| Summary: | 博士 === 國立雲林科技大學 === 工程科技研究所 === 107 === In the Taiwan, there were many contaminated agricultural lands, because that uses contaminated water for irrigation. The contaminated agricultural lands produce food crops that exhibit a high heavy metal concentration, posing a threat toward environmental and food safety. One of treatment methods of heavy metal contaminated agricultural lands, phytoremediation exhibits advantages of low cost and energy consumption, aligning with the trend of green and sustainable remediation treatment methods. The purpose of this study was to determine the ability of Bidens pilosa var. radiata with Symbiotic effect of Glomus mosseae of arbuscular mycorrhizal fungi(AMF) to absorb and accumulate heavy metal, in order to evaluate its potential as a candidate for phytoremediation.
The experiment method comprised two parts of pot experiment and field investigation, and a total of four soil types contaminated by heavy metals in this study. For containing Cd, Cu and Zn contaminated soil of Luzhu, Taoyuan; Cu contaminated soil of Douliu, Yunlin; Cr, Cu, Ni, Pb and Zn contaminated soil of Changzhi, Pingtung, and the heavy metal concentration of all contaminated soil exceeded the value of Taiwan agricultural land control standards.
The results of indoor pot experiment indicated that in the rhizosphere environment environment in which Plant growth-promoting rhizobacteria(PGPR) weren't present, there was no hindrance to the symbiotic effect of AMF and Bidens pilosa var. radiate. However, PGPR promoted the symbiotic effect between mycorrhizal fungi and plants, substantially improving phytoremediation of copper contaminated soil. The results of outdoor pot experiment indicated that in the cadmium contaminated soils, Bidens pilosa var. radiata tend to store cadmium at the aboveground portion so that achieved the purpose of phytoextraction. In the copper contaminated soils, AMF enhanced Cu tolerance of plant roots so that promoted the effect of phytostabilization. In the five heavy metals contaminated soils, Bidens pilosa var. radiat inoculated with AMF had significantly increased benefit of phytoremediation. A situation was increased benefit of phytostabilization for Cr, Ni and Zn, another situation was increased benefit of phytoextraction and phytostabilization for Cu and Pb. The results of field investigation showed that wild Bidens pilosa var. radiat had grown normally in the multiple heavy metals contaminated farmland, and that had the effect of phytoremediation. However, the heavy metal accumulated concentration of plant was influenced by soil heterogeneity and heavy metal bioavailability. Under the same soil conditions, the heavy metals accumulation characteristics of Bidens pilosa var. radiat was highly consistent.
Phytoremediation typically requires several decades to complete. Bidens pilosa was artificially inoculated or naturally infected with AMF that had accelerated plants adaptation to heavy metals contaminated environments, thereby improving phytoremediation effects and shortening the time required for soil remediation. In the future experiments, we suggest that should involve the adoption of nutrient salt, biodegradable chelators, and appropriate harvesting time to establish ecological management system for the use of Bidens pilosa var. radiate as phytoremediation for heavy metal contaminated agricultural lands.
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