Accumulation and translocation of ¹⁹⁸Hg in four crop species
2014
Cui, Liwei | Feng, Xinbin | Lin, Che‐Jen | Wang, Xinming | Meng, Bo | Wang, Xun | Wang, Heng
The uptake and transport of mercury (Hg) through vegetation play an important role in the biogeochemical cycling of Hg. However, quantitative information regarding Hg translocation in plants is poorly understood. In the present study, Hg uptake, accumulation, and translocation in 4 crops—rice (Oryza.sativa L.), wheat (Triticum L.), corn (Zea mays L.), and oilseed rape (Brassica campestris L.)—grown in Hoagland solution were investigated using a stable isotope (¹⁹⁸Hg) tracing technique. The distribution of ¹⁹⁸Hg in root, stem, and leaf after uptake was quantified, and the release of ¹⁹⁸Hg into the air from crop leaf was investigated. It was found that the concentration of Hg accumulated in the root, stem, and leaf of rice increased linearly with the spiked ¹⁹⁸Hg concentration. The uptake equilibrium constant was estimated to be 2.35 mol Hg/g dry weight in rice root per mol/L Hg remaining in the Hoagland solution. More than 94% of ¹⁹⁸Hg uptake was accumulated in the roots for all 4 crops examined. The translocation to stem and leaf was not significant because of the absence of Hg²⁺ complexes that facilitate Hg transport in plants. The accumulated ¹⁹⁸Hg in stem and leaf was not released from the plant at air Hg⁰ concentration ranging from 0 ng/m³ to 10 ng/m³. Transfer factor data analysis showed that Hg translocation from stems to leaves was more efficient than that from roots to stems. Environ Toxicol Chem 2014;33:334–340. © 2013 SETAC
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