講演情報
[ACG67-P02]ロシア・カムチャツカアイスコア中に含まれる微粒子の特性および起源の変動
*永塚 尚子1、長島 佳菜1、伊藤 彰記1、的場 澄人2 (1.海洋研究開発機構、2.北海道大学 低温科学研究所)
キーワード：
アイスコア、鉱物ダスト、カムチャッカ、ブラックカーボン、火山性粒子
The subarctic North Pacific is a high-nutrient, low-chlorophyll (HNLC) region, where the phytoplankton growth is limited by the scarcity of trace metals such as iron. In this region, Asian desert mineral dust and combustion-derived particles are considered the major contributors of dissolved iron, accounting for about 40% of the total input (Nagashima et al., 2023). Although combustion-derived iron is emitted in smaller quantities than natural mineral sources, its high solubility makes it an important source of bioavailable iron (Sholkovitz et al., 2009). In addition, volcanic ash from eruptions in the Kamchatka Peninsula has recently been recognized as a new iron source. Volcanic ash rapidly releases iron into seawater, and during large-scale eruptions it can significantly increase surface ocean iron concentrations (Hamme et al., 2010). However, the flux of iron-bearing particles exhibits strong regional and seasonal variability, and their sources and temporal variations remain unclear.
To establish reference information on microparticles transported to this region, we analyzed the size, morphology, and composition of microparticles preserved in a Kamchatka ice core (Ichinsky: 55.46°N, 157.55°E, 3607 m a.s.l.) from 1949 to 2003 using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). This ice core is located on the western margin of the subarctic North Pacific region. Furtheremore, we reconstructed temporal variations in ice-core mineral sources by applying a recently developed provenance-tracing technique, namely SEM-cathodoluminescence (CL) analysis of single quartz particles.
The results show that the Ichinsky ice core contains mainly silicate minerals, which are major constituents of the Earth’s crust, and that their compositions vary among samples. These minerals were supplied mainly from Asian desert regions, with a possible additional contribution from African desert regions. Their relative contributions likely changed from year to year.
In addition to these minerals, volcanic glass and black carbon were also observed. The abundance of black carbon was higher in years characterized by increased proportions of iron-rich minerals.
A detailed discussion will be presented at the meeting.
To establish reference information on microparticles transported to this region, we analyzed the size, morphology, and composition of microparticles preserved in a Kamchatka ice core (Ichinsky: 55.46°N, 157.55°E, 3607 m a.s.l.) from 1949 to 2003 using scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). This ice core is located on the western margin of the subarctic North Pacific region. Furtheremore, we reconstructed temporal variations in ice-core mineral sources by applying a recently developed provenance-tracing technique, namely SEM-cathodoluminescence (CL) analysis of single quartz particles.
The results show that the Ichinsky ice core contains mainly silicate minerals, which are major constituents of the Earth’s crust, and that their compositions vary among samples. These minerals were supplied mainly from Asian desert regions, with a possible additional contribution from African desert regions. Their relative contributions likely changed from year to year.
In addition to these minerals, volcanic glass and black carbon were also observed. The abundance of black carbon was higher in years characterized by increased proportions of iron-rich minerals.
A detailed discussion will be presented at the meeting.