Study On Application Of Thiobacillus Ferrooxidans And Red Mud In Cadmium Contaminated Paddy Fields

In recent years, China rice Cd pollution is increasingly serious, Cd can be enriched through the food chain and harm to human’s health. Therefore, control and reduce rice Cd pollution has become the current focus in our country. In this paper, combined with the reality of paddy production, hunan rice Cd pollution at present, with Cd pollution of heavy metals compound pollution of soil was selected preferentially, the calculation of rice pot and field plot test, adding of thiobacillus ferrous oxide and red mud conditioner on rice Cd pollution resistance point potential and repairing effect, so as to provide technical support for rice Cd pollution control. The main results are as follows:(1)A bacterial strain QBS-01, capable of utilizing Fe2+ as the main energy, was isolated from abandoned mine soil. The strain was identified as Thiobacillus ferrooxidans preliminarily, and grew well in 9K liquid medium; the optimum pH、 inoculation amount and temperature were 2.00、10% and 30℃.(2) Pot experiment showed that the adding of red mud and/or QBS-01 strain, can reduced the Cd contents of root, stem, leaf and brown rice effectively, while improved plant height and yield of rice. The effect of QBS-01 (150 1·hm-2) and red mud (4000 kg·hm-2) combined was the best decline. Although all treatments can reduce the Cd contents of in brown rice significantly (decreased 17.62%-23.13%), however both of them higher than the maximum permissible concentration of the national food hygiene standards(Cd≤0.2 mg·kg-1).(3) After QBS-01 strain and/or red mud added in the field, the Cd content of rhizosphere soil in four stages decreased, especially the QBS-01 (1501·hm-2) combined with red mud (4000 kg·hm-2) treatment with best decline. Compared with CK, QBS-01 and red mud added respectively or compound could decreased significantly the Cd contents of organs of rice, at the same time, could changed the transport migration of Cd in rice significantly, made Cd easier accumulated in inedible parts, such as roots, stems and leaves. Among them, the effect of decreased Cd concentrations of brown rice most was QBS-01 (150 1·hm-2) combined with red mud (4000 kg·hm-2), Cd contents of brown rice was 0.48mg·kg-1, decreased 57.55%.Although all treatments can reduce the Cd contents of brown rice, however both of them higher than the maximum permissible concentration of the national food hygiene standards(Cd≤0.2 mg·kg-1).(4) After QBS-01 strain and/or red mud added in the field, soil physical and chemical properties changed significantly. The soil pH value improved by adding red mud including single and combined, however the soil pH value reduced by adding QBS-01 single; both red mud and QBS-01 had no significant effect on soil organic matter content; both QBS-01 and red mud could improved soil urease, invertase and catalase activity.(5) In four best experimental zones of Cd were 2001·hm-2 QBS-01 strain treatments, different areas of farmland on the QBS-01 reduce influence on Cd contents of brown rice, and the effect of Cd on soil physical and chemical properties of the test area and total Cd content of background, only Qibaoshan tested area B, with lower Cd soil pollution the Cd concentration of brown rice lower than the national food hygiene standards (GB 2762-2012, Cd≤0.2 mg·kg-1).