Recent decrease trend of atmospheric mercury concentrations in East China: the influence of anthropogenic emissions

Yi Tang,Long Wang,Wei Gao,Zhijian Li,Jiming Hao,Haotian Zheng,Shuxiao Wang,Qingru Wu,Lei Zhang,Shu Li,Kaiyun Liu

doi:10.5194/acp-18-8279-2018

Abstract

Abstract. Measurements of gaseous elemental mercury (GEM), other air pollutants, including SO2, NOx, O3, PM2.5, and CO, and meteorological conditions were carried out at Chongming Island in East China from 1 March 2014 to 31 December 2016. During the sampling period, GEM concentrations significantly decreased from 2.68 ± 1.07 ng m−3 in 2014 (March to December) to 1.60 ± 0.56 ng m−3 in 2016 (March to December). Monthly mean GEM concentration showed a significant decrease, at a rate of -0.60±0.08 ng m−3 yr−1 (R2=0.64, p < 0.01 significance level). Combining the analysis of the potential source contribution function (PSCF), principle component analysis (PCA), and the emission inventory, we found that the Yangtze River Delta (YRD) region was the dominant source region of GEM in Chongming Island and the main source industries included coal-fired power plants, coal-fired industrial boilers, and cement clinker production. We further quantified the effect of emission change on the air Hg concentration variations at Chongming Island through a coupled method of trajectory clusters and air Hg concentrations. It was found that the reduction of domestic emissions was the main driver of GEM decline in Chongming Island, accounting for 70 % of the total decline. The results indicated that air pollution control policies targeting SO2, NOx, and particulate matter reductions had significant co-benefits on GEM.

Highlights

Mercury (Hg) is of crucial concern to public health and the global environment for its neurotoxicity, long-distance transport, and bioaccumulation
In 2016, the gaseous elemental mercury (GEM) concentrations were similar to the background concentrations in the Northern Hemisphere
The trend decomposition of the GEM concentration signal from March 2014 to December 2016 is shown in Fig. 2

Summary

Introduction

Mercury (Hg) is of crucial concern to public health and the global environment for its neurotoxicity, long-distance transport, and bioaccumulation. The atmosphere is an important channel for global Hg transport. Once atmospheric Hg deposits to the aquatic system, it can be transformed into methylmercury (MeHg), which bioaccumulates through the food web and affects the central nervous system of human beings (Mason et al, 1995). Hg is on the priority list of several international agreements and conventions dealing with environmental protection, including the Minamata Convention on Mercury. Atmospheric Hg exists in three operationally defined forms: gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM). The sum of GEM and GOM is known as total gaseous mercury (TGM). Hg is mainly present as GEM, accounting for over 95 % of the total at most obser-

Methods

Results

Conclusion