Quantifying anthropogenic emission of iron in marine aerosol in the Northwest Pacific with shipborne online measurements

Tianle Zhang; Junyi Liu; Yaxin Xiang; Xiaomeng Liu; Jie Zhang; Lin Zhang; Qi Ying; Yuntao Wang; Yinan Wang; Shuangling Chen; Fei Chai; Mei Zheng

doi:10.1016/j.scitotenv.2023.169158

Quantifying anthropogenic emission of iron in marine aerosol in the Northwest Pacific with shipborne online measurements

Sci Total Environ. 2024 Feb 20:912:169158. doi: 10.1016/j.scitotenv.2023.169158. Epub 2023 Dec 11.

Authors

Tianle Zhang¹, Junyi Liu¹, Yaxin Xiang¹, Xiaomeng Liu¹, Jie Zhang², Lin Zhang³, Qi Ying², Yuntao Wang⁴, Yinan Wang⁵, Shuangling Chen⁴, Fei Chai⁶, Mei Zheng⁷

Affiliations

¹ SKL-ESPC and SEPKL-AERM, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, China.
² Zachary Department of Civil and Environmental Engineering, Texas A&M University, College Station, TX 77845, USA.
³ Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China.
⁴ State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China.
⁵ Key Laboratory of Middle Atmosphere and Global Environment Observation, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
⁶ State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361005, China.
⁷ SKL-ESPC and SEPKL-AERM, College of Environmental Sciences and Engineering, and Center for Environment and Health, Peking University, Beijing 100871, China. Electronic address: mzheng@pku.edu.cn.

PMID: 38092217
DOI: 10.1016/j.scitotenv.2023.169158

Abstract

Anthropogenic emissions are recognized as significant contributors to atmospheric soluble iron (Fe) in recent years, which may affect marine primary productivity, especially in Fe-limited areas. However, the contribution of different emission sources to Fe in marine aerosol has been primarily estimated by modeling approaches. Quantifying anthropogenic Fe based on field measurements remains a great challenge. In this study, online multi-element measurements and Positive Matrix Factorization (PMF) were combined for the first time to quantify sources of atmospheric Fe and soluble Fe in the Northwest Pacific during a cruise in spring 2015. Fe concentration in 624 atmospheric PM_2.5 samples measured online was 74.58 ± 90.87 ng/m³. The PMF results showed anthropogenic activities, including industrial coal combustion, biomass burning, and maritime transport, were important in this region, contributing 31.4 % of atmospheric Fe on average. In addition, anthropogenic Fe concentration resolved by PMF was comparable to the simulation results of the CMAQ (Community Multiscale Air Quality) and GEOS-Chem (Goddard Earth Observing System-Chemical transport) models, with better correlation to CMAQ (r = 0.76) than GEOS-Chem (r = 0.26). This study developed a new method to estimate atmospheric soluble Fe, which integrates Fe source apportionment results and Fe solubility from different sources. Soluble Fe concentration was estimated as 3.93 ± 5.14 ng/m³, of which 87.0 % was attributed to anthropogenic emissions. Notably, ship emission alone contributed 27.5 % of soluble Fe, though its contribution to total Fe was only 2.2 %. Finally, the total deposition fluxes of atmospheric Fe (37.11 ± 38.43 μg/m²/day) and soluble Fe (1.85 ± 2.13 μg/m²/day) were estimated. This study developed a new methodology for quantifying contribution of anthropogenic emissions to Fe in marine aerosol, which could greatly help the assessment of impacts of human activities on marine environment.

Keywords: Deposition flux; Iron; Marine aerosol; Northwest Pacific; Soluble iron; Source apportionment.