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691.
The aim of the present investigation is to assess the impact of cypermethrin on reproductive physiology in catfish, Heteropneustes fossilis during prespawning phase. Results indicate that there is a decrease in the size of gonadotrophic cells with less granulation, pycnosis in the liver, presence of immature oocytes and atretic follicles in the ovaries and gross condensation of spermatogenic cells in testes after cypermethrin exposure at sublethal concentration. The gonado-somatic index (GSI), plasma levels of estradiol-17beta (E2) and 11-ketotestosterone (11-KT) also decreases. The motility of sperm cells is dependent on the dilution (2000 times) and duration of motility is recorded 2min maximally at 90s after post-activation. The dose 0.1 and 0.01ppm is sublethal, while 1ppm is lethal on sperm motility. Results indicate that cypermethrin causes inhibition of reproduction by acting at the hypothalamo-hypophyseal-gonadal axis as is manifest from the histological observations of gonadotrophs along with disruption of follicular wall and spermatogenic cells. Obviously such changes are responsible for decreasing the steroid hormone levels which result in decreasing scale and duration of sperm motility after 45d exposure of cypermethrin in this species. 相似文献
692.
Microbe-induced changes in metal extractability from fly ash 总被引:1,自引:0,他引:1
A low cost and eco-friendly technology to bioremediate toxic metals associated with fly ash dumps that contaminate ground and surface water in and around fly ash settling ponds, was investigated. The impact of augmentation of fly ash tolerant bacterial strains, isolated from Typha latifolia growing naturally on fly ash dumps, was studied for metal extractability. It was observed that most of the bacterial strains either induced the bioavailability of Fe, Zn and Ni or immobilized Pb, Cr, Cu, Cd in the fly ash. However, there were few exceptions also. In case of Ni, eight strains enhanced metal mobility, while others caused metal immobilization. The findings also suggest that metal solublization and immobilization are specific to bacterial strains. While induced bioavailability of metals by bacteria may be used to accelerate the phytoextraction of metals from fly ash by hyper accumulator plants, immobilization of metals can check their migration to water reservoirs and reduce the human suffering in affected areas. Thus, bacteria serve the dual purpose and may result in the microbe- assisted phytoremediation of contaminated sites. 相似文献
693.
Concentrations of hexachlorocyclohexane isomers (alpha-HCH, beta-HCH, gamma-HCH, and delta-HCH) were studied in soils samples collected from a small scale industrial unit of Lucknow associated with lindane production. All four isomers were detected from ten sites and the total HCH isomers in the analyzed samples varied from 53 to 99mgkg(-1). Cluster analysis was performed to group the soil sites in terms of their HCH contamination level. Low alpha/gamma HCH ratios were found and they indicate recent input of HCH. There is an urgent need for the on-site remediation of these contaminated sites in order to prevent the long-term environmental pollution. 相似文献
694.
Effect of sublethal treatment of (40% and 60% of 48 h LC50) of deltamethrin+MGK on phospholipid level and rate of lipid peroxidation in nervous and foot tissue of Lymnaea acuminata were studied. Maximum reduction in phospholipid (24.10%) level and increase in rate of lipid peroxidation (586.8%) were observed in foot tissue of snail exposed to 60% of 48 h LC50 of deltamethrin+MGK 264 for 96 h. Alterations in the levels of phospholipids and rate of lipid peroxidation were time and concentration dependent. Use of MGK-264 with deltamethrin increases the toxicity of deltamethrin and their action on membrane phospholipids and rate of lipid peroxidation. 相似文献
695.
A study was performed selecting one protected forest and an adjacent degraded forest ecosystem to quantify the impact of forest
degradation on soil inorganic nitrogen, fine root production, nitrification, N-mineralization and microbial biomass N. There
were marked seasonal variations of all the parameters in the upper 0–10 and lower 10–20 cm depths. The seasonal trend of net
nitrification and net N-mineralization was reverse of that for inorganic nitrogen and microbial biomass N. Net nitrification,
net N-mineralization and fine root biomass values were highest in both forests during rainy season. On contrary, inorganic
nitrogen and microbial biomass N were highest during summer season.
There was a marked impact of forest degradation on inorganic nitrogen, fine root production nitrification, N-mineralization
and microbial biomass observed. Soil properties also varied with soil depth. Fine root biomass, nitrification, N-mineralization
and microbial biomass N decreased significantly in higher soil depth. Degradation causes decline in mean seasonal fine root
biomass in upper layer and in lower depth by 37% and 27%, respectively. The mean seasonal net nitrification and N-mineralization
in upper depth decreased by 42% and 37%, respectively and in lower depth by 42.21% and 39% respectively. Similarly microbial
biomass N also decreased by 31.16% in upper layer 33.19% in lower layer. 相似文献
696.
Tiku DK Kumar A Sawhney S Singh VP Kumar R 《Environmental monitoring and assessment》2007,132(1-3):453-466
India has a large number of paper manufacturing units, with mills varying in size of operations and type of product, scattered
all over the length and breadth of the country. Present study deals with the survey of four different pulp and paper mills
(Mill A, Mill B, Mill C and Mill D) in India, differing in their scale of operation as well as raw material usage. Physico-chemical
characterization of wastewaters produced by different processing units like digestor house liquors, bleaching section, paper
machine backwaters, combined inlet to the ETP and outlet to ETP, for all the four mills, was conducted. Different parameters
like pH, Color, COD, BOD, percent Na, SAR, TDS and Total hardness were analyzed and compared. Highly significant differences
were thus found between all the processing units of all four mills with p values < 0.01. This evaluation showed that though these mills have effluent treatment facilities installed in their premises,
improvements are still needed to increase their efficiencies for treating the discharged wastewaters. 相似文献
697.
This study assesses the efficiency of various physico-chemical, biological and other tertiary methods for treating leachate.
An evaluation study on the treatability of the leachate from methane phase bed (MPB) reactor indicated that at an optimum
hydraulic retention time of 6 days, the efficiency of the reactor in terms of biological oxygen demand (BOD) and chemical
oxygen demand (COD) removal was 91.29 and 82.69%, respectively. Recycling of the treated leachate through the municipal solid
waste layers in the leachate recycling unit (LRU) resulted in a significant increase in the biodegradation of organics present
in the leachate. Optimum BOD and COD removal efficiencies were achieved at the third recycle; additional recycling of the
leachate did not produce any significant improvement. Physico-chemical treatment of the leachate demonstrated that alum and
lime (Option 2) were more economical than coagulants lime and MgCO3. A cost analysis of the economics of the various treatments revealed that the alternative treatment consisting of a MPB bed
followed by a LRU and aerated lagoon is the most cost-effective treatment. However, the alternative consisting of a MPB followed
by the LRU and a soil column, which is slightly more costly, would be the most appropriate treatment when adequate land is
readily available. 相似文献
698.
Spatial Variability of Groundwater Depth and Quality Parameters in the National Capital Territory of Delhi 总被引:3,自引:0,他引:3
The groundwater quantity and quality scenario is of much concern in the National Capital Territory of Delhi, India, which
necessitates an investigation to envisage the extent of spatial variability of groundwater depth and pollutant concentration
levels in this region. Therefore, in this study, an effort was made to generate the spatial variability map of groundwater
depth and quality parameters (viz. chloride, electrical conductivity, fluoride, magnesium, and nitrate). Ordinary kriging
was used to analyze the spatial variability of groundwater depth and quality parameters, whereas indicator kriging was used
to analyze groundwater quality parameters equal to or greater than the pollution threshold values. It was observed that the
semivariogram parameters fitted well in the exponential model for water depth and in the spherical model for water quality
parameters. The generated spatial variability maps indicated that in 43% of the study area, groundwater depth was within 20 m.
The salinity level was higher than 2.5 dS m−1 in 69% of the study area and the nitrate concentration exceeded 45 mg l−1 in 36% of the area. The probability maps showed that about 24% of the area had the highest probability (0.8–1.0) of exceedence
of the threshold electrical conductivity value and an area of 2% exhibited the highest probability of exceedence of the threshold
value of nitrate concentration in the groundwater. The generated spatial variability and probability maps will assist water
resource managers and policymakers in development of guidelines in judicious management of groundwater resources for agricultural
and drinking purposes in the study area. 相似文献
699.
Anjil Kumar Srivastava Ravi Ranjan Kumar Ashok Kumar Singh 《Environmental science and pollution research international》2014,21(24):13979-13986
Municipal solid wastes (MSW) are unavoidable sources of environmental pollution. Improper disposal of municipal waste results in the leaching of toxic metals and organic chemicals, which can contaminate the surface and ground water leading to serious health hazard. In this study, the toxic effects of the leachate prepared from municipal solid waste samples were examined in root meristem cells of barley (Hordeum vulgare L.) at various stages of cell cycle, i.e., G1, S, and G2. Seeds of barley were exposed to 2.5, 5, and 10 % of leachates in soil and aqueous media in 48 h at different cell cycle stages. The physicochemical data of the present study revealed that municipal solid waste leachate contains high amount of heavy metals, which significantly affected growth and physiological activities of barley. Significant inhibition in hypocotyl length, germination, and mitotic index were observed at all concentration of leachate treatment. Induction of chromosomal aberrations (CA’s) and micronuclei (MN) formation were also observed with different concentrations of leachate treatment at 7, 17, and 27 h of presoaking durations, which falls in G1, S, and G2 phase of the cell cycle, respectively. Also, exposure of leachate at S phase of the cell cycle had significant effects in barley through chromosomal aberration and micronuclei formation. 相似文献
700.
Vikas Singh Ranjeet S. Sokhi Jaakko Kukkonen 《Journal of the Air & Waste Management Association (1995)》2014,64(5):509-518
We report on the analysis of contributions from road traffic emissions to fine particulate matter (PM2.5) concentrations within London for 2008 with the OSCAR Air Quality Assessment System. A spatiotemporal evaluation of the OSCAR system has been conducted with measurements from the London air quality network (LAQN). For the predicted and measured hourly time series of concentrations at 18 sites in London, the medians of correlation, mean absolute error, index of agreement, and factor of two (FAC2) of all stations were 0.80, 4.1 μg/m3, 0.86, and 74%, respectively. Spatial evaluation of modeled and observed annual mean concentrations also showed a fairly good agreement, with all the values falling within the FAC2 range. According to model predictions, the urban increment (including the contributions from urban traffic and other urban sources) was evaluated to be on the average 18%, 33%, 39%, and 43% of the total PM2.5 in suburban environments, in the urban background, near roads, and near busy roads, respectively. However, the highest values of the urban traffic increment can be around 50% of the total PM2.5 concentrations near motorways and major roads. The total concentrations (including regional background, and the contributions from urban traffic and other urban sources) can therefore be almost three times the regional background. The total urban increment close to busy roads was around 7–8 μg/m3, in which the estimated traffic contribution is more than 2 μg/m3. On the average, urban traffic contributes approximately 1 μg/m3 of PM2.5 to the urban background across London. According to modeling, approximately two-thirds of the traffic increment originated from exhaust emissions and most of the rest was due to brake and tire wear.
Implications: The urban increment and traffic contribution to the total PM2.5 are significant and spatially heterogeneous across London. The highly heterogeneous distribution of PM2.5 hence requires detailed modeling studies to be carried out at high spatial resolution, which can be particularly important for exposure and health impact assessment. This type of information can be used to quantify health impacts resulting from specific sources of PM2.5 such as traffic emissions, to aid city and national decision makers when formulating pollution control strategies. 相似文献