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1.
The 48 and 96-hr LC50 values of Pb (Pb(NO3)2) with O. niloticus were 3.34 and 2.15 mg L?1, respectively, compared to 1.91 and 1.72 mg L?1, respectively, for C. lazera. C. tentans larvae and Benacus sp. demonstrated 48-hr LC 50 of 2.68 and 1.89 mg l?1 respectively. The 96-hr LC50 value was 1.77 mg L?1 for Chironomus and 1.36 mg L?1 for Benacus. Clarias appeared to be the most susceptible of the four to Pb poisoning; Chironomus being the least susceptible. Uptake pattern of Pb by fingerlings of O. niloticus and C. lazera exposed to 0.33 and 0.27 mg L?1 Pb, respectively, and the clearance of accumulated Pb were curvilinear. There was an initial ‘fast’ phase of accumulation occurring during the first 96 hr, followed by a slower phase over the remaining 240 hr. Mean Pb concentrations in gills, intestine, liver, muscle, bone, skin and whole body of O. niloticus were 33.30, 22.2, 5.3, 2.8, 1.8 and 14.9 μg g?1, respectively, compared to 28.7, 6.5, 11.5, 2.5, 5.6, 5.9 and 6.8 µg g?1 respectively in C. lazera. The half life of Pb in Oreochromis was 20 hr compared to 43 hr in C. lazera. Bioconcentration factors in Oreochromis and Clarias were 78.3 and 33.8, respectively. The data suggest that O. niloticus accumulates and eliminates Pb faster than C. lazera.  相似文献   

2.
Our contribution to Zr environmental hazard, arrived at by means of bioassays on bacteria, microscopic algae and fish, confirms the hypothesis that Zr has low toxicity. Toxic effects revealed with the Microtox test may be attributed to pH rather than specifically to Zr (5 min. EC50 > 4.3 mg L?1). Fish assays also confirmed the low toxicity of Zr (96-hr LC50 > 20 mg L?1; 96 hr minimal stress concentration > 20 mg L?1; Mutagenicity (Fluctuation test) and genotoxicity (S.O.S. Chromotest) assays failed to show any DNA-related effects linked to this metal. Only the algal assays (ATP energy stress) demonstrated genuine toxicity at Zr concentrations between 1.3 and 2.5 mg L?1.  相似文献   

3.
The acute toxicity of paraquat (1,1-dimethyl-4,4-bipyridinium dichloride) to fingerlings of Oreochromis niloticus (Trewavas) was determined in 96 hr staticbioassays. During the assays opercular ventilation and tailfin movement rates of the fish were determined.Haemotological parameters of the blood and histopathology ofthe gills were observed.The 96 hr LC50 of paraquat to fingerlings of O. niloticus was observed to be 11.84 mg L-1.Histopathology of gills of the fish exposed to 12.00 mgL-1, and 14.20 mg L-1 showed a dose-dependentdisruption of the architecture of the lamellae, filamenthyperplasia and atrophy, leading to impairment in oxygenuptake. Other symptoms of toxicosis in exposed fish includeloss of equilibrium; agitated swimming; air gulping;haemorrhaging of the gills, pectoral and pelvic fins; periodof quiescence and finally, death.  相似文献   

4.
The toxicity of U to Daphnia magna was determined in acute and chronic tests. The 48-hr LC50 of U (VI) in Columbia River water was 6 mg L?1. Acute toxicity diminished by a factor of 7.5 as mean water hardness and alkalinity values increased from 70 mg L?1. and 57 mg L?1. to 195 mg L?1. and 130 mg L?1. respectively. This effect was most likely the result of complexation of uranyl ion with carbonate ions. D. magna reproduction was suppressed in Columbia River water at U concentrations between 0.5 and 3.5 mg L?1. Potential hazards of U to aquatic life are discussed as they relate to mining practices.  相似文献   

5.
The effects of cadmium and copper on larval metamorphosis and mortality of cultured Capitella sp Y were investigated. Metatrochophore larvae were exposed to 0.013 (control), 0.030, 0.080, 0.120, and 0.170 mg Cd L?1 and 0.017 (control), 0.025, 0.060, and 0.075 mg Cu L?1 for 34 days. Larval mortality significantly (p < 0.01) increased with increasing Cd and Cu concentrations (Kruskal-Wallis test), with similar effects for both metals for day 10 (LC50 = 0.035 mg Cd L?1 and 0.035 mg Cu L?1). Metamorphosis was inhibited in larvae exposed to the two metals in the absence of food, the effect of Cu being the most severe. This study suggests that Cd and Cu exposure could be harmful to early developmental stages of Capitella sp Y producing a delay in recruitment into natural populations.  相似文献   

6.
The toxicity of organophosphate insecticides, mainly phosphamidon, monocrotophos and dichlorvos to the blood clamAnadara granosa, occurring in Kakinada Bay of the Godavari estuarine system was measured. The LC50 values of three insecticides for 24,48,72 and 96 hr exposure ranged from 4.26 to 11.53 mg L?1 for phosphamidon, 3.50 to 9.31 mg L?1 for monocrotophos and 1.79 to 6.20 mg L?1 for dichlorvos. Dichlorvos proved highly toxic even at low concentrations compared to either phosphamidon or monocrotophos. The animals showed decreasing activity with increasing insecticide concentrations and duration of exposure. However, there was no marked difference in the toxicity between phosphamidon and monocrotophos.  相似文献   

7.
Larvae of striped bass (Morone saxatilis (Walbaum)) were exposed to a mixture of organic and inorganic contaminants in fresh well water and 2 g L?1 saline water for 30 days and in 5 g L?1 saline water for 90 days. Environmental concentrations (ECs) of organic and inorganic chemicals were estimated for the Chesapeake Bay area. Striped bass were exposed to the EC, 0.25 EC, 0.5 EC, 2 EC, 4 EC, and a solvent control to simulate potential conditions in their spawning and nursery habitats of the Chesapeake Bay. The sensitivities of striped bass as determined by survival depended on the characteristics of the exposure water. Larvae exposed in fresh well water were the most susceptible to the contaminant mixture; the 2 and 4 EC treatments caused significant (P:5 0.05) mortality within 30 days. In the 2 g L?1 salinity water, the 4 EC treatment caused significant mortality after 30 days of exposure. Larvae exposed to the contaminant mixture for 90 days in the 5 g L?1 saline water incurred significant mortality in the 2 and 4 EC treatments. We concluded that the age of the larvae, concentration of the contaminants, and salinity of the environment must be considered in evaluating the influence of environmental contaminants on the decline of striped bass along the east coast.  相似文献   

8.
Nelson Lake, a moderately acidic (pH 5.7), metal-contaminated (Cu 22 μg L?1; Zn 18 ug L?1) lake, 28 km from the smelters at Sudbury, had a degraded fish community in the early 1970's, with lake trout (Salvelinus namaycush) scarce, smallmouth bass (Micropterus dolomieui) extinct, and the littoral zone dominated by the acid-tolerant yellow perch (Perca flavescens). Liming of the lake in 1975–76 increased pH to 6.4, and decreased metal concentrations. Chemical conditions have remained relatively stable in the 10 yr following base addition. Initially, it appeared that neutralization produced dramatic changes in the resident fish community. Yellow perch abundance declined rapidly after neutralization, lake trout abundance increased to the extent that 3.26 kg ha?1 were caught in the winter of 1980, and reintroduced smallmouth bass reproduced and established a large population. However, these changes in the fish community can not be directly attributed to liming, as water quality and the sport fisheries of an unlimed nearby lake also improved. Reduced emissions from Sudbury smelters were responsible for improvements in the untreated lake. Recovery of the lake trout population in Nelson Lake appears to have begun prior to liming. Of the lake trout sampled during the 1980 winter fishery, 65.8% were present prior to the chemical treatment. Predation by lake trout was the likely cause of the perch decline. Our results suggest that chemical conditions producing population level responses in fish have abrupt thresholds and that neutralization of lakes above these thresholds may not produce distinguishable effects.  相似文献   

9.
The present investigation was undertaken to evaluate the effect of sublethal concentrations (0.088 and 0.044 mg 1?1, i.e., 1/5th and 1/10th fraction of 96 h LC50) of mercuric chloride on Ca, inorganic phosphate, water content, ash, glycogen, Fe, total protein, lipid contents and vitamin A, C, D, and E of liver, muscles and ovary of the freshwater fish Notopterus notopterus exposed for 30 days. The results obtained indicate that Ca, inorganic phosphate, water, ash, glycogen, Fe, total protein contents and vitamin D decreased significantly or insignificantly in these tissues of the Hg exposed fishes. However, lipid content increased in liver and muscles, but decreased in the ovaries. Vitamin A and D increased in the liver but decreased in the muscles and ovaries. Moreover, vitamin E increased in all the tissues of the fish exposed to 0.088 mg 1?1 and decreased in the fish exposed to 0.044 mg 1?1 of Hg concentrations.  相似文献   

10.
Clarias anguillaris and Oreochromis niloticus were each exposed to solutions of Analar grade Cu sulphate in static bioassays at a temperature range of 20 to 23.5°C and CaCO3 hardness of 30 to 44 mg L?1. Copper accumulation was determined by Atomic Absorption Spectroscopy. The Cu residues in Clarias anguillaris exposed to 0.027, 0.055, and 0.11 mg Cu L?1. for 8 weeks were 15.7, 21.8, and 31.17 mg g?1 dry weight, respectively. Oreochromis niloticus exposed to 0.05, 0.1 and 0.2 mg Cu L?1. accumulated 34.69, 36.09, and 81.03 mg g?1 dry weight, respectively, over the 8-week period of exposure. The lowest and highest bioconcentration factors (BCF) were 117 and 581 for Clarias anguillaris and, 176 and 694 for Oreochromis niloticus. Copper concentrations in tissues of both species were directly related to the exposure concentrations and the duration of exposure. Increased accumulation towards the last 2 weeks of exposure may be due to impaired capacity of elimination or poor nutritional status.  相似文献   

11.
Tomato (Lycopersicon esculentum Mill.) plants were grown in silica sand in controlled environments. In the first experiment Ni was added as NiSO4 · 6 H2O to the nutrient solution at 0, 1.5, 7.5, or 37.5 mg L?1 for 6 day beginning 14 day from seeding, them plants were exposed to 0, 0.15, or 0.30 μL L?1 O3, and harvested 3 day later. Visible symptoms of Ni injury developed rapidly and there was distinctive O3 injury. Growth variables were markedly reduced by Ni but O3 response depended on Ni level. In the second experiment 0, 0.3, or 1.5 mg L?1 Ni was provided from the 5th or 14th day onward. There was little effect of duration of Ni treatment on growth. Increasing Ni and increasing O3 decreased growth but there was no interaction. In the third experiment 0, 1.5, and 3.0 mg L?1 Ni treatments were combined with 0, 3.0, and 6.0 mg L?1 Cu prior to 0 or 0.25 μL L?1 O3 treatment. There were complex interactive effects of all three factors on plant growth. Soybean (Glycine max Merr.) plants exposed to Ni and O3 were only slightly affected by Ni or O3 and there was no interaction.  相似文献   

12.
Nickel (Ni) is an ubiquitous, naturally occurring metalthat is associated with metal mining and other industrialactivities. Despite elevated Ni concentrations reportedfor many industrial receiving waters, Ni receives littleresearch attention addressing factors influencing itstoxicity to freshwater fish. This study examined theinfluence of water hardness, pH, and total suspended solids(TSS) in soft, reconstituted water on Ni toxicity to larvalfathead minnows (Pimephales promelas). Increasingwater hardness from 20 to 140 mg L-1 (as CaCO3) reduced acute Ni toxicity by 5-fold (96-h LC50s 0.45 and 2.27 mg Ni L-1, respectively). Low pH had a slight protective effect against Ni toxicity relative to neutral pH conditions. At pH 5.5, the 96-h LC50 was 0.69 mg Ni L-1, compared to 0.54 mg Ni L-1 at pH 7.0. However,Ni toxicity was significantly reduced at pH 8.5 where the 96-h LC50 was 2.21 mg Ni L-1. These results were explainedon the basis of Ni speciation. Total suspended solids also reduced Ni toxicity (expressed as 96-h LC50s) from 0.35 to 1.12 mg Ni L-1 over a TSS range of 10 to 100 mg L-1.This reduction of toxicity due to TSS is significant becausemine effluents often have a combination of elevated TSS andmetals. The ameliorative effect of TSS was not as significantas high hardness or pH probably because there is a TSS threshold, after which physical irritation to fish gills counteracts any protective effect conferred by TSS. This finding is relevant to choices made in design of mine effluenttreatment systems; i.e., there may be an optimum range ofTSS concentrations that protect aquatic biota againsteffects of metals that remain after treatment.  相似文献   

13.
The concentrations of Al in fish gills has been used as a measure of fish exposure to this metal in acidified waters. This experiment was designed to determine if other fish tissues also accumulate Al and thus possibly contribute to the cause of death. Rainbow trout (Salmo gairdneri) were exposed to the following fours test conditions for 48 hr or until death: (1) pH 6.8, <0.001 mg.L?1 Al (n=6); (2) pH 5.2, <0.001 mg1L?1 Al (n=2);(3) pH 5.2,1.0 mg.L?1 Al (n=5); (4) pH 6.8, 1.0 mg.L?1 Al (n=3). The trout were held in synthetic, low Ca water prior to, and during, experimentation. Esophagus-stomach, gonad, gall bladder, gill (left and right), heart, intestine, kidney, liver, muscle (epaxial), and spleen were digested in a 4:1 mixture of HNO3:HClO4 and analyzed by Inductively Coupled Plasma Emission Spectrophotometry. Elevated Al concentrations were found in gill and gastrointestinal tissues. Left and right gills of fish exposed to pH 5.2, 1.0 mg.L?1 Al were the only tissues found to be significantly different (p<0.01) between the test conditions. The mean total Al concentrations of these test 3 fish, for the left and right gill were 3.61 and 4.33 mg.g?1 Al dw. The Al concentration in thle gastrointestinal tissues of the fish exposed to pH 6.8 at 1.0 mg.L?1 Al was greater than that of the control fish, but not statistically significant. These results suggest that the analysis of whole gill remains an effective indicator of Al exposure in fishes at low pH.  相似文献   

14.
The effects of Hg, As, Pb, Cu, Cd, and Cr (1, 2, and 5 mg L?1 each) on Azolla pinnata R. Br. were analyzed. The treatments (2 and 5 mg L?1) of the heavy metal pollutants decreased Hill activity, chlorophyll, protein and dry wt, and increased tissue permeability over control values. The effects were most pronounced with the treatment of 5 mg L?1. The harmful effects of the metals were, in general, found by the treatments in the order: Cd 〉 Hg 〉 Cu 〉 As 〉 Pb 〉 Cr. There was no significant change in these parameters at 1 mg L?1 of the metals over control. Thus Azolla pinnata shows tolerance to the heavy metals tested up to 1 mg L?1 each.  相似文献   

15.
The treatment of perchloroethylene (PCE) was investigated by the promotion of Fenton-like reactions using the iron oxyhydroxide goethite (α-FeOOH) as the sole source of the iron catalyst. A silica sand-goethite matrix was contaminated with 5 mg L?1 PCE and the oxidative treatments were conducted with 0.15 mM, 2 mM, 5mM, 10mM, 20mM, and 30mM H2O2. Perchloroethylene was effectively degraded within 96 hr and the most efficient treatment stoichiometry was observed using 0.15 mM H2O2 at pH 3. The degree of heterogeneous catalysis was evaluated by conducting oxidation reactions in parellel systems with an equivalent concentration of soluble iron. The results showed that, within the first 24 hr, up to 94% of the PCE degradation was attributed to heterogeneous catalysis. This modified Fenton's process, when used to treat 5 mg L?1 PCE in natural subsurface materials with 2 mM H2O2 at pH 3, resulted in a residual of 0.20 mg L?1 PCE after 96 hr.  相似文献   

16.
Exposure of fish fingerlings (Cirrhina mrigala) and yearlings (Puntius sophore) to a concentration of 0.005 mg L?1 of linear alkyl benzene sulphonate for 24, 48, and 96 hr caused alterations in glycogen, lactic acid and sialic acid content in gill, liver, muscles and kidney. Significant decreases in the level of glycogen and elevation in the level of lactic acid demonstrated impairment of carbohydrate metabolism. Decrease in the sialic acid content suggested functional changes in membranes in toxicity.  相似文献   

17.
The effect of waterborne zinc on survival, growth, and feed intake of Indian major carp, Cirrhinus mrigala (Hamilton), advanced fry was studied under laboratory condition. Survival rates of C. mrigala advanced fry (2.71?±?0.49 g) after 30 days exposure to control (0.01), 0.03, 0.06, 0.10, and 0.15 mg/L zinc using the static renewal method in freshwater at pH 7.3?±?0.2, temperature 26?±?2°C, and total hardness 114?±?16 mg/L as CaCO3 were 100%. Growth of the fish exposed to 0.10 and 0.15 mg/L of zinc was significantly lower (P?<?0.05) than in control (0.01), 0.03, and 0.06 mg/L of zinc after 30 days of exposure. However, there were no significant differences (P?>?0.05) in fish growth between 0.03 and 0.06 mg/L zinc concentrations. Feed intake rates were significantly (P?<?0.05) reduced in the fish exposed to 0.10 mg/L and higher levels of zinc. The zinc accumulation in the whole body of the fish increased with increasing concentrations of the metal.  相似文献   

18.
The acute toxic effects of diflubenzuron (DFB) on various life stages of the grass shrimp, Palaemonetes pugio, were determined using a static renewal system. It was observed that the larvae and the postlarvae were the most sensitive to acute DFB toxicity; 96-hr LC50's being 1.44 and 1.62 μg L?1 respectively. Also variations among the 96-hr LC50's for these two life stages were the lowest (11.59% for larvae and 30.06% for postlarvae) compared to 68.9% for males and non-Ovgerous females. Ovigerous female grass shrimp (hence the embryos) appeared to be the most resistant to acute toxic effects of DFB with a mean LC50 of 6985 μg L?1. The limitations of LC50 data and the importance of molt-related sensitivity of the different life stages of P. pugio to diflubenzuron are discussed.  相似文献   

19.
This paper presents the results of monitoring the shallow groundwater quality around two municipal landfill sites in the Eastern Province of Saudi Arabia. Boreholes were installed at Dhahran and Juaymah sites upstream and downstream of the landfill. Twenty water samples were collected from each borehole and analyzed for various parameters mainly for BOD, COD, TOC, NH3-N, TKN, sulphate, chloride, hardness and metals. The result of the analysis of water samples from Dhahran boreholes shows an increase in the concentration of pollutants in downstream groundwater over that observed in upstream boreholes. The average concentration of BOD5, COD and TOC in the samples obtained from the downstream borehole was found to be 6.5, 23.5, and 34.3 mg L?1, respectively. On the other hand, the mean concentration of the same parameters in upstream monitoring wells was found to be less than 2.4, 11.5, and 10.0 mg L?1, respectively. The ammonia-N and organic-N in the downstream wells were 0.37 and 0.29 mg L?1, respectively, whereas, in upstream wells they were 0.11 and 0.15 mg L?1, respectively. At Juaymah, the average concentration of BOD and TOC in groundwater samples obtained from upstream boreholes were less than 3.0 and 7.2 mg L?1, respectively, while the concentration of the same parameters in downstream well samples were above 5.0 and 35.0 mg L?1, respectively. A similar trend of increment of ammonia-N, organic-N, phosphate, sulfate and metals in downstream samples was observed. Since the water from these shallow aquifers at both places is not being used for human consumptions or for any other commercial purpose, therefore, the minor increase in pollutants concentration at downstream level is not of a great concern.  相似文献   

20.
The increasing number of cases of soil contamination by heavy metals has affected crop yields, and represents an imminent risk to food. Some of these contaminants, such as cadmium (Cd) and lead (Pb), are very similar to micronutrients, and thus can be absorbed by plants. This study evaluated the translocation of increasing amounts of cadmium and lead and the effects of these metals in the production of beans. Bean plants were grown in nutrient solution Clark and subjected to increasing levels of Cd (from 0 to 0.5 mg L?1) and Pb (from 0 to 10 mg L?1). Cadmium concentration of 0.1 mg L?1 translocated 39.8% to the shoot, and dry matter production was reduced by 45% in shoots and 80% in roots, compared to the control treatment. Lead showed impaired movement in the plant, however the concentration of 1.0 mg L?1 was observed in 5.7% of metal translocation to the leaves. The concentration of 10 mg L?1 Pb reduced dry matter production of roots and shoots in 83% and 76%, respectively, compared to the control treatment.  相似文献   

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