The local impact of a coal-fired power plant on inorganic mercury and methyl-mercury distribution in rice (Oryza sativa L.)

- The impact of coal-fired power plant on soil and rice Hg concentrations was studied.
- Hg emissions from coal-fired power plant can increase both the Hg(II) and MeHg in rice.
- The positive relations between rice MeHg and soil biogeochemical Hg fractions, soil total S, and GEM were observed.
- Soil total S also was negatively correlated to the Hg(II) in rice, indicating the different sources of them.

Emission from coal-fired power plants is one of the major anthropogenic sources of mercury (Hg) in the environment, because emitted Hg can be quickly deposited nearby the source, attention is paid to the effects of coal-burning facilities on levels of toxic methyl-mercury (MeHg) in biota near such sources. Since rice is an agricultural crop that can bio-accumulate MeHg, the potential effects of a large Hg-emitting coal-fired power plant in Hunan Province, China on both inorganic Hg (Hg(II)) and MeHg distributions in rice was investigated. Relatively high MeHg (up to 3.8 μg kg−1) and Hg(II) (up to 22 μg kg−1) concentrations were observed in rice samples collected adjacent to the plant, suggesting a potential impact of Hg emission from the coal fired power plant on the accumulation of Hg in rice in the area. Concentrations of MeHg in rice were positively correlated with soil MeHg, soil S, and gaseous elemental Hg (GEM) in ambient air. Soil MeHg was the most important factor controlling MeHg concentrations in rice. The methylation of Hg in soils may be controlled by factors such as the chemical speciation of inorganic Hg, soil S, and ambient GEM.