Chronic toxicity of vanadium to flagfish

The 96-h LC50 of vanadium to adult American flagfish (Jordanella floridae) was 11.2 mg l⁻¹ in very hard water. Larvae showed 28-day LC50's of 1.13 and 1.88 mg l⁻¹ of vanadium with larger larvae being more resistant. These appeared to be thresholds of lethality. During continuous exposure for 96 days, larval growth and survival were the most sensitive indicators of vanadium toxicity and were marginally reduced at 0.17 mg l⁻¹. At 0.041 mg l⁻¹, there were no deleterious sublethal effects but there was definite stimulation of growth in females and of reproductive performance. The threshold for chronic toxicity was judged to be about 0.08 mg l⁻¹. The “safe”-to-lethal ratio was 0.007 and this could be used as an application factor for other species. There was no clear evidence that vanadium had any long-term cumulative toxicity.     

A preliminary study of metal distribution in three waterhyacinth biotypes

Two waterhyacinth (Eichhornia crassipes (Mart.) Solms) biotypes from Broward County, Florida, were collected and analyzed for chlorophyll content and metal distribution (potassium, calcium, magnesium, cobalt, copper, manganese and iron) in roots, stems and leaves. Two biotypes were distinguished by size (medium or “stunted”, and large or “super”) and by whether they were or were not eaten (“stunted” and ”super”, respectively) by the waterhyacinth weevil, Neochetina eichhorniae Warner. Results are compared with a third biotype (small or “normal”): i.e. plants from the Hillsborough and Peace Rivers where the weevils have not been released. The data indicate abnormal concentration of cobalt and iron in the leaves of the “super” plants relative to the third biotype. Fractions of calcium, magnesium, manganese, iron and copper in roots showed a significant, negative linear correlation coefficient, r, with solubility product constant (log K_sp) for metal carbonates of the small and medium biotypes.     

Growth of blue-green algae in the Manukau (New Zealand) oxidation ponds—II. Experimental studies on algal interaction

Water sampled from the Manukau oxidation ponds between 6 December 1973 and 12 July 1974 was tested for its ability to support blue-green algal growth. A local blue-green algal isolate of Anabaena grew well on membrane filtered pond water throughout the year, however the unfiltered water sustained Anabaena only when the resident green algal populations, in particular Chlorella, were low.Temperature and pH optima for growth of Anabaena and the Manukau pond algal dominant, Chlorella, were found to be significantly different: 28–35°C and pH 9–10 and 23–28°C and pH 7–8 respectively. The ambient conditions of the ponds favoured growth of Chlorella over blue-green algae during the period of study.     

Studies on the effects of sewage effluent on gastropod populations in experimental streams

Population density, biomass, growth and reproduction rate of the gastropods Lymnaea peregra (Müller) and Potamopyrgus jenkinsi (Smith) were monitored over a 21 month period in three experimental earth channels, one carrying clean river water and the others 25 and 50% treated sewage effluent mixed with river water. Each channel was divided into riffle and pool stretches; the abundance and biomass of both species were higher in the riffles. The abundance and biomass of L. peregra were significantly greater (P < 0.01) in the riffle in the presence of effluent. Concentration of effluent did not have a significant effect on abundance or biomass. The abundance and biomass of P. jenkinsi were significantly greater (P < 0.001) in riffle and pool in the absence of effluent. In addition, the abundance and biomass of P. jenkinsi were significantly greater (P < 0.05) in the 25% effluent channel than in 50% effluent. No significant differences in the growth of L. peregra between channels were observed. The average number of eggs and of egg masses laid by L. peregra was significantly greater (P < 0.01) in riffle and pool in the presence of effluent. In the riffle, significantly more masses (P < 0.05) and more eggs per adult (P < 0.01) were laid in the 25% effluent channel than in 50% effluent. No differences were observed in the reproduction rate per adult of P. jenkinsi between the 0 and 25% effluent channels. It is concluded that population differences between channels are probably largely the result of differing mortality rates.     

The dynamics of suspended algal populations in the lower Wye catchment

The algae of the R. Wye and its tributary the R. Lugg were described principally from samples collected from 7 sites in the lower Wye catchment during 1980 and 1981. The density of algae in the Wye was found to be correlated with river flow and solar radiation, highest numbers (12.5 × 10⁵ cells ml⁻¹), principally of Scenedesmus and Cyclotella, occurring at low stable flows and relatively high solar radiation. Algal populations in the Lugg were much smaller ( 1.3 × 10³cells ml⁻¹) than those of the Wye and were principally composed of species derived from the periphyton. Downstream increases in load (cell density × flow) of both Scenedesmus and Cyclotella in the Wye were generally equivalent to about 0.3 division d⁻¹; these rates were lower than those obtained in laboratory culture and this was probably largely related to underestimates arising from algal removal by filter feeders (principally simuliid larvae). Potential problems arising from the treatment of Wye water supporting substantial algal growths are considered: these include haloform production, deoxygenation in a transfer pipeline, algal penetration into potable supply and taste and odour.     

Acute and chronic toxicity of lead to rainbow trout salmo gairdneri, in hard and soft water

Lead was found to be highly toxic to rainbow trout in both hard water (hardness 353 mg l⁻¹ as CaCO₃) and soft water (hardness 28 mg l⁻¹. Analytical results differ greatly with methods of analysis when measuring concentrations of lead in the two types of water. This is exemplified in LC50's and maximum acceptable toxicant concentrations (MATC's) obtained when reported as dissolved lead vs total lead added in hard water. Two static bioassays in hard water gave 96-h LC50's of 1.32 and 1.47 mg l⁻¹ dissolved lead vs total lead LC50's of 542 and 471 mg l⁻¹, respectively. In a flow-through bioassay in soft water a 96-h LC50 of 1.17 mg l⁻¹, expressed as either dissolved or total lead, was obtained. From chronic bioassays, MATC's of lead for rainbow trout in hard water were between 18.2 and 31.7 μg l⁻¹ dissolved lead vs 120–360 μg l⁻¹ total lead. In soft water, where exposure to lead was initiated at the eyed egg stage of development, the MATC was between 4.1 and 7.6 μg l⁻¹. With exposure to lead beginning after hatching and swim-up of fry, the MATC was between 7.2 and 14.6 μg l⁻¹. Therefore, fish were more sensitive to the effects of lead when exposed as eggs.     

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.     

A rapid method for estimating log P for organic chemicals

The logarithm of the retention time (log RT) of organic chemicals on a permanently bonded (C-18) reverse-phase high-pressure liquid chromatography system is shown to be linearly related to the logarithm of the n-octanol/water partition coefficient (log P). A rapid, inexpensive technique based on reverse-phase high-pressure liquid chromatography has been developed to estimate the n-octanol/water partition coefficient of organic chemicals. The system consists of a preparative Micro-Pak^® C-10 reverse-phase column eluted with a 15% water/85% methanol solvent flowing at 2 ml min⁻¹ at room temperature.A linear calibration of the logarithm of retention time with the logarithm of the partition coefficient (log P) is attained by using a mixture of benzene, bromobenzene, biphenyl, bibenzyl, p,p'DDE, and 2,4,5,2′,5′-pentachlorobiphenyl as reference standards of known log P. Using a calibration mixture, the log P of other organic chemicals were estimated with a mean accuracy of 22.8% of the log P values reported in the literature. The technique permits estimation of log P in a maximum of 25 min and does not require a knowledge of the structure of the chemical for the estimate.     

Growth and nutrient uptake of green alga, Scenedesmus dimorphus, under a wide range of nitrogen/phosphorus ratio—I. Experimental study

In order to elucidate the relation between algal growth and nutrients such as nitrogen and phosphorus, a chemostat culture experiment using Scenedesmus dimorphus was performed under the conditions of T-N/T-P ratio of 2–50 mg N mg⁻¹ P and dilution rate of 1–4 day⁻¹. It was ensured from the results that nitrogen and/or phosphorus is the limiting nutrient for the growth of this alga under these conditions. The optimum T-N/T-P ratio for its growth was observed to change from 20 to 5 mg N mg⁻¹ P as the dilution rate varied from 1 to 4 day⁻¹ and, in most of the range of T-N/T-P ratio and dilution rate, its growth rate was not regulated by only one of the available nitrogen and phosphorus concentrations in the medium and algal nitrogen and phosphorus contents. Based on these facts, the multiplicative effect rather than the threshold effect of these two nutrients on its growth was considered to exist. It has been suggested, however, that algal nitrogen and phosphorus contents, especially nitrogen content, are the most important factors regulating its growth. Nitrogen uptake rate of this alga increased at a given concentration of available nitrogen in the medium as T-N/T-P ratio decreased down to 2 or 5 mg N mg⁻¹ P. It is also suggested that a multiplicative effect of nitrogen and phosphorus on uptake of these nutrients by S. dimorphus may exist.     

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.     

A pilot study on the lytic activity of bdellovibrio in wastewater

Domestic wastewater and 0.22 μm pore size wastewater filtrates in a small-scale laboratory wastewater treatment system were inoculated with qual numbers of Eschericia coli and of Bdellovibrio cells. Over a 9-day period, cell counts were made for Bdellovibrio and coliforms. A 3 log reduction within a 72 h incubation period was recorded for both Bdellovibrio and the coliform population inoculated into wastewater. A significant difference (P < 0.05) was observed between the Bdellovibrio populations in wastewater and in wastewater filtrates within an incubation period of 24h and between the coliform populations within an incubation period of 48 h. The data from the study indicate that steady-state conditions appear to exist concerning the interaction between Bdellovibrio and E. coli in waste-water and that Bdellovibrio has only a minor role in the elimination of E. coli from wastewater.     

Effect of oxidants on microalgal flocculation

The effects of chlorine, ozone and chlorine dioxide on Scenedesmus sp. cultures were studied. Algal cell viability and chlorophyll concentration decreased, and the concentration of dissolved organic substances increased with increasing applied oxidant concentration. Pretreatment with chlorine dioxide (1, 3 or 5 mg l⁻¹) or ozone (2.6, 4.6 or 8.1 mg l⁻¹) on algal cultures enhanced algal flocculation with alum, while prechlorination with 10 or 20 mg l⁻¹ increased the required dosage of alum by 15%. Scanning electron micrographs of oxidized cells revealed drastically adverse effects upon the cell surface architecture: in addition to the oxidation of noncellular organic materials, the oxidants damaged both cell surface structures and intracellular components. A model explaining the effects of the different oxidants on microalgal flocculation is suggested.     

Domestic and agricultural contributions to the inputs of phosphorus and nitrogen to Lough Neagh

Loadings of nitrogen and phosphorus from the major river catchments that contribute to Lough Neagh have been measured for the years 1971–1974. Analysis of this data indicated that there was a very significant correlation between soluble ortho-P loadings and the human but not the animal population densities of the catchments. The land drainage and agricultural contribution of soluble ortho-P to Lough Neagh was 0.14 kg P-ha⁻¹·yr⁻¹ which was about 25% of the measured soluble ortho-P loading to the Lough. It was estimated that the introduction of phosphorus removal treatment at sewage works connected to populations greater than 2000 could curtail 50% of the phosphorus available to support algal growth in the Lough. There was a good correlation between nitrogen fertilisers usage in Northern Ireland and the nitrate concentration in the major rivers.     

The use of algal assays for determining the effect of iron and phosphorus compounds on the growth of various algal species

Algal assays were performed with unialgal cultures of Oscillatoria rubescens. Asterionella formosa, Synedra acus. Haematococcus pluvialis and Scenedesmus quadricauda. The method we used differs in some important respects from the methods described in literature on this subject and these differences are explained in detail.The agal crop, measured as μg 1⁻¹ chlorophyll α was used to determine the productivity of the water samples tested. The following were tested: (1) untreated Wahnbach water; (2) Wahnbach water treated in a pilot plant for elimination of phosphorus and turbid materials; (3) water samples from the pre-reservoir effluent of the Wahnbach Reservoir; and (4) water samples from the Wahnbach Reservoir taken from near the dam.The fertility of the water samples decreased in all the test series in the following order: untreated Wahnbach water > pre-reservoir effluent > water from the Wahnbach reservoir > Wahnbach water treated in the pilot plant. The productivity of the water samples rich in turbid materials and algae, was higher in heat sterilized samples than those prepared by filtration. There is a clear correlation between the productivity of unfiltered sterilized water samples and their iron and total phosphorus content.Using algal assays we proved that the large decrease in productivity resulting from treating the Wahnbach, the main reservoir inflow, is chiefly due to the removal of phosphorus compounds, but also to the removal of iron and other unknown substances. There are indications that the amount of iron required for growth, as compared to that of phosphorus, varies greatly depending on the individual algal species.The significance of the algal assay and their results relating to measures for limiting eutrophication using phosphorus removal plants is discussed.     

Aquacultural approaches to recycling of dissolved nutrients in secondarily treated domestic wastewaters—I Nutrient uptake and release by artificial food chains

Wastewater based artificial food chains composed of sequential monocultures of a suspended unicellular green alga, of an herbivorous cladoceran crustacean, and of an herbivorous or a carnivorous teleost fish and of filamentous green algae were studied in an effort to find efficient, potentially economically viable mechanisms for the biological capture (tertiary treatment) of nutrients (especially nitrate and phosphate) in wastewaters processed by small to medium size two-stage treatment plants that primarily handle domestic and agricultural wastes.All experiments were carried out on laboratory scale systems with a low technology approach to keep apparatus and procedures as simple and reliable as possible.Among all organisms tested as components of the artificial food chains only the unicellular green alga Scenedesmus, the filamentous green algae Cladophora and Ulothrix, the cladoceran crustaceans Daphnia magna and Daphnia pulex, and the teleost fishes Notemigonus crysoleucas, Pimephales promelas and Notropis lutrensis were found to be suitable.Unmodified secondarily treated domestic effluents were both iron deficient and lacking in buffering capacity necessary for optimal algal growth. Additions of both ferrous iron (1 ppm) and carbon dioxide (5%) were required to achieve good quality cultures suitable for feeding cladocerans. Most removal of nutrients occurred in the first algal stage of the food chain. Nitrate removal averaged 78%, phosphate removal 55% in buffered algal cultures. In unbuffered cultures nitrate removal was 30%, phosphate removal 98%. The near complete removal of phosphate in unbuffered algal cultures was probably due to physico-chemical precipitation of phosphate complexes formed as a result of high pH levels (pH > 10) reached within 24 h of culture initiation. Cladoceran and fish stages added nutrients (mostly ammonia and phosphate) back into the effluent. A final stage of Ulothrix and Cladophora algae removed nutrients regenerated by cladocerans and fishes. A 12 h light–12 h dark cycle statistically significantly reduced levels of nutrient removal by both unbuffered and buffered algal cultures below removal rates measured in algae cultured in continuous light. Daily harvesting rates of 25–75% of culture volumes had no significant effect upon removals of nitrate by buffered algal cultures; phosphate removals were inversely proportional to harvesting rates in these cultures.Important theoretical and technical points are discussed.     

Algae and crustaceans as indicators of bioactivity of industrial wastes

Freshwater (Selenastrum capricornutum) and marine (Skeletonema costatum) algae were exposed to liquid wastes from 10 industrial sites in laboratory bioassays. All wastes affected algal growth, either by stimulation only or by stimulation at low concentrations and inhibition at high concentrations. Generally, S. capricornutum and Sk. costatum responded similarly to each waste: SC20's (concentration that stimulated growth by 20%) were between 0.01 and 20.0% waste; EC50's (concentration that inhibited growth by 50%), between 5.1 and 85.5% waste. Since toxicity to S. capricornutum was usually lost by the sixth or seventh day of exposure in all wastes except one, it is recommended that algal tests be carried out for 4 days. Both algal species were more sensitive to the wastes than were Daphnia magna (freshwater) and Mysidopsis bahia (marine). Only three wastes were toxic to D. magna and two were toxic to M. bahia. SC20 and EC50 values are used to calculate the 7-day, 10-year flow rate of the receiving stream required for dilution of effluents to non-toxic concentrations.     

Toxicity-, accumulation- and elimination studies of α-hexachlorocyclohexane (α-HCH) with saltwater organisms of different trophic levels

A short-term study with α-HCH was carried out with saltwater organisms of different trophic levels the alga—Dunaliella, the crustacean—Artemia, and the fish—Lebistes, acclimated to water of gradually increased salinity.Within the solubility range of α-HCH in saltwater (1.4 mg l⁻¹) there was no influence on the growth of Dunaliella. The LC50 (4 days) for Artemia was 0.5 mg l⁻¹, the EC50 (2 and 4 days)—E = mortality and immobilization, for Lebistes was 1.4 and 1.3 mg l⁻¹ respectively. In the longterm study the LC10 (35 days) for Lebistes proved to be 0.5 mg l⁻¹.In the accumulation studies the concentration factor was about 60–90 with Artemia and about 500 with Lebistes; equilibrium levels were reached within 24 and 48 h respectively. In the elimination studies the α-HCH concentration was halved within 48–72 h in Artemia and within 10 h in Lebistes.     

The application of critical state soil mechanics to the mechanical behaviour of porous sandstones

The mechanical properties of three cohesive sandstones of different porosities (φ) and average grain diameters (R) have been investigated. These were Tennessee sandstone (φ=0.07), Darley Dale sandstone (φ=0.12), and Penrith sandstone (φ=0.25). Unconfined uniaxial compression, constant displacement rate triaxial, and hydrostatic experiments were conducted. Yield stress data produced approximately circular envelopes that decreased in size with increasing porosity or grain size when plotted in the differential stress versus effective mean stress (Q−P) space. Normalization of these data with respect to the hydrostatic grain crushing pressure (P^*) resulted in a unique yield envelope for sandstone. Extending these data into the Q–P–φR space allows the principles of critical state soil mechanics to be applied. The critical state line for porous sandstone (the crestal line of the yield surface) appears to correspond to the transition from dilatant behaviour with localized faulting at low effective mean pressures (P/P^*<0.5), to pervasive cataclastic flow at high effective mean pressures (P/P^*>0.5). Post-yield, deformation progresses towards the critical state as observed by constant volume deformation. The critical state model developed for soil mechanics can be applied to make generalizations about the deformation of cohesive, porous sandstones. The expected behaviour of any porous sand appears to be predictable to a useful degree from a knowledge of P^*, which can be estimated from the simple parameters of porosity and mean grain size.Sensitivity to the presence of water, attributed to sub-critical crack growth, was observed in hydrostatic and uniaxial compression tests in all rock types tested. Considerable strength and elastic anisotropy was also observed.     

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.     

Simulation of water-bloom in a eutrophic lake—I. Photosynthetic characteristics of Microsystis aeruginosa

A perspective of how to simulate “emergence and/or disappearance of the water-bloom… dense population of a blue-green alga, Microcystis aeruginosa at the surface of eutrophic waters… ” was presented.The algal photosynthetic activity. Q_o2 as a function of irradiation light intensity. I, could be represented by the Blackman model, taking the algal content. C of chlorophyll-α and water temperature. 0 as parameters.When the cells that had been cultured under dim light were transferred to a new environment, wherein the light intensity was from 0 (dark) to the level much brighter than the dim light, the value of C exhibited various responses against time. Subtracting the rate of chlorophyll-α degradation from that of chlorophyll-α synthesis, the rate of change in C values during the light-adaptation period was studied.