Mercury Fractionation, Bioavailability, and the Major Factors Predicting its Transfer and Accumulation in Soil–Wheat Systems

Soil mercury (Hg) and its bioaccumulation in food crops have attracted widespread concerns globally due to its harmful effects on biota. However, soil mercury fractionation, bioavailability, and the major factors predicting its transfer and accumulation in soil–wheat-systems have not been thoroughly explored. Twenty-one (21) soil samples collected throughout China with a wide spectrum of Physico-chemical characteristics were contaminated with HgCl 2 and winter wheat ( Triticum aestivum L .) was grown on the soils in a greenhouse pot-culture experiment for 180 days. A four-step sequential extraction was used to segregate soil Hg into water-soluble (F1), exchangeable (F2), organic matter (OM) (F3), and residual fractions (F4). Stepwise multiple regression and path analysis were used to develop a prediction model and identify the major controlling factors. The results revealed that Hg contents in wheat parts positively correlated with total soil and available Hg, and Amo-Mn, while negatively correlated with soil pH, Amo-Mn, and cryst-Al. Among all soil groups, acidic soils showed the highest bioconcentration factor (BCF) with phytotoxic effects in some soils while BCF value in alkaline soils was significantly low. Furthermore, wheat phyto-available Hg was significantly correlated with available and NH 4 Ac-extractable Hg while wheat Hg accumulation had a good correlation with soil pH and available Hg. In conclusion, we suggest that the soil total Hg contents, water-soluble or exchangeable fraction, pH, OM, cryst, and Amo-Mn are the most important soil variables that supported Hg uptake in the wheat plants. thereby managing these above parameters, we can limit Hg accumulation in wheat plants