Atmospheric mercury can be a significant source of mercury to water and land areas relatively uncontaminated by the heavy metal. In this study, mercury concentrations were determined in air at various temperatures from December 2013 through the present. Air concentrations are strongly correlated with temperature and range from 1.905 ng m-3 at 34 ºC (the highest measured temperature) to 0.0515 ng m-3 at -15 ºC. Since measuring atmospheric mercury concentrations in air is difficult and time-consuming, a long-term goal of the research is to develop a model for estimating atmospheric mercury through the analysis of leaves. Studies indicate that many leaves which bioaccumulate the metal absorb a high percentage from the atmosphere. Leaves of P. deltoids (Plains Cottonwood), Salix (Willow), and E. angustifolia (Russian Olive) were collected and analyzed over their growing season beginning in April 2014. Willow has been studied as a promising biomonitor, and this study expands into the possible use of Cottonwood and Russian Olive as well. Samples were collected every week to every other week, dried in an oven at 40 ºC for two (2) to four (4) days, and homogenized using mortar and pestle. The samples were analyzed using a direct mercury analyzer and the mercury concentrations determined. All samples exhibited a general increase in the concentration of mercury as the growing season progressed. Concentrations of mercury in Willow leaves increased fairly linearly, while the concentrations in all three Cottonwood and the Russian Olive were more erratic. Total leaf concentrations ranged from 2.3 ± 0.2 to 24.1 ± 0.4 μg kg-1 but varied by species and leaf age. Work is ongoing to use the leaf concentrations to model the integrated atmospheric mercury concentrations while accounting for temperature effects.

Groundwork for the development of a model for determining atmospheric mercury in the arid West using leaves

249th National Meeting (2015)

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