Industrial Contaminants

Long-Term Deposition of Pollutants in Sediments on the Coast

Click on image for larger pdf version.

High concentrations of pollutants persist in sediments, mainly near industrial locations.

The pollutants shown on the map include PCBs, polycyclic aromatic hydrocarbons (PAHs), and mercury. They readily attach to sediment particles in water. They may settle to the bottom with the particles or be taken up by marine organisms, which pass the contaminants into the marine food chain.

Sediment samples from the B.C. coast show that:

• The input of pollutants has decreased as controls have taken effect, but previously deposited contaminants persist in marine sediments, especially near industrial sites. Buried contaminants tend to remain in place, with minor degradation, unless the sediment is disturbed.

• Sediments in the southern Strait of Georgia are generally more contaminated than those farther north, reflecting urban and industrial activity.

• Sediment cores show concentrations of PCBs were rising until controls on PCBs were introduced in the 1970s.

• PAH concentrations in sediments exceed provincial and federal guidelines at most sampling sites in the Fraser River estuary, Vancouver Harbour, and parts of the southeastern Georgia Strait.

• Mercury concentrations in sediments are lowest in the central Georgia Strait and near the mouth of the Fraser River. Some sites with high concentrations are located within False Creek, Howe Sound, Esquimalt Harbour, and Victoria Harbour.

For detailed information, including graph data, see In-Depth report [pdf].

Next: Cleanup of Contaminated Sites >>