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タイトル: Distributions of aluminum, manganese, cobalt, and lead in the western South Pacific: Interplay between the South and North Pacific
著者: Zheng, Linjie  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0002-5266-4939 (unconfirmed)
Minami, Tomoharu
Takano, Shotaro  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0002-6596-5327 (unconfirmed)
Sohrin, Yoshiki  kyouindb  KAKEN_id  orcid https://orcid.org/0000-0001-6744-6048 (unconfirmed)
著者名の別形: 鄭, 臨潔
南, 知晴
高野, 祥太朗
宗林, 由樹
キーワード: GEOTRACES
Scavenged elements
Biogeochemical cycling
Weathering
Anthropogenic pollution
発行日: 1-Dec-2022
出版者: Elsevier BV
誌名: Geochimica et Cosmochimica Acta
巻: 338
開始ページ: 105
終了ページ: 120
抄録: Aluminum (Al), manganese (Mn), cobalt (Co), and lead (Pb) are strongly scavenged from seawater. We reported that each element is uniquely related to ocean circulation in the North Pacific (Zheng et al., 2019). Herein, we present the full-depth distributions of these elements in the western South Pacific, which include meridional sections along 170°W (GEOTRACES GP19). We determined dissolved (d) and total dissolvable (td) concentrations using filtered and unfiltered seawater without UV treatment, and we calculated labile particulate (lp) concentrations as the difference between td and d concentrations. This and the previous studies present the basin scale distributions, which enable us to investigate first order processes that drive the biogeochemistry of Al, Mn, Co, and Pb in the Pacific Ocean. The meridional section of dAl along 170°W (GP19)-160°W (GPc06) from 64°S to 54°N indicates that elevated concentrations (maximum 6.1 nmol/kg) occur between 40°S and 10°S from surface to bottom. However, the maxima of lpAl occur at high latitudes. The lpAl/tdAl ratio has a minimum of 0.26 ± 0.12 (ave ± sd, n = 116) in the zone from 30°S to 0°S. Based on these results, we propose a hypothesis that weathering on land has a significant effect on the distribution of Al in the ocean. Intensive weathering on tropical and subtropical islands and Australia forms kaolinite-dominated soils and laterite. This process provides dAl and kaolinite to the ocean. The supply of kaolinite results in kaolinite-dominated sediments that become a major bottom source for dAl. In contrast, strong sources of Mn and Co are continental shelves around the northern boundary. Dissolved Mn and dCo are released from sediments by manganese reduction and carried by intermediate water circulation. In particular, dCo spreads in the North Pacific Intermediate Water (NPIW), Equatorial Pacific Intermediate Water (EqPIW), and Antarctic Intermediate Water (AAIW); 23–59 pmol/kg at a potential density anomaly (σθ) of 27.0. This is partly owing to the uptake of dCo by phytoplankton and remineralization from settling particles. The dPb concentrations are 10 ± 6 pmol/kg (n = 397) in the South Pacific and 30 ± 20 pmol/kg (n = 566) in the North Pacific. The distribution of dPb is characterized by a maximum in the Subtropical Mode Water (SMW) and Central Mode Water (CMW) with σθ∼26 in the North Pacific. These results indicate that Pb is predominantly supplied by anthropogenic aerosols from Asia and Russia to the Pacific Ocean. Because Pb is not actively taken up by phytoplankton, Pb enters mode waters during winter convection and is transported with mode waters.
著作権等: © 2022 The Author(s). Published by Elsevier Ltd.
This is an open access article under the CC BY-NC-ND license.
URI: http://hdl.handle.net/2433/282033
DOI(出版社版): 10.1016/j.gca.2022.10.022
出現コレクション:学術雑誌掲載論文等

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