3 results on '"Auro, Maureen"'
Search Results
2. Strong Margin Influence on the Arctic Ocean Barium Cycle Revealed by Pan‐Arctic Synthesis
- Author
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Whitmore, Laura M., Shiller, Alan M., Horner, Tristan J., Xiang, Yang, Auro, Maureen E., Bauch, Dorothea, Dehairs, Frank, Lam, Phoebe J., Li, Jingxuan, Maldonado, Maria T., Mears, Chantal, Newton, Robert, Pasqualini, Angelica, Planquette, Hélène, Rember, Robert, and Thomas, Helmuth more...
- Abstract
Early studies revealed relationships between barium (Ba), particulate organic carbon and silicate, suggesting applications for Ba as a paleoproductivity tracer and as a tracer of modern ocean circulation. But, what controls the distribution of barium (Ba) in the oceans?Here, we investigated the Arctic Ocean Ba cycle through a one‐of‐a‐kind data set containing dissolved (dBa), particulate (pBa), and stable isotope Ba ratio (δ138Ba) data from four Arctic GEOTRACES expeditions conducted in 2015. We hypothesized that margins would be a substantial source of Ba to the Arctic Ocean water column. The dBa, pBa, and δ138Ba distributions all suggest significant modification of inflowing Pacific seawater over the shelves, and the dBa mass balance implies that ∼50% of the dBa inventory (upper 500 m of the Arctic water column) was supplied by nonconservative inputs. Calculated areal dBa fluxes are up to 10 μmol m−2day−1on the margin, which is comparable to fluxes described in other regions. Applying this approach to dBa data from the 1994 Arctic Ocean Survey yields similar results. The Canadian Arctic Archipelago did not appear to have a similar margin source; rather, the dBa distribution in this section is consistent with mixing of Arctic Ocean‐derived waters and Baffin Bay‐derived waters. Although we lack enough information to identify the specifics of the shelf sediment Ba source, we suspect that a sedimentary remineralization and terrigenous sources (e.g., submarine groundwater discharge or fluvial particles) are contributors. We investigated the barium (Ba) cycle in the Arctic Ocean. The oceanic Ba cycle is supported by the interplay of seawater mixing, river inputs, sediment inputs, and particle formation and export from the water column. We determined that the distribution of dissolved Ba in the upper 500 m of the Arctic Ocean is largely set by a shelf sediment source; this is newly described, as previous literature assumed rivers and seawater mixing were the predominant contributors to the distribution. This discovery fits in with recent findings that the shelf sediments are a major source of radium and other trace metals to the surface Arctic Ocean. This is important to consider as the warming climate continues to erode Arctic ice cover (sea ice or glacial). Monitoring the relative sources of Ba to the water column can help define how warming impacts Arctic Ocean biogeochemistry. A mass balance approach indicates margin sources of barium (Ba) account for ∼50% of the budgetAmerasian Arctic Ocean samples exhibit inverted Ba isotope profiles, though still fall on the global arrayParticle supply from the shelves and dissolution in the deep Amerasian Arctic Ocean is a likely source of dissolved Ba A mass balance approach indicates margin sources of barium (Ba) account for ∼50% of the budget Amerasian Arctic Ocean samples exhibit inverted Ba isotope profiles, though still fall on the global array Particle supply from the shelves and dissolution in the deep Amerasian Arctic Ocean is a likely source of dissolved Ba more...
- Published
- 2022
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3. Vanadium Stable Isotopes in Biota of Terrestrial and Aquatic Food Chains
- Author
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Chételat, John, Nielsen, Sune G., Auro, Maureen, Carpenter, David, Mundy, Lukas, and Thomas, Philippe J.
- Abstract
Vanadium, a potentially toxic metal, is enriched in the environment from anthropogenic releases, particularly during fossil fuel production and use and steel manufacturing. Metal stable isotopes are sophisticated tools to trace pollution; however, only recent analytical advances have allowed for the accurate and precise measurement of vanadium isotope ratios (δ51V). To examine its potential as a tracer in terrestrial and aquatic ecosystems, δ51V was measured in soil, plant, lichen, marten, and lake sediment from sites near vanadium emissions at oil sands mines (Alberta, Canada) and in the sediment and biota (algae, zooplankton, fish) from a remote subarctic lake (Northwest Territories, Canada). Samples from Alberta had distinct δ51V values with marten liver the lowest (−1.7 ± 0.3‰), followed by lichen (−0.9 ± 0.1‰), soil (−0.7 ± 0.1‰), sediment (−0.5 ± 0.2‰), and plant root (−0.3 ± 0.2‰). Average values were lower than Alberta bitumen and petroleum coke (−0.1 ± 0.1‰). Plant roots had systematically higher δ51V than the soil from which they grew (Δ51Vplant-soil= 0.4 ± 0.1‰), while δ51V of lichen and aquatic biota were lower (0.1–0.3‰) than likely crustal sources. These δ51V measurements in terrestrial and aquatic biota demonstrate promise for tracer applications, although further study of its biological fractionation is needed. more...
- Published
- 2021
- Full Text
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