Document Type

Thesis

Comments

Department of Science and Technology

Abstract

Throughout human history terrestrial environments have been disturbed and contaminated through improper waste practices and disposal methods. New technology has emerged for cleanup and mitigation, but may cause additional ecosystem perturbance. One way of reducing ecological stress is to utilize bioremediation, mainly phytoremediation. Due to its persistence in polluted environments Lythrum salicaria (Purple Loosestrife), an invasive plant species, was thought to have the potential to uptake pollutants (such as heavy trace metals) from the environment and thus help to effectively clean up a polluted environment. Three Rhode Island sites with large stands of L. salicaria were studied by analyzing plant and soil samples. All sites had potentially been exposed to some contamination, as a result of being located near a roadway or industrial operation, or in the path of storm water runoff. ICP-MS was used to analyze trace metal levels of Zn, Mg, Ca, Cr, Ni, Mn, Cu, As, Se, Ag, Cd, Ba, and Pb in all samples. Trace metal levels were compared between the whole plant and soils as differentiated by site, as well as among plant leaves, stems, roots, and at each site. None of the trace metal levels (in soils or plant tissues) were above soil and plant regulatory standards. The highest concentration of metals within plant tissue varied among organs (e.g., Zn, Mg, and Ca concentrated in the leaves while other metals, e.g., Cr, concentrated in the roots). While some trace metal levels were higher in plant tissue than the soils (e.g., Ca, Zn, and Cr) others were not. The high density of clustered populations of L. salicaria would enhance the effectiveness of the plant’s phytoremediation capacity even when the concentration of a particular metal is only slightly higher than ambient soil levels.

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