Improved atmospheric mercury simulation using updated gas-particle partition and organic aerosol concentrations


Jinsheng Chen , Kaiyun Liu , Qingru Wu , Shuxiao Wang , Xing Chang , Yi Tang , Long Wang , Tonghao Liu , Lei Zhang , Yu Zhao , Qin''geng Wang , Yong Cai , Xinbin Feng , Huan Zhong , Ping Li , Yongguang Yin

DOI:10.1016/j.jes.2022.04.007

Received February 11, 2022,Revised , Accepted April 06, 2022, Available online April 14, 2022

Volume 34,2022,Pages 106-118

The gaseous or particulate forms of divalent mercury (HgII) significantly impact the spatial distribution of atmospheric mercury concentration and deposition flux (FLX). In the new nested-grid GEOS-Chem model, we try to modify the HgII gas-particle partitioning relationship with synchronous and hourly observations at four sites in China. Observations of gaseous oxidized Hg (GOM), particulate-bound Hg (PBM), and PM2.5 were used to derive an empirical gas-particle partitioning coefficient as a function of temperature (T) and organic aerosol (OA) concentrations under different relative humidity (RH). Results showed that with increasing RH, the dominant process of HgII gas-particle partitioning changed from physical adsorption to chemical desorption. And the dominant factor of HgII gas-particle partitioning changed from T to OA concentrations. We thus improved the simulated OA concentration field by introducing intermediate-volatility and semi-volatile organic compounds (I/SVOCs) emission inventory into the model framework and refining the volatile distributions of I/SVOCs according to new filed tests in the recent literatures. Finally, normalized mean biases (NMBs) of monthly gaseous element mercury (GEM), GOM, PBM, WFLX were reduced from −33%–29%, 95%–300%, 64%–261%, 117%–122% to −13%–0%, −20%–80%, −31%–50%, −17%–23%. The improved model explains 69%–98% of the observed atmospheric Hg decrease during 2013–2020 and can serve as a useful tool to evaluate the effectiveness of the Minamata Convention on Mercury.

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