Sulphur Application Associated With Water Management Enhance Hyperaccumulator Extraction Rate And Decrease Rice Uptake Of Cadmium In A Sedum plumbizincicolaOryza sativa Rotation

G.M. Wua, b, Pengjie Hua, Y. M. Luoa, P. Christiea and L. H. Wua

a Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, China

b University of the Chinese Academy of Sciences, China

pjhu@issas.ac.cn

Suitable chemicals can promote or inhibit the dissolution of heavy metals, which is not only related to the nature of chemical materials, but also related to soil water conditions. Pot experiments were carried out using two kinds of soils contaminated with cadmium (Cd), one is alkaline (L-soil, Primosols, pH 8.0) and the other is neutral (T-soil, Anthrosols, pH 6.5). Soils were amended with 0, 0.5, 1, 2 and 4 g kg-1 sulphur (S). The rotation of hyperaccumulator Sedum plumbizincicola in drying and Oryza sativa (rice) in flooding was conducted. The results showed that at the first 30 d of drying growth the oxidation of amended S significantly decreased soil pH and increased soluble SO42-, Cd and Mn in both soils. In rice season soil Eh decreased to below -150 mv and pH increased to neutral at the first few days of flooding. Meanwhile soluble SO42- and Cd at S treatments decreased significantly with the prolongation of flooding time. Compared to the control, S treatments promoted shoot Cd concentrations of S. plumbizincicola at 1.8 to 5.5 times in L-soil and 2.0 to 3.2 times in T-soil, while high dosage of S treatments inhibited plant growth mainly because of Al toxicity under low pH. Rice yields increased and Cd concentration decreased at suitable S dosage. This study concluded that appropriate amendment of sulphur according to soil properties associated with water management can be a feasible method to enhance the Cd remediation efficiency by hyperaccumulator and reduce the Cd accumulation in rice in rotation system of Cd contaminated soils.

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