An evaluation of the potential toxicity of treated bleached kraft mill effluent to striped bass (Morone saxatilis walbaum) larvae exposed through metamorphosis to the juvenile stage

Twenty-day-old striped bass (Morone saxatilis) larvae were exposed to a range of treated bleached kraft mill effluent (BKME) concentrations from 0 to 20% effluent by volume (v/v) under continuous flow test conditins. The experimental test concentrations in the 2–20% BKME test aquaria had a BOD₅ which ranged from < 1 to 5 mg l⁻¹, TSS 12–17 mg l⁻¹, and true color 35–416 mg l⁻¹. Bleached kraft mill effluent did not kill larvae exposed to it for 20 days through metamorphosis to the juvenile stage. The BKME did not alter growth in length, weight or condition factor in larvae over the 20-day exposure period as determined by multiple regression analysis. A linear regression analysis on the dry weight data at Day 20 only, however, indicated a trend of decreasing weight with increasing BKME concentration. Effluent-exposed larvae also developed normally during the 20-day study. All individuals examined completed the transformation from postlarvae to juveniles by the age of 40 days.     

Time-related mortality responses of striped bass (morone saxatilis) ichthyoplankton after exposure to simulated power plant chlorination conditions

Time related mortality responses of striped bass eggs and prolarvae were evaluated after exposure to interacting total residual chlorine (TRC), ΔT and exposure time representing condenser entrainment and effluent discharge conditions. Mortality observations were conducted at unequal time intervals for 36 h after exposure to the test conditions. A non-linear least square regression model was separately fit to the cumulative mortality data for both eggs and prolarvae. Analysis of the immediate mortality response (death at time 0) of both eggs and prolarvae showed no significant effects of ΔT or interactions between ΔT and the other variables; however, only a few hours after exposure ΔT does have a significant effect on the mortality response. Significant two-way interactions between life stage and exposure time (P < 0.001) as well as life stage and TRC (P < 0.003) were found. Analysis of maximum percent cumulative mortality using an arcsine transformation showed no significant interactions among factors affecting latent mortality responses of either life stage. Significant latent mortality effects (mortality after time 0) were due to life stage, exposure time, TRC and ΔT. Cumulative percent mortality increased for both life stages as each test condition increased; prolarvae experienced greater mortality than eggs at all levels. Time of peak mortality for prolarvae occurred later with lower levels of treatment. The mortality peak was sharper in prolarvae than in eggs.     

Combined toxicity of free chlorine, chloramine and temperature to stage I larvae of the American lobster Homarus americanus

The differential effects of free chlorine and chloramine on stage I larvae of the American lobster Homarus americanus have been investigated in continuous flow bioassay units. Applied chloramine was more toxic than corresponding concentrations of applied free chlorine to lobster larvae with estimated lc₅₀ values at 25° of 16.30 mg/l applied free chlorine and 2.02 mg/l applied chloramine. The synergistic effect of temperature on the toxicity of both free chlorine and chloramine has also been demonstrated. Exposure to applied free chlorine at 20° resulted in no significant mortality of test organisms, whereas exposure at 30° resulted in an estimated lc₅₀ value of 2.50 mg/l. Applied chloramine was considerably more toxic with an estimated lc₅₀ value at 20° of 4.08 mg/l and at 30° of 0.56 mg/l.The action of each toxicant appeared to be an alteration of standard metabolic activity as revealed by changes in respiration rates during and after exposure to applied free chlorine and chloramine. Initial respiratory stress was detected during exposure to 0.05 mg/l applied chloramine and 5.00 mg/l applied free chlorine. Reductions in respiration rates 48 h after exposure were observed with exposure to all concentrations tested, similar results being obtained following exposure to 0.05 mg/l applied chloramine and 0.10 mg/l applied free chlorine. These results are indicative of the need for information in addition to that obtained in standard bioassays for an adequate assessment of chlorine toxicity.The apparent chlorine demand of the seawater used in this study was determined after removal of particulate and dissolved organics and ammonia. Approximately 18% of the applied level of free chlorine and chloramine was recovered as residuals, measured by amperometric titration; however, no reason for this low recovery has been determined. Until it has been established that undetected chlorine and chloramine in seawater do not result in the production of toxic compounds, both applied and residual levels should be reported in toxicity studies.     

Histopathological effects of intermittent chlorine exposure on bluegill (Lepomis macrochirus) and rainbow trout (Salmo gairdneri)

Fish were exposed to multiple pulses of free residual chlorine in the water at four concentrations ranging from sublethal to lethal levels. Histological examinations were made of moribund fish and those surviving the exposures.Sublethal concentrations caused moderate gill hyperplasia and swelling of the lamellar epithelial cells. Lethal concentrations caused extensive hyperplastic lesions of gill epithelium. No kidney damage was seen in any of the fish. Liver glycogen was severely depleted, probably as a result of the hypoxemia produced by the gill damage. Hepatic necrosis was seen in fish exposed to high chlorine concentrations and these lesions were more extensive at elevated temperatures. From these observations and other physiological studies, it is concluded that death in fish from exposure to several pulses of free residual chlorine is due primarily to histological damage to the gills causing blockage of respiratory gas transport across the gill epithelium.     

The effects of variation in climatic temperature (1980–2001) on breeding activity and tadpole stage duration in the common toad, Bufo bufo

The effects of variation in climatic temperature on breeding behaviour and tadpole growth were investigated using data collected during a 22-year study of a single population of common toads, Bufo bufo, in southern England. Although the start of the breeding season each year, taken as the day when adult toads first arrived at their breeding pond in large numbers, showed no trend over time (1980–2001) it was highly correlated with climatic temperature. Thus, toads started breeding approximately 50 days earlier in the year following very mild winters (1993: February 2nd) compared with very cold ones (1986: March 23rd). Regression analysis of the relationship between the mean temperature of the 40 days immediately preceding the main arrival of toads at the breeding pond revealed that for every 1° increase (or decrease) the toads arrived 12 days earlier (or later). Although the duration of the tadpole stage was longer when spawning was early, toadlets still emerged from the pond earlier than when spawning was late. The increased length of the tadpole stage, in years when spawning was early, was due to an increase in the proportion of cold days when the minimum ground temperature was at or below 0 °C. Thus, the tadpole stage was approximately 6 days longer (or shorter) for every 5% increase (or decrease) in the proportion of cold days the tadpoles were exposed to.     

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 effects of temperature, pH, and ammonia concentration on the inactivation of Ascaris eggs in sewage sludge

The reported inactivation of Ascaris eggs during alkaline sludge stabilization is highly variable. The objective of our research was to better understand the sources of this variability by quantifying the effects of temperature, pH, and ammonia concentration on the inactivation of indigenous Ascaris eggs in wastewater sludge. Primary sludge was supplemented with ammonia (0, 1000, and 5000mg/l NH(3)-N) and Ca(OH)(2) and incubated in sealed bottles across the range of temperatures (20, 30, 40, and 50 degrees C) and pH (7 and 12) that may be encountered during treatment. Changes in egg viability over time were fit to a two-parameter kinetic model (shoulder and first-order region); to compare treatment conditions, the time for 99% inactivation (t(99)) was also calculated. Each 10 degrees C increase in temperature caused a significant decrease in t(99) at every pH and ammonia concentration tested. At 50 degrees C, the effect of temperature was dominant, such that no effect of pH or ammonia was observed. At 30 and 40 degrees C, raising the pH from 7 to 12 decreased t(99), but at 20 degrees C no pH effect was seen over 80 d (very little inactivation occurred). At 20, 30, and 40 degrees C, the addition of ammonia dramatically decreased t(99). The effect of pH could not be completely separated from that of ammonia, as the unamended sludge samples contained 100-200mg/l indigenous ammonia. Because temperature, pH, and ammonia all contributed to Ascaris egg inactivation, it is essential that these parameters are measured and accounted for when assessing the effectiveness of alkaline stabilization. Furthermore, inactivation by ammonia could be exploited to improve the effectiveness of alkaline sludge stabilization.     

The effects of free chlorine and chloramine on growth and respiration rates of larval lobsters (Homarus Americanus)

The length, dry weight and standard respiration rate of larval lobsters (Homarus americanus) were monitored for 19 days following a 60 min exposure at 25°C to 1.0 mg I⁻¹ applied free chlorine and 1.0 mg I⁻¹ applied chloramine. Compared to control organisms, significantly lower increases in dry weight (P < 0.05) and significant reductions in standard respiration rates (P < 0.01) were measured among exposed organisms; greater differences were detected among chloramine exposed organisms. From these results it can be concluded that acute exposure to either free chlorine or chloramine results in subsequent reductions in growth and metabolic activity of larval lobsters.     

Effects of species interactions on the survival and respiration of Limnodrilus hoffmeisteri and Tubifex tubifex (Oligochaeta, tubificidae) exposed to various pollutants and environmental factors

Laboratory tests were conducted to determine short-term (96 h LC 50) and physiological (respiration) effects of various pollutants (Cd, Hg, NaPCP) and environmental factors (temperature, pH, salinity, anoxia) on mixtures of two freshwater oligochaete species: Limnodrilus hoffmeisteri and Tubifex tubifex. Comparisons with similar data for individual species indicated that mixed species were significantly more tolerant of toxicants, similarly tolerant of environmental factors and less tolerant of anoxia. Although individually these species regulated respiration rate, in mixed culture they were non-regulators and respiratory changes in response to stress appeared to vary depending on test conditions.     

The effect of humidity,air temperature,and wind speed on fine fuel moisture content

A controlled environmental chamber was used to study the effects of relative humidity, air temperature, and wind speed on moisture content of tobosa grass. Prediction equations were developed to show rates of change in fine fuel moisture content and equilibrium fine fuel moisture content for both absorption and desorption. Note: Mr. Britton is a Research Associate at Texas Tech University; Mr. Countryman, a Project Leader, Forest Fire Laboratory, Riverside, California; Dr. Wright, Associate Professor of Range Management, Texas Tech University; and Dr. Walvekar, Associate Professor of Industrial Engineering, Texas Tech University. Mr. Britton’s current address is Range Science Department, Texas A & M University, College Station, Texas. Note: This paper is College of Agricultural Sciences, Texas Tech University Contribution No. T-9-111.     

Lethal toxicity of permethrin (NRDC-143) to rainbow trout, salmo gairdneri, in relation to body weight and water temperature

Lethal toxicity of permethrin varied inversely with water temperature and body weight. The 96 h LC 50 (median lethal concentration) for 1 g trout increased by an order of magnitude from 0.62 to 6.43 μg 1⁻¹ between 5 and 20°C. However between 5 and 10°C the 96 h LC 50 changed little from 0.6 μg 1⁻¹. Large trout (200 g) were considerably more tolerant to permethrin than small fish. Thus, the 96 h LC 50s for 1 and 200 g trout were 3.17 and 314 μg 1⁻¹ respectively at 15°C. The size effect was most pronounced between 1 and 50 g.It is to be noted that the application of permethrin for insect control coincides with the usual period of emergence of rainbow trout fry subsequent to a spawning period of April to late June.     

The effect of precipitation and air temperature on land‐cover change in the Sahel

Vegetation changes in the Sahel region are strongly affected by variation in rainfall, but air temperature has been considered a relatively minor climatic factor in previous studies. However, soil moisture, the major water source for vegetation in arid and semiarid regions, is generally dependent on temperature‐controlled evaporation. Therefore, we can hypothesize that air temperature modifies the sensitivity of vegetation greenness to rainfall because water loss in soil is critically vulnerable to temperature, although Sahel plants can tolerate high temperatures. In this study, the annual mean of daily maximum air temperature was used as a constraint in analyzing the relationships between annual changes in the cumulative enhanced vegetation index (EVI) and total rainfall. We found that rainfall increase in hotter years could not well induce land greening, and decreased rainfall in cooler years did not necessarily cause vegetation degradation. This presents the importance of temperature as a climatic component in understanding the mechanism of rainfall‐induced land‐cover changes in the Sahel region.     

The toxicity of jet fuels to fish—II: The toxicity of JP-8 to flagfish (Jordanella floridae) and rainbow trout (Salmo gairdneri) and golden shiners (Notemigonus chysoleucas)

JP-8 is a widely-used commercial and military jet fuel which may reach the aquatic environment by several avenues. The toxicity of JP-8 to cold and warm water fish was investigated to help define the impact on fresh water species. Fish were exposed to the water soluble fraction (WSF) of JP-8 in static acute bioassays and continuous-flow bioassays of approx. 4 months duration. The goal was to determine the 96-h LC₅₀ and the long-term no effect level on the life cycle. The acute toxicity to a warm water fish was found to be unaffected by pH in the range of 7.3–9.1. The no effect level with respect to growth was lower in rainbow trout than in flagfish. Fuel accumulation and depuration from fish tissues are compared for the two species, as are the effects on egg hatching. The relative toxicity of JP-8 and JP-9 (previously reported) is discussed.     

Comparison of various revised k–ε models and LES applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer

This paper compares computational fluid dynamics (CFD) results using various revised k–ε models and large eddy simulation (LES) applied to flow around a high-rise building model with 1:1:2 shape placed within the surface boundary layer. The first part of the paper examines the accuracy of various revised k–ε models, i.e. LK model, MMK model and Durbin's revised k–ε model, by comparing their results with experimental data. Among the computations using various revised k–ε models compared here, Durbin's revised k–ε model shows the best agreement with the experiment. The reason for the good performance of Durbin's model is discussed on the basis of ‘Realizability’ of predicted results. The second part of the paper describes the computations based on LES with and without inflow turbulence applied to the same flowfield. The results are compared with those of the experiments and Durbin's k–ε model in order to clarify the effect of velocity fluctuations on prediction accuracy of time-averaged velocity fields around the building. Special attention is paid to prediction accuracy for reproducing flow behind a building. The LES results with inflow turbulence show generally good agreement with experimental results in terms of the distributions of velocity and turbulence energy in this region. This improvement is mainly due to the fact that the periodic velocity fluctuation behind the building is well reproduced in LES.     

An evaluation of the relative importance of food and water as sources of p,p′-DDT to the goldfish, carassius auratus (l.)

Goldfish (Carassius auratus) were simultaneously exposed to p,p′-DDT from two sources—food ([³⁶Cl]p,p′-DDT) and water ([¹⁴C]p,p′-DDT). The concentration of p,p′-DDT in food was maintained at about 1 μg g⁻¹ while the water concentration of p,p′-DDT was varied for each experiment (2, 20 and 177 ng dm⁻³). In these experiments the contribution of p,p′-DDT from food to the total body residue varied over the duration of the exposure from 0 to 81% (water concentration about 2 ng dm⁻³) and from 3.8 to 4.8% (water concentration about 171 ng dm⁻³). The results from these experiments were compared with those of experiments in which some goldfish were exposed to DDT-contaminated food and others to DDT-contaminated water. Comparison suggested that goldfish exposed to DDT-contaminated food and water simultaneously, had accumulated p,p′-DDT from the two sources additively.The data supports the concept that p,p′-DDT residues in fish can be derived from both food and water. We suggest that the importance of each source is determined by its relative concentration over the period of exposure. p,p′-DDT taken up by goldfish was converted, slowly at first, then more rapidly to p,p′-DDE reaching a maximum of > 80% from both water and food sources after about 40 days. Dietary p,p′-DDT was converted to p,p′-DDD to a greater extent (max. 15.9%) than water-borne p,p′-DDT is converted to p,p′-DDD (max. 2.8%).     

The effect of wastewater phosphorus removal on shagawa lake, Minnesota: phosphorus supplies, lake phosphorus and chlorophyll a

In early 1973, the phosphorus supply to Shagawa Lake, Minnesota, was reduced by about 80% when a tertiary wastewater treatment plant began operating. Significant reductions in total and soluble reactive phosphorus concentrations have occurred in the lake since that time. By 1976 the average (volume weighted over the entire lake) total and soluble reactive phosphorus concentrations had declined from about 51 and 21 μg l⁻¹ to about 30 and 4.5 μg l⁻¹, respectively, corresponding to 40 and 80% reductions. During 1975 and 1976, chlorophyll a (averaged over the top 5 m) had decreased to less than 50% of the pretreatment level during May-June but during July-August little change had occurred.

A phosphorus residence time model projected equilibrium total phosphorus concentrations of about 12 μg l⁻¹ within 1.5 years. The fact that this level was not reached is attributed to a feedback of phosphorus from the sediments, primarily during summer. This phenomenon has been incorporated into a modified total phosphorus mass balance model which projects the phosphorus pattern through 1976 quite accurately. The close fit of the modified mass balance model implies that the phosphorus supply from the sediments has not diminished since treatment since treatment began, and that further recovery of the lake will depend upon how long this feedback of phosphorus from the sediments continues.     

The influence of substrate, pH, diet and temperature upon cadmium accumulation in the asiatic clam (Corbicula fluminea) in laboratory artificial streams

The influence of substrate, pH, diet and temperature upon the accumulation of cadmium (0.05 mg l⁻¹ dose < 0.001 mg l⁻¹ control) in the visceral mass of the Asiatic clam Corbicula fluminea was studied in laboratory artificial stream systems at intervals of 0, 3, 5, 7, 10 and 14-day exposures. Four substrate conditions, sand; sand, silt and clay (SSC); sand, clay and organic matter (SCO); and no substrate (NoS), were considered. The greatest tissue accumulation of cadmium in C. fluminea occurred at 0.05 mg l⁻¹ Cd in NoS and the lowest in clams occupying SCO. Complexation of available metals, lower clam filtering rates and physical protection by the substrate were attributed to the depressed cadmium accumulation of clams exposed in the SCO substrate. Lower pH exposures (5.0 vs 7.8) significantly (P 0.05 level) reduced cadmium uptake at 21°C but had little effect at 9°C. Uptake was higher in clams fed with cadmium-exposed Chlamydomonas reinhardt at 21°C but not at 9°C. In temperature exposures alone at 0.05 mg l⁻¹ Cd, accumulation was significantly higher in C. fluminea exposed at 21°C than at 9°C. The results are discussed relative to the importance of standardized laboratory protocol and the use of C. fluminea as a bioindicator of heavy metal stress.     

The reaction of whitefish, Coregonus clupeaformis, to the anionic detergent sodium lauryl sulphate and its effects on their olfactory responses

Whitefish, Coregonus clupeaformis, were attracted to an anionic detergent sodium lauryl sulphate (SLS) at sublethal concentrations, when tested in a trough where a choice between clean and modified water was presented. The olfactory bulbar electrical responses to odourants were depressed when the nares were perfused with SLS and household detergents. The lowest concentration of SLS to cause minimum effects within 15 min was 0.1 mg 1⁻¹. Possible modes of action of detergent are discussed.     

The effects of variation in climatic temperature (1980-2001) on breeding activity and tadpole stage duration in the common toad,Bufo bufo

The effects of variation in climatic temperature on breeding behaviour and tadpole growth were investigated using data collected during a 22-year study of a single population of common toads, Bufo bufo, in southern England. Although the start of the breeding season each year, taken as the day when adult toads first arrived at their breeding pond in large numbers, showed no trend over time (1980-2001) it was highly correlated with climatic temperature. Thus, toads started breeding approximately 50 days earlier in the year following very mild winters (1993: February 2nd) compared with very cold ones (1986: March 23rd). Regression analysis of the relationship between the mean temperature of the 40 days immediately preceding the main arrival of toads at the breeding pond revealed that for every 1 degrees increase (or decrease) the toads arrived 12 days earlier (or later). Although the duration of the tadpole stage was longer when spawning was early, toadlets still emerged from the pond earlier than when spawning was late. The increased length of the tadpole stage, in years when spawning was early, was due to an increase in the proportion of cold days when the minimum ground temperature was at or below 0 degrees C. Thus, the tadpole stage was approximately 6 days longer (or shorter) for every 5% increase (or decrease) in the proportion of cold days the tadpoles were exposed to.