The Immobilization of Copper in Peatlands: Characterizing the Interactions Between Copper and Natural Organic Matter

Organic soils cover large areas of Canada’s north and are vital to biogeochemical cycling. Near northern mining operations, organic soils of peatlands sequester potentially toxic metals. There is evidence that remobilization of metals takes place during cycles of freezing and thawing, which can be expected to cause seasonally elevated concentrations of metals in water discharging from peatland environments. This thesis investigates the potential seasonal export of metals from peat during freeze-thaw cycling. By characterizing different size fractions of natural organic matter and the respective complexes they form with copper, it was determined that freezing and thawing produces trends of increasing binding capacity and decreasing binding affinity in natural organic matter. Copper binding properties were also compared using two techniques commonly used to study organic matter; those being ultrafiltration and chemical extraction. It was determined that organic matter ≤ 5 kDa does not exhibit equal characteristics to chemically extracted fulvic acid.