Thiosulfate amendment reduces mercury accumulation in rice (Oryza sativa L.)
- 326 Downloads
Background and aims
Thiosulfate addition increases the solubility of mercury (Hg) in soil and Hg uptake by plants under oxic conditions. However, anoxic conditions could dominate the biogeochemical processes of Hg cycling during rice cultivation. The present study aimed to determine whether thiosulfate, a sulfur-containing fertilizer, could be used for Hg immobilization in paddy soil.
A pot experiment was conducted using soil newly spiked with Hg and different doses of thiosulfate. Total Hg concentrations in rice tissues, Hg speciation in roots, and geochemical fraction of Hg in soils were investigated. Hydroponic cultivation was conducted to determine the subcellular distribution of Hg in root tissues.
Thiosulfate application significantly reduced Hg concentration in rice plants. It increased the percentage of organic-bound Hg, but decreased the percentage of iron/manganese oxide-bound Hg. Thiosulfate enhanced iron plaque formation and Hg adsorption on the iron plaque. Its application increased the percentage of Hg forms similar to HgS and decreased those similar to Hg-glutathione [Hg(GS)2].
Thiosulfate amendments had a remarkable inhibitory effect on Hg accumulation in rice plants in newly Hg-spiked soil. This occurred because thiosulfate reduced Hg mobility in the rhizosphere and root tissues, promoted the formation of iron plaque, and facilitated more Hg adsorption by the iron plaque. Our findings suggest that appropriate thiosulfate treatment could be used as Hg-immobilizing agents in paddy soil.
KeywordsThiosulfate Mercury speciation Paddy soil Iron plaque Anoxic condition
This work was financially supported by National Natural Science Foundation of China (U1432241, 21377129, and 21777162) and the National Student’s Innovative Entrepreneurial Training Program of China (201710389032).
- Bo BJ, Bak F (1991) Pathways and microbiology of thiosulfate transformations and sulfate reduction in a marine sediment (Kattegat, Denmark). Appl Environ Microbiol 57:847–856Google Scholar
- Fu Y, Yu Z, Cai K, Shen H (2010) Mechanisms of iron plaque formation on root surface of rice plants and their ecological and environmental effects: a review. J Plant Nutri Fertil 16:1527–1534Google Scholar
- Kot FS, Rapoport VL, Kharitonova GV (2007) Immobilization of soil mercury by colloidal sulphur in the laboratory experiment. Cent Eur J Chem 5:846–857Google Scholar
- Qu D, Zhang YP, Schnell S (2003) Reduction of iron oxides and its effect on microbial processes in anaerobic paddy soil. Acta Pedol Sin 40:858–863Google Scholar