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151.
The measurement of roadway PM10 emission rates using atmospheric tracer ratio techniques 总被引:2,自引:0,他引:2
Ravi Kantamaneni Glen Adams Lee Bamesberger Eugene Allwine Hal Westberg Brian Lamb Candis Claiborn 《Atmospheric environment (Oxford, England : 1994)》1996,30(24):4209-4223
In this work, stationary and mobile point source tracer release techniques have been used to determine PM10 emission rates from four-lane commercial/residential paved roads under sanded and unsanded conditions, and from unpaved roads relative to site-specific vehicular and ambient parameters. Measured street (4 + lanes; ? 10,000 vehicles per day) emission factors for unsanded and sanded roads were 40 and 20% lower, respectively, than the EPA approved reference value. The sanded road emission factor was approximately 40% higher than that for the unsanded road. These results indicate a consistent relationship between PM10 and relative humidity under unsanded conditions. There is some evidence to suggest that street sweeping has a measurable effect on PM,, emission reduction during periods of low relative humidity (i.e. ? 30%). Within the constraints imposed by the variable experimental conditions, the emission factors determined for unpaved roads agreed reasonably well with the unpaved road empirical formula. Limited correlations were observed with ambient meteorological parameters. The capability of the “upwind-dowiawind” concentration modeling method to predict accurate emission was tested using a Gaussian dispersion model (SIMFLUX). Predictions agreed well with the experimentally determined emission factors. 相似文献
152.
Lion-Human Conflict in the Gir Forest, India 总被引:1,自引:0,他引:1
Vasant K. Saberwal James P. Gibbs Ravi Chellam A.J.T. Johnsingh 《Conservation biology》1994,8(2):501-507
153.
Nasreen Islam Khan David Bruce Ravi Naidu Gary Owens 《Environmental geochemistry and health》2009,31(Z1):221-238
Dietary intake of water and food has been identified as one of the major pathways for arsenic (As) exposure in the rural population
of Bangladesh. Therefore, realistic assessment and measurement of dietary intake patterns are important for the development
of an accurate estimate of As exposure and human health risk assessment. One important consideration is to identify an appropriate
tool for measuring dietary intake. In this study an interviewer-administered Food Frequency Questionnaire (FFQ) was implemented
to determine age and gender specific dietary intake. The developed FFQ was unique because it developed a synergy between field
dietary assessment and As concentration measurements in various environmental media. The resulting integrated database provided
an accurate framework for the process of As exposure and human health risk assessment. The preliminary results reported here
from the FFQ demonstrated that this technique could be used in rural areas as a tool to assess As exposure and the associated
human health risk. 相似文献
154.
Ajay Kumar Sabyasachi Rout R. K. Singhal P. M. Ravi R. M. Tripathi 《Journal of Coastal Conservation》2016,20(4):289-297
Bio-diffusion mixing rates (Db) were estimated from depth profiles of excess 210Pb and 137Cs in three sediment cores collected from Mumbai Harbour Bay (MHB) using a steady state vertical advection - diffusion model. The mean of 210Pb and 137Cs derived Db values along the studied area were obtained to be about 23 and 36 cm2y?1 respectively. These derived values were within the range of literature values reported for other equivalent environment internationally. The relatively higher Db values for 137Cs profiles demonstrated that particles have diffused more intensely within the surface layer of sediments over 1 year. Conversely, low Db values for 210Pb indicate slow mixing rates in the sediment profile which might be resulted from low 210Pb flux and diffusion of 222Rn to the seafloor. The significant differences between 210Pb and 137Cs derived Db values among cores indicate that there appeared to be as regional differences in sediment properties and local variability in the intensity of seafloor mixing. Furthermore, Db values also depend on differences in characteristic time and depth scales of radionuclides in cores, benthic fauna abundances, organic carbon flux to the sediments and primary production in overlying surface waters. Comparison of 210Pb derived Db values with those calculated from 137Cs distributions reveals better agreement for core 2 than core 1 and 3. The agreement may be fortuitous because 137Cs appears significantly deeper than 210Pb in all cores. It was also observed that Db values increases as sediment accumulation rate increases for both radionuclide. 相似文献
155.
为探究湛江近海域海洋沉积物中类二噁英多氯联苯(dioxin-like polychlorinated biphenyls,Dl PCBs)的生物学毒性效应,选取湛江近海域2个地点(近工业区TS和近生活区JSW)采集沉积物样品,制备近海域沉积物Dl PCBs提取物,将斑马鱼胚胎暴露于不同浓度的Dl PCBs提取物,测定斑马鱼胚胎7-乙氧基异吩恶唑脱乙基酶(ethoxyresorufin-O-deethylase,EROD)活性和cyp1a m RNA相对表达量。结果发现,JSW采样点Dl PCBs提取物染毒组EROD酶活性变化与TS采样点Dl PCBs提取物一致,在各染毒浓度下,斑马鱼仔鱼EROD酶活性为对照组的1.1~1.8倍。TS和JSW采样点不同浓度Dl PCBs提取物暴露斑马鱼胚胎96 h后,使斑马鱼仔鱼cyp1a m RNA相对表达量是对照组的3.36~19.45倍。说明一定浓度的近海沉积物Dl PCBs能诱导斑马鱼仔鱼EROD酶活性和cyp1a m RNA表达量升高,且呈现浓度-效应关系。 相似文献
156.
Mohammad Mahmudur Rahman ZuLiang Chen Ravi Naidu 《Environmental geochemistry and health》2009,31(Z1):93-102
We have developed a novel microwave-assisted extraction method for determining the arsenic (As) speciation in soils that is
based on extraction with phosphate solutions, including orthophosphoric acid, ammonium dihydrogen orthophosphate, and ammonium
hydrogen orthophosphate. The highest extracting efficiency was obtained with 1 M ortho-phosphoric acid solution as the extractant, and this efficiency is associated with the pH of the extractant. Total
As content and As species in the soil extracts were determined by inductively coupled plasma mass spectrometry (ICP-MS) alone
and by the combined ion chromatography (IC) with ICP-MS, respectively. The proposed extraction procedure was applied to National
Institute of Standards and Technology (NIST) standard reference material (SRM) 2711 (Montana soil) as well as to environmental
soil samples collected from the agricultural lands of Bangladesh. As(V) was detected in all the soil samples, and As(III)
was detected in nine soils of the 20. These results of extractable As testing indicate that the extraction of As species mainly
depends on the composition of the soils. The As speciation results also indicate that As adsorption is highly dependent on
the iron, aluminum, and manganese concentrations in the soil. The stability of As species in the extracts was also studied. 相似文献
157.
Mohammad Mahmudur Rahman R. Naidu Prosun Bhattacharya 《Environmental geochemistry and health》2009,31(Z1):9-21
The adverse impact of groundwater contaminated with arsenic (As) on humans has been reported worldwide, particularly in Asian
countries. In this study, we present an overview of the As crisis in the Southeast Asian region where groundwater is contaminated
with naturally occurring As and where contamination has become more widespread in recent years. In this region more than 100 million
people are estimated to be at risk from groundwater As contamination, and some 700,000 people are known so far to have been
affected by As-related diseases. Despite investments exceeding many millions of dollars, there are still substantial knowledge
gaps about the prevalence and impact of As, notably in its epidemiology, temporal variations, social factors, patient identification,
treatment, etc. Arsenic-affected people in the affected regions also face serious social problems. Of major concern is the
fact that many researchers from different countries have been conducting research in SE Asia region but with a lack of coordination,
thus duplicating their work. There is an urgent need to coordinate these various studies to ensure better delivery of research
outcomes. Further research is needed to improve field testing and monitoring of drinking water sources, and to develop new
treatments for chronic As toxicity and new sources of safe drinking water. 相似文献
158.
The present study was undertaken to evaluate biochemical markers of chronic carbofuran exposure to rats in terms of lipid peroxide and intrasynaptosomal calcium levels and to correlate them with the histopathological changes in brain regions. A significant increase in lipid peroxidation (LPO) in terms of thiobarbituric acid reactive substances (TBARS) was observed in the cerebral cortex (65%) and brain stem (33%) after carbofuran exposure. This was accompanied by a significant increase (87%) in the intracellular free-Ca2+ [Ca2+]i levels. N-acetylcysteine (NAC) administration, on the other hand, reversed the carbofuran-induced increase in LPO and [Ca2+]i. Histopathological studies of carbofuran-exposed brain revealed high frequency of pyknotic neurons in the cerebral cortex and microhaemorrhages in the brain stem. NAC supplementation to carbofuran-treated animals resulted in normalisation of the brain architecture as seen by a reduction in the number of pyknotic nuclei in the cerebral cortex. These findings indicate that increased LPO and elevated [Ca2+]i levels are involved in the development of carbofuran neurotoxicity and are eventually responsible for the pathological alterations. The study also demonstrates potential neuroprotective effect of NAC treatment in carbofuran neurotoxicity. 相似文献
159.
Ravi Babu Kalahasthi Rajmohan Hirehal Raghavendra Rao Rajan Bagalur Krishna Murthy M. Karuna Kumar 《毒物与环境化学》2013,95(2):393-400
The objective of this study was to determine the effect of nickel (Ni) exposure on serum amylase activity in nickel-plating workers in Bangalore (India). Sixty-nine subjects using Ni during the electroplating process formed the exposed group. An equal number of age- and sex-matched subjects working in the administration section formed the control group. Urine Ni levels were determined using a flameless atomic absorption spectrophotometer. Serum amylase activity was determined using spectrophotometric method with 2-chloro-4-nitrophenyl-α-D-maltotrioside as substrate. A significant increase in urine Ni and serum amylase activity was noted in nickel platers as compared with the control group. The level of serum amylase activity was positively and significantly associated with Ni content in urine of nickel platers. Stepwise multiple regression analysis was used to assess the effects of Ni exposure, life style confounding factors and presence of gastrointestinal problems on serum amylase activity. The analysis showed that the subjects who had urine Ni levels beyond 10?µg?g?1 of creatinine, nickel platers category, smoking and body mass index variables were significantly associated with serum amylase activity. The results of this study suggest that the increased serum amylase activity observed in nickel-exposed subjects could be used as a biomarker for investigating pancreatic function in Ni exposure. 相似文献
160.
The present study was carried out to observe the possible beneficial effects of Vitamin E, a natural antioxidant on methomyl-induced biochemical and histological alterations in rat liver. To carry out the investigations, animals were segregated in four different groups. Animals in Group I served as normal controls. Animals in Group II were given single methomyl dose orally in water (9 mg kg?1 b.wt). Animals in Group III were injected intraperitoneally with Vitamin E (50 mg kg?1 b.wt) for 1 week on alternate days. Animals in Group IV were administered Vitamin E 1 week before subjecting them to methomyl treatment. Animals in all the groups were sacrificed 24 h after the end of treatments. Different biochemical estimations were carried out, which included estimation of aspartate aminotransaminase (AST), alanine aminotransaminase (ALT), alkaline phosphatase (ALP) and acetylcholinesterase (AChE). Further, to examine the oxidative damage lipid peroxidation (LPO) and glutathione (GSH) levels as well as antioxidant enzymes such as superoxide dismutase (SOD), catalase, glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GSHPx), and glutathione-6-phosphate dehydrogenase were estimated in liver samples. AchE activity was inhibited significantly both in serum and liver following methomyl treatment. Administration of methomyl caused a significant increase in serum AST, ALT and ALP which indicated hepatic damage. LPO was found to be significantly increased, whereas GSH levels were decreased in the liver of methomyl-treated animals. The activities of SOD and catalase were significantly decreased whereas GST and GSHPx activities were found to be elevated significantly following methomyl treatment. No significant change in the enzyme activity of GR and glutathione-6-phosphatase dehydrogenase was observed after methomyl treatment. Vitamin E supplementation was able to attenuate appreciably the methomyl-induced changes in LPO levels along with SOD and GST activities. Histopathological studies following methomyl treatment revealed that hepatocytes, were not very well delineated and nuclei showed degenerative changes. Whereas, following Vitamin E supplementation in combined treatment group nuclei showing degenerative changes become less in number. The study, therefore, concludes that Vitamin E has a potential in mitigating most of the adverse effects induced by methomyl acute toxicity. 相似文献