Air pollution-aerosol interactions produce more bioavailable iron for ocean ecosystems

Weijun Li; Liang Xu; Xiaohuan Liu; Jianchao Zhang; Yangting Lin; Xiaohong Yao; Huiwang Gao; Daizhou Zhang; Jianmin Chen; Wenxing Wang; Roy M Harrison; Xiaoye Zhang; Longyi Shao; Pingqing Fu; Athanasios Nenes; Zongbo Shi

doi:10.1126/sciadv.1601749

Air pollution-aerosol interactions produce more bioavailable iron for ocean ecosystems

Sci Adv. 2017 Mar 1;3(3):e1601749. doi: 10.1126/sciadv.1601749. eCollection 2017 Mar.

Authors

Weijun Li¹, Liang Xu¹, Xiaohuan Liu², Jianchao Zhang³, Yangting Lin³, Xiaohong Yao², Huiwang Gao², Daizhou Zhang⁴, Jianmin Chen⁵, Wenxing Wang¹, Roy M Harrison⁶, Xiaoye Zhang⁷, Longyi Shao⁸, Pingqing Fu⁹, Athanasios Nenes¹⁰, Zongbo Shi¹¹

Affiliations

¹ Environment Research Institute, Shandong University, Jinan, Shandong 250100, China.
² Key Laboratory of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China.
³ Key Laboratory of Earth and Planetary Physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
⁴ Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
⁵ Environment Research Institute, Shandong University, Jinan, Shandong 250100, China.; Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
⁶ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, U.K.; Department of Environmental Sciences, Center of Excellence in Environmental Studies, King Abdulaziz University, P. O. Box 80203, Jeddah 21589, Saudi Arabia.
⁷ Key Laboratory of Atmospheric Chemistry, Chinese Academy of Meteorological Sciences, Beijing, China.
⁸ State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology, Beijing 100086, China.
⁹ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
¹⁰ School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.; School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.; Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas, Patras GR-26504, Greece.; Institute for Environmental Research and Sustainable Development, National Observatory of Athens, Palea-Pendeli GR-15236, Greece.
¹¹ School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, U.K.

Abstract

It has long been hypothesized that acids formed from anthropogenic pollutants and natural emissions dissolve iron (Fe) in airborne particles, enhancing the supply of bioavailable Fe to the oceans. However, field observations have yet to provide indisputable evidence to confirm this hypothesis. Single-particle chemical analysis for hundreds of individual atmospheric particles collected over the East China Sea shows that Fe-rich particles from coal combustion and steel industries were coated with thick layers of sulfate after 1 to 2 days of atmospheric residence. The Fe in aged particles was present as a "hotspot" of (insoluble) iron oxides and throughout the acidic sulfate coating in the form of (soluble) Fe sulfate, which increases with degree of aging (thickness of coating). This provides the "smoking gun" for acid iron dissolution, because iron sulfate was not detected in the freshly emitted particles and there is no other source or mechanism of iron sulfate formation in the atmosphere.

Keywords: Aerosol; Aerosol processes; NanoSIMS; coal fly ash; iron fertilisation; iron hypothesis; iron oxides.