EFFECTS OF PLANTING YEARS ON THE CONTENTS AND CHEMICALSPECIATION OF HEAVY METALS IN THE MATRIX OF COAL GANGUE WITH ECOLOGICAL RESTORATION BY VETIVER GRASS (VETIVERIA ZIZANIOIDES)

摘要

The arbitrary exploitation of coal resources has produced a large amount of coal gangue,which has produced lots of ecological and environmental problems.The research objective of this paper is the growth substrate under the vetiver grass (Vetiveria zizanioides) community of Dahe Coal Mine in Liupanshui City,Guizhou Province,China.The changes of the content and appearance of heavy metals (Cu,Zn,Pb,Cd,As) in coal gangue matrix with different recovery years were evaluated.The content of heavy metals in the matrix and its chemical speci-ation were determined by ICP-AES and Tessier's sequential extraction method,respectively.Correlation analysis and principal component analysis were carried out between heavy metal content,Chemical Speciation and physicochemical properties.Results showed that the growth of vetiver in coal gangue hills improved the physical and chemical properties of coal gangue matrix.Vetiver has a good adsorption effect on heavy metals in coal gangue matrix.On the whole,planting vetiver reduced the contents of heavy metals Cu,Zn,Cd,Pb and As in the matrix compared with the unplanted vetiver substrate.The different forms of five heavy metals showed different changes with the extension of vetiver planting years.The five heavy metals Cu,Zn,Cd,Pb and As are mainly in the most stable residual state and relatively stable organic combined state and carbonate bound state in the matrix.