Eco-physiological Response Of Brassica Chinensis On Additional Molybdenum Tailings

By 2011, the capacity of Lixi molybdenum mine tailings in Jinduicheng is 165 million cubic metres. Safety and environmental problems are caused by the tailings accumulation, and tailings utilization research is imminent. In order to achieve the molybdenum tailings utilization, expertsput forward a proposal,that the molybdenum tailings can be used as soil additives. And this measure will promote the sustainable development and utilization of molybdenum tailings resources. But the ecological risk has not been evaluated. In this paper the Brassica chinensis as experimental material, research on the chemical composition of molybdenum tailings and evalute the ecological risk of the molybdenum tailings as micro mineral additive for soil. Main research results are as follows:1.With the analysis of X-ray diffraction instrument and X-ray fluorescence spectrum, we come to a conclusion, that the main mineral composition of molybdenum tailings are: SiO₂,?KNaCaBa?(AlSiO₂, FeS₂, K(AlSi₃O₈, CdGa₂Se₄, Mn₂V₂O₇, KFeMg₂?AlSiO₃?, Sr₂CrO₄,CuGaTe₂, ZnT₂ and so on.The elements in molybdenum tailings, which benefit the growth of plant, areSi?31.56%??Ca?1.94%??Zn?0.0288%??Mg?1.54%??K?3.54%??Mn?0.141%? and Cu?0.0096%?. Main toxic heavy metal elements are:Pb?0.0027%??As?0.000011%?and Cd.2. Observation of Brassica chinensis growth by adding different concentrations of molybdenum tailings, research findings 1%-5% concentration of molybdenum tailings has certain stimulative effect on Brassica chinensis growth?chlorophyll content? enzyme activity and photosynthetic capacity. In the 5% concentration of molybdenum tailings, promote plant growth work best. When the concentration continues to rise, in 10% concentration, under the stress response, Brassica chinensis seedling wilting, stem and leaf growth retardation, large excess free radicals caused membrane lipid peroxidation, reduce the activity of antioxidant enzymes and the seriously affected by heavy metal toxicity.3. The concentration of Pb and Cd in Lixi Molybdenum tailings is higher, meanwhile, the concentration of As is lower. Adding different concentration of molybdenum tailings, Cd, Pb, Cu, Zn and Mn element content in soil were significant increase trend. The effect of adding 1%-5% concentrations of molybdenum tailings on Cd and Zn content in Brassica chinensis leaves are not significant; Adding 7.5% and 10% concentration of molybdenum tailings, compared with the control, Cd and zinc content in Brassica chinensis leaves is significant rise; With the increase of concentration of molybdenum tailings, the Pb content in Brassica chinensis leaves presents rising phenomenon. The content of As is not significant in soil and Brassica chinensis leaves?P>0.05?.4.When 5% concentration of molybdenum tailings is treated by humic acid, there is some facilitation to the growth of Brassica chinensis and obvious effect on mode of occurrence of soil heavy metal. Through the research, it was found that the concentration of 2.5% Humic acid is conducive to Brassica chinensis growth and cholorphyll content and enzyme activity, photosynthetic ability enhance; Acid can be extracted in the soil Cd and Brassica chinensis' s leaves Cd content decreased significantly?P<0.05?; Adding 10% concentration of humic acid decreased the biomass and chlorophyll content, inhibit enzyme activity and photosynthesis.From the experimental results, 5% molybdenum tailings and 2.5% humic acid mixture as soil additive, can promote the growth of Brassica chinensis and reduce the ecological risk.