Greenhouse Characterization of Inorganic Mercury, Methyl Mercury and Ethyl Mercury Migration and Transformation in Indian Mustard and Chinese Pakchoi

Soil mercury (Hg) contamination has long been a problem that threatens the environment and organisms. Thus, exploring the migration and transformation of Hg from soil to vegetable is vital. In this study, different Hg solutions were employed in greenhouse experiments. The Hg contents in soil and vegetable samples were determined by inductively coupled plasma – mass spectrometry. The results showed that the Hg accumulation depended on its concentration and form. A greater accumulation of inorganic Hg was observed in the roots (2.2–27.4 mg/kg) than in the aerial parts (0.6–6.0 mg/kg). A similar trend was also found in the methyl mercury (MeHg) and ethyl mercury (EtHg) irrigated groups. The MeHg contents were 0.7–8.0 μg/kg in roots and 0.1–3.7 μg/kg in aerial parts. The EtHg concentrations were 0.5–3.3 μg/kg in roots and 0.3–1.1 μg/kg in aerial parts. The translocation factors of inorganic Hg and organic Hg for both vegetables in most treatments were less than 0.5, which suggested that Hg primarily accumulated in the roots. The biological concentration factors of inorganic Hg were less than 0.4, and those for MeHg and EtHg were between 0.4 and 0.95, which indicated that the vegetables were more likely to absorb organic Hg from the soil. The methylation of inorganic Hg occurred in the roots. The potential hazards of Hg on food safety and human health must be considered in regions with serious Hg pollution.