Phragmites autralis control and its effects on trace metal concentration in sediments and water quality of Utah Lake in a formally industrial site.

Phragmites australis was observed spreading in a former industrial site that was remediated in 2001 along the shores of Utah Lake. Introduced in the 1980's it has dramatically impacted the ecosystem of Utah Lake by choking out native plants, reducing biodiversity and decreasing the aesthetic value of the lake. State legislators have thus allocated significant funding for its elimination. The current method of removal involves aerial application of glyphosate-based herbicides followed by mowing, leaving the roots in the sediment. However, studies have shown that Phragmites plants sequester trace metals in their roots. Thus, management in this fashion only recycles the contaminants into the lake. It is important to control proliferation of P. autralis for ecosystem stability, its removal must be done holistically and thoughtfully. This study evaluates the impact of Phragmites spp. destruction by herbicide on water quality at a site previously contaminated by industry. Five replicate plant, water and sediment samples (0-45 cm depth) were collected near Geneva Steel where Aqua Neat herbicide has been applied. Samples were collected one month prior to aerial treatment and five months after herbicide application and analyzed for trace metals (As, Cd, Zn, Cr, Ni, Pb and Cu). Sediment core samples were divided into 15 cm increments to determine the vertical migration of trace metals in the sediment. All samples were acid digested, filtered and analyzed for trace metal content using the ICP-OES. Preliminary results show that there was a significant increase in trace metal concentration for water, sediment, and plant during the first month following AquaNeat application. For example, Cr increased from ND to .05 mgkg^-1(water); .3 mgkg^-1(plant); and .01 mgkg^-1(sediment), respectively, showing decrease in lake water quality However, from month 0 to month 1, Cr decreased gradually from .01 mgkg^-1 to .004 mgkg^-1(water), from .03 mgkg^-1 to .01 mgkg^-1(plant), and from .01 mgkg^-1 to .002 mgkg^-1(sediment), which indicate an improvement in water quality over time. These unexpected results reveal that other factors, such as plant uptake and the mobility of trace elements in the sediment play a vital role in mitigating trace metal concentration in Utah Lake.