Environmental recovery in Sydney Harbour, Nova Scotia: Evidence of natural and anthropogenic sediment capping

• Published in: Marine pollution bulletin Vol. 74; no. 1; pp. 446 - 452
• Main Authors: Walker, Tony R., MacAskill, Devin, Weaver, Peter
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 15.09.2013; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Coke; Conservation, protection and management of environment and wildlife; Ecotoxicology, biological effects of pollution; Environmental degradation: ecosystems survey and restoration; Environmental Monitoring; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Harbour dredging; Marine; Marine and brackish environment; Natural recovery; Nova Scotia; Polychlorinated Biphenyls - analysis; Polycyclic Aromatic Hydrocarbons - analysis; Sea water ecosystems; Sediment capping; Sediment contaminants; Steel; Sydney Tar Ponds remediation; Synecology; Water Pollutants, Chemical - analysis; Canada; Nova Scotia; North America; America; Canada, Nova Scotia; Canada, Nova Scotia, Cape Breton I., Sydney Harbour; ANW, Canada, Nova Scotia, Cape Breton I., Sydney Harbour; Sydney Tar Ponds remediation; Natural recovery; Sediment contaminants; Harbour dredging; Sediment capping; Dredging; Harbor zone; Sediments; Freshwater environment; Marine environment; Pond; Ecological recovery; Rehabilitation; Contaminant; Anthropogenic factor
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2013.06.013

•We report new baseline sediment contaminant concentrations in Sydney Harbour.•Current contaminant concentrations were much lower than in previous studies.•Measured natural sediment recovery rates were comparable to predicted levels.•Natural sediment recovery was not impeded by remediation of the Sydney Tar Ponds.•Enhanced recovery also occurred during large scale dredging operations. Contaminants were assessed in Sydney Harbour during baseline and three years of remediation of a former coking and steel facility. Concentrations of PAHs; PCBs; and lead measured in surface sediments indicate overall spatial distribution patterns of historical contaminants remains unchanged, although at much lower concentrations than previously reported due to natural sediment recovery. Recovery rates were in broad agreement with predicted concentrations; or in some cases lower, despite remediation at the Sydney Tar Ponds (STP) site. Contaminants showed little temporal variability, except for detection of significant increases in PAH concentrations during onset of remediation compared to baseline which represented a short term interruption in the overall long term natural recovery of sediments in Sydney Harbour. Recovery (via “capping”) was enhanced following recent harbour dredging activities where less contaminated outer harbour sediments were discharged into a confined disposal facility (CDF) required for a new container in the inner harbour.