The toxicity of chlorine to a common vascular aquatic plant

Myriophyllum spicatum was exposed to various chlorine concentrations on a continuous and intermittent basis in 96-h toxicity studies utilizing a proportional diluter. Continuous exposure to chlorine concentrations as low as 0.05 mg l⁻¹ total residual chlorine (TRC) depressed shoot and total plant dry weights approx. 30% relative to controls. Shoot length was depressed approx. 16% at this concentration. Chlorophyll a was depressed 25% at 0.1 mg l⁻¹ TRC. However, intermittent exposure of plants to chlorine for three 2-h periods daily for 96 h indicated an insensitivity to repeated short term chlorine exposure at all concentrations but 1.0 mg l⁻¹ TRC. These results indicate that high level chlorine discharges from waste water facilities and electric generating plants could be a contributing factor impacting nearby submerged aquatic vegetation.     

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.     

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.     

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).     

Comparative effectiveness of chlorine and chlorine dioxide biocide regimes for biofouling control

The effectiveness of chlorine (Cl₂) and chlorine dioxide (ClO₂) in controlling biofouling of 304L stainless steel heat exchanger tubing was compared using an experimental trough system. Three combinations of dose and contact time were evaluated. Chlorination coupled with a dispersant was also tested. Three criteria were used to assess the degree of fouling; organic carbon and dry weight of the fouling material accumulated on metal specimens and the visual appearance of this material on the specimens. These parameters correlated well with one another and therefore, collectively provided an effective means of evaluating biocide efficacy.Metal specimens in all troughs receiving biocide treatment were much less fouled than those in the trough receiving no biocide. Continuous application of Cl₂ at about 0.15 ppm was more effective than four 15-min 1 ppm Cl₂ applications per day. Both of these treatment regimes were more effective than a dose of about 1 ppm for 1 h day⁻¹. Use of a dispersant in combination with Cl₂ showed no significant reduction in the amount of biofouling material accumulation, although a difference in the texture of this material was observed. Unlike the Cl₂ results, low-level continuous ClO₂ treatment at 0.15 ppm resulted in biofouling similar to that when 1 ppm of ClO₂ was used for 1 h day⁻¹. Overall, ClO₂ was significantly (P < 0.05) more effective in controlling biofouling than Cl₂.     

Acute toxicity tests with Daphnia magna straus and Pimephales promelas rafinesque in support of national pollutant discharge elimination permit requirements

The purpose of this study was to determine the static acute toxicity of aniline, p-chloro-m-cresol and 2(2,4,5-trichlorophenoxy) propionic acid (silvex) to daphnids (Daphnia magna) and bis(2-chloroethoxy)methane and 2-sec-butyl-4,6-dinitrophenol (dinoseb) to both daphnids and fathead minnows (Pimephales promelas). These data were needed to fulfill requirements established in the NPDES Permit (National Pollutant Discharge Elimination System) issued to the Michigan Division of The Dow Chemical Co. (Midland, Mich., U.S.A.) by the State of Michigan. Where appropriate, water quality-based effluent limitations could be recommended based on the acute toxicity data generated during this study. The results of the acute toxicity tests indicated that bis(2-chloroethoxy)methane was practically non-toxic to both daphnids and fathead minnows (LC₅₀ values of 201 and 184 mg l⁻¹, respectively); additionally, silvex was also found to be practically non-toxic to daphnids (LC₅₀ value > 140 mg l⁻¹). Aniline was highly toxic and p-chloro-m-cresol moderately toxic to daphnids, with calculated LC₅₀ values of 0.17 and 2.0 mg l⁻¹, respectively. Dinoseb was highly toxic both to daphnids and fathead minnows, with reported LC₅₀ values of 0.24 and 0.17 mg l⁻¹, respectively.     

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 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.     

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.     

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.     

Avoidance response of rainbow trout (Salmo gairdneri) to single-dose chlorination in a power plant discharge canal

Rainbow trout (Salmo gairdneri) were exposed to 20 min single-dose chlorine additions designed to achieve maximum total residual chlorine (TRC) concentrations of 0.04, 0.2, 0.6, and 1.0 mg l⁻¹. First retreats from the chlorine front occurred at 0.05 mg l⁻¹ TRC. Approximately 95% of the fish had moved downstream when TRC reached 0.5 mg l⁻¹, well before cumulative time-dose exposure approached lethal limits. Percentage of fish remaining near the discharge decreased linearly as TRC concentration rose, suggesting that a rapid rise in receiving water chlorine level might be beneficial in reducing cumulative time-dose exposure. Rainbow trout demonstrated the initial sensitivity to avoid lethal chlorine exposure, but complete assessment of the utility of the avoidance response must also consider distribution throughout chlorination and the potential for repeated exposure.     

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.     

Some physiological responses of rainbow trout (Salmo gairdneri) to intermittent monochloramine exposure

Rainbow trout (Salmo gairdneri) were exposed for 2.5 h to monochloramine (NH₂Cl) at an average concentration of 0.16 or 0.23 mg l⁻¹ (and with peak concentrations of 0.4 or 0.6 mg l⁻¹) three times daily. This simulates conditions in the outfall area of many electric power plants. Heart rate, opercular movement, cough frequency, arterial PO₂, lactate, hemoglobin and methemoglobin were monitored. The trout responded to chloramine pulses with slight increases in opercular movement, bradycardia, and a large increase in cough rate. These factors approached control rates between periods of exposure to a peak concentration of 0.4 mg l⁻¹, but not when the peak was 0.6 mg l⁻¹. Neither hemoglobin or lactate changed, while arterial PO₂ decreased slightly but not significantly. Methemoglobin concentration increased markedly at the end of each period of exposure with some recovery between them. In contrast to free chlorine, which causes acute hypoxemia due to gill damage, chloramine at these concentrations causes little if any hypoxemia. The elevated methemoglobin levels, not seen following exposure to free chlorine, indicate that perhaps chloramine is entering the blood stream to an extent that does not occur with free chlorine. Methemoglobinemia is probably not the proximate cause of death.     

The interaction of treated bleached kraft mill effluent and dissolved oxygen concentration on the survival of the developmental stages of the sheepshead minnow (Cyprinodon variegatus)

The interactions of treated bleached kraft mill effluent (BKME) and dissolved oxygen concentration (DO) on the survival of the embryo, fry, juvenile and adult stages of the sheepshead minnow, Cyprinodon variegatus, were studied under continuous-flow 96 h bioassay conditions. Embryo survival was dependent on effluent concentration only and showed no interaction at nominal DO concentrations of 1.0, 3.0 and 5.0 mg l⁻¹. Survival of the fry was related solely to DO concentration with no interaction with BKME concentrations up to 100%. Juvenile sheepshead minnows showed increased sensitivity to BKME at a nominal DO concentration of 1.0 mg l⁻¹. Adult fish were not affected by BKME at any of the DO concentrations tested. This study shows that the acute toxicity of BKME effluent to sheepshead minnows is a function of the developmental stage of the organism and DO concentration in the receiving stream.     

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%).     

Conditions required for the precipitation of aluminium in acidic natural waters

Laboratory and field studies were carried out in order to define the conditions necessary for the precipitation of Al in natural waters of pH 4–6. It is concluded that if precipitation does occur it involves the formation of Al(oxy)hydroxide, not aluminosilicates or basic aluminium sulphates. The solubility product of the Al(oxy)hydroxide is highly temperature dependent (ΔH = −30.5 kcal⁻¹). It is also sensitive to concentrations of SO₄²⁻ and, more markedly, humic substances (HS); both of these decrease solubility, HS by more than an order of magnitude at a concentration of approx. 5 mg l⁻¹ (equivalent to approx. 2.5 mg l⁻¹ dissolved organic carbon). A semi-empirical equation is proposed that allows the prediction of the effective solubility product at different temperatures and at humic concentrations in the range 0–7 mg l⁻¹. Of the 113 natural water samples analysed, only one was calculated to be oversaturated with respect to Al(oxy)hydroxide.     

Influence sur la survie jusqu'a eclosion des embryons de carpe commune (cyprinus carpio l.) apres traitement, pendant la fecondation et le developpement precoce, par le carbendazime, un fongicide antimitotique de synthese

The toxicity of the systemic antimitotic fungicide carbendazim, a benzimidazol compound, was studied both by trout and common carp insemination, as well as on the early development of the common carp.The toxicity is several grades of magnitude higher for these stages of the vital cycle compared with the effect on the adult stages: whereas The Pesticide Manual states that for the adult Carp, an LC₁₀₀ (24 h) > 1000 mg 1⁻¹ we find, during insemination at pH 9: LC₁₀₀ (30 min) < 5 mg l⁻¹ and during insemination at pH 7: LC₁₀₀ (30 min) <2.5 min l⁻¹.During early development we find, for instance, LC₁₀₀ (30 min) < 5 mg 1⁻¹ before the end of activation and LC₁₀₀ (24 h) < 1 mg l⁻¹ before the end of epiboly.In the course of insemination, the egg is more sensitive to carbendazim at pH 7 than at pH 9: this difference may be attributed to a greater solubility of the non ionic form of the molecule in the biological membranes.The resistance of the embryo to short treatment grows at the end of activation. This may be attributed to the decrease of the shell permeability during activation.Before the end of activation, the resistance to short intoxication seems to be able to fluctuate, which perhaps corresponds to the existence of sensitive stages in the mitotic cycle.The resistance to an over 24-h exposure increases abruptly at the end of epiboly, which could correspond to a protective part played by the enveloping layer.We suggest the possibility of classifying aquatic pollutants by correlating their physiological mode of action to the resistance profile of the fish embryo.The carp egg seems to be a favourable biological model for studying the effects of aquatic pollutants.     

Comparative effectiveness of antifouling treatment regimes using chlorine or a slow-releasing bromine biocide

Five chlorine (Cl₂) and three slow-releasing bromine biocide [1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH)] treatment regimes were compared under laboratory conditions to determine their effectiveness in controlling the fouling of 304L stainless steel heat exchanger tubing. The most effective Cl₂ treatments were low level (0.1 ppm or less) continuous applications. Three intermittent Cl₂ treatments (1 h day⁻¹ at 1.0 ppm, 1 h day⁻¹ at 0.5 ppm, and 3 × 20 min day⁻¹ at 0.5 ppm) were about equally effective. However, all three intermittent regimes were significantly less effective than the low level continuous treatments. The effectiveness of BCDMH treatment was similar to Cl₂ when used intermittently at similar residual concentrations as Cl₂ for 1 h day⁻¹ and continuously at low levels. These experiments indicated that low level continuous treatment was more effective than intermittent treatment for controlling biofouling.     

The effects of depressed pH on flagfish reproduction, growth and survival

Breeding communities of flagfish, Jordanella floridae, were exposed to northern Ontario lake water (hardness 28 mg l⁻¹ CaCo₃) adjusted to depressed pH levels of 6.0, 5.5, 5.0 and 4.5. Control water (pH 6.8) received no acid treatment. Egg production, egg fertility and fry growth was impaired (P < 0.05) at all exposure levels. Flagfish fry survival was reduced (P < 0.05) at pH 5.5 and 5.0 and no fry survived at pH 4.5. Variability of hatching in all treatments precluded any identifiable hatching response to depressed pH. Reduction in the reproductive processes monitored indicated the following order of sensitivity: egg production > fry survival > fry growth > egg fertility.Results of this study coincide with reproductive investigations on brook trout and fathead minnows indicating the “no effect” level of pH depression for successful reproduction to be pH 6.5.     

Detoxification of seawater used for gas scrubbing in the steel industry

Cyanide ion present in seawater after scrubbing blast furnace and coke ovens gases can be removed by sedimentation of hexacyanoferrate complexes followed by oxidation of residual cyanide with Caro's acid. Zinc ion is removed at the same time by adsorption on the hexacyanoferrate/hydrous ferric oxide precipitate.Sulphide is precipitated as ferrous sulphide, then oxidised by atmospheric oxygen. At 25°C and using an Fe/CN ratio of 1·00, initial concentrations of 50 mg l⁻¹ of CN⁻ and 10 mg l⁻¹ of Zn²⁺ in seawater are reduced to 5–7 mg l⁻¹ and 0·1 mg l⁻¹. Subsequent treatment with H₂SO₅/CN = 1·2 reduces the [CN⁻] to 0·1 mg l⁻¹.Treatment of a combined blast furnace/coke ovens effluent ([CN⁻] = 24 mgl⁻¹, [Zn²⁺] = 4·0 mgl⁻¹) with Fe/CN = 1·5 reduced [CN⁻] to 0·2 mg l⁻¹ and [Zn²⁺] to <0·1 mgl⁻¹. Subsequent treatment with H₂SO₅/CN = 2·0 reduced [CN⁻] to 0·2 mg l⁻¹. The process operates best in the pH range 7–9 and so is not affected by the buffer characteristics of seawater.