TITLE:
Monitoring Re-Suspension and Transport of Dioxin Contaminated Sediment to Evaluate the Recovery of a Shallow Urban Creek Post Sediment Remediation
AUTHORS:
Lisa Richman, Liad Haimovici, Terry Kolic, Sladjana Besevic, Eric Reiner
KEYWORDS:
Dioxins, Furans, Sediment, Remediation, Contamination
JOURNAL NAME:
Journal of Environmental Protection,
Vol.7 No.3,
February
29,
2016
ABSTRACT: Pringle
Creek, identified as the source of dioxin/furan (PCDD/F) contamination to a
Lake Ontario harbour was remediated in 2008. Surface sediment collected in 2013
near the floodplain remediation was no longer contaminated (∑17PCDD\Fs ∑17PCDD\Fs
2900 pg/g dw). Nevertheless, sediment ∑17PCDD/F concentrations were lower in 2013 than
pre-remediation suggesting that cleaner sediment was being deposited in the
creek. Core data confirmed the decrease in sediment contamination through time
since the most contaminated sediment was buried. Prior to the development of a
remediation strategy for the harbour, the transport of bed-load and suspended
sediment contaminated with PCDD/F was assessed. The challenge was the shallow
water depth (0.6 m) throughout the creek thereby requiring non-standard
sediment traps designed for this study. Suspended sediment collected in traps
in 2014 showed residual contamination at the remediated site (∑17PCDD\Fs: 380 pg/g
dw; TEQ (TEF fish) ∑17PCDD\Fs concentration for suspended sediment at the creek mouth was
2200 pg/g (SD 260 pg/g dw) indicating PCDD/F contributions to the harbour.
However, congener patterns in bottom sediment and suspended sediment near the
remediated site and extending about 100 m downstream were similar to background
upstream patterns consistent with atmospheric deposition as the source rather
than the historical source which indicated that floodplain remedial actions
were successful.