Rio Tinto Alcan (RTA) is applying for a permit to increase production and improve environmental standards at its smelter in Kitimat British Columbia. A potential effect of the upgrade is an increase in SO2 emissions. Limnotek worked with a team led by ESSA Technologies Ltd to examine critical loads of acidity to soils and surface waters within areas receiving deposition from the emission plume, among other analyses associated with vegetation and public health. The acidity comes from oxidation of SO2 to form SO4 that combines with hydrogen to form sulphuric acid. Critical load of acidity is an estimate of exposure to pollutants below which harmful effects on elements of the environment do not occur according to present knowledge.
Limnotek worked with ESSA, RTA, and regulatory authorities to indentify valued ecosystem components that may be sensitive to the critical load of acidity. Limnotek then designed and implemented a water sampling program to capture necessary chemical data from remote and logistically challenging areas ranging in elevation from sea level to the snow-covered alpine within and outside of the expected plume. Major cations and anions plus pH, Gran acid neutralizing capacity, and dissolved organic carbon was measured. Field and lab quality control was strictly followed, resulting in some of the highest quality data recorded for this type of application. The data were used by ESSA Technologies for running the critical load calculations.