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| Preliminary study on the mechanism by which silicon application reduces lead bioavailability in alkaline soil |
| Received:November 09, 2018 |
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| KeyWord:silicon;lead;rice;alkaline soil;bioavailability |
| Author Name | Affiliation | E-mail | | LIU Ming-da | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | ZHANG Jing-ting | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | MA Cong | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | WANG Yao-jing | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China
College of Science, Shenyang Agricultural University, Shenyang 110866, China | wyjsau@163.com |
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| Abstract: |
| In order to clarify the mechanism of silicon reduces the bioavailability of lead in alkaline soils, by neutralizing the effects of sodium silicate alkalinity and eliminating sodium ions, the effects of silicon affected the behavior of lead, liquid, solid-liquid, and solid-liquid interfaces in alkaline soils, rice yields and lead content in rice were studied. Testing included adsorption-desorption testing, infrared analyses and pot experiments. The results showed that silicon addition reduced the capacity and strength of lead adsorption in alkaline soils, while enhancing the lag effect in lead adsorption-desorption processes. The reaction products of silicon-lead in solution were characterized by infrared spectroscopy, and it was found that both the bending vibration absorption peak of Si-O, and the anti-symmetric stretching vibration characteristic peak of Si-O-Si appeared to red shift, suggesting that the coordination reactions of either silicic acid or polysilicic acid with lead resulted in the formation of water-soluble complexes. Silicon addition reduced the contents of acid extractable and reducible lead by 11.18% and 18.54% respectively. Oxidizable lead and residual lead were observed to increase by 42.56% and 7.84% respectively, while compared with the control, rice yield decreased by 64.5% (P<0.01), and the lead content of brown rice increased significantly (P<0.01),reaching 0.31 mg·kg-1. Compared with lead stress treatment, silicon addition increased rice yield by 152.3% (P<0.01), while the lead content in brown rice decreased significantly, to the extent that the content of lead in brown rice (P<0.01) met the safety requirements specified in the applicable national standard. In conclusion, the experiments showed that silicon addition promoted the transformation of soil liquid and solid lead to an ineffective state and inhibited desorption of solid lead, thus demonstrating the chemical mechanism which reduced the bioavailability of lead in alkaline soils. |
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