HR: 1400h
AN: B13B-02    [Abstracts]
TI: Examining trace metal contamination in an unanthropogenically impacted lake in Algonquin Park: implications for environmental bacterial communities and antibiotic resistance
AU: * Elliott, A V
EM: elliotav@mcmaster.ca
AU: Plach, J
EM: janinaplach@gmail.com
AF: McMaster University, 1280 Main Street, Hamilton, ON L7R 4A6, Canada
AU: Droppo, I
EM: Ian.Droppo@ec.gc.ca
AF: National Water Research Institute, Environment Canada, 867 Lakeshore Roaad, Burlington, ON L8S 4K1, Canada
AU: Warren, L A
EM: warrenl@mcmaster.ca
AF: McMaster University, 1280 Main Street, Hamilton, ON L7R 4A6, Canada
AB: Identifying the biogeochemical processes influencing the interactions amongst trace metals, microbial communities, pathogenicity and antibiotic resistance (ABR) is key to predicting the emergence, dissemination and maintenance of ABR in the environmental arena. The co-selection of heavy metal resistance and ABR has been documented in metal-contaminated environments. However, as yet, little research has been conducted assessing the metal status of 'pristine' area lakes and associated environmental bacterial communities. As part of a larger project evaluating metal-bacterial-ABR-pathogen interactions, a field survey of 6 variably contaminated aquatic systems was conducted in the summer of 2008, including Brewer Lake -a highly organic, circumneutral, Fe stained lake in Algonquin Park. To our knowledge, this study is the first to assess metal concentrations for the suite of Ag, As, Cd, Co, Cu, Ni, Pb, Se, Zn amongst the water column, suspended floc and bed sediments for this lake. The characterization and sampling protocol included 1) in situ characterization of overlying water column physicochemical parameters and 2) collection of water samples, suspended flocs (by field flow centrifugation) and bed sediment samples (by core; surficial and at depth) for subsequent metal analysis. Floc- and sediment-associated metals were partitioned into 6 operationally defined solid matrix fractions by sequential extraction: the exchangeable (loosely bound); carbonate; reducible amorphous Fe/Mn hydrous oxides; reducible crystalline Fe/Mn oxides; and residual fractions. Results indicate that the partitioning of metals between solid (floc, sediments) and dissolved compartments is largely element- dependent. Mean total metal concentrations in the sediments ranged from nM (Ag,Se, Cd) to μM (As, Co, Cu, Ni, Pb, Zn) with only Cu and Co (nM) and Zn ( μM) being detected in the water column. However in all cases floc-associated metal concentrations were an order of magnitude greater than in any other compartment (with the exception of Cd), indicating the role of floc as a metal-sink in this system. Moreover, within the floc, metal retention and affinities for the solid matrix fractions were in general different than those observed within the bed sediments (surficial and at depth) indicating differing suspended vs bed sediment controls in metal sequestration. These results will be discussed in the context of metal distributions within Brewer Lake as well as the possible implications for microbial community and ABR dynamics.
DE: 0458 Limnology (1845, 4239, 4942)
DE: 0461 Metals
DE: 0489 Trace element cycling (4875)
DE: 0496 Water quality
DE: 4875 Trace elements (0489)
SC: Biogeosciences [B]
MN: 2009 Joint Assembly