日本地球惑星科学連合2023年大会

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セッション記号 A (大気水圏科学) » A-CG 大気海洋・環境科学複合領域・一般

[A-CG45] 海洋表層-大気間の生物地球化学

2023年5月21日(日) 09:00 〜 10:30 102 (幕張メッセ国際会議場)

コンビーナ:亀山 宗彦(北海道大学)、岩本 洋子(広島大学大学院統合生命科学研究科)、野口 真希(国立研究開発法人海洋研究開発機構 地球表層システム研究センター)、小杉 如央(気象研究所)、座長:小杉 如央(気象研究所)、野口 真希(国立研究開発法人海洋研究開発機構 地球表層システム研究センター)

09:15 〜 09:30

[ACG45-02] Distribution and determinants of nutrients and primary production in the eastern Indian sector of the Southern Ocean

*戸澤 愛美1野村 大樹1,2,3山崎 開平4、木内 政彰1平野 大輔4,5青木 茂6、佐々木 裕子7、村瀬 弘人8 (1.北海道大学大学院水産科学院、2.北海道大学北方生物圏フィールド科学センター、3.北海道大学北極域研究センター、4.国立極地研究所、5.総合研究大学院大学、6.北海道大学低温科学研究所、7.水産研究・教育機構、8.東京海洋大学)


キーワード:栄養塩、群集純生産、南極海インド洋セクター、季節海氷域

To investigate the spatial distributions and determinants of nutrient concentrations, we measured NO3+NO2, PO43−, and Si(OH)4concentrations in the eastern Indian Ocean sector of the Antarctic Ocean (80−150°E, south of 60°S) between December 2018 and February 2019. In the Antarctic Circumpolar Current (ACC) domain, nutrient concentrations were increased by nutrients supplied from the deep layer and by organic matter decomposition and remineralization within the seasonal pycnocline after the development of strong stratification. Strong stratification also enhanced phytoplankton growth and nutrient consumption by photosynthesis. In contrast, in the subpolar region, nutrient concentrations were increased by nutrients supplied by brine discharged during sea ice formation and decreased by dilution with sea ice meltwater. Although high salinity in the surface and subsurface layers corresponded well to upwelling areas around subpolar subgyres, high salinity was not necessarily correlated with nutrient concentrations. We estimated primary production both from in situ nutrient data and from satellite-acquired chlorophyll-a data. According to both estimation methods, primary production was high in the subpolar region, especially around 120−130°E. However, nutrient-based estimation also showed high production in coastal areas where, because of sea ice and cloud cover, estimation based on satellite data was not possible. To understand primary production in seasonal ice areas, the best estimation method should be selected for the research goals or multiple methods should be used in combination.