| This paper combined with the actual production in the paddy field, with the aim to recover advance subjects on rice Cadmium(Cd) pollution control and Non-point source of soil heavy metal pollution control in Hunan province. The paper selected two kinds of Cd contaminated soil types(single Cd contaminated soil and heavy metals compound contaminated soil), based on the method of rice pot experiment, during the process of rice (early rice and late rice) cultivation exerted silicon fertilizers, selenium fertilizer, lime and red mud as amendments and combined with water management measure to research on the potential and effect of rice Cd pollution control, simultaneously, explored the impacts of amendments on heavy metals migration in soil erosion. With a view to provide scientific basis of rice Cd pollution control technology and the migration laws of soil heavy metals in Hunan province. The main results of the experiment were as follow:(1) With acquired Multi-metals contaminated soil in Zhuzhou Qingshuitang Xiawan area to carry out rice pot experiment, Studied microelement fertilizers on resistance potential of rice Cd. According to the Cd resistance potential of various amendments in brown rice and milled rice showed that, compared with CK, in addition to Spraying with selenium fertilizer treatment(Yse) had no significant effect on reduction of Cd contents in brown rice and milled rice,other amendments treatments can significantly reduced the Cd concentrations of brown rice and milled rice, particularly the two kinds of silicon fertilizers treatment(Ysi+Si) effect was best, for brown rice of early rice and late rice decreased range of Cd were77.21%and58.43%, and for milled rice of early rice and late-rice decreased range of Cd were77.21%and65.71%, other treatments of Cd reduction effections are inferior.(2) With used the single Cd pollution paddy soil in Zhonglu village, Majiahe town, Tianyuan district, Zhuzhou, Hunan province to carry out rice pot experiment. Studied.kinds of amendments with water management on effects of rice Cd pollution control. It can be seen from the early rice experiment results, compared with CK, other treatments could significantly reduce the Cd contents in brown rices, especially the SiYsi+W treatment decreased the Cd content of brown rice most, Cd reduction rate reached82.70%, Cd content in brown rice was0.30mg/kg. It can be seen from the late rice experiment results, compared with CK, except Lime treatment didn’t reach the significant level, other treatments could significantly reduce the Cd contents in brown rices, the Lime+W, RM and SiYsi+W treatments decreased the Cd concentration of brown rice most, Cd reduction rates reached90.06%,87.24%and86.70%respectively, Cd contents in brown rice respectively was0.15mg/kg,0.19mg/kg and0.20mg/kg, reached the national rice production safety standard (Cd<0.2mg/kg) basically, while the others were more than the rice production standards; And compared with CK, except Yse treatment wasn’t significant, other treatments could significantly reduce Cd contents in milled rices, especially the SiYsi+W and Lime+W treatments decreased the Cd concentrations of brown rices most, RM treatment was inferior. Above three kinds of treatments’Cd reduction rates in milled rice reached respectively91.18%,90.44%and87.09%, Cd concentrations of milled rice were0.12mg/kg,0.13mg/kg and0.18mg/kg, have reached the national standard of rice safe production. Overall, in addition to RM and RM+W treatments which had different rule, other flooding treatments were more obvious Cd reduction rate than corresponding non-flooding treatments.(3) Based on rice pot experiment, author had an investigation on the impact of rainfall events and amendments(lime and silicon fertilizer) and planting early rice on heavy metals migration and loss from soil runoff solutions. Seven continuous rainfall events during seedling grown to the rice mature period of soil runoff solutions were collected, the dissolved Cu, Zn, Cd, As were measured and the total loss amounts of heavy metals were caculated. The results showed that loss water volume is proptional to the rainfall under conventional rice planting density condition. The Lime treatment could immediately increase pH of the loss solution, and the alkaline effect lasted for almost a month before returned to normal level;The results showed that, compared with CK, the Lime treatment could increase significantly concentrations and loss amouts of Cu and As in runoff solutions, but it decreased significantly the concentration and loss amout of Cd in solutions at the same time. Compared with CK, silicon fertilizer treatment could decreased significantly the concentration and loss amout of As, but it had no remarkable impacts on other heavy metals.(4) An in situ field experiment was conducted in a Cd contaminated paddy soil to reveal the effects of optimized agricultural management strategy on Cd absorption and accumulation by rice, in the smelting area of Hunan province. A popular late rice variety Excellent978was used in this experiment, lime application at end of booting stage combined with following continuous water-logging was selected as optimized agricultural management, simultaneously traditional agricultural management as a control, and Cd concentration in different rice tissues at five key growth stage was examined to evaluate effects of optimized agronomic management on Cd uptake by rice. Results showed that, rice yield increased by33.24%in optimized agronomic management of lime application and subsequent continuous water-logging treatment compared to control treatment, Cd concentration of brown rice decreased by39.32%compared to control treatment. So, lime application at end of booting stage combined with following continuous water-logging should be an effective measure to reduce rice Cd concentration standard exceeding risk and showed favorable practicality because of its easy operability, and also can provide scientific support and basis for food safety production and supervision. |
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