Growth responses of periphyton and chironomids exposed to biologically treated bleached kraft pulp mill effluent

~

Pergamon

Waf. Sci. Tech. Vol. 35. No. 2-3. pp. 339-345.1997. Copyright © 1997 fA WQ. Published by Elsevier Science Ltd Printed in Great Britain. 0273-1223/97 $17'00 + 0'00

PH: S0273-1223(96)00949-3

GROWTH RESPONSES OF PERIPHYTON AND CHIRONOMIDS EXPOSED TO BIOLOGICALLY TREATED BLEACHED KRAFT PULP MILL EFFLUENT M. G. Dube*,** and J. M. Culp*** * Department of Biology, University ofSaskatchewan, Saskatoon, S7N 5E2, Canada ** Current address: Jacques Whitford Environment Limited, P.O. Box 1116,

711 Woodstock Road, Fredericton, NB, E3B 5C2, Canada *** National Hydrology Research Institute, Environment Canada, Illnnovation Boulevard, Saskatoon, S7N 3H5, Canada

ABSTRACT Experiments were conducted in artificial streams to determine the effects of increasing concentrations of biologically treated bleached kraft pulp mill effluent (BKPME) on periphyton and chironomid growth in the Thompson River, British Columbia. Periphyton growth, as determined by increases in chlorophyll a, was significantly stimulated at all effluent concentrations tested (0.25%, 0.5%, 1.0%, 5.0% and, 10.0%). Chironomid growth (individual weight) was also significantly stimulated at low effluent concentrations (::;;1.0%). At higher concentrations (5.0% and 10.0%), chironomid growth was inhibited relative to the 1.0% treatment streams. Increases in growth were attributed to the effects of nutrient and organic enrichment from BKPME. The effluent contained high concentrations of phosphorus and appears to be an important source of carbon for benthic insects grazing on the biofilm. In high concentration effluent streams, chironomid growth decreased despite low levels of typical pulp mill contaminants. This suggests that other compounds in the effluent, such as wood extractives, may be inhibiting chironomid growth. These results support findings of field monitoring studies conducted in the Thompson River where changes in periphyton and chironomid abundance occurred downstream of the bleached kraft pulp mill. © 1997 IAWQ. Published by Elsevier Science Ltd.

KEYWORDS Chironomid; growth; periphyton; pulp mill effluent. INTRODUCTION Effects of biologically treated bleached kraft pulp mill effluent (BKPME) on aquatic communities can be growth enhancing due to nutrient and organic enrichment or growth inhibiting due to chronic contaminant toxicity (McLeay and Associates, 1987). It is most probable that these effects are not mutually exclusive but co-exist along a gradient of effluent concentration. Typically, enrichment effects are evident at lower effluent concentrations (Bothwell and Stockner, 1980; Hall et al., 1991) and contaminant effects are evident at higher concentrations (NCASI, 1982; Lowell et al., 1995). At moderate concentrations, such as those found in many lotic environments receiving effluent discharges, both effects may be present but one effect 339

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may mask the other. This interaction between effects creates difficulties for regulatory bodies to manage effluent discharges to receiving environments effectively. Field monitoring studies conducted in the Thompson River, British Columbia, Canada, suggested that periphyton and chironomid communities downstream of a bleached kraft pulp mill (BKPM) were responding to the combined effects of nutrient enrichment and contaminant toxicity from BKPME. However, the field studies could not establish a cause-effect relationship between nutrients and toxicants in the effluent and periphyton and chironomid growth because important environmental factors could not be directly manipulated. In our studies, artificial streams were used to examine the interaction between nutrient and toxicant effects of BKPME on periphyton and chironomid growth under controlled environmental conditions. Thus, changes in periphyton chlorophyll a (chI a) and individual chironomid weight were measured after exposure to increasing concentrations (0.25%-10%) of BKPME. METHODS Our study was conducted at the National Hydrology Research Institute's outdoor, experimental stream facility located on the Thompson River beside the Weyerhaeuser Canada Ltd. BKPM in Kamloops, British Columbia. This mill produces approximately 1250 ADMt/d of 100% chlorine dioxide bleached pulp from softwood furnish which is typically pine 36%, douglas fir 25%, spruce 20%, hemlock 7%, balsam fir 7% and cedar 6%. The effluent treatment system consists of a pH adjustment system, primary clarifier, settling ponds, and a three celled, 4.5 m deep, aerated stabilization basin with a 6-7 d retention time. Effluent discharges average approximately 150,000 m 3/d and mean total phosphorus loadings have increased from 110 kg/d in 1992 to 272 kg/d in 1994 as a result of treatment basin fertilization which was initiated to improve performance of the aerated basins. Experiments were conducted for 19 d in the autumn (October 1993) and for 15 d in the spring (March 1994). Effluent treatment concentrations were used to simulate reduced effluent discharge to the Thompson River (0.25 and 0.5%), concentrations at complete mix during low river flow (1 %), and increased effluent discharge (5 and 10%). In the autumn, three treatment conditions were established: control river water, 1%, and 10% BKPME. In the spring, five treatments were established: control river water, 0.25%, 0.5 %, 1%, and 5% BKPME. Samples for periphyton chI a and chironomid biomass (individual dry weight) were collected at the beginning, middle and at the end of the autumn (n=5) and spring (n=5) experiments. Water and effluent chemistry samples were collected at the beginning and end of each experiment. Samples were taken of river water, full strength effluent and mixed (l0% and 5%) effluent. Samples were analyzed for general ions, metals, nutrients (nitrogen and phosphorus), chlorophenolics, resin acids, PAHs, and AOX. In the spring, algal samples were collected from the control and 5% treatment reservoirs. These samples were analyzed as above except that EOX analysis replaced AOX analysis. Analyses of water and effluent chemistry samples were conducted by Zenon Environmental Laboratories (Burnaby, BC, Canada). Methods used by Zenon are based on those found in Standard Methods, U.S. Environmental Protection Agency protocols, or other methodologies approved by the British Columbia Ministry of Environment. RESULTS Water and effluent and tissue chemistry Chlorophenolics were not present in the river water in either experiment. All mono, di, tri, tetra and pentachlorophenols were 0.03 IlglL or less in the full strength effluent and diluted effluent treatments. Mono, di, tri ~d tetrachloroguaiacols in the full strength effluent were between 0.09 Ilg/L and 0.32 Ilg/L in the both expenments. These concentrations were diluted to 0.05 IlglL or less in the 10% and 5% effluent

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treatments. Monochlorocatechols were below detection in all samples and di, tri and tetrachlorocatechols were 1.85 IlglL or less in the full strength effluent samples which were diluted to below detection. AOX concentrations in the full strength effluent were 5050 IlgIL and 4500 IlglL in the autumn and spring experiments, respectively. Concentrations were diluted to 650 IlglL in the 10% effluent treatment and 230 IlgIL in the 5% effluent treatment. The total concentration of 7 resin acids (abietic acid, dehydroabietic acid, isopimaric acid, levopimaric acid, neoabietic acid, pimaric acid, and sadaracopimaric acid) was 40 IlglL in the full strength effluent in both experiments which was below British Columbia freshwater criteria (45 IlgIL) (Nagpal and Pommen, 1994). Pimaric and isopimaric acid accounted for over 50% of the total resin acid concentration. PAHs (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene) were at or below minimum detection limits (0.01 IlglL) in river water and in 10% and 5% effluent treatment reservoirs. PAHs in the effluent were 0.06 IlglL or less which was less than provincial water quality criteria (Nagpal and Pommen, 1994). In both the spring and autumn experiment, concentrations of most forms of nitrogen (total organic, total ammonia, Kjeldah1, nitrate/nitrite and total) and phosphorus (dissolved soluble reactive phosphorus (SRP), total dissolved and total) were higher in the full strength and diluted effluent when compared to samples of river water. Concentrations of SRP in the full strength effluent measured 11161lgIL (autumn) and 1490 IlglL (spring) and measured 1411lgIL in the 10% treatment and 38 IlglL in the 5% effluent treatment. Analysis of periphyton samples from the control and 5% reservoirs was conducted in the spring and showed that phosphorus was 4.5 fold higher in periphyton sampled from the 5% effluent reservoir (4.18 mg/g) when compared to samples from the control reservoir (0.89 mg/g). Periphyton growth Addition of pulp mill effluent to treatment streams significantly stimulated periphyton growth in the autumn experiment (ANOVA with contrasts on log lO(x+1) transformed data, F(2,1O)=31O.14, p
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chironomid growth at lower effluent concentrations but this effect decreased with increasing effluent concentration, until growth was significantly less at the 5% effluent exposure. 45

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DISCUSSION Increased concentrations of BKPME significantly stimulated periphyton growth at all effluent concentrations tested. Interestingly, with each increment in effluent concentration (0.25%, 0.5%, 1%, 5%, and 10%), periphyton growth increased. Stimulation of periphyton growth by exposure to BKPME in artificial streams has been recorded in Canada, Finland, and the United States. Bothwell and Stockner, (1980) have reported that prolonged exposure (8-28 d) of periphyton communities to secondary treated BKPME stimulated growth at concentrations ranging from 0.5% to 25%. In large-scale, outdoor

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experimental streams in the United States, periphyton biomass stimulation occurred at the lowest effluent concentrations tested (approximately 1%) (Hall et al., 1991). Our experiments also illustrated that, after 30 d exposure to 5% and 10% BKPME, there was no indication of decreased periphyton growth. A lack of periphyton growth inhibition at high effluent concentrations was also noted by McLeay and Associates Ltd., (1987) such that algal productivity was not inhibited after prolonged exposure to 40% concentrations of treated BKPME. 1.0

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High phosphorus concentrations in the pulp mill effluent undoubtedly increased periphyton growth because the Thompson River is a highly oligotrophic, phosphorus limited system (Bothwell et al., 1992). Thus, addition of phosphorus set new upper limits for growth and biomass production. SRP in the control river water averaged 2.0 IJ.glL, whereas concentrations in full strength effluent averaged 1303.0 Ilg/L, a 650 fold

34..l

M. G. DUBE and 1. M. CULP

increase. Similarly, SRP concentrations in the 10% and 5% effluent treatments were .+7 times .0 41 /lglL) and 38 times (38 Ilg lL ) greater than measured in control river water. The ambient conce.ntrat~on of SRP required to saturate specific growth rates of periphyton communities in the Thompson River IS very ,low (approximately 1.0 IlglL ) but biomass accrual continues to increase with ambient SRP concentratIOns approaching 28 IlglL (Bothwell, 1992). Furthermore, periphyton collected from the 5% effluent treatment reservoir had 4.5 times more phosphorus than control reservoir tissue. Bothwell (1992) has d.emo?strated that algae uptake and store phosphorus in excess of immediate needs to facilitate growth dunng tImes of nutrient deficiency. BKPME had both stimulatory and inhibitory effects on chironomid growth which were dependent ~pon effluent concentration. At low effluent concentrations (~l %), chironomid biomass increased but, at hIgher effluent concentrations (5% and 10%), chironomid biomass decreased relative to the 1% effluent treatment. Stimulation of invertebrate growth in other artificial stream experiments, by additions of 1% to 5% treated BKPME, has been attributed to the concurrent stimulation of periphyton which was used as a food source (Hall et ai., 1991). Lowell et ai., (1995) also reported stimulation of mayfly growth at low effluent concentrations (1 %). Pulp mill effluent may stimulate chironomid growth by increasing periphyton quantity or by providing an additional food source. Nutrients (phosphorus) in pulp mill effluent increased the quantity of food available to chironomids and this increased food quantity appeared to transfer up the food web to produce larger chironomids in the 0.25%, 0.5%, and 1% treatment streams. However, compounds in the effluent also may have contributed to increased chironomid growth by providing an additional, and possibly more palatable or higher quality, food source. Residual suspended solids or biosolids in treated BKPME consist of non• settleable individual or flocculated bacterial cells which are generated in the aerated basin during biological oxidation of organic waste. These biosolids have been shown to be ingested and incorporated into the cellular materials of both grazing and filter feeding macroinvertebrates (Costa et ai., 1979). Stable isotope analyses conducted in the Thompson River also suggest that, in addition to algae, chironomids consume a terrestrially derived, isotopically depleted, carbon and nitrogen source which may originate from dissolved organic matter in pulp mill effluent (Wassenaar and Culp, 1995). Results from our studies also showed that despite continual increases in periphyton growth with each increment in BKPME concentration, individual chironomid weight decreased at higher (5% and 10%) effluent concentrations. This result suggests that higher concentrations of BKPME may have a toxic effect on chironomid growth. Exposure of fish to BKPME can cause sublethal, chronic responses including stress and other metabolic effects, respiratory and circulatory effects, reduced tolerance to natural environmental conditions, and behavioral responses (McLeay and Associates, 1987). Although data on pulp mill effluent toxicity focuses on fish, kraft effluents can also be toxic to various invertebrates. Lowell et ai., (1995) suggest mayfly moulting may be inhibited at 10% concentrations of treated BKPME (10%). In addition, Robinson et ai., (1994) report negative effects in Ceriodaphnia dubia reproduction when exposed to water chemistry samples collected downstream of pulp mills with primary effluent treatment. Chironomid growth inhibition at high BKPME concentrations (5% and 10%) occurred in the presence of low levels of contaminants which, when in high concentrations, are typically considered toxic in BKPME (i.e., resin acids, chlorinated phenolics). Studies conducted in aquatic environments receiving secondary treated BKPME have reported that a consistent relationship does not exist between BKPME toxicity to fish and invertebrates, and levels of AOX, chlorophenols, or chlorinated resin acids (Robinson et ai., 1994, Munkittrick et ai., 1994). These authors have suggested that a previously unidentified group of toxic constituents in BKPME may exist and be the cause of physiological disruptions in fish near pulp mills. They also suggest that these compounds originate in the pulping process prior to the bleaching stage, and are components of the pulped wood which are not removed during secondary effluent treatment. Wood extractives in pulping effluents may be agents which reduced chironomid growth in the 5% and 10% effluent treatments. Extractives occur as small fractions (3 to 10%) in wood and include low molecular weight carbohydrates, terpenes, steroids, alcohols, proteins, tannins, alkaloids, aromatic acids, colour substances, phlobaphenes, alkaloids, and inorganic salts. Some wood extractives function as part of a tree's

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natural defense mechanism against insect infestation, and interfere with normal insect growth and development by mimicking insect growth (juvenile hormone) and moulting hormones which regulate metamorphosis (Subramanian and Varadaraj, 1993). Juvenile hormone analogues, or "paper factors", were originally discovered in American paper products and in the wood of Canadian balsam fir (Slama, 1966). The wood of certain evergreen trees (e.g., pine, fir, and spruce) contains several juvenile hormone mimics and Subramanian and Varadaraj, (1993) found that pulp mill effluent had a juvenomimetic effect on dragonfly larvae which inhibited moulting and growth. Interestingly, McLeay and Associates Ltd., (1987) and Leach et ai., (1975) have reported that these hormone analogues are toxic to fish. ACKNOWLEDGEMENTS We thank Nancy Glozier, Richard Lowell, Gordon Kerfoot, Daryl Halliwell, Todd Pugsley and Weyerhaeuser Canada Ltd. in Kamloops, BC for their assisstance and cooperation. Funding was provided by Environment Canada through the Fraser River Action Plan and the National Hydrology Research Institute, as well as by BC Environment in Karnloops, Be. REFERENCES Bothwell, M. L. and Stockner, J. G. (1980). Influence of secondarily treated kraft mill effluent on the accumulation rate of attached algae in experimental continuous-flow troughs. Can. J. Fish. Aquat. Sci., 37,248-254. Bothwell, M. L. (1992). Eutrophication of rivers by nutrients in treated kraft pulp mill effluent. Water Pol/ut. Res. J. Can., 27, 447-472. Bothwell, M. L., Derksen, G., Nordin, R. N. and Culp, 1. M. (1992). Nutrient and grazer control of algal biomass in the Thompson River, British Columbia: a case history of water quality management. In: Aquatic Ecosystems in Semi-Arid Regions: Implications for Resource Management, R D. Robarts and M. L. Bothwell (Eds.), Symposium Series 7. National Hydrology Research Institute, Environment Canada, Saskatoon, SK, 253-266. Costa, H. S., McKeown, 1. 1. and Blosser, R O. (1979). Studies on characterization, fate, and impact of residual solids of biological treatment origin. TAPPI, 62, 41-46. Hall, T. J., Haley, R. K. and LaFleur, 1. E. (1991). Effects of biologically treated bleached kraft mill effluent on cold water stream productivity in experimental channels. Environ. Toxicol. Chern., 10, 1051-1060. Leach, 1. M., Thakore, A. N. and Manville, J. F. (1975). Acute toxicity to juvenile rainbow trout (Salmo gairdneri) of naturally occurring insect juvenile hormone analogues. J. Fish. Res. Board Can. 32,2556-2559. Lowell, R B., Culp, J. M. and Wrona, F. J. (1995). Stimulation of increased short-term growth and development of mayflies by pulp mill effluent. Environ. Toxicol. Chern., 14, 1529-1541. McLeay, D. J. and Associates Ltd. (1987). Aquatic toxicity of pulp and paper mill effluent: a review. EPS 4/PF/1. Technical Report. Environment Canada, Ottawa, ON. Munkittrick, K. R., Van Der Kraak, G. 1., McMaster, M. E., Portt, e. B., van den Heuvel, M. R. and Servos, M. R (1994). Survey of receiving-water environmental impacts associated with discharges from pulp mills. 2. gonad size, liver size, hepatic erod activity and plasma sex steroid levels in white sucker. Environ. Toxicol. Chern., 13, 1089-1101. Nagpal, N. K. and Pommen, L. W. (1994). Approved and working criteria for water quality. Water Quality Branch, Environmental Protection Department, British Columbia Ministry of Environment, Lands, and Parks, Victoria, Be. NCASI (1982). Effects of biologically stabilized bleached kraft mill effluent on cold water stream productivity as determined in experimental streams - first progress report. No. 368. Technical Bulletin. National Council of the Paper Industry for Air and Stream Improvement Inc., New York, NY. Robinson, R D., Carey, J. H., Solomon, K. R., Smith, I. R, Servos, M. R. and Munkittrick, K. R (1994). Survey of receiving• water environmental impacts associated with discharges from pulp mills. I. mill characteristics, receiving-water chemical profiles and lab toxicity tests. Environ. Toxieol. Chern., 13, 1075-1088. Slama, K. (1966). Entomology: 'paper factor' as an inhibitor of the embryonic development of the European Bug, Pyrrhoeoris apterus. Nature, 210, 329-330. Subramanian, M. A. and Varadaraj, G. (1993). The effect of industrial effluents on moulting in Macromia eingulata (Rambur) (Anisoptera: Corduliidae). Odonatologiea, 22, 229-232. Wassenaar, L. I. and Culp, 1. M. (1995). The use of stable isotopic analyses to identify pulp mill effluent signatures in riverine food webs. In: Environmental Fate and Effects of Pulp and Paper Mill Effluents, M R Servos, K R Munkittrick, J H Carey, and G J Van Der Kraak (Eds.), St. Lucie Press, Boca Raton, FL, 413-423.