Master of Science (MSc)
Faculty of Science
Dr. Jim McGeer
The potential for aquatic ecosystem recovery as a result of dissolved organic matter (DOM) protecting against metal toxicity has become a significant area of research in environmental toxicology. It is a well-characterized relationship that DOM binds free metal ions in a concentration-dependant manner, making them unavailable for toxic action and a reduction in toxicity is seen. Less understood is source variability and how the upland terrestrial environment influences the protective quality of DOM. The aim of this study was to examine the influence of land disturbance (logging, fire, smelter emissions) on DOM quality by comparing the protective capacity of different sources on Cu toxicity and bioaccumulation in Hyalella azteca. Acute (96h) and chronic (28d) toxicity tests were done according to Environment Canada standard methods, and were completed in duplicate (acute) or triplicate (chronic) using 10 Hyalella aged 2-9 days old added to solutions of Cu (0-4µM) and DOM sources at a DOC concentration of 5mg C/L (acute) or 7mg C/L (chronic). Test solutions were maintained at pH 7.2±0.1, 21±1ºC, and 13mg/L CaCO3 hardness. Both acute and chronic toxicity tests showed significant variability among sources, with disturbed sites offering less protection than reference sites. The acute results were supported with 6h Cu uptake/binding experiments and optical characterizations (excitation-emission matrix spectroscopy, absorbance at 340nm and fluorescent indices). Chronic toxicity was associated with the dry weight of organisms at Day 28, but not bioaccumulation because it appears that H. azteca are capable of regulating Cu. Both acute and chronic toxicity predictions were generated and improved by incorporating SAC340 and % humic acid content into the biotic ligand model (BLM). This project contributes toward an improved understanding of DOM quality characteristics and in conjunction with additional studies; it can potentially be applied to large scale ecosystem remediation efforts.
Livingstone, Kelly, "DOES ECOSYSTEM DISTURBANCE ALTER THE CAPACITY OF DISSOLVED ORGANIC MATTER TO MITIGATE THE IMPACT OF COPPER TO HYALELLA AZTECA?" (2013). Theses and Dissertations (Comprehensive). 1622.