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1.
Laboratory acclimated Labeo rohita, common fresh water edible fish, were exposed to a sublethal concentration (2.5 ppm) of DDT for 2, 4, 8, 16 and 32 days. Residues of three isomers of DDT were estimated in the kidney of Labeo rohita using the gas liquid chromatographic technique. The maximum residues of DDT, DDE and DDD were 1.4327, 0.4172 and 0.2913 ppm, respectively. The total DDT residues concentration was 2.1412 ppm on the final day of the experiment. The tabulated tcalculated t at all intervals.  相似文献   

2.
The effects of chronic exposures to sublethal concentration of two pesticides Carbaryl and Endosulfan on alkaline and acid phosphatase activities in the intestine of a fresh water teleost Channa striatus have been observed by exposing the fish for a period of two to thirty days to 10 ppm and 20 ppm of Carbaryl and 0.00075 and 0.001 ppm of Endosulfan. The inhibition of alkaline phosphatase activity has been dependent on the duration of exposure, concentration and the type of pesticide used. The acid phosphatase activity increased with the duration of exposure in higher concentration of Carbaryl and both the concentrations of Endosulfan. Endosulfan produced more pronounced effects than Carbaryl.  相似文献   

3.
Residues of DDT isomers accumulated in the testes of Channa punctatus (BLOCH) were quantitatively estimated by exposing the fish to 2.5 ppm sublethal concentration for 32 days. The study revealed a high accumulation of DDT residues in the testes. The maximum concentration of residues was noted on the 32nd day of the experiment. The DDT isomer accumulated in maximum concentrations was followed by DDE and DDD isomers. The maximum residue concentrations were 0.3221 ppm (DDT), 0.1119 ppm (DDE) and 0.0695 ppm (DDD) on the 32nd day of the experiment. The total DDT residue concentration at the final interval was 0.563 ppm.  相似文献   

4.
The blood pyruvate levels of a freshwater tropical teleost Colisa fasciatus were investigated from 3 to 96 h following sublethal intoxication of 48 ppm hexavalent chromium. The blood pyruvate levels rose at every time period studied from 3… 96 h. A statistically significant elevation is observed from 24 h and progresses up to 96 h. The maximum elevation of 92.86% has been recorded at 72 h (p<0.001).  相似文献   

5.
Short-term tests of the acute toxicity of Cu2+ (from copper sulphate) to a freshwater ostracod, Cypris subglobosa SOWERBY were carried out at five different pH values from 5.5 to 8.5. The toxicity of copper abruptly decreased with an increase in pH of the Cu-containing medium. The 48 h EC50 value of Cu increased from 0.35 ppm at pH =5.5… 5.1 ppm at pH =8.5. The per cent survival, median period of immobilization (ET50), slope functions and the 95 per cent confidence limits were determined at each pH level. The direct correlation between EC50 value and pH indicated that the acute toxicity of Cu decreased as the pH increased from 5.5… 8.5.  相似文献   

6.
This paper presents a field study conducted in northwest Turkey and characterizes the NH3 concentration and emission measured in summer season from three chicken farms. The influence of environmental conditions on NH3 concentration and emission was also investigated in this study. Ammonia concentration, temperature, relative humidity and airflow rate were continuously recorded for four sequential days. The environmental conditions were measured using a multifunction temperature and humidity‐meter with a hot wire probe. Portable multiple gas detectors with electro‐chemical sensors were used to measure NH3 concentration. The NH3 emission rates for houses were calculated by multiplying simultaneously measured NH3 concentrations and air flow rates. The average daily mean (ADM) house concentrations of house 1 (H1), house 2 (H2), and house 3 (H3) were measured as 4.43, 3.71, and 6.20 ppm, respectively. NH3 concentration was inversely proportional to temperature (r = ?0.279), relative humidity (r = ?0.063) and airflow rate (r = ?0.554) for all monitored houses. The ADM house NH3 emission was 135 g/(h house) for H1, 255 g/(h house) for H2, and 117 g/(h house) for H3. The combined average emission rate in this study (0.26 g/(d bird)) was lower than the emission rate measured in chicken farms in the USA. However, our results were comparable to rates calculated in European studies because house design, ventilation system and bird diet applied in Turkish chicken farms are very similar to those employed in European countries. The NH3 emissions were significantly correlated to NH3 concentrations (r = 0.45, p ≤ 0.001) and airflow rates (r = 0.97, p ≤ 0.001). A clear diurnal pattern was obtained for NH3 concentrations rather than NH3 emissions at the end of the study.  相似文献   

7.
Phosphorus has been traditionally regarded as the controlling nutrient for phytoplankton growth, however, N-limitation is likely to occur in several environments. For example, nitrogen is considered the main nutrient limiting phytoplankton in floodplain lakes of the Paraná River basin. However, N2-fixing heterocystous cyanobacteria (N2-cyano) are usually absent in these water bodies. The low pH values frequently found may limit the development of these algae. We hypothesise that long-term lake isolation allows conspicuous phytoplankton growth during summer, resulting in high photosynthetic rates and pH. This scenario combined with low DIN (dissolved inorganic nitrogen) would favour the development of N2-cyano. Phytoplankton composition was studied during 16 months in a vegetated and isolated floodplain lake in the Paraná basin. Additionally, pH was artificially increased in in situ mesocosms to test effects on phytoplankton structure. Lake phytoplankton was dominated by flagellates (cryptophytes and euglenophytes) and small coccoid algae (chlorophytes and colonial cyanobacteria). Algal biomass was highest during warm periods. Although pH increased up to 8.8 during the second summer period, N2-cyano remained rare, most likely because of the high DIN concentration recorded. The alkalophilic diatom Cyclotella meneghiniana dominated and was positively correlated with pH. Conversely, PO4= concentrations in the mesocosm experiment were high and DIN remained relatively low. pH enhancement in the treated mesocosms (avg. pH = 8.2) promoted the development of N2-cyano (Anabaena spp.) and C. meneghiniana, which after 1 month of incubation accounted together for 50% of the biomass in contrast to less than 1.6% in control containers. Our results support the hypothesis that during the warm season and under low DIN concentration, high pH favours N2-cyano growth in these lakes. We provide new evidence supporting the idea that even under optimal nutrient conditions, N2-cyano do not thrive unless other requirements are satisfied.  相似文献   

8.
The effect of a sublethal concentration of malathion (95% E. C.) on the nucleic acids (DNA, RNA) and protein content in the liver of fingerlings of Channa punctatus, a freshwater murrel was investigated. 10 days of exposure brought non-significant alteration (P < 0.05) neither in the nucleic acids nor in protein content. However, significant quantitative decline in the liver's RNA (P < 0.01) and protein (P < 0.001) but not in the DNA content was observed after 20 days of exposure. Possible causes for such decline have been discussed.  相似文献   

9.
The photocatalytic decolorization and mineralization of Reactive Black 5 (RB5) dye in presence of TiO2 Degussa P25 has been studied using artificial light radiation in a shallow pond slurry reactor. The equilibrium adsorption of dye, influence of pH (3–11), catalyst load (0.5–3.0 g/L), and dye concentration (20–100 mg/L) on decolorization kinetics were studied. The effect of area to volume ratio of photoreactor on decolorization kinetics has been also studied. Mineralization studies were performed at optimized conditions of pH (3) and catalyst load (1.5 g/L). The maximum adsorption (26.5 mg/g) of dye was found to occur at pH 3. The apparent pseudo first order decolorization rate constant (kapp) value followed the order pH 3 > pH 11 > pH 9 > pH 7. As compared to available literature reduction in total organic carbon (TOC) was minimal by the time there was complete decolorization. Initial reduction in TOC was followed by subsequent increasing trend till complete decolorization. Final decreasing trend in TOC was observed only after complete decolorization. Twelve hours of treatment under experimental conditions reduced TOC content by 70% only. Discussion of results suggest that photocatalytic treatment of colored effluent under low UV intensity, and low A/V ratio may result in completely decolorized effluent but still having high COD.  相似文献   

10.
The effects of DDT on the regeneration of cutaneous wounds has been studied in Mystus (mystus) vittatus. The fishes were locally collected, they were inflicted incised wounds surgically and kept in 0.01 and 0.15 ppm concentrations of DDT. The regenerating skin at different stages of development ranging from 15 min to 25 d after the injury was studied through microtomy sections. The following toxic effects were studied:
  • A small amount of DDT accumulated in the subcutis at the 25 days stage,
  • the regeneration of wounds under DDT stress has been slower, delayed or irregular,
  • the secretion of fibrinous exudate has been copious,
  • epithelization and fibroblastic activities have been slower,
  • the higher concentration of 0.15 ppm of DDT produced more toxic effects than the lower concentration of 0.01 ppm,
  • the earlier stages of wound healing up to 3 d have been more adversely affected than later stages.
  相似文献   

11.
Atmospheric carbon dioxide is an important kind of greenhouse gas which influences global temperature. Its concentration variation could indicate the distribution of human and natural activities in various regions. Through the non-dispersive infrared method, flask sampling of atmospheric CO2 concentration was measured weekly at four national background stations including Waliguan, Shangdianzi, Lin’an, and Longfengshan. Based on the data collected from September 2006 to August 2007, along with the Waliguan station’s experience on in situ observational data processing, the selection methods for sampling data through the atmospheric background CO2 concentration analysis were preliminarily discussed. On the basis of this result, the variation features of the four typical regions’ atmospheric background CO2 concentration was analyzed for the first time. The results show that the atmospheric CO2 concentration at Waliguan, Shangdianzi, Lin’an, and Longfengshan is 383.5, 385.9, 387.8, and 384.3 ppm, respectively. During the research period, CO2 concentration at the Waliguan station changed slightly. However, the CO2 concentration changed sharply at the Shangdianzi and the Lin’an stations due to the great influence of human activities in the Jingjinji and the Changjiang Delta economic zones, and changed regularly with seasons at Longfengshan station under dual influences of human activities and plant photosynthesis. The results from this study can lay the foundation for more profound studies on atmospheric CO2 concentration level of different areas in China, and could be used to improve the understanding of carbon source and sink distribution.  相似文献   

12.
Freshwater Indian catfish H. fossilis was exposed to a sublethal concentration of 192 mg/1 nickel sulphate from 3 to 96 h. Blood glucose of the nickel exposed fish increased significantly at 6, 12, 24, 72 and 96 h. The maximum elevation was recorded at 72 h (P < 0.001). The possible role of glucagon and insulin has been discussed.  相似文献   

13.
In this study, the adsorption of reactive red 120 (RR 120) on pistachio husk, and the modeling of the adsorption was investigated. Characterization of the pistachio husk was confirmed by Fourier transform infrared spectroscopy. The pHzpc of pistachio husk was found to be pH 8.5. Increasing the initial pH value decreased (p < 0.01) the amount of dye adsorbed. However, increasing the initial dye concentration from 50 to 900 mg/L at pH 1 increased (p < 0.01) the equilibrium dye uptake from 20.83 to 182.10 mg/g. Results indicated that this adsorbent had great potential for the removal of RR 120 dye. The logistic model was found to be the most suitable of the kinetic and equilibrium models tested to describe the adsorption of the dye. The parameters determined from the logistic model were well correlated with the initial dye concentration, and were seen to increase with the increasing initial dye concentration, but this was not observed from pseudo‐second order kinetics.  相似文献   

14.
Median times to narcotization (ET50) of Cirolana borealis Lilljeborg by various levels of toluene in seawater were determined. Narcotization quickly became irreversible, and the ET50 values can be regarded as estimates of median lethal times. Respiratory rate, ATP concentration, and energy charge (E.C.) were not significantly affected by sublethal toluene levels which caused behavioural disturbance. At 12.5 ppm of toluene (nominal concentration; ET50:69 h) ATP dropped gradually to less than 1% and E.C. to about 50% of the control values during 8 days, after which time all the individuals were dead. At 125 ppm neither ATP concentration nor E.C. changed significantly during 24 h although the animals were inactive after about 1 h and died within 100 h. Due to the high degree of stabilization of adenine nucleotide levels and E.C. during environmental changes, these parameters do not appear useful as general indices of stress in environmental pollution studies.  相似文献   

15.
Fingerlings of Channa punctatus, a freshwater murrel, when subjected to a sublethal concentration of 12 mg l?1 zinc for 20 days elicited a significantly decreased (P<0.01) RNA content and hypoproteinemia in their liver. However, an exposure for 10 days under the same condition did not produce a significant alternation (P>0.05) neither in the nucleic acids (RNA – DNA) nor in the protein content. Results are discussed in relation to the pollutional stress of this heavy metal.  相似文献   

16.
The degradation of two pesticides: atrazine and metazachlor was investigated in aqueous solution under UV-irradiation with and without H2O2. Rate constants of the photochemical degradation were determined applying a first order kinetics and quantum yields of the processes were calculated. This approach leads to an apparent decrease of the quantum yield with increasing initial pesticide concentration. At low H2O2 initial concentrations, the pesticide degradation was shown to be much more efficient than the degradation under UV-irradiation only. However, at high H2O2 concentrations (>2 mmol L?1), the efficiency of the UV/H2O2 system dropped down and the quantum yields of degradation were lower than for the direct photolysis. In the absence of H2O2, no influence of the pH value on the photodegradation of the pesticides could be noticed in a range between pH 3 and pH 11. At low H2O2 initial concentrations, the photochemical degradation of the pesticides was much faster at pH 3 and pH 7 compared with the degradation at pH 11. The results emphasize the potential of optimized reaction conditions in advanced oxidation.  相似文献   

17.
太湖3种优势微囊藻对不同形态磷的吸收利用   总被引：1，自引：0，他引：1  
岳涛  张德禄  胡春香 《湖泊科学》2014,26(3):379-384
微囊藻(Microcystis)是最常见的淡水水华蓝藻,它们对磷营养盐的竞争力是其成为优势种的最主要影响因素.本文以太湖水华中的3种优势微囊藻(Microcystis flos-aquae,Microcystis wesenbergii和Microcystis aeruginosa)为材料,比较研究了它们对正磷酸盐(K2HPO4)、三聚磷酸盐(Na5P3O10)、小分子溶解态有机磷(葡萄糖-6-磷酸,G-6-P)和大分子溶解态有机磷(卵磷脂)的吸收和利用能力.结果发现,3种微囊藻对4种磷形态有明显的嗜好.当磷浓度为0.2 mg/L时,M. flosaquae只在正磷酸盐下生长最快,M. wesenbergii在三聚磷酸盐和大、小分子有机磷下生长最快,M. aeruginosa在所有磷形态下生长都最慢.而当磷浓度为2.0 mg/L时,M. flos-aquae在所有形态磷下生长都最快.在2种磷浓度下M. wesenbergii都表现出最高的溶解态无机磷比例和光合活性Fv/Fm.以上结果说明,3种藻在磷形态利用方面存在明显的互补性差异,即低磷浓度下M. wesenbergii适宜利用的磷形态更多,高磷浓度下M. flos-aquae适宜利用的磷形态更多,而不论磷浓度高低,M. aeruginosa对4种形态磷的适应性最差.由此可知,可利用磷形态的丰富性只是部分优势微囊藻的竞争策略.  相似文献   

18.
Ocean Drilling Program Leg 199 Site 1220 provides a continuous sedimentary section across the Paleocene/Eocene (P/E) transition in the carbonate‐bearing sediments on 56–57 Ma oceanic crust. The large negative δ13C shift in seawater is likely due to the disintegration of methane hydrate, which is expected to be rapidly changed to carbon dioxide in the atmosphere and well‐oxygenated seawater, leading to a reduction in deep‐sea pH. A pH decrease was very likely responsible for the emergence of agglutinated foraminiferal fauna as calcareous fauna was eliminated by acidification at the P/E transition at Site 1220. The absence of the more resistant calcareous benthic foraminifera and the presence of the planktonic foraminifera at Site 1220 is interesting and unique, which indicates that calcareous benthic foraminifera suffered greatly from living on the seafloor. Box model calculation demonstrates that, assuming the same mean alkalinity as today, pCO2 must increase from 280 ppm to about 410 ppm for the calcite undersaturation in the deep ocean and for the oversaturation in the surface ocean during the P/E transition. The calculated increased pCO2 coincides with paleo‐botanical evidence. The current global emission rate (～7.3 peta (1015) gC/y) of anthropogenic carbon input is approximately 30 times of the estimate at the P/E transition. The results at the P/E transition give an implication that the deep sea benthic fauna will be threatened in future in combination with ocean acidification, increased sea surface temperature and more stratified surface water.  相似文献   

19.
Abstract

The solubility of manganese in natural water is strongly influenced bychemical equilibria involving Mn+2, Mn+3 and Mn+4 species, redox potential, pH, and dissolved species of bicarbonate and sulfate. The solubility of manganese is shown by graphs as a function of Eh and pH in the absence of sulfate and in the presence of several different fixed activities of bicarbonate and sulfate ranging from 10 to 2,000 ppm (parts per million). Solubility is increased by the complexes MnHCO+ 3 and MnSO4 aq. whose association constants are 63 and 190, respectively.

Divalent manganese is soluble to the extent of 0.10 to 1.0 ppm at equilibrium in most ground and surface water. Manganese is more soluble than iron under most possible conditions, especially inthe Eh-pH range common in river water.  相似文献   

20.
Experiments to study the influence of biomass concentration and pH on copper uptake by blue-green algae were performed. Differential pulse anodic stripping voltammetry (DPASV) was used for copper analysis. The maximum copper uptake per unit of biomass depends only on copper concentration and not on biomass concentration. Hence the copper toxicity is independent of biomass over a wide range. A main factor influencing copper uptake is the pH. Whereas the copper uptake of Aphanizomenon gracile is rapid at pH = 8.2 we did not find a significant uptake at pH = 5.7. The copper uptake at the higher pH value is followed by a nearly complete release of this copper, accompanied by a fast shortening of trichomes. There was no significant copper uptake in Oscillatoria redekei at pH = 8.2, but at pH = 7.2 the uptake pattern of this species is similar to that of Aphanizomenon at pH = 8.2. The results suggest that the metal ion uptake mechanisms of different species have not the same pH optima.  相似文献   

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