Ron Voss

Assessing the biological status of fish in a river receiving pulp and paper mill effluents

This study compared the use of sentinel species- and community-based field approaches for assessing the biological status of fish living in a river receiving pulp and paper mill effluents. Three approaches were compared. Two approaches used sentinel species. One of these involved an internal/external examination of the fish that leads to the calculation of a fish health assessment index (HAI) and the other involved biochemical measurements of hepatic mixed function oxidase (MFO) activity and plasma steroid levels. The third approach characterized the fish community structure according to an index of biotic integrity (IBI). The comparison focused on how the methods respond to the hypothesis that recent process modifications/effluent treatment changes, resulting in demonstrable improvements in effluent quality, have beneficial effects on fish. Neither of the approaches using sentinel fish indicated clear mill-related influences either before or after the process modifications/effluent treatment changes. There was no evidence of depressed plasma steroids and increased MFO activity in fish frequently associated with mill effluent exposure in previous studies. While the HAI was higher at stations downstream from two mills, this could not be linked to effluent exposure alone. In contrast, the study of community structure showed a substantial improvement in fish assemblages at all the mill sites.

A survey of pulp and paper mill effluents for their potential to induce mixed function oxidase enzyme activity in fish

The potential of 31 secondary-treated pulp and paper mill effluents from eight different mills to induce mixed function oxidase (MFO) activity, in the liver of rainbow trout (Oncorhynchus mykiss), was investigated by short-term (4-day) laboratory exposures to 10% effluent concentration. Two of six thermomechanical pulp (TMP) mill effluents investigated caused increased EROD activity while there was no increase caused by the two chemi-thermomechanical pulp (CTMP) mill effluents tested. In contrast, with one exception, EROD activity was significantly induced as a result of exposure to bleached as well as unbleached kraft mill effluents. The replacement of chlorine in the bleaching of kraft pulp by chlorine dioxide or non-chlorine containing compounds (such as peroxide) did not eliminate the final mill effluents ability to induce EROD activity. Rather, the kraft cooking process used to convert wood into pulp may itself be a source of MFO-inducing substances.

Further Insights Into The Potential Of Pulp And Paper Mill Effluents To Affect Fish Reproduction

As part of a continuing survey, effluents from five mills in Canada were tested in the laboratory for their potential to affect fish reproduction. The study included effluents from two thermomechanical pulp (TMP) mills, two kraft pulp mills, and one mill that used both chemical and mechanical pulping. The laboratory test used adult fathead minnows and involved a 21-day exposure to each effluent. All the effluents were tested at 2 and 20% concentration. The effluent from 1 of the kraft mills was also tested at 40% concentration. The endpoints of the test included, egg production, gonad size, sex steroids, secondary sexual characteristics, and vitellogenin concentration in males, considered to be an indicator of estrogenicity. The results of this study were similar to the results of our previous survey. None of the effluents produced noteworthy changes at 2% concentration. At 20% concentration, only the effluent from the multiprocess mill produced a significant reduction in eggs, which was considered to be the most important indicator of reproductive performance. Some effluents did produce an increase and/or a decrease in a variety of endpoints other than egg production, but the most consistent response was an induction of vitellogenin in males exposed to three of the five effluents tested. In summary, these results indicate that most mill effluents up to 20 or 40% concentration do not affect the overall reproductive capacity of minnows in the laboratory. However, the mill effluents do seem to contain substances that cause vitellogenin induction. We thank the staff members of mills participating in this survey for collecting and shipping effluent samples to the laboratory. We are also grateful to Robert Bourbonnais of Paprican and two anonymous referees for reviewing our article and offering helpful comments for improvement. Jessica Michaud is currently with Environment Canada, Montreal; Ron Voss has retired.

Biological and chemical characterization of newsprint/specialty mill effluents

Abstract A survey of the biological and chemical characteristics of effluents without secondary (i.e. biological) treatment from Canadian newsprint/specialty mills was completed. The acute lethal toxicity of the effluents to rainbow trout, fathead minnows and Ceriodaphnia, expressed as LC50s, ranged from ∼5 to ∼50% . Sublethal effects on minnow growth occurred at ∼2 to ∼15% concentrations, whereas effects on Ceriodaphnia reproduction occurred at ∼0.01 to ∼2% levels. The impact of these effluents on Photobacterium phosphoreum (Microtox test) occurred at levels similar to those affecting minnow growth. The growth of algae was a less sensitive response than even acute lethal toxicity to fish or Ceriodaphnia. The concentrations of wood extractives in the effluents correlated well with acute lethal toxicity, but could not fully explain all toxic effects. The ranking of the impact of the effluent only on the basis of pulping process was not possible due to a range of other seemingly more important variables which could affect the effluent quality including the wood furnish, age of wood and other as yet unidentified factors.

PERSPECTIVES ON CANADIAN FIELD STUDIES EXAMINING THE POTENTIAL OF PULP AND PAPER MILL EFFLUENT TO AFFECT FISH REPRODUCTION

The results and interpretations of published Canadian field studies on the reproductive status of fish in waters receiving pulp and paper mill effluent discharges were reviewed. Most of the information was obtained from indicator measurements such as gonad size, fecundity, and serum steroid levels in wild fish sampled at reference and effluent-exposed sites. Difficulties in selecting appropriate sampling sites, natural variability, and the ecological relevance of the indicator measurements were identified as major complicating factors for the interpretation of the field data. Consequently, it was not possible to conclude to what extent, if any, widespread effects on fish reproduction are being caused by pulp and paper mill effluents or that specific manufacturing processes are causing such effects. Further research on the normal variability and predictive capability of reproductive indicators, for example, using an integrated approach (i.e., laboratory testing, mesocosm studies, and field work), is recommended.

Effects of a secondary-treated thermomechanical pulp mill effluent on aquatic organisms as assessed by short- and long-term laboratory tests

The chronic effects of secondary-treated effluent from a thermomechanical pulp (TMP) mill were assessed by means of long-term and short-term laboratory toxicity tests. The effluent used for the tests was sampled at a western Canadian mill using mostly softwoods and < 10% recycled fiber as furnish. In the long-term test, the effects of the effluent on the life cycle of fathead minnows (Pimephales promelas) were studied. In this experiment, which began with the egg stage and continued through to sexual maturity and reproduction, the fish were exposed in the laboratory to well water (control) and five concentrations (1.25%, 2.5%, 5%, 10%, or 20%) of effluent for 202 d. None of the effluent concentrations significantly affected the hatching of the eggs, the mortality, weight, length, gonad size, gender balance, and reproduction of the hatched fish, the prevalence of gross morphological and histopathological changes, and the hatchability of the first generation eggs. Two short-term tests, each lasting 7 d, were also performed. In these tests, 100% effluent caused no change in the survival/growth of minnow larvae or in the survival/reproduction of Ceriodaphnia.

Evaluation of caged freshwater mussels as an alternative method for environmental effects monitoring (EEM) studies

On three occasions between 1998 and 2000, freshwater mussels were collected by divers in Lake Memphremagog during the spring and transplanted to various locations in the St-François River (Quebec, Canada). Mussel growth was monitored by comparing total weight and length at the beginning and end of the exposure period. In 1998, mussels were caged for 60 days at 10 stations, including locations receiving treated effluents from three pulp and paper mills. Overall, there was an apparent trend of increased mussel growth from upstream to downstream along the river. However, mussels caged downstream from the effluent discharge of a bleached kraft pulp and paper mill grew more slowly than those caged immediately upstream in the river. In 1999 and 2000, we further investigated the situation in the vicinity of this bleached kraft mill. The measurements again indicated that growth of mussels in the effluent plume from this mill was reduced in comparison to sites upstream. Overall, in terms of growth, the caged mussels responded both positively and negatively to different environmental conditions. Compared with other monitoring approaches used at these sites during the same period, the caged mussel experiment results were consistent with the trends observed with the benthic invertebrate survey but not with the trends observed for fish.

A laboratory exposure procedure for screening pulp and paper mill effluents for the potential of causing increased mixed function oxidase activity in fish

To better understand the relationships between pulp manufacturing processes and mixed function oxidase (MFO) enzyme induction in fish, a practical and standardized exposure procedure is required. This study was undertaken to develop a laboratory-based exposure procedure to quantify the relative MFO induction potencies of different types of pulp and paper mill effluents. One major consideration in developing the procedure was to ensure that the protocol was practical so that tests could be performed in a short time, with small volumes of effluents and using simple experimental conditions. A series of concentration-response and time-course experiments were conducted to find the minimum time and effluent concentration which could distinguish the ability of different effluents to cause significant MFO induction in rainbow trout in the laboratory. Experiments were also conducted to determine the effects of biotic and abiotic factors such as loading density, fish size and feeding regime. This study showed that the exposure of rainbow trout in the laboratory to 10% concentration of secondary-treated effluent for 96 h caused significant increases in hepatic MFO activity. The magnitude of MFO induction was comparable to other field and laboratory observations. While fish size, loading density and feeding regime were found to affect the test results, consistent responses within a laboratory using this protocol are possible, provided that these factors are standardized. Therefore, the short-term exposure approach described in this paper could be a relevant tool for assessing the ability of different types of pulp and paper mill effluents to cause MFO induction in fish.

An appraisal of the effect of biological treatment on the environmental quality of high-yield mechanical pulping effluents

Abstract Before biological treatment, the effluents from one CTMP (chemi-thermomechanical pulping) and three TMP (thermomechanical pulping) mills were acutely lethal to fathead minnows ( Pimephales promelas ) and the water flea Ceriodaphnia with 48-h LC 50 values of 2.2 to > 50%. The effluents also caused chronic effects at concentrations of 0.01–5.3%. After biological treatment, effluents from the three TMP mills were not acutely lethal to either test species. Biotreated effluents from the CTMP mill were also not acutely lethal to minnows but were lethal to Ceriodaphnia (48-h LC 50 : 54–80%). The chronic effects of biotreated effluents occurred at concentrations of 47 to > 100% for fathead minnows and at 5–37% for Ceriodaphnia . Biological treatment also reduced the levels of BOD (>80%), COD (>60%) and wood extractives (>99%).