Copper Alloy Mesh Pens Easily Meet Stringent Water Quality Standards for Copper in British Columbia
Researchers monitoring copper concentrations from two copper-alloy mesh (CAM) pens installed in the Fortune Channel in British Columbia (BC), found full compliance with strict BC environmental regulations. The International Copper Association worked with Mainstream Canada to install the copper alloy mesh pens in the Fortune Channel near Tofino, B.C. in November of 2012.
An aquatic chemistry team from Wilfrid Laurier University in Ontario monitored copper concentrations in the channel before, during, and after CAM pen installation, to identify any increases in copper concentrations above preexisting background levels associated with the installation. The team also monitored the potential corrosion of the CAM materials. The monitoring was required to ensure compliance with British Columbia’s marine water quality standards for copper – the most stringent in the world (2.0 ug/L total copper average and no single value higher than 3.0 ug/L).
The results of this monitoring study were presented by the Wilfrid Laurier Team at Aquaculture Canada 2013 in Guelph, Ontario in the “Innovative Technologies” session on June 3.
The results were quite favorable. Pre-installation background copper concentrations averaged 0.3 ug/L, with a few excursions as high as 1.5 ug/l. Copper concentrations were monitored for 15 days once the installation started. Concentrations downcurrent of the pens averaged about 0.4 ug/l, with one set of samples, nine days after the installation was completed, with a maximum of 2.6 ug/L. The team concluded that all of the monitoring data demonstrated full compliance with the BC copper standards.
The Laurier team also showed that the BC copper standards were more protective than necessary. The marine Biotic Ligand Model (BLM) was used. This model estimates how much of the total copper is bioavailable (and thus potentially toxic) to aquatic organisms. The BLM was also used to predict an alternative standard based on the copper’s bioavailability to blue mussels (the most sensitive organism to copper). The BLM model’s predictions indicated that copper concentrations in these waters could be as high as 7 to 11 ug/L before being toxic to mussels and other aquatic biota (post-installation measured concentrations averaged 0.4 ug/L, up to one sample at 2.6 ug/L). Thus, the BLM predictions show that the BC standards for copper are 3-to 5-times more protective than needed for all aquatic biota in these waters.
The Copper Alliance advocates the adoption of copper bioavailability and the use of tools like the BLM to set science-based copper standards with regulatory agencies worldwide. Environment Canada is now reviewing both freshwater and marine versions of the BLM for updating its copper standards.
Prepared May 30, 2013
By: Bob Dwyer
Associate Director for Environment in the Health, Environment and Sustainable Development (HESD) Initiative
International Copper Association (ICA)