1 Mercury Methylation in paddy soil: Source and distribution of 2 mercury species at a Hg mining area, Guizhou Province, China 3 4 L. Zhao1,2, C.W.N. Anderson3, G.L. Qiu2, B. Meng2, D.Y. Wang1, and X. B. Feng2 5 6 1College of Resources Environment, Southwest University, Chongqing 400716, P. R. China 7 2State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of 8 Sciences, Guiyang 550002, P.R. China 9 3Soil and Earth Sciences, Institute of Agriculture and Environment, Massey University, Palmerston 10 North, New Zealand 11 Correspondence to: X. B. Feng (
[email protected]) and B. Meng (
[email protected]) 12 13 Abstract. 14 Rice paddy plantation for human consumption is dominant land uses throughout Asia. Rice paddy fields 15 have been identified as important sites for methylmerucry (MeHg) production in the terrestrial 16 ecosystem, and a primary pathway of MeHg exposure to human in mercury (Hg) mining areas. We 17 compared the source and distribution of Hg species in different compartments of the rice paddy during a 18 complete rice-growing season at two different typical Hg-contaminated mining sites in Guizhou 19 province, China: an abandoned site with high Hg concentration in soil but low concentration in 20 atmosphere, and a current-day artisanal site with low concentration in soil but high concentration in 21 atmosphere. The flux of new Hg to the ecosystem from irrigation and atmospheric deposition was 22 insignificant relative to the pool of old Hg; the dominant source of MeHg to paddy soil is in situ 1 1 methylation of inorganic Hg (IHg).