<p> Metal contamination from anthropogenic activities is of great concern due to the
associated detrimental effects on ecosystem health. An increase in metal concentrations
in the dissolved phase creates greater ecosystem impacts. Thus, the relative extent of
metal distribution between sediment and dissolved compartments, and an understanding
of the factors that control this partitioning is key to assessing metal impacts. In this
thesis, metal concentrations were determined for a suite of 12 metals (Cr, Mn, Co, Cu,
Sn, Ag, As, Ni, Zn, Cd, Se and Fe) associated with three compartments, dissolved,
surficial bed sediment and suspended particulate matter (SPM) in Hamilton Harbour,
Ontario. Due to highly dynamic interactions of anthropogenic impacts that may work
together to affect metal distributions as well as processes that occur over small or rapid
scales, a high-resolution temporal and spatial scale was used to evaluate these metal
distributions over a seasonal timeframe. </p> <p> Concentrations of metals amongst sediment fractions indicated that sediment
metal uptake was largely controlled by the concentration of the sediment associated
amorphous and crystalline oxyhydroxide fractions accounting for up to 90% of total
sediment bound metal, even though the oxyhydroxides only accounted for a maximum of
23% of the total sediment mass for both surficial bed sediment and SPM compartments.
The formation and dissolution of amorphous oxyhydroxides is commonly a microbially
mediated process. Thus, these results underscore the important role of oxyhydroxides
and the microbial processes that contribute to their formation and dissolution m
controlling metal dynamics, and likely metal impacts in Hamilton Harbour. </p> <p> Metal partitioning was found to be both spatially and temporally variable for all
compartments, temporally ranging 0.5 to 4 orders of magnitude for a given element;
indicating highly dynamic metal exchanges between sediment and solution compartments
and fluctuating distributions over the time and spatial scales examined. </p> <p> The suite of variables that are considered to control metal distribution between
dissolved and sediment compartments, and thus impact metal toxicity (i.e., temperature,
pH, specific conductivity, oxidation-reduction potential, dissolved organic carbon
concentration, SPM concentration (for SPM associated metals only), fraction
concentrations i.e. g carbonate /g solid, g amorphous oxyhydroxide I g solid, etc., and
dissolved metal concentrations) did not constrain the variability in observed metal
distribution behaviour, indicating that other factors in this system, such as hydrodynamic
disturbances associated with shipping traffic and channelized water currents, as well as
specific point source metal discharges, may play a larger role in determining metal
partitioning in Hamilton Harbour, compared to less anthropogenically, impacted systems.
Furthermore, no one master variable defming metal partitioning between the dissolved
and sediment compartments was found, rather relationships controlling metal distribution behavior were site, compartment, sediment fraction and element specific highlighting the
challenges for the development of a Harbour-wide management plan for priority metal
contaminants. The results presented in this thesis, show that it is necessary to consider
metal, site and compartment specific conditions as well as fully addressing temporal
variability in metal behaviour. In addition, the results of this thesis point to the need to
address hydrodynamic disturbance and point source influences on metal behaviour in
Hamilton Harbour and likely extend to other multi-impacted metal contaminated systems. </p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/21636 |
| Date | 03 1900 |
| Creators | Nelson, Tara |
| Contributors | Lesley, Warren, Geography and Earth Sciences |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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