Monitoring Re-Suspension and Transport of Dioxin Contaminated Sediment to Evaluate the Recovery of a Shallow Urban Creek Post Sediment Remediation

Abstract

PringleCreek, 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 < 60 pg/g dw), but residual contamination extended downstream to the creek mouth (surface sediment maximum: ∑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) < 0.6 pg/g), with concentrations increasing with distance downstream mirroring surface sediment: mean ∑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.

Riparian Spiders: Sentinels of Polychlorinated Dibenzo‐p‐dioxin and Dibenzofuran–Contaminated Sediment

“…Sediments contaminated with PCDD/F are the source of PCDD/F uptake in aquatic food webs, which can culminate in harmful exposure to humans via wildlife fish consumption. Concerns over health risks from these exposures have resulted in the issuance of fish consumption advisories, the implementation of costly remediation projects to mitigate exposure risks (Cornelissen et al, 2012; Richman et al, 2016), and the initiation of extensive monitoring studies to track PCDD/F in the environment (Gandhi et al, 2019; Turyk et al, 2012; White & Birnbaum, 2009).…”

A review of the determination of persistent organic pollutants for environmental forensics investigations

“…The QuEChERS procedure uses 16 a modified extraction procedure to significantly reduce sample preparation time. Haimovici et al [131]; 17developed a method for site cleanup that significantly enhances productivity and reduces analytical 18 turnaround time by a factor of 3 or more[154, 131].19…”