Potentially harmful elements in rice paddy fields in mercury hot spots in Guizhou, China Marthe-Lise Søvik a , Thorjørn Larssen a,b,⇑ , Rolf D. Vogt b , Grethe Wibetoe b , Xinbin Feng c a Norwegian Institute for Water Research, Gaustadalléen 21, 0349 Oslo, Norway b Department of Chemistry, University of Oslo, POB 1033, 0315 Oslo, Norway c State Key Laboratory of Environmental Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China article info Article history: Available online 30 November 2010 abstract Levels of the chalcophile metals Hg, Pb, Cd, Cu and Zn and the metalloid As in soils from rice paddy fields were assessed in two regions impacted by different industrial activities in Guizhou province, China. The two study areas (Wanshan and Qingzhen) have previously received attention in the international litera- ture due to heavy Hg pollution, though levels of other potentially harmful elements have not previously been reported. The regions were selected as representing two important, but categorically different metal(loid) contaminated areas in China: Wanshan has been a major region for Hg production while Qingzhen is an important region for a large range of various heavy industries based on coal as an energy source. Within a limited distance of the Hg mine tailings in Wanshan the rice paddy fields are heavily contam- inated by Hg (median concentration 25 lgg À1 , maximum 119 lgg À1 ) and moderately contaminated by Zn and Cd (median concentrations of 86 and 0.9 lgg À1 , respectively). Zinc and Cd levels correlate well with Hg contamination, which indicates a similar source and mechanism of transport and accumulation. Other studies have concluded that the main sources of Hg contamination in Wanshan are the numerous Hg mine tailings. This is likely as these metals are all geochemically associated with the mineral cinnabar (HgS). The other chalcophile elements (Pb, Cu and As) are nevertheless found at background levels only. In Qingzhen the soils were found to contain elevated levels of As and Hg (median concentrations of 38 and 0.3 lgg À1 , respectively). These are elements that are known to be more associated with coal and released during coal combustion. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction Potentially harmful elements (PHE) are ubiquitous and are nat- ural constituents of rock and bedrock and are generally rather immobile in soils. For this reason, soils have natural background levels of these elements as a result of rock weathering. In addition to this, anthropogenic releases contribute to an increase in PHE concentrations in the environment (Alloway, 1995). Typically, the contaminants are released to air and water, and accumulate in the soil as a consequence of the strong affinity of PHE for humic matter and clay colloids (Alloway and Ayres, 1997). Due to the anthropogenic emissions the human exposure to elevated levels of PHE continues, despite well known adverse health effects, and in some emerging economies the level of exposure is increasing (Järup, 2003). China’s rapidly developing industry and energy sector has led to an increase in emissions of pollutants, including releases of a wide range of reactive forms of PHE to the environment. Widespread coal combustion and industries, such as mining and smelting, are important emission sources of PHE to air and water (Alloway, 1995). Metal mining and smelting activities release not only the metal of interest but also PHE which are associated in the ores (Alloway, 1995). China’s cinnabar (HgS) deposits rank third in the world (Jiang et al., 2006). Guizhou province, located on the circum pacific mer- curiferous belt, holds approximately 70% of the total Hg reserves in China. Mercury has been mined in this province for more than 600 a(Jiang et al., 2006) causing elevated levels of Hg in the environ- ment. Furthermore, the mercuriferous belt causes generally high Hg levels in the bedrock and in other natural resources, such as coal (Feng et al., 2002). Mercury mining, which has generally ceased during the last decade, and industrial production based on coal fired energy have been important industrial sectors in Guizhou province. Both the Hg mining and refining activities and the intense use of coal in power plants have led to large anthropogenic releases of Hg into the envi- ronment (Feng et al., 2003a). In the present study, two sampling areas were chosen, representing each of the two types of industrial 0883-2927/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeochem.2010.11.015 ⇑ Corresponding author at: Norwegian Institute for Water Research, Gaustadalléen 21, 0349 Oslo, Norway. E-mail address: tla@niva.no (T. Larssen). Applied Geochemistry 26 (2011) 167–173 Contents lists available at ScienceDirect Applied Geochemistry journal homepage: www.elsevier.com/locate/apgeochem