Concentration and speciation of mercury in atmospheric particulates in the Wuda coal fire area, Inner Mongolia, China

Abstract

Coal-seam re is a source of atmospheric mercury that is di cult to control. The Wuda Coal eld in Inner Mongolia, China, is one of the most severe coal re disaster areas in the world and has been burning for more than 50 years. To investigate atmospheric mercury pollution from the Wuda coal re, gaseous elemental mercury (GEM) concentrations and atmospheric particulate mercury (PHg) speciation were measured using a RA-915 + mercury analyzer and the temperature-programmed desorption (TPD) method. Near-surface GEM concentrations in the Wuda Coal eld and adjacent urban area were 80 ng m − 3 (65-90 ng m − 3 ) and 52 ng m − 3 (25-95 ng m − 3 ), respectively, which are far higher than the local background value (22 ng m − 3 ). PHg concentrations in the coal eld and urban area also reached signi cantly high levels, at 33 ng m − 3 (25-45 ng m − 3 ) and 22 ng m − 3 (14-29 ng m − 3 ), respectively. There is no clear evidence that PHg combines with organic carbon (OC) or elemental carbon (EC), but PHg concentration appears to be controlled by air acidity. PHg mainly exists in inorganic forms, such as HgCl 2 , HgS, HgO, and Hg(NO 3 ) 2 •H 2 O. This work can provide references for the speciation analysis of atmospheric PHg and the safety assessment of environmental mercury.