|Institution:||Colorado State University – Pueblo|
|Keywords:||Biomonitoring; Leaves; Mercury – Environmental aspects; Atmospheric mercury; Vegetation monitoring|
|Full text PDF:||http://hdl.handle.net/10217/173049|
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 July 2015. Air concentrations measured range from 1.905 ng m-3 at 34 °C to 0.0515 ng m-3 at -15 °C. The correlation of atmospheric mercury concentrations with temperature resulted in an equation with an R2 value of 0.8 indicating that the line fits the data well. The equation developed here was used to estimate atmospheric mercury concentrations on days leaf samples were collected. 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. Deciduous trees such as oak and birch have been studied as potential biomonitors, and this study expands into the possible use of willow, cottonwood and Russian olive. Samples were collected every week to every other week, dried in an oven at 40 ºC for three days to one week, and homogenized using mortar and pestle. The samples were then analyzed using a direct mercury analyzer. Three cottonwood trees from which samples were collected had mercury concentrations that ranged from 4.2 ±0.3 μg kg-1 to 9.9 ± 0.2 μg kg-1, 2.3 ± 0.2 to 8.5 ± 0.2 μg kg-1 and 3.6 ± 0.1 μg kg-1 to 17.1 μg kg-1 ± 0.4. Willow and olive samples contained mercury concentrations of 8.6 ± 0.3 to 24.1 ± 0.4 μg kg-1 and 5.6 ± 0.1 to 20.8 ± 0.3 μg kg-1 respectively. Linear relationships over the growing season were observed for the willow and cottonwood 2 (especially over the first ten weeks of growth) and the olive. The concentrations of mercury in the leaves from the first ten weeks of growth were plotted against the approximate atmospheric mercury concentration for the willow and cottonwood 2 which resulted in a linear fit with R2 values of 0.76 and 0.84, respectively. Advisors/Committee Members: Lehmpuhl, David W. (advisor), Kinney, Chad (committee member), Ramos, Claire (committee member), Farrer, Richard (committee member).