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.     

Copper toxicity to fishes and an extremely sensitive shrimp in relation to a potential Australian tropical mining‐waste seep

Ephemeral or seasonal streams tributaries to Magela Creek (Alligator Rivers Uranium province, Northern Territory), containing perennial pools, lie adjacent to a 1 km² tailings storage dam, still being filled, whose partial seepage collecting system contains an increasing concentration of copper. Acute copper toxicity to local fauna was determined in a flow‐through apparatus at 27°C and pH 6. The 4‐day LC50 values (μg L^‐1) for total copper were: rainbowfish Melanotaenia splendida inornata 170–190, pennyfish Denariusa bandata 75, and atyid shrimp Caridina sp. 3–4, and the 3‐day LC50 of the catfish Porochilus rendahli 85. Free ionic copper approximated the total copper. Test water quality was as predicted for seepage‐affected streams during a brief critical period in some years: of low hardness and alkalinity but enriched in Mg²⁺ and SO₄ ^2‐. The relative LC50 values correspond to the relative occurrence of similar species among zones of the metals‐affected Finniss River. Magela Creek system waters often had naturally low pH and ion‐concentrations (pH < 6, conductivity < 20 μS cm^‐1); the total copper concentration has repeatedly been similar to the free ionic copper LC50 of Caridina sp. The abundance and distribution of Caridina sp. are likely already influenced by local natural copper concentrations. Seepage total copper has increased to the fishes’ free ionic copper LC50.The hydraulic head of the wet tailings will increase further from 15 to 20 m.     

Toxicity of lipid-soluble copper(II) complexes to the marine diatom Nitzschia closterium: Amelioration by humic substances

Algal assays, using the marine diatom Nitzschia closterium, have established that humic acid (5 mg kg⁻¹) can ameliorate the toxicity of the lipophilic complex Cu(oxine)₂ (3 × 10⁻⁸ mol l⁻¹ in unsupplemented seawater). The toxicity of Cu(PAN)₂ is not ameliorated [PAN = 1-(2-pyridylazo)-2-napthol]. In conjunction with previous visible absorption spectrophotometry and polarographic measurements it was established that humic acid sequesters copper(II) from the hydrophobic complexes, releasing a ligand molecule. The copper(II) toxicity may be ameliorated provided the ligand itself is not toxic.Fulvic acid was significantly less effective in ameliorating toxicity. Because of the significant competition from Ca(II) and Mg(II) in seawater, it is inferred that humic substances may be more effective in ameliorating toxicity of hydrophobic copper complexes in fresh water.     

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.     

Studies on the toxicity of copper sulphate to stone loach Noemacheilus barbatulus (L.) in hard water

The toxicity of copper sulphate to Noemacheilus barbatulus was studied for 64 days in a water of total hardness 249 mg l⁻¹ as CaCO₃. The 63-day lc₅₀ was approximately 0.25 mg Cu l⁻¹. Larger fish survived longer, and at concentrations greater than 0.29 mg l⁻¹ fish hid less during daylight. Noemacheilus surviving 0.12 mg Cu l⁻¹ for 64 days shed copper when placed in clean water for 7 days: gill, muscle, eye and vertebrae lost significant amounts of copper during this period. The opportunity to shed copper during a short period when the poison supply to their tank failed, may have allowed fish exposed to 0.49 mg l⁻¹ to live 12 days longer than expected. The sensitivity of Noemacheilus to copper, cadmium and zinc was compared with that of rainbow trout. Salmo gairdneri.     

Temporal and spatial inhibitory effects of zinc and copper on wastewater biofilms from oxygen concentration profiles determined by microelectrodes

To understand the temporal and spatial toxic effect of heavy metals on the microbial activities of biofilms, microelectrodes were used to measure the inhibitory oxygen (O₂) concentration profiles resulted from the effects of zinc (Zn²⁺) and copper (Cu²⁺). Using the O₂ microprofiles as bases, the spatial distributions of net specific O₂ respiration were determined in biofilms with and without treatment of 5 mg/L Zn²⁺ or 1 mg/L Cu²⁺. Results show that microbial activities were inhibited only in the outer layer (∼400 μm) of the biofilms and bacteria present in the deeper sections of the biofilms became even more active. The inhibition caused by the heavy metals was evaluated by two methods. One was derived from the oxygen influx at the interface and the other was based on the integral of the oxygen consumption calculated from the entire O₂ profile. The two methods yielded significantly different results. We argue that the integral method results in more accurate assessment of toxicity than the surface flux determination.     

Copper dispersal in a water-supply reservoir

Granular (“diamond”) copper sulfate was applied for algal control to the surface of Hoover Reservoir, Franklin Co., Ohio. Soluble and particulate Cu²⁺ concentrations were measured by atomic absorption spectrophotometry at several depths for up to 96 hr after application. The soluble Cu²⁺ concentration decreased to near baseline values in 2 or 6 hr when 0.2 or 0.4 g Cu²⁺/m² was applied was applied respectively. Most of the copper sulfate dissolved in the first 1.75 m of the water column and only 2% of the total copper sulfate reached a depth of at least 4.5 m. A concentration of 0.4 g Cu²⁺/m² controlled a diatom bloom consisting primarily of Melosira spp., Stephanodiscus astraea var. minutula and Asterionella formosa. The largest decrease in dry weight and algal cell numbers was observed 24 hr after copper sulfate treatment.     

Surface runoff estimation over heterogeneous foothills of Aravalli mountain using medium resolution remote sensing rainfall data with soil conservation system‐curve number method: A case of semi‐arid ungauged Manesar Nala watershed

Manesar Nala watershed, having an aerial extent of 71.53 km², was subjected to modelling of its hydrological behaviour for assessing its water resource potential. Modern tools and techniques of Remote Sensing (RS) and Geographic Information System (GIS) were used for assessment of runoff generating potential using the Hydrologic Soil Cover Complex (HSCC) Method [U.S. Department of Agriculture (USDA)‐Soil Conservation System‐Curve Number (SCS‐CN) approach]. RS and GIS were used in generation and integration of thematic maps [such as Land use/Land cover (using LISS‐III data) and Hydrologic Soil Group (HSG), (using soil map of study area) to derive the Curve Number (CN) for simulating Runoff (R_o)]. The daily rainfall (P) data for the study period 2002–2015 were acquired from NOAA Climate Prediction Center (NCPC). Corresponding R_o from the watershed for intense storm events for 14 years were calculated through RS and GIS. GIS and SCS‐CN model was employed for modelling the runoff production to study its hydrological behaviour. The study showed that the Manesar Nala watershed was having a composite Curve Number – II (CN_II) value of 82.5 for normal conditions. For dry and wet conditions these values were estimated at 66.44 (CN_I) and 91.56 (CN_III), respectively. This investigation showed that Manesar Nala watershed exhibited an annual average (of 14 years, 2002–2015) R_o volume of 4 542 514.37 m³ based on the average annual rainfall (P) of 0.72 m (720 mm). The average annual surface runoff (R_o) was predicted to be approximately 0.21 m with annual runoff coefficient (C_R) of 0.29. During the study, we also found a strong correlation ‘r’ between satellite driven P and R_o from NRCS‐CN method of the order of 0.94. The methodology so developed has the potential to be used in other similar ungauged watersheds in the same agro‐climatic conditions for the purpose of planning of watershed conservation measures and other developmental activities.     

Speciation and rate of loss of copper from lakewater with implications to toxicity

The rates of disappearance of total dissolved copper in six prairie “pothole” hard water lakes treated with copper were measured. The first-order rate constants ranged from 1.01 to 0.11 day⁻¹, and the half-times from 1 to 7 days. Concentrations of 12 inorganic copper species and the humic acid-copper complex were calculated for the pH range of each lake. Less than 0.5% of total dissolved copper was calculated to be present at any time as free cupric ion. The total dissolved concentration of added copper was reduced with time probably through precipitation of tenorite (in some cases malachite) and by adsorption on solids.The effectiveness of copper as an algicide in these lakes at the relatively low concentration of added copper is explained in terms of a “total toxic copper” concept, which includes the species Cu(OH)₂⁰ and CuOH⁺ in addition to cupric ion, the generally recognized toxic species.     

Changes in bimodal oxygen uptake of an obligate air breather Anabas testudineus (Bloch) exposed to lindane

Bimodal [aquatic (V_O2) and aerial (V_O2)] oxygen consumption of the air-breathing fish, Anabas testudineus (Bloch) exposed to 0.075 and 0.59 mg 1⁻¹ lindane was measured for 120 and 6 h respectively. In the controls 67.9% of O₂ was obtained from air (V_O2) whereas only 32.1% was obtained from water (v_O2) indicating that A. testudineus predominantly relies on aerial gas exchange. The fish held in both the concentrations of lindane showed a consistent increase in v_O2, V_O2 and (v + V)_O2 (total O₂ consumption) in most of the periods of exposure; but the increases observed in mean O₂ consumption at higher concentration were relatively lower than those in lower concentration. In 0.075 mg 1⁻¹ lindane, the stimulation seen in aerial respiration was more than that in aquatic respiration up to 24 h. The oxygen consumption returned to normal at 96 h in the lower concentration of lindane.     

The effects of copper on maximum respiration rate and growth rate of perch, Perca fluviatilis L.

Addition of copper to the ambient water of perch resulted in decreased daily maximum respiration rates (R_max) and growth rates. The time-course of the effect in R_max was characterized by: (1) an initial decrease over three additions; (2) a minimal “trough” lasting some 10–15 days; and (3) a phase of increasing R_max. The variation in R_max was due to copper concentration and exposure time. The decrease in growth rate was most dramatic initially and was correlated to copper concentration and perch weight. The subsequent increase in growth rate was constant and independent of copper concentration. The increase in R_max and in growth rate was interpreted as acclimatization. Up to a given sublethal copper concentration acclimatization resulted in a return to the control level of R_max but not of growth rate.     

Inhibition of the activities of β-galactosidase and dehydrogenases of activated sludge by heavy metals

Heavy metal inhibitions of the activities of β-galactosidase and dehydrogenases in activated sludge were studied.The activities of β-galactosidase and dehydrogenases were strongly inhibited by Cd and Hg. To produce 50% inhibition of β-galactosidase by Cd and Hg required 1.3 and 0.004 mmol g⁻¹ MLSS, respectively. In the case of dehydrogenase, 50% inhibition appeared by Cd 0.16 and Hg 0.04 mmol g⁻¹ MLSS, respectively.The inhibitions of the activities of β-galactosidase and dehydrogenases with Cd and Hg were easily recovered with the addition of thiol compounds. Reactivation by thiols suggested that Cd and Hg form reversible mercaptides with SH groups of β-galactosidase and dehydrogenases.The inhibitions of the activities of β-galactosidase and dehydrogenases by Cd and Hg gave reversible non-competitive type of kinetics. The inhibitor constant (K_i) values of β-galactosidase for Cd and Hg were calculated to be 1.6 mM (1.7 mmol g⁻¹ MLSS) and 0.005 mM (0.005 mmol g⁻¹ MLSS), respectively. K_i values of dehydrogenases for Cd and Hg were 0.6 mM (0.3 mmol g⁻¹ MLSS) and 0.02 mM (0.01 mmol g⁻¹ MLSS), respectively.     

A comprehensive study on the biological treatabilities of phenol and methanol—III Treatment system design

The effects of temperature, pH, salinity, and nutrients on bacterial activities were investigated and evaluated using a statistical method. The substrate utilization rate coefficient (k) decreased as pH deviated from neutral and as salinity increased, and the unfavorable pH and salinity alleviated the temperature effect on k. The modified Arrhenius equation, k_T2 = k_T1 θ(^T2−T1), was not effective in describing the temperature effect on k: the temperature coefficient (θ) ranged between 1.0–1.4 depending on the temperature range, pH, salinity, and substance (phenol or methanol). The endogeneous respiration activity was affected by various environmental factors such as pH, temperature, and salinity; however, the cell decay coefficient (k_d) turned out to be correlated to a single parameter, k. Thus, k_d = 0.066 k^0.87 and k_d = 0.0115 k^0.634, where k and k_d are based on the unit of h⁻¹, were proposed for the prediction of cell decay coefficient for phenol and methanol acclimated activated sludge, respectively. In batch treatment of 770 mg l⁻¹ of phenol and 1000 mg l⁻¹ of methanol as TOC, nitrogen and phosphorus did not have any recognizable effect on k, while trace elements such as Fe²⁺, Mg²⁺, Mn²⁺, Ca²⁺, and Zn²⁺, etc. showed a slightly perceptible effect on it. The absence of extra-cellular nitrogen and phosphorus resulted in a greater cell yield; however, the cells in this condition decayed more rapidly than normal cells. The primary factor affecting the substrate decomposition rate in natural systems was pH: phenol decomposition resulted in a considerable decrease in pH so that the buffering capacity of the water was the most important factor, and methanol decomposition did not affect pH significantly so that the initial pH of the water was the most important factor. An initial lag phase was observed in 8 out of 115 phenol batch tests and 31 out of 66 methanol batch tests.     

Oxygen utilization and biochemical stabilization rate constants for a brewery effluent

Composite samples of brewery effluents were obtained from a brewery in Benin City, Nigeria. They were analysed for their biochemical oxygen demand (BOD) values at 20°C for definite periods in days. From the values obtained, oxygen utilization and biochemical stabilization rate constants, k and K, respectively, were determined. The mean values obtained for them were 0.37 day^‐1 and 0.16 day^‐1 respectively. The ultimate BOD (L_o) value for the brewery effluent was 757.1 mg/l, and the ratio of the 5‐day BOD (BOD₅) to the Ultimate BOD (L_o) (i.e., BOD₅/L_o) was found to be 0.85.     

Effect of copper and hexavalent chromium on the specific growth rate of ciliata isolated from activated-sludge

After growing mass and monoxenic cultures of three species of Ciliata (Vorticella microstoma, Colpidium campylum, and Opercularia sp.) with Alcaligenes faecalis as the sole protozoan food, and confirming that copper and hexavalent chromium did not affect the bacterial growth, the effect of these metals on the specific growth rate of each protozoa was examined. The term IL_m (median inhibitory limit) was used to define the metal concentration required to reduce the specific growth rate of protozoa to one-half of that of a control. The IL_m for copper was: 0·25 mg 1⁻¹ (V. microstoma), 0·32 mg 1⁻¹ (C. campylum), and 0·27 mg 1⁻¹ (Opercularia sp.). Regarding hexavalent chromium, IL_m for V. microstoma, C. campylum, and Opercularia sp. were 0·53, 12·9 and 20·2 mg 1⁻¹, respectively. Acclimation of each protozoa to these metals for 96 h resulted in IL_m enhanced values of 1·2–2·2 times as large as that for the control.     

A comprehensive study on the biological treatabilities of phenol and methanol—I. Analysis of bacterial growth and substrate removal kinetics by a statistical method

An unbiassed statistical method was developed to evaluate kinetic parameters in the biological oxidation of wastewaters. Through the statistical analyses of the biological oxidation kinetics, it was shown that the kinetic equations satisfactorily described the bacterial growth and substrate removal kinetics where X is biomass concentration, S is substrate concentration, t is time, a is cell yield coefficient, k_d is cell decay coefficient, K_s is Michaelis-Menten constant, and k is substrate removal rate coefficient. The coefficients K_s and a changed with temperature insignificantly while k and k_d were closely related to it. The temperature independent coefficients K_s and a were estimated to be 236 mg 1⁻¹ (standard deviation, σ = 70 mg 1⁻¹) and 1.21 (σ = 0.06) respectively for phenol, and 2330 mg 1⁻¹ (σ = 1410 mg 1⁻¹) and 1.25 (σ = 0.45) respectively for methanol based on total organic carbon (TOC) and volatile suspended solids (VSS). The oxygen utilization rate can be formulated as where Rr is the oxygen utilization rate (mg 1⁻¹ O₂ time⁻¹), as′ is a coefficient designating oxygen requirement per substrate utilized, and b′ is a coefficient designating oxygen requirement per biomass for endogeneous respiration. The coefficient a′ was 1.39 for phenol and 2.23 for methanol, and b′ was 1.42 k_d for both substances based on TOC and VSS.     

The use of Pb/210Pb ratios in lake sediments for estimating atmospheric fallout of stable lead in South-Central Ontario,Canada

The ratio of Pb concentrations (μg g⁻¹) to excess ²¹⁰Pb (²¹⁰Pb_exc) activities (dpm g⁻¹) in the surface (0–1 cm) sediments of lake cores, together with a knowledge of atmospheric ²¹⁰Pb fluxes, were used to estimate the atmospheric deposition of stable Pb in south-central Ontario, Canada. Between three and five cores were collected from each of 10 lakes, while in one lake (Red Chalk - Main Basin) a total of 25 cores were obtained.The average atmospheric ²¹⁰Pb_exc flux to the main basin of Red Chalk Lake was calculated to be 1.1 dpm cm⁻² year⁻¹, a value which compares favourably with literature estimates of ²¹⁰Pb deposition for Ontario. The surface Pb/²¹⁰Pb_exc ratios for 61 cores ranged between 1.26 and 3.44 μg dpm⁻¹(average 2.15 ± 0.45 μg dpm⁻¹). Therefore, the predicted atmospheric Pb deposition was 14–38 mg m⁻² year⁻¹ (average 24 ± 5.0 mg m⁻² year⁻¹). This estimate of stable Pb fallout is similar to those measured by alternate methods and indicates that elemental ratios in lake sediments might be useful for predicting the behaviour of other contaminants in lakes.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—II: Features of fatty acids for polluted and unpolluted waters

Fatty acids were analyzed for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to elucidate their features for polluted and unpolluted waters. Fatty acids ranging from the carbon chain length of C₈-C₃₄ including unsaturated and branched acids were found with the great predominance of even-carbon numbers and lower molecular weight ranges (C₁₃–C₁₉) in the water samples from the Tokyo area and Ogasawara Islands. It was thus confirmed that no marked changes in fatty acid composition between polluted and unpolluted waters are absent. However, the total contents of the acids (average, 270 ± 120 μg 1⁻¹ at 90% confidence limits) as well as the FAC (fatty acids as carbon)/TOC (total organic carbon, 2.6 ± 0.93%) and FAC/EOC (extractable organic carbon with ethyl acetate, 16 ± 6.7%) of river water samples from the Tokyo area were considerably higher than those of the waters from the Ogasawara Islands (58 ± 29 μg 1⁻¹, 0.79 ± 0.48% and 2.1 ± 0.51%, respectively). These higher values for the Tokyo area should be due to sewage.A filtering method showed that most of fatty acids (>95%) was present in particulate fractions. In addition, the content of free fatty acids was fairly lower than that of combined fatty acids. Further, unsaturated fatty acids were detected only in combined forms both in particulate and dissolved fractions. They are considered to be present as esters in polluted and unpolluted waters.     

CuFe2O4 as heterogeneous catalyst in degradation of p-nitrophenol with photoelectron-Fenton-like process

In this research, the heterogeneous photoelectron-Fenton-like process using copper ferrite (CuFe₂O₄) as catalyst was employed to remove p-nitrophenol (PNP). The CuFe₂O₄ catalyst was prepared by a co-precipitation process and characterised with X-ray fluorescence analysis, X-ray diffraction analysis and BET surface area. The results confirmed that CuFe₂O₄ was prepared successfully. Under the optimum conditions, namely 0.05?mol?L^?1 Na₂SO₄, the electrical potential of ?0.6?V, pH 3.0 and 0.067?g?L^?1 CuFe₂O₄, 92.8% of 0.1?mM?L^?1, the PNP removal efficiency could reach 92.8% for 0.1?mM?L^?1 PNP after 180-min treatment. This technology can be applied for the treatment of organic compounds which are not readily biodegradable.     

Formation and conditional stability constants of complexes formed between heavy metals and bacterial extracellular polymers

The strength and nature of the binding of heavy metal ions to bacterial extracellular polymers has been investigated. The conditional stability constants (K_t) for complexes formed between extracted Klebsiella aerogenes polymer and copper, cadmium, cobalt and nickel were determined, using a gel chromatographic technique, and log K_t values of 7.69, 5.16, 5.48 and 5.49 respectively were obtained. Adsorption isotherms constructed for copper, cadmium and cobalt indicated that metal uptake occurred after the initial complexation capacity had been exceeded, suggesting the presence of more than one binding site, but nickel adsorption ceased when the complexation capacity was reached. Nickel was found to be associated predominantly with the soluble form of polymer, and copper and cadmium with the colloidal fraction when metals were added to the polymer simultaneously, rather than individually. The overall specific metal uptake by polymers extracted from activated sludge was approximately ten times higher than that by K. aerogenes polymer.