Kraft Pulp Mills and Pollution
Coastal scene investigation conducted by Shannon Bard to date has surveyed marine impacts of five British Columbia Kraft pulp mills with marine outfalls. The two mills in the Howe Sound region are the Howe Sound Pulp and Paper partnership mill in Port Mellon and Western Pulp Ltd. Partnership mill in Woodfibre. The mill in the Powell River region is the NorskeCanada mill and the mill in the Prince Rupert region is the Skeena Cellulose mill, located near Prince Rupert.
Historically these Kraft pulp mills have created three main environmental problems: settleable wood fibers, increased biochemical oxygen demand (BOD) and toxic effluents. Settleable wood fibres are measured as total suspended solids (TSS). Wood fibres that are discharged in pulp mill effluents will settle around diffuser pipes that can range in depth from a few centimeters to 15 meters making it very difficult for benthic organisms to survive. The wood fibers can also combine with free floating green algae in the water column and form fibrous mats that may wash ashore and smother intertidal organisms. Increased biochemical oxygen demand (BOD) in mill effluents can have lethal and sublethal effects on benthic and pelagic organisms by depleting dissolved oxygen in the water. Organochlorines like dioxins and furans are generated when elemental chorine is used during pulp mill bleaching processes and have been discharged in effluents. To measure the total amount of halogens associated with organic compounds in the effluent, absorbable organic halides (AOX) are measured.
Elevated dioxin levels in sediments and organisms near British Columbia's pulp mills were first discovered in 1980. Environment Canada first publicly announced the dioxin contamination in 1988 and issued widespread fishery and duck hunting closures surrounding the mills. An annual dioxin testing program was also started at this time as part of more stringent pollution abatement programs for the mills. In 1992, these initiatives combined into the Environmental Effects Monitoring (EEM) Program. Currently, the EEM program's objectives include ensuring that the present regulations are adequate by monitoring the environmental effects at sites receiving effluent and achieving national uniformity in site monitoring. Mills are required to monitor the effects of their effluent on fish and invertebrate habitat and resources using a national standardized suite of protocols.
Federal Fisheries Act Pulp and Paper Effluent Regulations obligated mills to install effluent treatment systems to significantly lower levels of BOD, TSS and toxic chemicals in mill effluent. To decrease the levels of dioxin and furan in the effluent, elemental chlorine was substituted partially or fully by chlorine dioxide. Chlorine dioxide substitution decreased the AOX output, and hence the output of dioxins and furans. Another improvement was the introduction of primary clarifiers, which allow fibres to settle out of the effluent, preventing the build up of fibre mats near the diffuser. Wood chips treated with wood preservatives ceased to be used as hog fuel in the power boiler and, in the pulping process, the use of defoamers contaminated with dioxin and furan precursors was also put to an end. As a result, effluent quality has improved since the late 1980s.
EEM ecological studies have focused on the subtidal benthos through grab sample analysis. Monitoring of intertidal community structure and habitat in proximity to pulp mill with marine outfalls is lacking under the EEM regime. The intertidal zone serves as a nursery for many subtidal species and the potential for using intertidal biodiversity as a sensitive indicator of ecosystem exposure to mill effluent (Bard, 1998) is currently underappreciated. We recommend the adoption of intertidal monitoring for Pacific region mills with marine outfalls as a complement to the current EEM program.
Our studies of intertidal species diversity in the early 1990's established baseline data for before changes in mill pollution abatement took effect. This data was then compared with data collected in 2004 to evaluate whether the improved treatment of pulp mill effluent is reflected in improvements in habitat and species diversity. See pages on Howe Sound, Powell River and Prince Rupert for data on the changes in pollution and intertidal species diversity over a decade.