Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (4): 629-637.DOI: 10.3773/j.issn.1005-264x.2009.04.001

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EFFECTS OF NATURAL INHABITATION BY MISCANTHUS FLORIDULUS ON HEAVY METAL SPECIATIONS AND FUNCTION AND DIVERSITY OF MICROBIAL COMMUNITY IN MINE TAILING SAND

ZHANG Chong-Bang(), WANG Jiang, KE Shi-Xing, JIN Ze-Xin   

  1. School of Life Sciences, Taizhou University, Linhai, Zhejiang 317000, China
  • Received:2008-09-01 Revised:2009-01-13 Online:2009-09-01 Published:2009-07-30
  • Contact: ZHANG Chong-Bang

Abstract:

Aims Our objectives are to 1) evaluate the transformation of heavy metal speciations, the mineralization of soil microbial community and diversity of soil microbial community along an inhabitation gradient of Miscanthus floridulus and 2) test relationships between heavy metal speciations and microbial parameters during natural inhabitation by M. floridulus. This is the first step towards large scale application of M. floridulus to the revegetation of mine tailings.
Methods On the basis of the cover of M. floridulus, four levels of inhabitation were selected, along with one bare site for comparison. Three sample plots were randomly placed in each of the five sites, and rhizosphere soil samples were collected from five randomly selected plants in each plot. Heavy metal speciations were analyzed using Tessier’s sequent extraction techniques plus ICP-OES apparatus. Mineralization of the microbial community was determined using soil-culturing methods, and diversity of the microbial community was tested using BIOLOG-Ecoplate.
Important findings Natural inhabitation by M. floridulus significantly increased ratios of individual heavy metal content bound to carbonates and sulfide-organic matter to total corresponding heavy metal content (p<0.05), but decreased the heavy metal ratios bound to residual fraction (p<0.05). Cellulose decomposition, phenol transformation, nitrogen fixation, ammonification, nitrification, organic phosphorus decomposition, functional diversity of the soil community and utilization by the soil microbial community of four carbon substrate groups (carbohydrates, polymers, amines/amides and miscellaneous) significantly increased with inhabitation by M. floridulus (p<0.05), but the utilization of amino acids significantly decreased (p<0.05). Canonical correlation analysis showed that the aggregated changes in microbial functional parameters were significantly and positively related to the heavy metal ratios bound to carbonates and sulfides-organic matter, but were significantly and negatively related to the heavy metal ratios bound to residuals fractions. Our results indicated that natural inhabitation by M. floridulus not only promoted transformation of heavy metals in the mine tailing sand to precipitated and chelated speciation, but also significantly improved functioning of the microbial community. Therefore, M. floridulus exhibited potential for the revegetation of abandoned mining lands contaminated with heavy metals.

Key words: Miscanthus floridulus, mine tailing sand, heavy metal speciations, function and diversity of microbial community