Quantitative estimation of anthropogenic iron in the Northeast Asian aerosol using rock-magnetic proxies

Abstract

Soluble Fe in atmospheric dust is considered as an important source of micronutrient to the oceans, affecting phytoplankton growth, carbon export and nitrogen fixation. Recent Fe isotope studies suggested that highly soluble Fe was released by combustion processes. However, it is hard to define the quantity of anthropogenic Fe in aerosol using elemental analysis techniques due to Northeast Asian aerosols are contributed from both natural and anthropogenic sources. In the present study, we apply rock-magnetic methods to quantify soluble anthropogenic Fe for the aerosol samples acquired by high-volume PM sampler in Jeju, Korea. Acquisition behaviour of isothermal remanent magnetization identifies that >95% of magnetization is acquired by soft anthropogenic Fe-containing materials. As these materials are behaved like magnetite showing Curie temperature of 530