Mercury Stable Isotopic Compositions in Coals from Major Coal Producing Fields in China and Their Geochemical and Environmental Implications

• Published in: Environmental science & technology Vol. 48; no. 10; pp. 5565 - 5574
• Main Authors: Yin, Runsheng, Feng, Xinbin, Chen, Jiubin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 20.05.2014
• Subjects: Analysis methods; Applied sciences; ash content; Atmospheric pollution; Chemical Fractionation; China; Coal; Coal - analysis; combustion; Emissions; Environment; Exact sciences and technology; fractionation; Geochemistry; Geography; geometry; Isotopes; Mercury; Mercury - analysis; Mercury Isotopes; Pollution; sulfur; Sulfur - analysis; Sulfur content; Asia; China; Isotopic analysis; Geochemistry; Combustion; Neurotoxic; Heavy metal; Concentration measurement; Trace element; Spatial distribution; Stable isotopes; Coal; Pollution source; Coal power plant; Fossil fuel; Isotopic fractionation; Air pollution; Poison; Mercury; Tracers
• ISSN: 0013-936X; 1520-5851; 1520-5851
• DOI: 10.1021/es500322n

Total mercury (Hg) concentrations (THg) and stable mercury isotopic compositions were measured in coal samples (n = 61) from major coal producing fields in China. The THg concentrations in coals ranged from 0.05 to 0.78 μg g–1, with a geometric mean of 0.22 μg g–1. Hg isotopic compositions in coals showed large variations both in mass-dependent fractionation (MDF, δ202Hg: −2.36 to −0.14‰) and mass-independent fractionation (MIF, Δ199Hg: −0.44 to +0.38‰). The MIF signatures in coals may reveal important information on the coal-forming conditions (e.g., humic and sapropelic). The Δ199Hg/Δ201Hg of ∼1 determined in coals indicated that a portion of Hg has been subjected to photoreduction process prior to being incorporated to coals. On the basis of THg, Hg isotopic signatures, and other geological factors (e.g., total ash content and total sulfur content), the potential sources of Hg in coals from different coal producing regions were estimated. The main source of Hg in coals from southwestern China and eastern part of northern China is likely geogenic Hg, whereas the source of Hg in coals from other parts of northern China is mainly biogenic Hg. Finally, we estimated that Hg emission from coal combustion in China is characterized by diagnostic Hg isotopic signatures (δ202Hg: ∼−0.70‰ and Δ199Hg: ∼−0.05‰). The present study demonstrates that Hg isotopes can serve as a tool in understanding the sources and transformation of Hg in coals and may also be used as a tracer to quantify Hg emissions from coal combustion.