycling of chromium (Cr) and how chromium stable isotopes (δ53Cr) are altered in response to different processes in the modern ocean is important in our interpretation of marine sedimentary δ53Cr records, a promising redox proxy. Therefore, it is crucial to investigate the geochemical processes of Cr in reducing environments such as oxygen deficient zones (ODZs). In this study, we investigated the cycling of Cr in the Eastern Tropical North Pacific (ETNP) ODZ by analyzing the [Cr] and δ53Cr of total dissolved Cr and Cr(III). Our Cr(III) data at two inshore stations shows profile features and Cr reduction isotopic fractionation factor (-1.5‰) similar to an offshore station in a previous study. We also observed significant Cr scavenging signals in the upper 1000 meters (m) throughout the ODZ with an inshore-offshore variability in its magnitude. Specifically, anoxic bottom waters on the continental slope see the greatest Cr scavenging with heaviest δ53Cr (+1.85‰). Our estimates of the scavenged Cr isotopic composition are within error of the anoxic and euxinic marine sedimentary δ53Cr. This implies that the vertical transport of Cr to the seafloor and subsequent diagenesis may not generate significant isotopic fractionation for Cr. This is the first thorough investigation into the Cr cycling in the ETNP ODZ and demonstrated promising usage of marine sedimentary δ53Cr as a redox proxy for ancient oceans.\n\nIn the ODZ, oxygen is consumed by degrading sinking particles and reaches extremely low levels (too low to support aerobic life) from 100m to 800m depth. However, microbes that can use other oxidants such as nitrate to metabolize organic carbon live there, and we showed that they also convert soluble anionic chromate Cr(VI) to cationic Cr(III), about half of which is scavenged onto sinking particles and removed to the seafloor. This reduction is accompanied by preferential reduction of light Cr isotopes, so the Cr(III) is 1.3‰ lighter than the source Cr(VI). The removal of part of this light Cr(III) by scavenging leaves the residual total Cr heavier than the source Cr. The analyzed samples listed here were chosen to be from the center and margins of the ETNP ODZ and over extremely reducing continental margin sediments.\n\ncdm_data_type = Other\nVARIABLES:\nCruise (unitless)\nStation (unitless)\nLatitude (degrees_north)\n... (9 more variables)\n | https://erddap.bco-dmo.org/erddap/info/bcodmo_dataset_925782_v1/index.htmlTable | https://www.bco-dmo.org/dataset/925782
| https://erddap.bco-dmo.org/erddap/rss/bcodmo_dataset_925782_v1.rss | https://erddap.bco-dmo.org/erddap/subscriptions/add.html?datasetID=bcodmo_dataset_925782_v1&showErrors=false&email= | BCO-DMO | bcodmo_dataset_925782_v1 |