Elevated CO₂ increases Cs uptake and alters microbial communities and biomass in the rhizosphere of Phytolacca americana Linn (pokeweed) and Amaranthus cruentus L. (purple amaranth) grown on soils spiked with various levels of Cs

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• 作者：Ningning Song ; Ximei Zhang ; Fangli Wang ; Changbo Zhang ; Shirong Tang
• 关键词：Elevated CO2 ; Cesium ; Hyperaccumulation ; Phytolacca americana Linn ; Amaranthus cruentus L
• 刊名：Journal of Environmental Radioactivity
• 出版年：2012
• 出版时间：October, 2012
• 年：2012
• 卷：112
• 期：Complete
• 页码：29-37
• 全文大小：847 K

文摘

General concern about increasing global atmospheric CO₂ levels owing to the ongoing fossil fuel combustion and elevated levels of radionuclides in the environment, has led to growing interest in the responses of plants to interactive effects of elevated CO₂ and radionuclides in terms of phytoremediation and food safety. To assess the combined effects of elevated CO₂ and cesium contamination on plant biomass, microbial activities in the rhizosphere soil and Cs uptake, Phytolacca americana Linn (pokeweed, C3 specie) and Amaranthus cruentus L. (purple amaranth, C4 specie) were grown in pots of soils containing five levels of cesium (0, 100, 300, 500 and 1000?mg?Cs?kg^?1) under two levels of CO₂ (360 and 860?¦ÌL?L^?1, respectively). Shoot and root biomass of P.?americana and Amaranthus crentus was generally higher under elevated CO₂ than under ambient CO₂ for all treatments. Both plant species exhibited higher Cs concentration in the shoots and roots under elevated CO₂ than ambient CO₂. For P.?americana grown at 0, 100, 300, 500 and 1000?mg?Cs?kg^?1, the increase magnitude of Cs concentration due to elevated CO₂ was 140, 18, 11, 34 and 15 % in the shoots, and 150, 20, 14, 15 and 19 % in the roots, respectively. For A.?cruentus, the corresponding value was 118, 28, 21, 14 and 17 % in the shoots, and 126, 6, 11, 17 and 22 % in the roots, respectively. Higher bioaccumulation factors were noted for both species grown under elevated CO₂ than ambient CO₂. The populations of bacteria, actinomycetes and fungi, and the microbial C and N in the rhizosphere soils of both species were higher at elevated CO₂ than at ambient CO₂ with the same concentration of Cs. The results suggested that elevated CO₂ significantly affected plant biomass, Cs uptake, soil C and N concentrations, and community composition of soil microbes associated with P.?americana and A.?cruentus roots. The knowledge gained from this investigation constitutes an important advancement in promoting utilization of CO₂ fertilization for improvement of phytoextraction of soils contaminated with radionuclides.