Comparison of chlorine and chlorine dioxide toxicity to fathead minnows and bluegill

The comparative toxicity of total residual chlorine (TRC) and chlorine dioxide (ClO₂) was evaluated by conducting 96 h flow-through bioassays with three types of fish. The fish were subjected to an intermittent exposure regime in which biocide residuals were present for approx. 2-h periods beginning at 0, 24, 48 and 72 h into the tests. These conditions simulated the antifouling procedure (1 h day⁻¹ biocide addition) used to control biofouling of nuclear reactor heat exchangers at the Savannah River Plant near Aiken, South Carolina. LC₅₀ values showed that ClO₂ was approx. 2–4 times more toxic than TRC to: (1) juvenile and 1-year-old fathead minnows (Pimphales promelas); and (2) young-of-the-year bluegill (Lepomis macrochirus).The TRC mean 96-h LC₅₀ values were: 0.08 mg l⁻¹ for juvenile fathead minnows, 0.35 mg l⁻¹ for adult fathead minnows and 0.44 mg l⁻¹ for young-of-the-year bluegills. The ClO₂ mean LC₅₀ values were: 0.02 mg l⁻¹ for juvenile fathead minnows, 0.17 mg l⁻¹ for adult fathead minnows and 0.15 mg l⁻¹ for young-of-the-year bluegills.     

Comparative toxicity of ten organic chemicals to ten common aquatic species

The susceptibilities of 10 aquatic organisms to 10 organic chemicals were determined using lethality tests. The species included six fishes, two crustaceans, a chironomid and an amphibian. The chemicals were selected to span the toxicity range from 26 g l⁻¹ to 1 μg l⁻¹ and include chemicals which were lethal by four modes of toxic action. There was no consistent relative susceptibility among the test species because the sensitivity to specific modes of toxic action varied among the chemicals. Nonetheless, the toxicities of the chemicals to any given species were highly correlated to the toxicities to other species, particularly among fishes. The 96-h median lethal concentration (LC₅₀) of the chemicals to rainbow trout (Salmo gairdneri) could be estimated from the 96-h LC₅₀ with fathead minnows (Pimephales promelas) with a correlation coefficient greater than 0.99. Equations for estimating the lethal concentration of chemicals with each species from the 96-h LC₅₀ for fathead minnows are presented.     

Effects of pH increases and sodium chloride additions on the acute toxicity of 2,4-dichlorophenol to the fathead minnow

The observable toxic effects produced by short-term exposure of fathead minnows (Pimephales promelas) to 2,4-dichlorophenol were reduced when the pH of the test water was increased by the addition of NaOH. After exposure for 192 h to 7.43 mg 2,4-dichlorophenol l^-1, the average survival of fathead minnows ranged from 28% at pH 7.57 to 100% at pH 9.08. Normal schooling behaviour was completely disrupted, and the equilibrium of most fish was affected after a 24-h exposure to 7.43 mg 2,4-dichlorophenol 1^-1 at pH 7.57, but neither schooling nor equilibrium were affected even after 192 h at pH 8.68 and 9.08. Schooling and swimming behaviour of fathead minnows exposed to 12.33 mg 2,4-dichlorophenol l^-1 were affected at all pH levels. Survival of these fish after 24 h ranged from 0% at pH 7.84–46% at pH 8.81. Sodium chloride in concentrations ranging from 0 to 13.9 mg l^-1 had no observable effects on the acute toxicity of 2,4-dichlorophenol to fathead minnows.     

A comparison of toxicity tests conducted in the laboratory and in experimental ponds using cadmium and the fathead minnow (Pimephales promelas)

Acute toxicity tests were conducted in the laboratory with fathead minnows (Pimephales promelas) to determine the 96-h LC₅₀ of cadmium under three conditions: (1) in laboratory water, (2) in water from experimental ponds, and (3) in pond water underlain by sediment. Cadmium was then applied at doses equivalent to the estimated LC₅₀ values to 0.07-ha ponds containing caged fathead minnows. A cadmium ion selective electrode, ultrafiltration, and equilibrium calculations were used to determine cadmium speciation, and several water quality characteristics were measured to correlate differences in mortality between test systems (laboratory and field) with observed differences in water quality. The LC₅₀ estimates (mg l⁻¹) for the bioassays were 4.39 for the laboratory water, 3.52 for the pond water with sediment, and 2.91 for the pond water. Concentrations of Cd²⁺ decreased and those of cadmium in the particulate (> 1.2 μm) and 300,000 mol. wt (0.018–1.2 μm) fractions increased over the 96-h; cadmium in these fractions was believed to consist of colloidal sized CdCO₃ precipitates. Concentrations of Cd²⁺ decreased at different rates between test systems, regulated by the degree of CdCO₃(s) supersaturation which in turn depended on pH and total metal concentrations. Differences in toxicity in the laboratory tests were attributed to differences in water hardness and Cd²⁺ concentrations. Mortality of fathead minnows was low (0–10%) during the 96-h test period in the ponds due to the higher pH, which produced supersaturated conditions resulting in the rapid formation of nontoxic CdCO₃ precipitates and a more rapid decrease in Cd²⁺ concentrations as compared to the laboratory bioassays.     

Reduction of aquatic toxicity of linear alkylbenzene sulfonate (LAS) by biodegradation

Partial biodegradation of LAS is shown to significantly reduce the specific toxicity (i.e. per unit weight) of the remaining LAS to Daphnia magna (water fleas) and Pimephales promelas (fathead minnows). This results from the fact that the longer homologs and more terminal isomers, which are the more toxic, are also the more rapidly degraded under bacterial action. The acute aquatic LC₅₀ of LAS may range from 0.5 to 50 mg/l depending mainly upon the chain length of the particular homolog. A high molecular weight commercial type LAS with LC₅₀ around 2 mg/l before biodegradation may show Daphnia LC₅₀'s of 30–40 mg/l. for the LAS remaining after 80–85% degradation.A further contribution to this toxicity reduction may occur if the methylene blue analytical method is used to determine the amount of LAS remaining, since some of the biodegradation intermediates show methylene blue activity but no significant toxicity. For example, sulfophenylundecanoate, a model of early intermediates, shows Daphnia and fathead lc₅₀'s 200 and 75 mg/l., respectively. Sulfophenylbutyrate, modeling somewhat later intermediates, gives lc₅₀ values around 5000–10,000 mg/l. Dialkyl tetralin/indane sulfonates (the major non-linear components in commercial LAS) exhibit 1/2–1/10 the toxicity of the corresponding LAS homologs.These results re-emphasize that analysis simply for methylene blue active substances (MBAS) gives no basis for predicting the aquatic toxicity of an environmental sample. And furthermore, that meaningful water quality criteria and standards cannot be established in terms of MBAS content while based on toxicity studies on intact, undegraded LAS.     

Acute toxicities of five nitromusk compounds in Daphnia,algae and photoluminescent bacteria

Acute toxicities of five nitromusk compounds in Daphnia, algae and photoluminescent bacteria were investigated. In order to obtain some basic data for ecotoxicological tests, physicochemical parameters were determined. The water solubility and log K_ow values were: nitromusk xylene 0.15 mg l⁻¹ and 4.4, nitromusk ketone 0.46 mg l⁻¹ and 3.8, nitromusk ambrette 0.79 mg l⁻¹ and 4.0, nitromusk moskene 0.046 mg l⁻¹ and 4.4 and nitromusk tibetene 0.052 mg l⁻¹ and 4.3. None of these compounds exhibited a toxic effect in any of the toxicity tests even at the highest concentrations achievable except for nitromusk ambrette which was toxic to Daphnia.     

Toxicity of sodium nitrilotriacetate (NTA) to the fathead minnow and an amphipod in soft water

Amphipods, Gammarus pseudolimnaeus Bousfield and fathead minnows, Pimephales promelas Rafinesque, were submitted to acute (96-h) and chronic (generation-cycle) bioassays with sodium nitrilotriacetic acid (NTA). All measurements are reported as Na₃NTA. The average 96-h TL50 values under flow-through conditions were 98 mg 1⁻¹NTA for the amphipod and 114 mg 1⁻¹ for the fathead minnow. The acute toxicity of NTA was caused in part by the high pH resulting from the addition of large amounts of NTA (> 100 mg 1⁻¹) to soft water. Controlling pH reduced the lethality of NTA by at least one-half to fathead minnow larvae. The chronic no-effect level of NTA to the amphipods was 19 mg 1⁻¹; in fathead minnows, it exceeded the highest exposure level (> 54 mg 1⁻¹).     

Absence of selenate avoidance by fathead minnows (Pimephales promelas)

Forty fathead minnows (Pimephales promelas) were individually offered a choice between “clean” water and water containing selenate in a flow-through. Sprague-type avoidance system. During a control period beginning each trial, fatheads exhibited no significant avoidance of either end of the test chamber. Mean residence times in the two ends equalled 48.8 and 51.2% of total time.Similarly fathead minnows did not avoid selenate at concentrations of 0.3–11.2 mg Se l^?1 in 4 separate trials. Overall, the 40 fish partitioned 48.5 and 51.5% of their time in the selenate and selenate-free ends, respectively. These results demonstrate that fathead minnows do not behaviorally avoid harmful concentrations of selenate.     

The effects of cyanide on the methanogenic degradation of phenolic compounds

The effects of cyanide on the degradation of phenol, m-cresol, p-cresol, catechol and hydroquinone in acclimated methanogenic consortia were studied. Batch cultures with cyanide concentrations up to 10 mg l⁻¹ were monitored for phenolic removal and methane production. Results showed that the methanogens were more sensitive to cyanide inhibition than the phenolic-degrading bacteria. The former group was inhibited by lower cyanide concentrations and took longer to adapt to the toxicant. Phenolic degradation was slowed to varying degrees depending upon the phenolic substrate. The addition of 400 mg l⁻¹ acetate or 10⁻² M bromoethanesulfonic acid, a specific inhibitor of methanogenesis, also slowed the rates of phenolic degradation. Thus cyanide can affect a phenolic-degrading consortium by causing an accumulation of endproducts of the non-methanogenic fermentation (e.g. acetate) because of the inability of the methanogens to consume them.A draw and feed culture adapted to phenol degradation in the presence of 5 mg l⁻¹ cyanide was able to produce methane from feed solutions containing 5 mg l⁻¹ cyanide and 250 mg l⁻¹ phenol at the same rate as a control culture receiving 250 mg l⁻¹ phenol but no cyanide.     

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

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 LC₅₀ 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 LC₅₀: 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%).     

The toxic effects of trinitrotoluene (TNT) and its primary degradation products on two species of algae and the fathead minnow

The effects of alpha trinitrotoluene (alpha TNT) and its primary degradation product (TNTcc), commonly referred to as “pink water”, were determined on members of two trophic levels. The growth responses of the algae Selenastrum capricornutum and Microcystis aeruginosa were examined through static bioassays. Death and behavioral responses of the fathead minnow (Pimephales promelas) were determined using a proportional diluter. Alpha TNT and TNTcc were both more toxic to the fathead minnow than to either species of alga. Five and 15 mg l⁻¹ alpha TNT inhibited S. capricornutum and M. aeruginosa growth, respectively. TNTcc inhibited S. capricornutum growth at concentrations above 9 mg l⁻¹; it was lethal to M. aeruginosa at 50 mg l⁻¹, but stimulated growth at lower concentrations. The 96-h lc₅₀ values based on the death response of the fathead minnow to alpha TNT and TNTcc were 2.58 and 1.60 mg l⁻¹, respectively. The 96-h ec₅₀ values based on the behavioral responses were 0.46 and 0.64 mg l⁻¹, respectively. There was no response to concentrations of 0.05 mg l⁻¹ alpha TNT and 0.07 mg l⁻¹ TNTcc.     

Effects of methoxychlor exposure of flagfish eggs (Jordanella floridae) on hatchability,juvenile methoxychlor tolerance and whole-body levels of tryptophan,serotonin and 5-hydroxyindoleacetic acid

One-day-old flagfish eggs pulse-exposed for 2 h to 0 (control), 0 (ethanol-carrier control), 1.29, 2.58, 3.51 or 5.48 mg l⁻¹ methoxychlor showed respective hatching successes of 92.5, 92.5, 86.3, 77.5, 72.5 and 75.0%. The methoxychlor impact was modified by the age of the eggs at exposure. Two and 3-day-eggs subjected to the same protocol showed 100% hatch for all treatments. Exposure of 1-day-old eggs also reduced the subsequent methoxychlor tolerance of the resulting juveniles. Eight-day-old juveniles hatched from 1-day-old eggs which had been exposed to 0 or 3.51 mg l⁻¹ methoxychlor showed mean 96 h pulse-exposure methoxychlor LC₅₀s of 3.04 and 0.62 mg l⁻¹ respectively. Conversely, exposure of 3-day-old eggs had no impact on subsequent methoxychlor tolerance of 8-day-old juveniles; 96 h pulse-exposure LC₅₀s for all treatments ranged from 2.48 to 2.55 mg l⁻¹. Both pre-exposure of 1-day-old eggs and pulse-exposure of 8-day-old juveniles significantly reduced whole-body tryptophan, serotonin and 5-hydroxyindoleacetic acid levels in juvenile flagfish. It was concluded that some form of protective mechanism prevented methoxychlor from affecting the embryo by 48 h post-fertilization. Up to 24 h post-fertilization, however, the embryo was detrimentally affected, as evidenced by reduced hatching success, juvenile tolerance and indoleamine levels.     

Inhibitory effects of odor substances,geosmin and 2-methylisoborneol,on early development of sea urchins

Geosmin (1α,10β-dimethyl-9α-decanol) and 2-methylisoborneol ((1-R-exo)-1,2,7,7-tetramethyl-bicyclo-(2,2,1)-heptan-2-ol) (MIB) are volatile terpene derivatives, and have received a great deal of attention because they can cause musty/muddy off-flavor in water and food resources. By the Ames test, these metabolites showed no mutagenicity but antimicrobial activity toward tester strains. While these compounds are produced by various organisms living in aquatic environments, there are few reports of their effects on aquatic organisms. The effects of geosmin and MIB on sea urchin development were examined. The estimated IC₅₀ (50% inhibitory concentration) values for the formation of the fertilization membrane were 16.67 mg geosmin l⁻¹ and 68.77 mg MIB l⁻¹; those for the cell cleavage were 16.58 mg geosmin l⁻¹ and 66.86 mg MIB l⁻¹, suggesting that the toxicity of geosmin and MIB toward sea urchins are comparable to their toxicity toward Salmonella tester strains in the Ames test. These values are far greater than concentrations of these substances observed in aquatic environments with severe muddy off-flavor problems.     

Copper lethality to rainbow trout in waters of various hardness and pH

The 96 h median lethal concentration (LC₅₀) of total dissolved copper varied from 20 μg 1⁻¹ in soft acid water to 520 μg l⁻¹ in hard alkaline water, in tests with hardness ranging from 30 to 360 mg l⁻¹ as CaCO₃ and pH from 5 to 9. The 3-dimensional response surface was complex, although an increase in hardness usually made copper less toxic. A good prediction of copper LC₅₀ at usual combinations of hardness and pH was given by the equation: LC₅₀ = antilog (1.933 + 0.0592 P_T + 0.4912 H_T + 0.4035 P_TH_T + 0.4813 P²_T + 0.1403 H²_TThe transformed variables are and A somewhat less accurate equation is provided for extreme combinations of hardness and pH.Trout of 10 g weight were 2.5 times more resistant than 0.7 g trout. Effect of size was apparently the same at different combinations of hardness and pH, and was predictable by an equation of the form LC₅₀ = Constant × Weight ^0.348.Ionic copper (Cu²⁺) and two ionized hydroxides (CuOH⁺ and Cu₂OH²⁺₂) seemed to be the toxic species of copper, since they yielded the smoothest response surface with the best fit to measured LC₅₀'s. The sum of these ions produced LC₅₀'s ranging from 0.09 μg l⁻¹ copper in soft alkaline water to 230 μg l⁻¹ in hard acid water. The ions were different in relative toxicity, or became more toxic at high pH, or both.     

The acute toxicity of vanadium and copper to eyed eggs of rainbow trout (Salmo gairdneri)

The effects of vanadium (25–595 mg l⁻¹) and of copper (0.03–4.78 mg l⁻¹) on embryonic survival and hatching of eyed eggs of rainbow trout, Salmo gairdneri, were investigated. Copper was approx. 300-fold more toxic than vanadium (96-h LC₅₀ = 0.4 and 118 mg l⁻¹, respectively) but had little effect on the timing of hatch. Vanadium induced premature hatching of eyed eggs at concentrations from 44 to 595 mg l⁻¹. Concentrations of copper required to produce lethality in eyed eggs were similar to concentrations required to produce mortality in juveniles. Vanadium concentrations approx. 15 times higher were required to produce mortality in eyed eggs than in juveniles. Therefore, acute exposure of eyed rainbow trout eggs to vanadium is not a sensitive toxicity test for use in establishing water quality criteria or maximum acceptable toxicant concentrations.     

The toxicity of various mining flotation reagents to rainbow trout (Salmo gairdneri)

Preliminary testing of eight collectors (xanthates) and four frothers in 96-h static and 28-day flow-through bioassays using rainbow trout as the test organism show a great disparity in the toxicity of the chemicals administered in these two ways.For the short-term tests, the relative toxicity of the compounds is expressed as an lc₅₀ or as a range of concentration in mg l⁻¹ in which the lc₅₀ is expected to fall. Of the collectors tested in this way sodium ethyl and potassium amyl xanthate were the most toxic, with lc₅₀'s in the range of 30–50 mg l⁻¹. Among the frothers, xylenol (cresylic acid) was found to be the most toxic (5.6 mg l⁻¹ >lc₅₀ > 3.2 mg l⁻¹) while polypropylene glycol was least toxic (lc₅₀ > 1000 mg l⁻¹).The long-term tests using potassium ethyl, sodium isopropyl, sodium ethyl, and potassium amyl xanthate indicated that in the flow-through system, the toxicity of the chemicals was in the order of 100 fold greater compared with the static bioassay results.     

Application of tracer techniques to continuous-flow toxicity testing

Frequent toxicant analyses are essential for good quality data in long-term continuous-flow tests. Due to the time consuming and costly chemical analyses, exposure levels are measured at best on a daily basis. These infrequent determinations may not detect variability in toxicant concentrations that could result in test failures. To minimize repetitive testing and improve data quality, a dye tracer method was evaluated. Rhodamine WT was selected as a toxicant tracer because of easy detectability, low toxicity to aquatic organisms, and negligible transformation in the aquatic environment.Results over a 24 h period showed that rhodamine reliably predicted the toxicant (diquat) concentrations with an r value of 0.99. Based upon these data, two replicate long-term tests with and without tracer were carried out exposing fathead minnows Pimephales promelas to diquat (1:1′-ethylene-2:2′-dipiridium dibromide). The test results indicated that the added rhodamine WT did not alter the diquat toxicity to fathead minnows using LC₅₀ and EC₅₀ values for comparisons. From these findings it is concluded that dye tracers are suitable toxicant surrogates. Their use in flow-through tests allow more frequent analyses which result in better data and minimizes experimental failure.     

Acute and chronic toxicity of copper to the fathead minnow in a surface water of variable quality

Acute and chronic toxicity tests conducted with the fathead minnow and copper used as the source of dilution water a natural stream to which a sewage treatment plant upstream contributed a variety of materials known to affect acute copper toxicity. Nominal total copper 96-h median tolerance limit values (96-h TL50), determined with static testing procedures, ranged from 1.6 to 21 mg l⁻¹. Dissolved copper 96-h TL50 values ranged from 0.60 to 0.98 mg l⁻¹. The maximum acceptable toxicant concentration (MATC) based on survival, growth, reproduction, and hatchability of eggs was between 0.066 and 0.118 mg l⁻¹.     

Acute toxicity of 12 industrial chemicals to freshwater and saltwater organisms

Aquatic animal toxicity is a major criterion used by the U.S. EPA to designate and classify hazardous substances other than oil. This research developed basic toxicity data for twelve industrial chemicals with which little or no previous testing had been done. Static 96h toxicity tests were performed with one freshwater species (fathead minnow, Pimephales promelas) and one saltwater species (grass shrimp, Palaemonetes pugio or white shrimp, Penaeus setiferus) on the following chemicals: ammonium fluoride, arsenic trisulfide, benzoyl chloride, benzyl chloride, cupric acetate, o-dichlorobenzene, p-dichlorobenzene, mercuric acetate, mercuric thiocyanate, resorcinol, sodium hypochlorite and toluene-2,4-diisocyanate (TDI). As defined by 96 h LC50's ≤ 500 mg l⁻¹, all 12 chemicals were hazardous to freshwater minnows, and all but TDI were hazardous to saltwater shrimp. The physicochemical behaviors of the compounds greatly influenced their aquatic toxicities.     

Acute toxicity and behavioral responses of coho salmon (Oncorhynchus kisutch) and shiner perch (Cymatogaster aggregata) to chlorine in heated sea-water

The acute toxicity and behavioral response to chlorinated and heated sea-water was determined for coho salmon smolts and 1–3 month old shiner perch. LC₅₀'s were determined for 7.5, 15, 30 and 60 min exposure times; 13, 16 and 20°C (Δt = 0, 3, 7°C) temperatures and total residual oxidant (TRO) concentrations ranging from 0.077 to 1.035 mg l⁻¹. The mean 60 min LC₅₀ for shiner perch was significantly reduced (P ≤ 0.05) from 308 μg l⁻¹ TRO at 13°C to 230 μg l⁻¹ TRO at 20°C. The 60 min LC₅₀ for coho salmon decreased from 208 μg l⁻¹ TRO at 13°C to 130 μg l⁻¹ at 20°C. The LC₅₀'s for coho salmon in chlorinated sea-water averaged 55% of those for shiner perch. The relationship between TRO concentration, exposure time, and percent survival in chlorinated sea-water at 13°C is presented for both species.A significant (P ≤ 0.01) avoidance threshold for coho salmon occurred at 2 μg l⁻¹ TRO and was reinforced with increasing temperature. A significant (P ≤ 0.01) avoidance threshold for shiner perch occurred at 175 μg l⁻¹ TRO, while a significant preference (P ≤ 0.05 or 0.01) response at 16°C and 20°C occurred at 10, 25, 50 and 100 μg l⁻¹ TRO. The ecological implications of the toxicity tests and the behavioral responses are discussed.