Treatment of Dioxin and Mercury Contaminated Soil by Phytoremediation

• Main Authors: Yu-Ming Wu, 吳裕民
• Other Authors: Yang Lei
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/ez2xk4

博士 === 國立中山大學 === 海洋環境及工程學系研究所 === 101 === The purpose of this study is to investigate the treatment efficiencies of PCDD/Fs and Hg contaminated soil by phytoremediation, and to learn the translocation and distribution of PCDD/Fs and Hg in the plant tissues. In addition, the object of tests of adding amendments (citric acid, P. mendocina NSYSU and EDTA) into the testing systems are to assess the effects of plants on removal rates of PCDD/Fs and Hg from the contaminated soil. The results of this research were expected to provide important reference for remediating similar contaminated sites in the future. In this study, the pot tests in greenhouse were conducted by using the contaminated soils sampled from China Petrochemical Development Corporation (CPDC) An-shun site located in Tainan City, Taiwan. The selected plant species included Bidens pilosa, Leucaena glauca, Vetiver, Paspalum vaginatum, Commelina diffusa, Maize, Physic Nut and Squash. These plant species were all characterized as rapid growth, so it would be helpful and convenient for using them in different stages of test runs. The experimental results showed that the toxicity of PCDD/Fs and Hg might inhibit the growth of plants. The higher the concentrations of PCDD/Fs were controlled in soils, the less the height and biomass of the plant were observed. In addition, the plant roots were found able to promote the activities and diversity of microbial in the areas of rhizosphere. Besides, the congener profiles and concentration levels of PCDD/Fs between the contaminated soil and the shoot and root of plant species are highly positive correlation. In this study, it is also confirmed that the PCDD/Fs and Hg were first phytoextracted into the plant roots, and then were translocated into the shoot. However, the concentrations of PCDD/Fs and Hg of root were measured much higher than the shoot. The results of tests of adding amendments showed that citric acid, P. mendocina NSYSU and EDTA would promote the uptake ability of plants for PCDD/Fs and Hg, especially the plant species of vetiver and maize. In additions, adding EDTA into test systems presented effective improvement for the plant species of vetiver and maize uptaking Hg. The experimental results for PCDD/Fs and Hg accumulating in plant tissues showed that the species of vetiver performed better than the species of maize, which meant that the species of vetiver exhibited better resistance and higher biomass than the species of maize. Moreover, the removal rates of PCDD/Fs from soils were found higher for the species of maize than the species of vetiver. However, for Hg removal rates, the experimental results indicated that the species of vetiver was found greater than the species of maize. Thus, the removal effects of PCDD/Fs and Hg from contaminated soils would vary with the different plant species. It was concluded that the higher capability of extracting PCDD/Fs and Hg into plant tissues and the ability of promoting the rhizosphere microbial activity make both species of vetiver and maize become suitable candidates for phytoremediation in soils contaminated by PCDD/Fs and Hg.