1. The Atmospheric Input of Dissolvable Pb Based on the Radioactive 210 Pb Budget in the Equatorial Western Indian Ocean.
- Author
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Lee, Huisu, Lee, Jaeeun, Lee, Hyunmi, and Kim, Intae
- Subjects
BUDGET ,ATMOSPHERIC deposition ,OCEAN ,SEAWATER - Abstract
To estimate the atmospheric deposition flux of
210 Pb in the equatorial western Indian Ocean, we determined the dissolved (<0.45 μm) and particulate210 Pb (>0.45 μm) in the water column. In addition, we calculated the atmosphere-derived dissolvable Pb in seawater using the budget of210 Pb. The dissolved210 Pb and total210 Pb were higher in the surface layer and, overall, showed a decreasing distribution with depth. In particular, radioactive210 Pb activities in the surface-to-upper layer (<1000 m depth) were 1.5 to 2 times higher than those reported in the 1970s (in nearby regions), suggesting that there has been additional210 Pb input in recent years. Based on the mass balance of the total210 Pb budget in the water column, we estimated the atmospheric deposition flux of210 Pb and the residence time of Pb for the first time in this region. The atmospheric deposition flux of210 Pb was estimated to be 0.1–0.5 dpm cm−2 yr−1 , and these values agreed with the general global estimations for the major oceans (0.1–0.7 dpm cm−2 yr−1 ). Considering the residence time of210 Pb (29–41 years) in the water column (estimated from the210 Pb inventory and234 Th-based Pb scavenging rate), the atmospheric input of seawater-dissolvable Pb was quantified to be 0.08–0.1 nmol cm−2 yr−1 , which is about eight times higher than the estimated input in the early 1990s in the region. Therefore, these results imply that radioactive210 Pb could be a useful tracer for quantifying Pb flux in seawater. [ABSTRACT FROM AUTHOR]- Published
- 2023
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