Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Biology

Program Name/Specialization

Integrative Biology

Faculty/School

Faculty of Science

First Advisor

Jim McGeer

Advisor Role

Thesis Supervisor

Abstract

The effects of natural organic matter (NOM) source on Cu complexation were characterized chemically, optically and biologically in soft waters. NOM from different Canadian Shield soft water lakes were concentrated using reverse osmosis and for comparison NOM was also sampled from a hard water source. NOM complexation capacity was assessed directly in Cu spiked solutions (with and without additions of NOM) by measuring free Cu activity using an ion selective electrode. Additional chemical and optical characterizations of NOM included specific absorbance coefficient (SAC; at 340 nm), excitation-emission matrix spectroscopy, protein content, and molecular weight fractionation (fraction of DOCkDa). The biological characterization of the ability of various NOMs to complex Cu was measured in rainbow trout (Oncorhynchus mykiss) using short term (3 h) gill accumulation, 96h-LC50, and the inhibition of gill Na+/K+ ATPase. Results indicate that a more allochthonous NOM having a higher HA content and a higher UV/Vis absorbance complex better with Cu and usually reduce gill Cu accumulation more effectively than autochthonous NOM sources. Those NOM sources which were used for toxicity experiments did not reveal many differences in their chemical or optical properties, yet there was still a 3.5 fold difference in NOM ability to reduce acute Cu toxicity. The geochemical prediction model Windermere Humic Aqueous Model (WHAM), was modified to account for SAC340 which increased its predictive capabilities by 18%. This suggests that SAC340 could be an important measure when considering NOM quality for better predicting Cu speciation and toxicity in aquatic environments.

Convocation Year

2009

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