A Decade of Research on the Environmental Impacts of Pulp and Paper Mill Effluents in Canada (1992-2002)
- Publishing Information
- 1.0 Executive Summary
- 2.0 General Information
- 3.1 Field Studies and Mechanistic Research - Summary
- 3.2 Canadian Research Leading Up to the 1992 Pulp and Paper Regulatory Package
- 3.3 Research Program to Identify the Causative Compounds, How to Eliminate Them, and Determine Their Short and Long-Term Environmental Effects
- 3.4 Evolution of the Research Questions
- 3.5 Evolution of the Research Questions: Monitoring Sites over the Long-term for Evidence of Recovery Following Process and Treatment Changes.
- 3.6 Evolution of the Research Questions: Need to Identify Process and Treatment Changes Responsible for Partial Recovery and Chemicals Involved
- 3.7 Evolution of the Research Questions : Cycle 2 EEM Results, What Were the Major Response Patterns and How Widespread Were They?
- 3.8 Conclusions
- 4.1 Development and Application of Bioassays - Summary
- 4.2 History
- 4.3 Mesocosms
- 4.4 Lifecycle Studies
- 4.5 Conclusions
- 5.1 Characterization of Bioactive Chemicals - Summary
- 5.2 Introduction
- 5.3 Causal Investigations of Bioactive Substances
- 5.4 Characteristics of bioactive substances revealed during field and laboratory studies
- 5.5 AOX: Regulation and relationship to effects
- 5.6 Effluent and Receiving Environment Chemistry
- 5.7 Conclusions
- 6.0 References
3.5 Evolution of the Research Questions: Monitoring Sites over the Long-term for Evidence of Recovery Following Process and Treatment Changes.
Although a number of Canadian studies had documented reproductive effects in wild fish downstream of effluent discharges, a number of these mills had only primary treatment of their effluent. Following the implementation of the new pulp and paper effluent regulations, mills started to install secondary treatment systems and mills that bleached their pulp were altering mill processes to reduce the use of elemental chlorine. We knew now that chlorine was not required for reproductive effects and that secondary treatment did not eliminate effects at some sites. As some modernized mills failed to demonstrate effects, mills that were being modernized were monitored for potential recovery in the receiving environment over the next several years (Figure 1).
Over the years of study at Jackfish Bay there had been multiple changes in processes and treatment strategies. There was corresponding evidence of reduced activity of the effluents and recovery in reproductive potential in wild fish populations. Steroid depressions seen in 1990-1993 were associated with effects on the steroid biosynthetic pathway (Van Der Kraak et al., 1992; McMaster, 1995; McMaster et al., 1995a, 1996b). These effects varied with season (McMaster, 1995; McMaster et al., 1995a) and were not consistent at all mills (McMaster et al., 1996b). Reductions in production of hormones in vitro could be seen following 4 to 8 days of exposure to effluent at Jackfish Bay until the summer of 1993 (McMaster et al., 1996a). In the summer of 1993, there was a partial recovery in the steroid impacts (McMaster et al., 1996a), and goldfish during short- term exposures did not show depressions in steroid levels for exposure periods as long as 20 d in 100% effluent (McMaster et al., 1996a; McCarthy et al., 1997). No specific in-plant change was identified which could account for the improved performance.
It was necessary to evaluate whether wild fish showed a response to the apparent changes in effluent treatment. Fish collected in Jackfish Bay during early September of 1993 showed a recovery in hormone levels (Munkittrick et al., 1997a), however differences were present again in samples collected during late September and late October 1993 at this site (McMaster et al., 1996a). Male gonad sizes were not significantly different in the fall of 1995 and although some improvements in MFO induction had been seen, levels in both sexes remained substantially elevated relative to reference fish (Munkittrick et al., 1997a). Although there was evidence of improvement in gonadal development in the fall of 1993 during early gonadal recrudescence (gonadal growth), white sucker collected immediately prior to spawning did not show as marked an improvement. Female white sucker did show an increase in median ovarian weight of more than 50 g relative to 1988 and 1989, but gonadosomatic indices were still significantly reduced relative to reference fish. Although circulating hormone levels in both males and females remained at low levels, there was an apparent recovery in secondary sex characteristics (Munkittrick et al., 1997a). In 1989 and 1990 males showed a marked reduction in the expression of secondary sex characteristics (McMaster et al., 1991), whereas in the spring of 1996 males showed similar or higher prevalence of tubercles relative to the reference site. However, some tubercle development was displayed in 50% of female fish, especially on their anal fin (Munkittrick et al., 1997a).
The partial reproductive recovery identified may also have been associated with changes in the biosynthetic pathway. Although the circulating levels of hormone had not recovered, there had been significant changes within the steroid biosynthetic pathway. Previous experiments demonstrated lesions at several places within the pathway (McMaster, 1995; McMaster et al., 1995a, 1996b) that converts cholesterol to the active steroid hormones. Although prespawning lesions were seen at the bottom of the pathway in 1992 and 1993 (McMaster, 1995; McMaster et al., 1996b), incubations conduced during prespawning in 1996 showed no disruptions within the pathway. It was unclear why circulating levels of the hormones remained depressed to levels similar to the early 1990s despite the apparent recovery of function within the pathway. The low basal in vitro production would appear to be related to cholesterol availability as opposed to previous disruptions within the steroid biosynthetic pathway.
It was possible that fish exposure in Jackfish Bay also changed with the installation of secondary treatment. The effluent temperature and oxygen levels changed substantially following treatment, potentially allowing fish to increase their exposure concentration to the responsible compounds. This may account for some of the continued reproductive effects at Jackfish Bay . The relationship between steroid hormone changes and reductions in gonadal development was still unclear.
Studies also continued in the Moose River Basin in Northeastern Ontario with a number of objectives. Research conducted in 1991 at Kapuskasing and Smooth Rock Falls had shown that fish downstream of these mills exhibited induction of liver detoxification enzymes and depressions of plasma sex steroid hormones during the period of gonadal growth (Munkittrick et al., 1994a). Subsequent studies were initialed to follow process changes and waste treatment installation at Kapuskasing (TMP) and Smooth Rock Falls (BKME) (Nickle et al., 1997; Munkittrick et al., 2000a). Both of these mills were situated on rivers that had a number of obstacles to prevent fish movement. Both mills were situated at a small run of the river dam and additional waterfalls were located downstream. These obstacles prevented fish from altering their exposure profiles following the installation of secondary treatment as they may have at Jackfish Bay . The Kapuskasing mill initiated changes in late 1991, and by the fall of 1993, both the magnefite and groundwood processes were switched over to TMP (Munkittrick et al., 2000a). White sucker collected in the fall of 1993 had similar gonad size but markedly increased liver size. The downstream site (Freddy Flats) was 12 to 14 kms below the mill outfall, and in 1994 a second downstream site was added within 2 km of the discharge. Fish from these sites showed much larger livers than the Freddy Flats fish and no reductions in gonad size (McMaster et al., 1997a,b; Munkittrick et al., 2000a).
Kapuskasing installed an activated sludge waste treatment system, which became operational in April 1995, after which liver size was reduced substantially but still remained larger than that at the reference sites. Condition factor also showed a gradual decline back to reference levels (Munkittrick et al., 2000a). At Smooth Rock Falls , ovarian sizes and hormone levels remain depressed despite 100% chlorine dioxide substitution as well as secondary waste treatment (Munkittrick et al., 1998). However, gonadal sizes recovered 40km downstream, when effluent concentrations had fallen to about 1.3% (McMaster et al., 1997b). Tightening the pulping process to reduce black liquor losses in 1997 may have contributed to the improvements in fish performance (Munkittrick et al., 2000a).
It was not known what process changes were responsible for reducing the reproductive responses seen at some locations. The best information was available from a series of studies conducted by Kovacs et al. (1995a,b; 1996) in which they conducted fathead minnow life cycle studies at a bleached kraft mill before and after a series of mill upgrades and process changes. The first studies demonstrated a number of reproductive effects, however no reproductive responses were demonstrated in the follow-up experiment. Mill process changes implemented included increasing ClO 2 substitution from 45 to 100%, improved brownstock washing, increased efficiency of the steam strippers, increased recycling of the foul condensates, changes in some sewer destinations, and increasing the retention time in the secondary effluent treatment system (Kovacs et al., 1996). This was also consistent with field collections, as wild spoonhead sculpin ( Cottus ricei) downstream of the mill discharge after modernization, were larger than upstream fish and showed no decreases in reproductive parameters (Table 1) (Gibbons et al., 1996).
The Northern River Basins Study (NRBS) was established in 1991 and represented a joint federal, provincial and territorial agreement between the governments of Canada , Alberta and the Northwest Territories . The primary objective of the study was to advance the understanding of how developments, particularly the seven pulp mill developments, within the Peace, Athabasca and Slave river basins had cumulatively impacted the aquatic ecosystem. The study was also to provide the necessary knowledge base and tools required to assess the potential consequences of future pulp and paper mill developments in these basins. Fish health in the NRBS was assessed using a suite of biomarkers and measures of general condition. The weight of evidence indicated that many of the fish in these basins exhibited signs of physiological stress. Of particular concern was the finding that sex hormone levels in burbot and longnose sucker collected from near-field pulp mill locations were significantly depressed, and that numbers of immature fish in these same locations were unexpectedly high and were more likely to show signs of external abnormalities (Wrona et al., 1997). As with fish, the primary effects on benthic macroinvertebrates appeared to occur in the areas immediately downstream from pulp and paper mill and municipal sewage discharges. Measures of benthic macroinvertebrate community structure in the areas immediately above and below pulp and paper mills indicated that while communities did not differ in terms of major taxa, there was a tendency for downstream communities to show higher diversity and density (Wrona et al., 1997). This was most likely a consequence of nutrient enrichment, an observation supported by Chambers (1997), indicating that pulp and paper mills contributed approximately 13% of the annual total nitrogen and phosphorus loads in the Athabasca and Smoky-Wapiti Rivers.
3.5.1 Cycle 1 of the Environmental Effects Monitoring Program
In 1992, as part of the amendments to the Pulp and Paper Effluent Regulations (PPER), every mill was also required to conduct an Environmental Effects Monitoring (EEM) program. The objective of the EEM program was to determine if the fish, fish habitat and the utilization of the fisheries resources were protected by the requirements of the regulations. Given the results from previous research studies in Canada , this program would provide evidence as to how widespread impacts of pulp and paper mill effluents on the Canadian receiving environment were. The study components included: an adult fish survey; an invertebrate community survey; measurements for chlorinated dioxins and furans in fish tissue for mills using chlorine; and a fish tainting study if there were public concerns about this issue. It was developed as a tiered, site-specific, cyclical program, which would iteratively lead to conclusions concerning the presence of effects in the effluent discharge area, their geographic magnitude and extent, and the relationship of the effects to the discharge. As the pulp and paper program developed towards cycle 1 in 1993, there was considerable controversy about the design of the program and the potential interpretability of the data. This led to a change in the primary objective of the first cycle Adult Fish Survey to obtain estimates of fish variability in order to allow a proper statistical design in the next cycle of the program. After the first cycle of monitoring was completed in 1996, expert working groups were formed to review the results and to make recommendations to improve the requirements for the second cycle. They reviewed the successes, problems, variability, and suitability of methodology and summarized the data. These groups developed additional guidance and streamlined methodologies, and in many cases, revised guidance documents that were used in the development of Cycle 2 of the EEM program.
One of the primary components of the EEM program was the fish survey, which monitors the growth, reproduction and condition of fish populations in waters receiving mill effluents. Specific fish measurements reflect the energy use (growth rate, gonad weight, fecundity, age at maturity), energy storage (condition, liver weight) and age (mean age or age distribution) of two sentinel fish species (Munkittrick et al., 2002a). The objective of the first cycle of EEM was to collect baseline information (fish species selected, capture techniques, sampling areas) and to determine variability in fish measurements. In Cycle 1, the fish survey was poorly conducted at many mills. The key issues identified by the fish survey expert working group (FSEWG) included: the inability to catch sufficient numbers of fish, uncertain exposure, poor reference site selection, the presence of confounding factors and poor or incomplete reporting of the data (Fish Survey Expert Working Group, 1997). The FSEWG recommended a number of improvements to the fish survey including: the selection of appropriate sentinel species such as small-bodied (presumably more sedentary) fish, study design and sampling to ensure the required numbers of fish were collected. As well, a decision tree was developed to help assess whether the fish survey or an alternative was appropriate at any specific site (Fish Survey Expert Working Group, 1997).
The objective of the invertebrate community survey was to delineate the magnitude and spatial extent of habitat degradation due to organic enrichment or other forms of contamination (Environment Canada, 1998a). The intent of the first cycle of EEM was to characterize the benthic invertebrate communities in major habitats that may be affected by mill effluent and to establish a baseline against which future cycles could be compared. Results from Cycle 1 indicated that 69% of pulp and paper mills found differences between reference and exposure sites for the endpoints of species richness and abundance (Walker et al., 2002). However, data interpretation was often confounded by factors such as multiple effluents, inappropriate reference site selection, and lack of standardized methodology for sampling and data analysis (Benthic Invertebrate Community Survey Expert Working Group, 1997). Similar to the Fish Survey EWG, the Benthic Invertebrate Community Survey EWG made a number of recommendations to address these problems, which were then incorporated into the Technical Guidance Documents (Environment Canada, 1998a).
3.5.2 3rd International Conference on the Environmental Fate and Effects of Pulp and Paper Mill Effluents
The third international conference on the Environmental Fate and Effects of pulp and paper mill effluents was held in Rotorua , New Zealand from November 9-13, 1997 . Munkittrick and Sandström (1997) examined the proceedings from the first two conferences and compared how the studies and study designs had changed over the last 6+ years. Since the 1991 conference, there had been a marked increase in the number of conference presentations documenting effects of process changes, a direct result of massive investments by industry in new processes and waste treatments to deal with changing regulations specifically in Canada and Sweden . There had not been however, corresponding increases in large ecological studies examining effects in the receiving environment or improvements following process changes. At the conference, there was also considerable controversy about several aspects, including the range of perspectives from, 1) there was no issue, versus 2) the issue was solved, versus 3) more work was still needed. As well, there was also considerable controversy regarding the role of ecological field studies and their usefulness (Munkittrick & Sandström, 1997).
- Date Modified: