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(244) Phytoremediation of Perchlorate in Aquatic and Terrestrial Plants at Field Scale.
Tan, K.1, Jackson, W.1, Anderson, T.1, 1 Texas Tech University, Lubbock, TX, U.S.A.
ABSTRACT- Perchlorate (ClO4-) in surface and groundwater has become a major nationwide water quality concern. Numerous laboratory-scale studies have shown perchlorate uptake and transformation potential by a variety of plant species. Most research suggests that perchlorate is mostly accumulated in leaves rather than other tissues. However, less information is available on the seasonal uptake potential and release at field scale. The Naval Weapons Industrial Reserve Plant (NWIRP), located in central Texas, was a facility historically associated with perchlorate-containing solid propellant motors. The purpose of this study was to investigate perchlorate uptake in a variety species of aquatic and terrestrial macrophytes from multiple streams surrounding NWIRP, including seasonal variation, factors affecting phytoremediation such as distance to the stream, plant size, and plant species, as well as redistribution potential to the environment of deciduous vegetation. Studies included: (1) one year of aquatic plant and bulk water sampling (e.g. Smartweed and Watercress) from multiple streams; (2) short-term sampling of terrestrial plants (e.g. Willow and Elm) from multiple streams; (3) one year of seasonal leaf sampling during the growing season (from budding to leaf drop) of a terrestrial plant habitat along a defined reach with consistent perchlorate concentration; (4) fate of perchlorate in deciduous leaves trapped in leaf litter from this reach. Results indicated a large potential of perchlorate uptake in aquatic and terrestrial plants. Seasonal tree leaf sampling indicated that uptake of perchlorate is dependent on exposure duration, and the highest tissue concentrations were observed late in the growing cycle. In addition, different tree species (i.e. Ash, Elm, Chinaberry, Mulberry, and Hackberry) have variable uptake potential, with Hackberry having the highest. Terrestrial plants had significant perchlorate uptake up to 30 ft from the stream. The decrease of perchlorate concentration in deciduous leaves was probably associated with leaching, rainfall events, and microbial degradation.
Key words: uptake, Perchlorate, phytoremediation, plants
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