Effects of Variable Soil Moisture Content on Elemental Mercury Emissions from Naturally Contaminated Sub-Zero Temperature Soils

• Main Author: Glassford, Shannon
• Other Authors: Van Heyst, Bill
• Format: Thesis
• Language: English
• Published: University of Guelph 2016
• Subjects: Elemental mercury flux; water table; freeze-thaw; soil moisture; phase change; Arctic
• Online Access: http://hdl.handle.net/10214/9603

Mercury is an omnipresent element in the environment with a distinct set of properties that has caused its classification as a persistent and toxic global pollutant with the ability to bioaccumulate in aquatic environments. Although knowledge surrounding both natural and anthropogenic sources is well understood, research describing species transformation and global transport is limited. Researchers recognize that extreme northern and southern latitudes, such as the Arctic, act as sinks for Hg species. However, numerous studies neglect the potential for re-emission from terrestrial substrates under sub-zero temperatures. The objective of this thesis was to investigate how elemental mercury (Hg0) flux from soils behave in the presence of a water table during seasonal temperature cycling. A laboratory scale experiment was conducted using a Dynamic Flux Chamber (DFC) to monitor Hg0 flux being emitted from Hg enriched soil and water samples under temperature cycling conditions representative of northern climates. The results showed that a water table does influence Hg emission. During freeze thaw (FT) soil trials, water lost through evaporation was replenished by the water table, wicking Hg from deep within the column to the surface, increasing the Hg flux. During the water trials, Hg flux maximums were correlated with the water temperature occurring during the phase change in the thawing cycle. Modifications to the experimental setup have been recommended to increase accuracy in future trials.