Date of Award

8-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Huan Feng

Committee Member

Frank J. Gallagher

Committee Member

Meiyin Wu

Committee Member

Yang Deng

Committee Member

Qingzhi Zhu

Abstract

Soil metal contamination has been a concern due to the potential ecological and human health risks. In order to assist with the management and sustainable restoration of vegetated metal contaminated land, this dissertation targets at understanding the biogeochemical processes that control the assimilation of metals by plants on urban costal brownfield soils. The dissertation includes: i) micro-scale measurement of metal spatial distribution and speciation using synchrotron techniques to investigate the mechanism of metal uptake and translocation in roots based on the association between metal localizations in plant roots, ii) study on the biogeochemical factors that control plant metal assimilation efficiency and metal distribution in plan, and iii) environmental assessment of the potential ecological risk of metal contaminated brownfield sites. The micro-scale study of metal uptake and transportation were conducted on the root sections of Typha latifolia L. The results indicated that iron plaque on root surface acted as a barrier for Pb root uptake and a buffer for Zn, Mn and Cu root uptake. The accumulation of Zn, Mn and Cu in the vascular bundles and dermal tissues might follow a similar mechanism. This study also identified metal uptake efficiencies by roots, stems and leaves, which varied with soil pH, soil TOC, metal element, metal concentration, growth season, and plant species. In an evaluation of potential ecological risk of metal contaminated soil, criteria such as geoaccumulation index, enrichment factor, and ecological risk index were applied to assess metal enrichment and divided the contaminated sites into three regions with low, moderate, and high potential ecological risks. Overall, this research investigated the transport and behavior of metals in contaminated land at both the micro and macro scales. Results from this dissertation research could be used as a reference for land management agencies and environmental protection agencies in their decision-making efforts toward sustainable redevelopment and restoration of contaminated land.

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