Shoreline cleanup and sampling is complete following the Dinan Bay diesel spill last month.
Taan Forest spilled approximately 4,500 litres of diesel into the bay on April 22, when a valve feeding fuel to the electrical generator on the Toba Barge failed.
According to a release from the Council of the Haida Nation’s business arm HaiCo and its company Taan Forest, sampling of water, soil and marine life was completed on May 10, and “there has been no observed fish kills by response personnel, sampling personnel or shoreline assessment personnel.”
“Samples have been taken in accordance with the approved sampling plan and are being analyzed,” the release said, adding the labs that are doing the analysis are located in Vancouver and Ontario. “Once this data has been reviewed by the environmental unit and Unified Command, which are made up of representatives of the Council of Haida Nation, the federal government, the provincial government, and Taan Forest, the results will be released.”
Impact of Diesel Spills
In the meantime, an assistant professor at Simon Fraser University has provided some general insights into the impact of diesel spills on the environment.
Vicki Marlatt, associate professor of environmental toxicology and biology, told the Observer that while “these types of spills are very specific” and “different environments are going to respond differently,” the main toxic component in the diesel that would have been spilled into Dinan Bay is a group of chemicals called polycyclic aromatic hydrocarbons (PAHs), which are on the List of Toxic Substances under the Canadian Environmental Protection Act.
“When oil or fuel spills occur, such as the diesel spill in Dinan Bay, PAHs may be introduced at high concentrations that cause harmful effects to animals immediately or during longer-term exposure, depending on the types of PAHs and other components present in the spilled product,” Marlatt said.
Evaporation & Dissipation
She also noted that an earlier release on April 25 said over 50 per cent of the spilled diesel evaporated and dissipated within the first 24 hours.
While the diesel evaporating is good for marine life, she said PAHs do not degrade rapidly in air, “so they’ll be transported a short or long distance and potentially be deposited back on land.”
The PAHs that dissipated would have been most likely to sorb to particulates in the water column, she added, and could then be ingested by animals in the water column or sink to the bottom and become incorporated into bottom sediments.
Once PAHs are bound to bottom sediments, “there won’t be a lot of risk from inhalation or dermal exposure via water” for humans.
Harmful To Aquatic Life
However, “during this second, longer-term exposure to PAHs, depending on the concentration and types of PAHs present, they may cause harmful effects in bottom-dwelling aquatic wildlife, such as decreased reproduction, growth and survival.”
Marlatt said ongoing measurements of the PAHs in marine sediment, water, fish and shellfish will be key in understanding the extent of contamination of Dinan Bay, the effects this diesel spill had on the survival and growth of aquatic wildlife in the area, and on water quality issues relevant to humans.
“Ideally the cleanup and the monitoring effort, they’ll … let the residents know if the concentration of PAHs is low, and wouldn’t cause any adverse effects,” she said. “The reality is that particular bay is going to have some elevated levels of PAHs to some degree after this spill, which is very unfortunate.”
Transport Canada Assessing Situation
Alexandre Desjardins, senior communications advisor for Transport Canada, told the Observer the department is following up on the incident.
“Until our assessment is complete, we are not in a position to speculate on the types of fines that could be incurred,” Desjardins said.
“In general, there are a range of federal (Fisheries and Oceans Canada, Transport Canada, Environment and Climate Change Canada) and provincial (Province of B.C.) statutes that could apply, depending on the circumstances of an oil spill on water. Aligned with this are a range of measures in place to prevent spills, and a range of penalties to discourage behavior that could lead to spills, on water.”
Top photo credit: The Dinan Bay diesel spill is pictured on the day it was discovered, which was Wednesday, April 22, 2020, shown via National Aerial Surveillance Program overflight. (Transport Canada/Submitted photo)