This experiment was conducted to study the genotoxic potentials of sodium arsenite (NaAsO2) in freshwater fish Oreochromis mossambicus by using alkaline comet assay and micronucleus (MN) test. Fish were exposed to three different concentrations (3 ppm, 28 ppm and 56 ppm) of arsenic and gill, liver and blood tissue samples were collected after 48 h, 96 h and 192 h of exposure. Arsenic exposure induced DNA damage in all tissues examined in a concentration dependent manner. A significant (p < 0.05) increase in the comet tail DNA (%) of the exposed fish liver, gill, and blood was observed after 48 h and 96 h of exposure, but a decline in DNA damage was recorded in all the tissues at all the three concentrations studied after 192 h of exposure. Liver tissue exhibited significantly (p < 0.05) higher DNA damage at all the concentrations examined, followed by gill and blood. Higher liver tail DNA (51.38 ± 0.21%) refers that it is more prone to injury to arsenic toxicity than the gill and blood. In blood samples arsenic induced micronucleus formation in a concentration dependent manner and highest (5.8 ± 0.46%) value was recorded in 56 ppm after 96 h of exposure, whereas, it was decreased after 192 h of exposure at all the three concentrations of NaAsO2 examined which refers to the DNA repairing ability of fish to arsenic toxicity. The results of this study depict the genotoxic potentials of arsenic to fish which in turns provide insight on advanced study in aquatic toxicology. 相似文献
A pot-culture experiment was conducted in open-field conditions with highly cultivated locally transplanted (T) aman rice
(Oryza sativa L.) named BR-22 in arsenic (As)-amended soil (0, 1.0, 5.0, 10.0, 20.0, 30.0, 40.0 and 50.0 mg kg−1 As) of Bangladesh to see the effect of As on the growth, yield and metal uptake of rice. Arsenic was applied to soil in the
form of sodium arsenate (Na2HAsO4). Arsenic affected the plant height, tiller and panicle numbers, grain and straw yield of T-aman rice significantly (P ≤ 0.05). The grain As uptake of T-aman rice was found to increase with increase of As in soil and a high grain As uptake
was observed in the treatments of 30–50 mg kg−1 As-containing soil. These levels exceed the food hygiene concentration limit of 1.0 mg kg−1 As. However, the straw As uptake varied significantly (P ≤ 0.05) from a low concentration of As in soil (5 mg kg−1) and the highest uptake was noticed in 20 mg kg−1 As treatment. 相似文献
Paech, Simon J., John R. Mecikalski, David M. Sumner, Chandra S. Pathak, Quinlong Wu, Shafiqul Islam, and Taiye Sangoyomi, 2009. A Calibrated, High‐Resolution GOES Satellite Solar Insolation Product for a Climatology of Florida Evapotranspiration. Journal of the American Water Resources Association (JAWRA) 45(6):1328‐1342. Abstract: Estimates of incoming solar radiation (insolation) from Geostationary Operational Environmental Satellite observations have been produced for the state of Florida over a 10‐year period (1995‐2004). These insolation estimates were developed into well‐calibrated half‐hourly and daily integrated solar insolation fields over the state at 2 km resolution, in addition to a 2‐week running minimum surface albedo product. Model results of the daily integrated insolation were compared with ground‐based pyranometers, and as a result, the entire dataset was calibrated. This calibration was accomplished through a three‐step process: (1) comparison with ground‐based pyranometer measurements on clear (noncloudy) reference days, (2) correcting for a bias related to cloudiness, and (3) deriving a monthly bias correction factor. Precalibration results indicated good model performance, with a station‐averaged model error of 2.2 MJ m?2/day (13%). Calibration reduced errors to 1.7 MJ m?2/day (10%), and also removed temporal‐related, seasonal‐related, and satellite sensor‐related biases. The calibrated insolation dataset will subsequently be used by state of Florida Water Management Districts to produce statewide, 2‐km resolution maps of estimated daily reference and potential evapotranspiration for water management‐related activities. 相似文献
In this paper, we show that FARS data can be a comparable alternative to observational NOPUS data in estimating seat belt use in the United States once we correct for sample selection bias.
Results
Based on assumptions of independence for seatbelt choice, we establish a lower and upper bound for seatbelt usage rates, and find that once we correct for sample selection bias, the seatbelt usage estimates from the corrected FARS emerge at least as a comparable alternative to NOPUS estimates.
Impact on Industry
This implies that researchers can use corrected FARS to complement NOPUS, thus being able to utilize the rich cross-sectional details available in FARS data to analyze various relevant research questions. 相似文献
In the present work, sawdust reinforced polypropylene composites were fabricated using an extruder and an injection molding
machine. Raw sawdust was chemically treated with benzene diazonium salt in order to improve the mechanical properties of the
composites. The effect of the chemically treated sawdust reinforced PP composites was evaluated from their mechanical and
surface morphological properties. The values of the mechanical properties of the chemically treated sawdust–PP composites
were found to be significantly higher than those of the raw ones. Water uptake tests revealed that composites prepared from
the chemically treated sawdust absorb lower amount of water compared to the ones prepared from raw sawdust, suggesting that
hydrophilic nature of the cellulose in the sawdust has significantly decreased upon chemical treatment. The surface morphology
obtained from scanning electron microscopy (SEM) showed that raw sawdust–PP composites possess surface roughness with extruded
filler moieties, and weak interfacial adhesion between the matrix and the filler while the chemically treated one showed improved
filler–matrix interaction. This indicates that better dispersion of the filler with the PP matrix has occurred upon chemical
treatment of the filler. 相似文献
Environmental Science and Pollution Research - Trace metals contamination in commercial fish and crustaceans have become a great problem in Bangladesh. This study was conducted to determine seven... 相似文献
This study investigated the characteristics of iron corrosion scales in pipes at tube well, overhead tank, and consumers’ end in older untreated water distribution system in Peshawar city, Pakistan. Effect of water quality conditions on corrosion scales and that of scales on drinking water quality in such systems was also assessed by undertaking a comparison with new piped distribution systems. The scales were analyzed for chemical composition and morphology using X-ray diffraction (XRD), inductively coupled plasma (ICP), and a scanning electron microscope (SEM), while water quality was examined for physicochemical and biological characteristics. The main crystalline phases of corrosion scales were goethite, magnetite, siderite, and quartz. From tube well to consumers’ end, goethite increased from 36 up to 48%, quartz declined from 22 to 15%, while magnetite fluctuated and siderite disappeared. Elemental composition of scales showed the deposition of Zn, Al, Mn, Cr, Pb, Cu, As, and Cd with Zn (13.9 g/kg) and Al (3.6 g/kg) in highest proportion. The SEM analysis illustrated the presence of microbial communities indicating the formation of biofilms in the corrosion scales. The significant difference (P <?0.05) in levels of dissolved oxygen (DO), Cl?, SiO44?, electrical conductivity (EC), SO42?, NO3?, alkalinity, hardness, and trace metals between old (DS-O) and new piped systems indicated their role in corrosion scale formation/destabilization and the effect of scale dissolution on water quality. In DS-O, EC, Cu, and Mn were significantly higher (P?<?0.05), whereas turbidity, EC, DO, and SiO44? significantly increased from source to consumers’ end implying a higher dissolution of scales and lowered corrosion rates in DS-O to utilize SiO44? and DO for iron oxidation.
The production of biodiesel is gaining momentum with the ever increasing demand of the fuel. Presently, limited literature is available with respect to well designed solid heterogeneous catalyst for biodiesel production considering all the characteristics, process and operation parameters. Hence, a study was conducted to design effective heterogeneous catalyst for biodiesel production. Further, the significant impact of different catalysts, different feed stock, various reaction conditions such as temperature, methanol oil molar ratio, catalyst concentrations and stability/inactivation of the catalysts, are detailed out for transesterification process of biodiesel production. Based on the studies it can be concluded that well designed heterogeneous catalyst can yield high throughput of biodiesel. 相似文献
Frequent erosion along the banks of the river Bhagirathi–Hooghly constitutes one of the most important hazards in West Bengal, India. This frequent nature of erosion is induced by hydraulic control by the construction of Farakka Barrage in 1975 and Indo-Bangladesh water sharing treaty of 1977 and 1996. Water sharing treaties result in fluctuating discharge on 10-day scale in the lean period (January–May). The stream discharge variability affects the bank erosion through its impacts on erodibility factors of banks. It has been observed that in the pre-Farakka period bank erosion was huge only during the monsoon months, and rest of the year, there was little or no bank erosion because in the pre-monsoon and post-monsoon periods, the river Bhagirathi received very little or no discharge from the river Ganga. But in the post-Farakka period, the river Bhagirathi received considerable amount of water in variable quantities from the river Ganga, especially in lean period which has steadied the river bank erosion in the year round. It is to mention that benefits of this planning are to survive the port-industrial economy of South Bengal and provision of fresh water for inhabitants of Kolkata. So beneficiaries of this controlled hydrology must have to pay affluent tax for the victims by this project. In this paper, the nature, mechanism and pattern of bank erosion and its impact on socio-economic vulnerability of the people in the selected erosion-prone areas have been depicted. At the end, a search for social justice for the victims has been articulated from the perspective of Pareto-optimal justice. 相似文献