Zinc,Cadmium and Lead Accumulation and Characteristics of Rhizosphere Microbial Population Associated with Hyperaccumulator <Emphasis Type="Italic">Sedum Alfredii</Emphasis> Hance Under Natural Conditions |
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Authors: | Long Xin-Xian Zhang Yu-Gang Jun Dai and Zhou Qixing |
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Institution: | (1) College of Natural Resources and Environment, South China Agricultural University, 510642 Guangzhou, China;(2) Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology, Chinese Academy of Sciences, 110016 Shenyang, China |
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Abstract: | A field survey was conducted to study the characteristics of zinc, cadmium, and lead accumulation and rhizosphere microbial
population associated with hyperaccumulator Sedum alfredii Hance growing natively on an old lead/zinc mining site. We found significant hyperaccumulation of zinc and cadmium in field
samples of S. alfredii, with maximal shoot concentrations of 9.10–19.61 g kg−1 zinc and 0.12–1.23 g kg−1 cadmium, shoot/root ratios ranging from 1.75 to 3.19 (average 2.54) for zinc, 3.36 to 4.43 (average 3.85) for cadmium, shoot
bioaccumulation factors of zinc and cadmium being 1.46–4.84 and 7.35–17.41, respectively. While most of lead was retained
in roots, thus indicating exclusion as a tolerance strategy for lead. Compared to the non-rhizosphere soil, organic matter
and total nitrogen and phosphorus content, CEC and water extractable zinc, cadmium, and lead concentration were significantly
higher, but pH was smaller in rhizosphere soil. The rhizosphere soil of S. alfredii harbored a wide variety of microorganism. In general, significantly higher numbers of culturable bacteria, actinomycetes,
and fungi were found in the rhizosphere compared to bulk soil, confirming the stimulatory effect of the S. alfredii rhizosphere on microbial growth and proliferation. Analyses of BIOLOG data also showed that the growth of S. alfredii resulted in observable changes in BIOLOG metabolic profiles, utilization ability of different carbon substrates of microbial
communities in the rhizosphere soil were also higher than the non-rhizosphere, confirming a functional effect of the rhizosphere
of S. alfredii on bacterial population. |
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Keywords: | Sedum alfredii Hance Rhizosphere Soil microbial population Hyperaccumulation |
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