Research press release


Nature Geoscience

Giant icebergs leave trail of carbon sequestration in their wake



Grant Biggたちは、海色(海洋表面の植物プランクトン生産性の指標となる)の人工衛星画像を解析し、南洋の外洋における少なくとも長さ18 km以上の氷山の範囲と関連付けた。彼らは巨大な氷山から数百キロメートルにわたって植物プランクトンの生産性が強い範囲が広がり、氷山が通過した後も少なくとも1か月は継続していることを発見した。Biggたちは、この新しい解析が巨大な氷山が南洋の炭素循環に対して桁外れの役割を果たしていることを明らかにしたと示唆している。

Melting water from giant icebergs, which contains iron and other nutrients, supports phytoplankton growth that is responsible for as much as 20% of the carbon sequestered to the depths of the Southern Ocean by biological metabolism and growth, reports a study published online this week in Nature Geoscience. These giant icebergs, dozens of which are floating in the Southern Ocean at one time, influence phytoplankton over an area ten times larger than typical icebergs do, even when accounting for the difference in size.

The Southern Ocean plays a significant part in the global carbon cycle, and is responsible for approximately 10% of the ocean’s total carbon sequestration through a mixture of biologically driven and chemical processes, including phytoplankton growth. However, previous studies have suggested that ocean fertilization from icebergs-in the form of iron and other micronutrients from meltwater-makes relatively minor contributions to phytoplankton uptake of CO2, some of which is subsequently sequestered in the deep ocean.

Grant Bigg and colleagues analysed satellite images of ocean colour-an index of phytoplankton productivity at the ocean’s surface-associated with a range of icebergs at least 18 km in length in the open Southern Ocean. They find enhanced phytoplankton productivity extends hundreds of kilometres from giant icebergs, and persists for at least one month after an iceberg passes. The authors suggest their new analysis reveals that giant icebergs may play an outsize role in the Southern Ocean carbon cycle.

doi: 10.1038/ngeo2633


メールマガジンリストの「Nature 関連誌今週のハイライト」にチェックをいれていただきますと、毎週各ジャーナルからの最新の「注目のハイライト」をまとめて皆様にお届けいたします。