Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago
<p>As a shelf-dominated basin, the Arctic Ocean and its biogeochemistry are heavily influenced by continental and riverine sources. Radium isotopes (<span class="inline-formula"><sup>226</sup>Ra</span>, <span class="inline-formula"><sup>2...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/4937/2020/bg-17-4937-2020.pdf |
| _version_ | 1819230602870652928 |
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| author | C. Mears C. Mears H. Thomas H. Thomas P. B. Henderson M. A. Charette H. MacIntyre F. Dehairs C. Monnin A. Mucci |
| author_facet | C. Mears C. Mears H. Thomas H. Thomas P. B. Henderson M. A. Charette H. MacIntyre F. Dehairs C. Monnin A. Mucci |
| author_sort | C. Mears |
| collection | DOAJ |
| description | <p>As a shelf-dominated basin, the Arctic Ocean and its biogeochemistry are
heavily influenced by continental and riverine sources. Radium isotopes
(<span class="inline-formula"><sup>226</sup>Ra</span>, <span class="inline-formula"><sup>228</sup>Ra</span>, <span class="inline-formula"><sup>224</sup>Ra</span>, and <span class="inline-formula"><sup>223</sup>Ra</span>), are transferred from the
sediments to seawater, making them ideal tracers of sediment–water exchange
processes and ocean mixing. As the two long-lived isotopes of the radium
quartet, <span class="inline-formula"><sup>226</sup>Ra</span> and <span class="inline-formula"><sup>228</sup>Ra</span> (<span class="inline-formula"><sup>226</sup>Ra</span> with a <span class="inline-formula"><i>t</i><sub>1∕2</sub></span> of 1600 years and <span class="inline-formula"><sup>228</sup>Ra</span> with a <span class="inline-formula"><i>t</i><sub>1∕2</sub></span> of 5.8 years) can provide insight into the water mass
compositions, distribution patterns, as well as mixing processes and their
associated timescales throughout the Canadian Arctic Archipelago (CAA). The
wide range of <span class="inline-formula"><sup>226</sup>Ra</span> and <span class="inline-formula"><sup>228</sup>Ra</span> activities, as well as of the
<span class="inline-formula"><sup>228</sup>Ra∕<sup>226</sup>Ra</span>, measured in water samples collected during the
2015 GEOTRACES cruise, complemented by additional chemical tracers –
dissolved inorganic carbon (DIC), total alkalinity (AT), barium (Ba), and
the stable oxygen isotope composition of water (<span class="inline-formula"><i>δ</i><sup>18</sup>O</span>) –
highlight the dominant biogeochemical, hydrographic, and bathymetric features
of the CAA. Bathymetric features, such as the continental shelf and shallow
coastal sills, are critical in modulating circulation patterns within the
CAA, including the bulk flow of Pacific waters and the inhibited eastward
flow of denser Atlantic waters through the CAA. Using a principal component
analysis, we unravel the dominant mechanisms and apparent water mass
end-members that shape the tracer distributions. We identify two distinct
water masses located above and below the upper halocline layer throughout
the CAA and distinctly differentiate surface waters in the eastern
and western CAA. Furthermore, we highlight water exchange across
80<span class="inline-formula"><sup>∘</sup></span> W, inferring a draw of Atlantic water (originating from Baffin
Bay) into the CAA. This underscores the presence of an Atlantic water “U-turn”
located at Barrow Strait, where the same water mass is seen along the
northernmost edge at 80<span class="inline-formula"><sup>∘</sup></span> W as well as along the southeasternmost
confines of Lancaster Sound. Overall, this study provides a stepping stone
for future research initiatives within the Canadian Arctic Archipelago,
revealing how quantifying disparities in the distributions of radioactive
tracers can provide valuable information on water mass distributions, flow
patterns, and mixing within vulnerable areas such as the CAA.</p> |
| first_indexed | 2024-12-23T11:31:41Z |
| format | Article |
| id | doaj.art-7515c8f21ab542a3bb94a8e439117113 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-23T11:31:41Z |
| publishDate | 2020-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-7515c8f21ab542a3bb94a8e4391171132022-12-21T17:48:47ZengCopernicus PublicationsBiogeosciences1726-41701726-41892020-10-01174937495910.5194/bg-17-4937-2020Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic ArchipelagoC. Mears0C. Mears1H. Thomas2H. Thomas3P. B. Henderson4M. A. Charette5H. MacIntyre6F. Dehairs7C. Monnin8A. Mucci9Department of Oceanography, Dalhousie University, Halifax, NS, CanadaInstitute for Coastal Research, Helmholtz Centre Geesthacht, Geesthacht, GermanyDepartment of Oceanography, Dalhousie University, Halifax, NS, CanadaInstitute for Coastal Research, Helmholtz Centre Geesthacht, Geesthacht, GermanyDepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USADepartment of Oceanography, Dalhousie University, Halifax, NS, CanadaAnalytical, Environmental and Geo-Chemistry, Vrije Universiteit Brussel, Brussels, BelgiumCNRS – Université Paul Sabatier-IRD-OMP, Geosciences Environnement Toulouse (GET), Toulouse, FranceGeotop and Department of Earth and Planetary Sciences, McGill University, Montréal, QC, Canada<p>As a shelf-dominated basin, the Arctic Ocean and its biogeochemistry are heavily influenced by continental and riverine sources. Radium isotopes (<span class="inline-formula"><sup>226</sup>Ra</span>, <span class="inline-formula"><sup>228</sup>Ra</span>, <span class="inline-formula"><sup>224</sup>Ra</span>, and <span class="inline-formula"><sup>223</sup>Ra</span>), are transferred from the sediments to seawater, making them ideal tracers of sediment–water exchange processes and ocean mixing. As the two long-lived isotopes of the radium quartet, <span class="inline-formula"><sup>226</sup>Ra</span> and <span class="inline-formula"><sup>228</sup>Ra</span> (<span class="inline-formula"><sup>226</sup>Ra</span> with a <span class="inline-formula"><i>t</i><sub>1∕2</sub></span> of 1600 years and <span class="inline-formula"><sup>228</sup>Ra</span> with a <span class="inline-formula"><i>t</i><sub>1∕2</sub></span> of 5.8 years) can provide insight into the water mass compositions, distribution patterns, as well as mixing processes and their associated timescales throughout the Canadian Arctic Archipelago (CAA). The wide range of <span class="inline-formula"><sup>226</sup>Ra</span> and <span class="inline-formula"><sup>228</sup>Ra</span> activities, as well as of the <span class="inline-formula"><sup>228</sup>Ra∕<sup>226</sup>Ra</span>, measured in water samples collected during the 2015 GEOTRACES cruise, complemented by additional chemical tracers – dissolved inorganic carbon (DIC), total alkalinity (AT), barium (Ba), and the stable oxygen isotope composition of water (<span class="inline-formula"><i>δ</i><sup>18</sup>O</span>) – highlight the dominant biogeochemical, hydrographic, and bathymetric features of the CAA. Bathymetric features, such as the continental shelf and shallow coastal sills, are critical in modulating circulation patterns within the CAA, including the bulk flow of Pacific waters and the inhibited eastward flow of denser Atlantic waters through the CAA. Using a principal component analysis, we unravel the dominant mechanisms and apparent water mass end-members that shape the tracer distributions. We identify two distinct water masses located above and below the upper halocline layer throughout the CAA and distinctly differentiate surface waters in the eastern and western CAA. Furthermore, we highlight water exchange across 80<span class="inline-formula"><sup>∘</sup></span> W, inferring a draw of Atlantic water (originating from Baffin Bay) into the CAA. This underscores the presence of an Atlantic water “U-turn” located at Barrow Strait, where the same water mass is seen along the northernmost edge at 80<span class="inline-formula"><sup>∘</sup></span> W as well as along the southeasternmost confines of Lancaster Sound. Overall, this study provides a stepping stone for future research initiatives within the Canadian Arctic Archipelago, revealing how quantifying disparities in the distributions of radioactive tracers can provide valuable information on water mass distributions, flow patterns, and mixing within vulnerable areas such as the CAA.</p>https://bg.copernicus.org/articles/17/4937/2020/bg-17-4937-2020.pdf |
| spellingShingle | C. Mears C. Mears H. Thomas H. Thomas P. B. Henderson M. A. Charette H. MacIntyre F. Dehairs C. Monnin A. Mucci Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago Biogeosciences |
| title | Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago |
| title_full | Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago |
| title_fullStr | Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago |
| title_full_unstemmed | Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago |
| title_short | Using <sup>226</sup>Ra and <sup>228</sup>Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago |
| title_sort | using sup 226 sup ra and sup 228 sup ra isotopes to distinguish water mass distribution in the canadian arctic archipelago |
| url | https://bg.copernicus.org/articles/17/4937/2020/bg-17-4937-2020.pdf |
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