Controls on barium and radium-226 distributions along GEOTRACES GP15

Roy, Emilie Le; Charette, Matthew A.; Henderson, Paul B.; Horner, Tristan J.; Shiller, Alan M.; Moore, Willard S.; Casciotti, Karen L.; Beek, Pieter van; Souhaut, Marc; Auro, Maureen E.; Lawrence, Rian; Shrikumar, Avanti

doi:10.7185/gold2021.5843

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“…Pacific GEOSECS found the highest 226 Ra values ever measured in the ocean at that time in bottom waters at their nearby station 204 (31.38°N., 150.03°W, 5,292 m depth, Chung & Craig, 1980). Our measurements of 226 Ra at station 14 agreed with the GEOSECS results (Le Roy et al., 2021). The 226 Ra distribution also reflects a strong bottom source with sluggish circulation.…”

Section: Discussionsupporting

confidence: 89%

“…Almost all samples collected within 100 m of the seabed contained measurable 228 Ra. In the deep waters, there is one primary enriched area between stations 8–16 from 47° to 27°N, where values within 110 m of the seabed reach 0.4 to 2.1 dpm/100 L. In this region 226 Ra values are also high, ranging from 38 to 47 dpm/100 L on both GP15 (Le Roy et al., 2021) and GEOSECS (Chung & Craig, 1980). Slight near bottom 228 Ra enrichments occur along 152°W at stations 19 (17.5°N), 23 (7.5°N), 25 (5°N), and 35 to 39 (10°–20°S).…”

Section: Resultsmentioning

confidence: 99%

“…Near‐bottom 228 Ra inventories average 1,110 dpm m −2 for stations 8–16 but only 280 dpm m −2 for the other stations. Stations 8–16 are also strongly enriched in 226 Ra (Le Roy et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

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Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Moore,

Charette,

Henderson

et al. 2024

JGR Oceans

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The half‐life of 228Ra (5.7 years) aligns well with near‐surface and near‐bottom ocean mixing timescales. Because 228Ra is sourced from sediments, regions of enhanced activity represent water that has recently interacted with sediments on the continental margin or seabed. The GP15 meridional transect from Alaska to Tahiti along152°W encountered several regions in the upper ocean where 228Ra was enriched. These enrichments follow surface and subsurface ocean current patterns and pair with earlier measurements of 228Ra and transient radionuclides to reveal the origins of these enriched regions. An enriched region at Alaska margin stations 1–3 was sourced locally but did not extend to the Alaskan trench at station 4. A large shallow region between 47° and 32°N. was sourced from the west by the North Pacific Current; another shallow enriched region between 11° and 5° N was also sourced from the west by the North Equatorial Countercurrent. Subsurface enrichments (100–400 m) between 18 and 47°N were associated with Central Mode Water and North Pacific Intermediate Water. The 228Ra activities in the upper Pacific were six times lower than activities in the Atlantic. In deep waters the primary enrichment was 27°–47°N. Two stations (32° and 37°N) were especially enriched, having near‐bottom inventories several times greater than other stations. With these two exceptions the remaining Pacific stations exhibited averaged inventories lower than those in the Atlantic. There was one region of enriched 223Ra (half‐life = 11 days) above the Puna Ridge near Hawaii.

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Section: Discussionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

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Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Moore,

Charette,

Henderson

et al. 2024

JGR Oceans

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Controls on barium and radium-226 distributions along GEOTRACES GP15

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Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

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Controls on barium and radium-226 distributions along GEOTRACES GP15

Cited by 1 publication

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Enriched Regions of 228Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Enriched Regions of 228Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

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Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)

Enriched Regions of ²²⁸Ra Along the U.S. GEOTRACES Pacific Meridional Transect (GP15)