Model for evaluation of the phytoavailability of chromium (Cr) to rice (Oryza sativa L.) in representative Chinese soils.

Anthropogenic chromium (Cr) pollution in soils poses a great threat to human health through the food chain. It is imperative to understand Cr phytoavailability to rice (Oryza sativa L.), which is a major staple food crop for the largest population of people on Earth. This study was aimed to establish a model for evaluation of the phytoavailability of Cr to rice in six representative Chinese soils based on soil properties. Simple correlation analysis indicated that Cr concentration in polished rice was significantly correlated with total Cr, Mehlich-3 extractable Cr, and Cr(VI) in soil. Stepwise multiple regression analysis also demonstrated that the Cr phytoavailability was strongly correlated with soil total Cr, Mehlich-3 extractable Cr, Cr(VI) concentration, soil organic matter, Fe(II), and particle size distribution. Critical Cr concentrations in the six soils were evaluated for rice based on the maximum safe level for daily intake of Cr. Mehlich-3 extractable Cr are the most suitable Cr thresholds for Periudic Argosols, Udic Ferrisols, Mollisols, and Ustic Cambosols with values of 1.54, 0.56, 0.42, and 2.18 mg kg(-1), respectively, while Cr(VI) are adequate thresholds for Calcaric Regosols and Stagnic Anthrosols with values of 0.68 and 0.84 mg kg(-1), respectively.