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1.
Static bioassay acute toxicity tests of Zinc, Copper and Mercury were conducted to determine the median lethal concentrations (LC50s) of a freshwater teleost Channa marulius (HAM .) The 96 h LC50 and 95% confidence limits for Zn2+ were 25.61 (24.13 … 27.12) mg/l; 0.90 (0.80 … 1.038) mg/l; for Cu2+ and 0.314 (0.257 … 0.371) mg/l for Hg2+. However, these values decreased at 240 h of exposure and were: 21.09 (18.29 … 24.60) mg Zn2+/l; 0.66 (0.568 … 0.841) mg Cu2+/l; and 0.131 (0.103 … 0.158) mg Hg2+/l. The relative potency ratio of Zn/Hg, Zn/Cu and Cu/Hg suggests that fish were most sensitive to Hg, followed by Cu and Zn ions. The acute toxicities of mixtures of Zn2+?Cu2+; Zn2+?Hg2+, Cu2+?Hg2+ and Zn2+?Cu2+?Hg2+ up to 48 h of exposure were also investigated. The additive index and ranges for Zn2+?Cu2+ were ?0.241 (-0.577 … 0.054); 0.056 (-0.269 … 0.475) for Zn-Hg; 0.285 (-0.043 … 0.718) for Cu-Hg; and -0.542 (-1.215 … 0.005) for Zn-Cu-Hg. All the mixtures tested showed a greater than additive toxicity because index ranges overlapped zero.  相似文献   

2.
The short-term toxicity of mercury, copper and zinc was studied using a freshwater pulmonate snail, Lymnaea luteola (LAMARCK ). The median period of survival increases with decreasing the toxicant concentration. The 96 h LC50 values and their confidence limits were 0.135 (0.112 … 0.186) ppm of Hg2+; 0.172 (0.118 … 0.355) ppm of Cu2+; and 6.13 (5.73 to 7.19) ppm of Zn2+. The relative potency ratio indicates that the Hg2+ ions were most toxic, followed by Cu2+ and Zn2+ ions.  相似文献   

3.
In the daily exchange of the medium with only 7.1 mg/l Ca2+ and 0.7 mg/l Mg2+ during the batch experiment the LC50,96h for Cyprinus carpio is 0.063 mg/l Cu2+ and 3.12 mg/l Zn2+ at water temperatures of 11 to 14°C. Significant differences in mortality as referred to the LC50,12h occur for copper only after 72 h of exposure and for zinc after 48 h of exposure. The values of LC50,96h are clearly lower for both metals in the investigations described than most data given in literature for different fish species.  相似文献   

4.
The acute toxicity of copper and copper plus complexing agents to common guppy Lebistes reticulatus was studied for 96 h by a static bioassay technique. The addition of complexing agents viz. disodium salt of EDTA, citric acid, sodium thiosulphate and glycine in Cu2+ solutions caused a great decrease in the per-cent mortality as compared to that of Cu2+ test solutions alone. 10 mg/l of complexing agent was added in each copper concentration in all the test series. The 96 h LC50 values and 95% confidence limits in mg/l of Cu2+ plus were 1.23 (0.95…1.65) for Cu2+ alone; 4.30 (4.04 … 4.55) for Cu2+ plus EDTA; 1.94 (1.69 … 2.18) for Cu2+ plus citric acid; 3.44 (2.96 … 3.74) for Cu2+ sodium thiosulphate and 2.29 (2.22 … 3.02) for Cu2+ plus glycine.  相似文献   

5.
The lethal toxicity of mixtures of Zn2+ —Ni2+, Cu2+ —Ni2+ and Zn2+ —Cu2+ —Ni2+ to common guppy at 21£C in hard water (total hardness = 260 mg/l as CaCO3) was studied under static bioassays test conditions with renewal of the test solutions every 24 h. The heavy metals were tested separately and in mixtures. The 48 h median lethal concentrations (LC50) for individual salts were 75 mg/l Zn2+, 37 mg/l for Ni2+ and 2.5 mg/l for Cu2+. Concentrations were expressed in “toxic units” by taking them as proportions of LC50 values. Experiments showed that in the Zn2+-Ni2+ mixture, when Ni2+ was more in proportion, the toxicity was more than additive. The 48 h LC50 value and 95% confidence limits in the Ni2+-Cu2+ mixture were 0.684 (0.484 … 0.807) toxic units and the mixture produced more than the additive toxicity (synergism.). The LC50 value and its 95% confidence limits in a Zn2+?Cu2+?Ni2+ mixture also suggested that the mixture was again strictly additive. The results indicate that heavy metallic mixtures would pose a greater toxicological danger to fish than the respective individual metals.  相似文献   

6.
In batch experiments for 6 to 48 h, individuals of Cyprinus carpio (2 g individual weight) were exposed to mixed solutions of copper and zinc sulphate: pH = 6.3, temperature 15 °C, 6.8 mg/l O2, 7.1 mg/l Ca2+, 0.7 mg/l Mg2+. The LC50 for the individual substances on exposures of 24 and 48 h amount to 9.04 and 7.28 mg/l, resp., of Zn and 0.11 and 0.095 mg/l, resp., of Cu. The sum of the biological activity of the two kinds of metal ions is assessed according to MARKING'S index: at low concentrations of the mixed solutions the two metals show an additive effect, at higher concentrations a synergistic effect occurs.  相似文献   

7.
In static bioassays the toxicity of heavy metal ions against Lymnaea acuminata over 24 … 96 h is tested. The values of the LC50,96h for the metals tested are, in mg/l: Hg2+ ?0.023; Cu2+-0.034, Cd2+ ?0.872, Ni2+ ?2.78, Cr6+ ?5.97 and Zn2+ ?10.49. In the combined solutions of Cu2+, Ni2+ and Zn2+ at least an additive effect of toxicity occurs in the presence of two metals. The same holds for the presence of the three metals; in this case, the relative toxicity against the mixture of two metallic salt solutions appears to be slightly reduced. The acute manifestation of the toxic effect occurs within 48 h, subsequently the relative mortality decreases especially in the mixed solutions.  相似文献   

8.
The LC50-values of As3+-compounds for Channa punctatus are determined for a 48-h exposure to 19.4 (18.02… 21.3) mg/1 and for a 96-h exposure to 14.3 (13.06… 16.80) mg/1. At a long-time exposure to 7.0 mg/1 As3+, during the first seven days there does not occur any change of growth, then the growth in length and the increase in weight decreased by 6.6 and 11.7%, respectively, till the 31st day. At the same time, the RNA content of the muscle decreased by 11.5% to 966.7 μg/g fresh weight and the protein content decreased by 12.5 % to 95.39 mg/g fresh weight.  相似文献   

9.
In the batch test with daily exchange of medium the effect of copper ions at 2.4 mmol/l (Ca2+ + Mg2+) over 10 d of exposure is investigated. The LT50 values and 95% confidence limits at 3.7, 2.1 and 1.0 ppm of Cu were 26.7 (23.6… 29.9), 47.5 (39.6… 57.0) and 101.5 (78.5… 130.7) h, respectively. The LC50 values of copper in ppm were 4.05 (24 h), 1.69 (48 h), 0.829 (9.96 and 0.776 (240 h).  相似文献   

10.
There is determined the LC50 for 24 … 96 h of phenol, 2,4-dinitrophenol and pentachlorophenol as sodium salt by static assay at water temperatures of 16, 23 and 36°C. In addition, the combinations of the three substances were tested in the same way. With decreasing temperature, the toxicity of the individual substances decreased by 6.5 … 22%, that of the mixtures by 10 … 87%; with rising temperature, the toxicity increased by 38 … 747% and 75 … 744%, respectively. The safety limits at 23°C lie between 0.3 μg/l for a synergistically acting mixture and 0.9 mg/l for an antagonistically acting one; for the individual substances this range is 3.5 μg/l to 0.5 mg/l.  相似文献   

11.
Lebistes reticulatus (Peters) was exposed to various concentrations of phenol, pentachlorophenol and sodium pentachlorophenolate to determine their toxicity, lethal concentrations and slope functions by a static bioassay procedure. Simultaneous controls were also run. The 94h LC50 values were 47.5mg/l (42.04 … 53.68) for phenol, 0.77 mg/l (0.616 … 0.963) for sodium pentachlorophenate and 0.97 mg/l (0.866 … 1.086) for pentachlorophenol. On this basis, the rank order is sodium pentachlorophenolate-pentachlorophenol-phenol. During the treatment, fish showed an abnormal swimming reflex, excessive mucus secretion, haemorrhage near lips, abdomen and basis of fins and loss of equilibrium followed by death.  相似文献   

12.
The LC50 of Malathion for Channu punctatus is determined for 24… 96 h of exposure as 10.95… 3.22 mg/l. At exposure to 2.5 mg./l Malathion, growth–measured by increase in weight–is significantly reduced from the 19th day and reduced by 10 % till the 31st day. During the same period of time, the RNA and protein contents of the muscle is lowered by 10 and 15 %, respectively, as compared with the control. In addition to an acute toxic effect, in sublethal concentrations Malathion has also pronounced effects on growth and metabolism.  相似文献   

13.
The LC50 for exposure of 48 and 96 h is 34.64 and 18.5 mg/l Cd2+, respectively. During the exposure to 3.5 mg/l Cd2+ from the 13th day significant differences of length and mass occur with respect to the control. Over a total of 31 days of experiment the reduction of growth rates is 11% for the longitudinal growth and 16% for the increase in weight.  相似文献   

14.
The toxicity of phenol, pentachlorophenol and Na-pentachlorophenate to Cypris subglobosa is determined in the batch experiment for 96. h. In the sequence mentioned, the LC50,96h of the three substances are 71.8, 6.56 and 4.41 mg/l, respectively. In the range of 6 … 95 h the mean survival time shows a negative regression to the toxicant concentration, which, however, is not significant statistically for Na-pentachlorophenate. In agreement with this, the LC50 for 12, 24, 48, 72 and 96 h of exposure shows a significant decrease. Due to the comparatively high LC50,96h for pentachlorophenol and Na-pentachlorophenate for C. subglobosa about in comparison with fish, the species is little suited to the toxicological investigation of wastewater.  相似文献   

15.
Fish were kept in non-toxic water or at 0.5, 0.25 and 0.125 of the LC50,96h of the ten-side or insecticide for 24 h and fed with toxified and non-toxified feed. Toxified feed in normal water resulted in a maximum feed intake, while normal feed in toxified water resulted in a minimum one. In each case, the feed intake was lower compared with the control, and the feed intake was inversely proportional to the toxicant concentration. In a simple respirometer the oxygen consumption in mg · kg?1 · h?1 was tested for 1, 2, 4, 6, 8, 10, 12, 24, 36, 48, 60, 72, 84 and 96 h of exposure to 1.5, 1.0 and 0.5 of the LC50,96h of both substances. It was a flow device which was closed only for measurement for one hour. 1.5 LC50 Aldrin causes a continuous reduction of respiration until death. The same effect occurred with Cl. batrachus for 1.5 LC50 of the tenside, whereas with C. mrigala death was caused by a pronounced increase of respiration. In all other cases, after a phase of sensitization for 4 … 8 h respiration increased considerably to more than 300% of the control, which was followed after 12 … 24 h by acclimatization to normal respiration values.  相似文献   

16.
The LC50 for 12… 96 h of a distillery waste water were determined for Lebistes reticulatus, Lymnaea luteola, Lymnaea acuminata and Viviparus bengalensis in the batch experiment with daily exchange of the medium. The sensitivity of the species increases in the given sequence with values of the LC50,96 h of 10.77 to 3.72 % proportion of wastewater in the medium. Compared with this, with values of the LC50,48 h of 14.06… 15.71 % after 48 h of exposure there is no significant difference in sensitivity, whereas after exposure for 12 and 24 h the sensitivity grows in the following order: V. bengalensis, L. acuminata, L. luteola, Lebistes reticulatus. Toxicity is obviously primarily determined by the sulphides; with increasing time of exposure also the suspended matter and other factors act toxically.  相似文献   

17.
To prevent infection with Dracunculus medinensis, a carrier host, the copepod Cyclops, has to be controlled. After preceding laboratory investigations a field trial with well water and different additions of chlorine and sodium permanganate is carried out. The exposure is performed at an ambient temperature of 25… 40 °C and in bright and dark samples (5… 11 h of sunshine/d) as well as in the well. The residual concentrations of the two chemicals are an exponential function of the time of exposure with half-times between 6 and 23 h for chlorine and 11… 30 h for sodium permanganate. The depletion of the two oxidizing agents under light is faster than in darkness. Dosage should be done in such a way that the LC90,24h after 24 h of exposure will not be fallen below; in a specific case, this guarantees at the same time that the permissible concentrations for drinking water will not be reached 96 h after addition. For this, initial concentrations of 30 mg 1 Cl2 or 50 mg/l KMnOr are necessary. Under these conditions, the Cyclops population had died on the seventh day after the application of chemicals, but after seven weeks it reached the original density again. With one application of chloride or sodium permanganate a week Dracunculiasis can be completely controlled.  相似文献   

18.
Sea catfish (Arius felis) were exposed to aqueous solutions of reagent grade cupric chloride in artificial seawater (30.0±2.0‰, 21–23°C) in four static bioassays. The 24, 48, 72 and 96 h LC50 were calculated and found to be 5.43, 4.17, 3.57 and 2.40 mg l.?1 copper, respectively. Experimental concentrations of copper producing subtle behavioral changes in this species correspond to less than 0.3% of the 72 h LC50. Based on this comparison with literature values, a new, maximum ‘safe’ concentration for copper in marine waters of 0.01 mg l.?1 is proposed.  相似文献   

19.
Sea mullet (Mugil cephalus) were exposed to aqueous suspensions of tech-DDT in seawater, salinity 29.5±0.5‰. The 48 h LC50 calculated from these static bioassays ranged from 0.042 to 0.056 mg l.?1 DDT. Median survival times were then estimated at 15, 20, 25 and 30°C using the upper level of the 48 h LC50 range of concentrations, i.e. 0.056 mg l.?1. Results indicated that an increase in temperature produced a decrease in toxicity. However, 25°C was the only temperature at which the increase in survival time was statistically significant. Size differences within experimental fish did not contribute to MST.  相似文献   

20.
The treatment of a highly eutrophic raw water is investigated by a differentiated microscopic analysis of the seston particles in three size classes, an analysis of the assimilation pigments and of the seston solids. At an average number of particles of 106/ml elimination amounts to 31… 44%. The average pigment content of 124 mg/m3 chlorophyll a plus phaeopigments is reduced by 34%, the average dry matter of 14.6 mg/l being reduced by 50%.  相似文献   

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