Departmental Bulletin Paper オホーツク海における海氷が関わる鉄の供給過程の解明

漢那, 直也  ,  西岡, 純  ,  豊田, 威信

74pp.105 - 114 , 2016-03-31 , 低温科学第74巻編集委員会
季節海氷域であるオホーツク海では,融解期に植物プランクトンの大増殖が起こる.海氷融解と植物プランクトン増殖との関わりを明らかにするために,海洋で不足しやすく,植物プランクトンの必須微量栄養物質である鉄に着目し,海氷によるオホーツク海表層への鉄供給過程を定量的に評価した.南部オホーツク海の雪及び海氷中の鉄濃度は,海氷下の海水に比べて数倍高いことから,海氷は表層への鉄の供給源となることがわかった.海氷の輸送に伴い,北部から南部の海盆域へ輸送される鉄の 総量を,およそ1.2 万トンと見積もった.海氷による鉄供給過程は,鉄の供給が限られるオホーツク海海盆域の基礎生産に大きな影響を与えている可能性がある.In the Sea of Okhotsk, which is a seasonally covered with sea ice, the phytoplankton bloom starts after sea ice retreat. In order to elucidate relation between the sea ice melting and phytoplankton growth, we quantitatively evaluated the supply process of micro-nutrient, iron (Fe), associated with the sea ice melting to surface waters in the Sea of Okhotsk. Our results showed that concentrations of Fe both in snow and sea ice were several times greater than that in under-ice seawater. Therefore, it was revealed that sea ice is a potential source of Fe for supporting phytoplankton growth in the Sea of Okhotsk. Based on the Fe measurements in snow and sea ice, we estimated the amount of Fe transported from north to south via sea ice transport to be ~1.2 × 107 kg yr-1. The Fe introduced to surface waters during the sea ice melting has great impact on primary production in the basin region of the Sea of Okhotsk.

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