细化搜索
结果 31-40 的 3,243
Evaluating the consequences of the new standards on noise conditions in ships
2015
Bouzón, Rebeca | Costa, Angel M | Roshan, Gholamreza | Orosa, J.A.
Noise is one of the main parameters to be considered to achieve a healthy indoor ambience in ferries. Therefore, the noise standards need to be more specialized and specifically based on real sampled data and case studies. In the present research, the noise levels in a ship, under different working conditions, were sampled and compared with those specified in the new and old standards. An initial study showed two main noise sources- clients and main engine- that influence other indoor environments, reducing the quality of life on board. The real-time data revealed that the maximum noise level limits set by the International Maritime Organization (IMO) in the older Resolution A.468 (XII) was mostly respected, except in areas where maintenance of the noise level was difficult, owing to the continuous influx of people, especially at the time of boarding and disembarking of the passengers and at the food self-service areas. In this sense, under the new Resolution MSC.337 (91), the maximum noise level allowed in the accommodation has been reduced by 5 dB (A), but this environment does not meet the standard. More results show that future standards must not only consider the noise level in a working place and add another variable, such as, the number of working hours, to obtain a representative equivalent energy, and they must also consider that a simple modification of this standard implies a redesign of most of the indoor ambiences onboard.
显示更多 [+] 显示较少 [-]Hematological responses of Goldfish (Carassiusauratus) to different acute concentrations of Silver Sulfate as a toxicant
2015
Abarghoei, Safoura | Hedayati, Seyed Aliakbar | Ghafari Farsani, Hamed | Gerami, Mohammad Hasan
This study aimed to evaluate the efficacy of silver sulfate (AgSO4) as a toxicant in goldfish (Carassiusauratus). One hundred and forty-seven live specimens of C. auratus were obtained and exposed to 1, 10, 100, 500, 1000 and 2000 ppm of AgSO4for 96 hours. There was one control group (no AgSO4) and three replicates. The physicochemical properties of water and the following parameters were constant: pH: 7.56±0.45 (TS1); temperature: 19±1°C; hardness: 293±2.35 ppm and dissolved oxygen: 8.80 ±0.06 mg L-1 (DO-5510). LC1, LC10, LC30, LC50, LC70, LC90 and LC99 were calculated in 24, 48, 72 and 96 hours. For assessing the impact ofAgSO4 on physiological responses of goldfish hematological indices, blood glucose and cortisol levels were measured. Results showed that LC50 96-h of AgSO4 for goldfish was 687.81 ppm. In addition, the use of AgSO4induces a significant decrease in MCHE after 48 hours, MCV and MCH after 96 hours and lymphocyte after 96 hours in contrast to the control group (P<0.05). Furthermore, increased lymphocyte was significant after 24 hours exposure (P<0.05). In addition, glucose increased significantly at P<0.05 with time increase24 hours after experiment but this (). In conclusion, the study showed that acute toxicity of AgSO4induced hematological alterations in goldfish and offers a tool for the evaluation oftoxicity-derived alterations.
显示更多 [+] 显示较少 [-]Development of a new low-cost procedure for wind farm maintenance with a view to decrease soil pollution
2015
Costa, Angel M. | Fraguela, Feliciano | Orosa, Jos&eacute; A. | Roshan, Gholamreza
The purpose of this article is to present the development of a wind farm, with a condition monitoring system (CMS) based on control charts as the algorithm, centred on a new index, to prevent soil pollution by oil spills in wind farms. To this end, temperature sensors can be considered as one of the more significant sensors to be employed in this study, because the information obtained with regard to anemometers and electrical power output counters can be employed by the control system. As a result, among the other variables, oil temperatures sampled in multipliers used in the wind turbines of a real wind farm were employed. Statistical analyzes were developed and the relationship between wind farm maintenance (usually related to wind farm oil spills) and oil temperature was obtained. Furthermore, a practical case study, centered in the statistical process control, based on the low-cost sample variable was developed and showed that this new procedure would improve deficiencies in the maintenance process, thus, reducing the failure detection time under low sensor cost, as also the related soil pollution.
显示更多 [+] 显示较少 [-]Assessment of indoor cancer linked to accumulated radiation dose from different types of television sets in dwellings
2015
Njinga, Raymond | Mamman, Sameul
Exposure to radiation from different types of television sets was measured to ascertain the levels of hazards posed to the human biological system. Measurement of the annual radiation dose hazards was performed using a halogen-quenched GM tube with thin mica end window having a density of 1.5 mg/cm2, effective window diameter of 0.360 inch and side wall of 0.012 inch thick. The GM tube was placed for 180 minutes and the sensor faced the screens of the various TV sets, one meter apart. The annual radiation dose ranged from 0.012 ± 0.006 mSv/yr for plasma-SONY to 0.13 ± 0.012 mSv/yr for SHARP and SAMSUNG 24 inch TV sets, containing cathode ray tubes. The annual doses from the 15 and 24 inch-LG TVs (manufactured with cathode ray tubes) were relatively low, with values of 0.031 ± 0.017 and 0.035 ± 0.005 mSv/yr, respectively. The 21 inch THERMOCOOL and PROTECH (with cathode ray tubes), produced annual doses of 0.110 ± 0.052 Sv/yr and 0.063 ± 0.002 mSv/yr, respectively. This provides an insight into the amount of radiation generated by different TV sets in households, on an annual basis. After some years of exposure to TV radiation, health complications such as carcinogenesis or other adverse cellular events may occur, due to cumulated (but does not always) doses which may result in DNA damage, to the human biological system.
显示更多 [+] 显示较少 [-]Residual archives on organochlorine insecticides in the core sediment of a tropical estuary, India
2015
P.S., Akhil | H, Sujatha
A comprehensive evaluation of the residual levels of Organochlorine insecticides (OCIs) in the sediment cores of Cochin Estuarine System (CES) is highlighted in this research article. It assessed the distribution pattern and impact of these xenobiotics in this environmental niche. Fifteen persistent organochlorine compounds (OCs) were quantitatively analysed in the six sediment core samples collected from specific sites of CES, during November 2009. Among these contaminants, residual levels of HCH, Cyclodienes and DDT were the dominant entities. According to the sediment quality guidelines (SQGs), the higher concentration of these persistent toxicants found in the CES was enough to pose ecological risk to the bottom dwelling consumers. This study provides a better understanding of these trace organics in the environment and could develop more effective strategies for protecting this vulnerable ecosystem from further pollution. Further, sediment screening bioassays can also be conducted for both sediment quality evaluation and identification of existing potent toxicants.
显示更多 [+] 显示较少 [-]Assessment and control of VOCs emitted from gas stations in Tehran, Iran
2015
Eisaei, Hamid Reza | Ahmadi Dehrashid, Seyed Shaho | Khani, Mohammad Reza | Hashemi, Seyed Mukhtar
In this research, gasoline vapours including Benzene, Toluene, Xylene (BTX) and Total Volatile Organic Compounds (TVOCs) emitted from vent pipes of underground storage tanks (USTs) were measured at six gas stations in Tehran. Thereafter, gas station No. 29 was selected as a pilot station and equipped with a vapour control system. The vapours were measured during the summer of 2013 and winter of 2014 in two states, before and at the time of gasoline discharge from a petrol tanker to the UST. The results reveal that the average of BTX and TVOCs are 161.22, 200.81, 229 and 647.01 ppm, respectively, higher than the World Health Organisation (WHO) guidelines. The average of TVOCs and BTX in the situation in which the control system is inactive at the pilot station, are 259.13, 55.9, 73.03 and 96.88 ppm, respectively. After activating the control system at the pilot station, the VOCs were reduced by 0.01 ppm. Almost 99.99% control was obtained for this system and 87% of the people living around the pilot station were satisfied and no longer had any complaints about the bad odour of VOCs. It can be concluded that gasoline discharge from the petrol tanker to UST, is the main reason behind the overproduction of VOCs in Tehran's gas stations (P<0.001). So, the most important element is to reduce VOCs at Tehran's gas stations by installing a vapour control systems in all the stations and activating the systems at the time of gasoline discharge.
显示更多 [+] 显示较少 [-]Potential of Lemna minor in Ni and Cr removal from aqueous solution
2015
Goswami, Chandrima | Majumder, Arunabha
Duckweeds are of special interest, as they are naturally growing weeds that have the capacity to tolerate and remove toxic pollutants, including heavy metals from the environment. Studies have revealed that duckweed (Lemna minor) can tolerate and remove heavy metals from aqueous solutions. In the present study, the efficiency of L. minor in the removal of Ni and Cr individually from aqueous solutions was investigated at concentrations of 3.05, 3.98 and 4.9 mg/L for Ni and 1.91, 2.98, and 4.2 mg/L for Cr. Experiments were run for 22 days, after which the metal content in the plant was estimated by atomic absorption spectrophotometer (AAS). The duckweed showed higher percentage of Ni removal than Cr. Specific Growth Rate (SGR) was found to be reduced at high concentrations of both Ni and Cr. Statistical analysis suggested that the growth of the plant was affected by the toxic effect of both Ni and Cr. Bioaccumulation of Ni was higher than Cr in L. minor. The mechanism of removal of both Ni and Cr followed second order kinetics. It is suggested that these duckweeds can remove Ni and Cr from aqueous solution and can also accumulate the same in considerable concentrations, at low initial metal concentrations.
显示更多 [+] 显示较少 [-]Application of AERMOD to local scale diffusion and dispersion modeling of air pollutants from cement factory stacks (Case study: Abyek Cement Factory)
2015
Noorpoor, Alireza | Rahman, H. R.
Today, the cement industry is one of the major air polluting industries in the world. Hence, in this study, owing to the importance and role of contaminants from the plant, an appraisal of the emission contributions in addition to other factors have been discussed. There are several reasons behind the importance of modeling air pollutants. First, the assessment of standards for air pollution, and the fact that the measurement points are limited. Furthermore, in all industrial areas, measurement and installation of assessment and monitoring stations are not feasible. The AERMOD model is a dispersion steady state model which is utilized to determine the concentration of various pollutants in different areas from urban and rural, flat and rough, shallow diffusion in height, from standpoint and different shallow sources. In this model, it is assumed that the dispersion of concentration in Stable Boundary Layer (SBL) in two horizontal and vertical directions are similar to that of horizontal within Gaussian convectional boundary layer (CBL). With regard to assessment of the parameters and pollutants of stack outlet, the amount of particulate matter was measured as the most important pollutant in the region. Then, via dispersion and diffusion modeling of pollution (AERMOD) along with environmental measurements, the nature of dispersion of this pollutant in the analysis of the surrounding areas was verified. According to the presented results, the highest level of concentration for particulate matters in all areas affected by cement factory amounts to 43.68 (μg/m3) which occurred at a distance of 1500 m in the east direction and 2100 m in the north direction.
显示更多 [+] 显示较少 [-]Positive effects of Vitamin C in arsenic trioxide and sodium fluoride induced genotoxicity and oxidative stress in mice in vivo
2015
Roy, Prasenjit | Mukherjee, Anita | Giri, Sarbani
The aim of the present study was to evaluate Vitamin C (VC) as a potent natural antioxidant to mitigate the genotoxic effects of Arsenic trioxide and sodium fluoride in Swiss albino mice in vivo. The study was divided into eight groups consisting of control treated with normal saline (Group I), Group II, III, IV, V, VI, VII and the VC group with only Vitamin C (500 mg/kgbw). Arsenic trioxide (4 mg/kgbw) and Sodium fluoride (8 mg/kgbw) were administered singly, as well as in combination to swiss albino mice, with and without VC. In this study, the genotoxic effect of arsenic (As) and fluoride (F) in mice using comet, chromosomal aberration and lipid peroxidation assay was investigated. The results revealed that VC efficiently ameliorates the genotoxic effect of As and F by increasing the frequency of chromosomal aberrations and primary DNA damage along with increased malondialdehyde (MDA) level. In conclusion, VC mitigates the genotoxic effects of the two well-known water contaminants (As and F) effectively and efficiently at the given concentration in vivo.
显示更多 [+] 显示较少 [-]Micro and Small Enterprises in Solid Waste Management: Experience of Selected Cities and Towns in Ethiopia: A Review
2015
Damtew, Yohannes Tefera | Desta, Biniyam Negussie
Municipalities in developing countries spend the highest proportion of their annual budget on unsatisfactory solid waste management service. Until recently, solid waste management services in Ethiopia were mainly the responsibilities of municipalities, which culminated in inadequate service provision. Thus, the integration of Micro and Small Enterprises (MSEs) by the government has recently being considered as an option. Participation of MSEs in SWM started in 2003/04 in Addis Ababa, the capital city of Ethiopia and expanded to other cities following the proclamation of a National Solid Waste program in 2007. This review is aimed at identifying the role of MSEs in solid waste management in selected cities, including the opportunities and challenges for future directions. Limited resources and lack of support, perception and awareness of the community, inadequate training, unorganized fee collection strategy and limited revenue were among the challenges identified. The benefits and potential opportunities include organized and quality service delivery, environmental protection and safety, job opportunity, willingness to pay and social equity. In conclusion, the findings in this review show the importance of MSEs in solving solid waste management problems. However, the challenges need due considerations and appropriate interventions such as legalization of the informal sector, clear working guidelines and regulations, close support and monitoring, and transparent system in general.
显示更多 [+] 显示较少 [-]