The Mass Spectrometry society of Japan - The 71st Annual Conference on Mass Spectrometry, Japan

Abstract

Symposium Sessions

Day 2, May 16(Tue.) 15:20-15:35 Room B (Room 1202)

Source Estimation of Fe in Marine Aerosols and Surface Seawater using Fe Stable Isotope Ratios in the Subarctic North Pacific

(1JAMSTEC, 2NIES, 3Hokkaido Univ., 4Univ. Tokyo, 5USF)
oMinako Kurisu1, Kohei Sakata2, Jun Nishioka3, Hajime Obata4, Tim Conway5, Katsuhiko Suzuki1, Teruhiko Kashiwabara1, Yoshio Takahashi4

Deficiency of dissolved iron (Fe) is one of the limiting factors of primary production in the surface ocean. Among several Fe sources, mineral dust in atmospheric aerosols is one of the main sources of Fe, whereas Fe emitted by anthropogenic combustion is another important source due to its higher solubility than that in mineral dust. However, the impact of combustion Fe in the atmosphere and surface ocean is still unknown. We aimed to clarify the contribution of combustion Fe in marine aerosols and surface seawater using Fe stable isotope ratio (δ56Fe) as a tracer. Using the mixing equation assuming the δ56Fe of natural and combustion Fe, the contribution of combustion Fe was up to 10% and 40% in total and fine particles, respectively. These are the first observation-based estimations of the contribution of combustion Fe in the North Pacific including the pelagic regions, which will also help estimate the Fe sources using model calculations. The δ56Fe of dissolved Fe in the surface seawater was mostly higher than those of aerosols collected simultaneously because of the contribution of Fe from the deeper parts of the ocean and/or by the isotope fractionation during biological uptake processes.