Migration Study Of Mn In The Gangue-Water-Plant System Influenced By The Growth Of Pinus Massoniana

There are a large amount of coal mining and consumption in C hina.With the prerequisite of pursuing high-speed society and economy development,the fact is left out that the ecological environment has been devastated seriously.Large amount of mines and other resources have been exploited unduly and created tremendous waste rocks and tailings which were stocked alongside mines irregularly,occupying lands,generating dust,emitting poisonous gases and large amount of acid water.It has caused obvious ecological damage towards ambient environment and gradually become the focused object of national management administrations and many domestic scholars.Plants,as a source of life activities and material production in nature,become a critical part of material circulation.Some plants have high resistivity and the ability to absorb and accumulate pollutants,thus become key objects of mine soil restoration study.Pinus massoniana,the main vegetation form in our country's southern forest ecological system,has a special biological resistivity which makes it an advantageous and avant-garde species for mountain forestation and mine vegetation recovery.So,studying the ecological function of pinus massoniana for pollutant migration in gangue stocking yard is of great significance.Based on the investigation about the pollution conditions of the coal gangue stocking yard and its ambient environment,this article focused on the coal gangue in the stocking yard,analyzed the main pollutants of the stocking yard influencing ambient environment,studied their absorption and accumulation status caused by pinus massoniana which growed on the stocking yard.This article further analyzed the influences of the root system of pinus massoniana on the growth media of coal gangue,also sampled and analyzed soil of the root system,rhizosphere soil solution,infiltration water of the stocking yard and etc..Finally it discussed the migration of Mn in the gangue-water-plant system influenced by the growth of pinus massoniana through many approaches such as potting plant cultivation,content analysis of organic acid in rhizosphere soil,leaching simulation of rhizosphere organic acid in the stocking yard,element form analysis of gangue in wild rhizosphere soil and after indoors leaching simulation,mineral component analysis of X-ray diffraction inspection and etc..The main conclusions are as follows:(1)Affected by water drainage of coal gangue storage yard,contents of most ions such as Fe and Mn in the surface water body around the yard were significantly higher than in natural water.The concentrations of Mn are up to 8.78 to 34.47 mg/L,and they were 88 to 345 times that of the limit of Surface Water Quality Standards.Obvious accumulations of Fe and Mn also appeared in soil around the yard,and the concentrations of Mn are up to 226 to 1039 mg/kg,the accumulation index of Mn reached 2.77.Fe,Mn and other elements in ambient soil created evident ambulation phenomenon.(2)Pinus massoniana has certain cumulative action of element Fe and Mn,and the action is especially stronger for Mn.The concentrations of Mn in dead leaves reached to 1477 to 2352mg/kg,and its enrichment factor is likely to reach 9.02.By pinus massoniana's root exudates,root uptake and accumulation in leaves,the contents of Fe and Mn in rhizosphere soil solution of pinus massonianas growing on the coal gangue storage yard were significantly lower than in non-rhizosphere soil solution,besides,the contents of Fe and Mn in the potting infiltration water where pinus massoniana grows were significantly lower than in the potting infiltration water without the growth of pinus massonianas,the damp of Mn reached to 23.50 to 93.27%.Resulting for that the migrations of Mn to the water is reduced to a certain extent.(3)The content of total organic acids in rhizosphere soil of pinus massonianas that grow on coal gangue storage yard is merely 0.34 to 0.66mmol/kg.Low molecular organic acid and fulvic acid can increase the exsolution of Fe and Mn in coal gangue and with the increase of organic acid concentration,the exsolution amount evidently increases.When the concentrations of organic acids rise to 25 mmol/L,the concentrations of Mn are 1.11 to 2.32 times as high as that of in the 0.5 mmol/L organic acids.For organic acids of different types,the difference in the exsolution amounts of Fe and Mn in coal gangue is great.O xalic acid has strong exsolution effect on Fe,followed by citric acid,tartaric acid and malic acid,fulvic acid has weak exsolution effect on Fe while strong exsolution effect on Mn,followed by oxalic acid.The exsolution effect of citric acid,tartaric acid and malic acid is relatively smal.(4)Organic acid can increase the contents of Mn in water-soluble form,exchangeable form and amorphous iron o xidation form in coal gangue,and the contents will enhance with the increase of the concentration of organic acid;the content of Mn in exchangeable form and amorphous iron oxidation form can be significantly enhanced by oxalic acid leaching,the increment of them can reach to 30% and 11% respectively.But the fulvic acid can further increase the content of Mn in exchangeable form;the increment of it can reach to 140%,which significantly increases the effectiveness and viability of Mn in coal gangue.(5)Changes in environmental factors also exert obvious effect on the exsolution of Fe and Mn in the coal gangue.As temperature rises,contents of Fe and Mn in the treating leaching liquid increase in varying degrees and the increase of water content can also promote the release of Fe and Mn in the coal gangue.The alternant warming and cooling treatment can significantly reduce the exsolution of Fe and Mn in the coal gangue,the decreasing amplitude of fulvic acid treatment is the most obvious,and Fe has more obvious decreasing amplitude than Mn,besides the degree of reduction of Fe can reach to 36.59%.