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81.
Soil is the major environmental reservoir of organic compounds and soil-air exchange is a key process in governing the environmental fate of these compounds on a regional and global scale. Samples of air and soil were collected to study the levels of PAHs in the air and soil of the Agra region. Concentrations of PAH measured at four locations in the city of Agra, covers industrial, residential, roadside and agricultural areas. Samples were extracted with hexane by ultrasonic agitation. Extracts were then fractioned on a silica-gel column and the aromatic fraction was analysed by GC-MS. The mean concentration of the total PAH (T-PAH) in the air of Agra was 24.95, 17.95 and 14.25 ng m(-3), during winter, monsoon and summer respectively. The average concentration of T-PAH in the soil of Agra was 12.50, 8.25 and 6.44 μg g(-1) in winter, monsoon and summer seasons respectively. The aim of this study was to investigate the rate of approach to equilibrium partitioning of PAHs between air and soil compartments and to determine the direction of net flux of the studied PAH between air and soil. Calculated soil-air fugacity quotients indicate that the soil may now be a source of some lighter weight PAHs to the atmosphere, whereas it appears to be still acting as a long-term sink for the heavier weight PAHs to some extent in this region. 相似文献
82.
Matlou Daniel Pheeha Bissong Marie Ebob AgborTabot Tchatchouang Christ-Donald Kaptchouang Adem Mohomud Rashid Foka Frank Eric Tatsing Kumar Ajay Ateba Collins Njie 《Environmental science and pollution research international》2019,26(15):15105-15114
Environmental Science and Pollution Research - Vancomycin-resistant enterococci (VRE) have been responsible for numerous outbreaks of serious infections in humans worldwide. Enterococcus faecium... 相似文献
83.
Ratshiedana Rudzani Kuvarega Alex Tawanda Mishra Ajay Kumar 《Environmental science and pollution research international》2021,28(9):10357-10374
Environmental Science and Pollution Research - The paper reviews graphitic carbon nitride–based nanostructured photocatalytic materials and nanofibres for applications in water purification.... 相似文献
84.
In the present study total 21 forest stands on different aspects and locations (Hill base, mid slope and ridge top) on the
slope were studied to assess the importance of these two parameters in supporting species regeneration and biodiversity in
a mixed broadleaved forest between 380 and 850 m elevation in the Kumauau Himalayan region. A total of 36 tree species were
recorded in the forest. In all aspects the tree, sapling and shrub richness was higher at hill base stands in comparison to
mid slope and ridge top stand. Maximum tree richness (average across all aspects) was 9.7 and shrub richness was 9.3. Higher
richness at hill base may be attributed to more soil moisture and deeper soils which accumulate the hill base where the slope
steepness declines. The tree richness was higher in the northern aspect whereas southern aspect was more suitable for the
shrub species. From the present study it becomes evident that the base of the hills can support higher biodiversity and are
instrumental in supporting regeneration of several tree and shrub species in sal mixed broadleaved forest. 相似文献
85.
Ashok Kumar Ravindranath Madasu Ajay Manocha 《Environmental monitoring and assessment》1996,42(3):211-228
This paper presents the risk associated with the release of toxic chemicals from a manufacturing facility, following the State of California's approach to risk assessment. The facility emits five toxic substances from eight stacks. The building downwash is considered during dispersion calculations. The zone of impact, identified using a risk criteria (i.e. excess cancer risk of 10 in a million), is located in the southeast quandrant from the plant. The size of the impact area is 3.3 km2. The cancer and non-cancer effects are considered for chromium (VI), benzene, formaldehyde, gasoline vapors, methylene chloride, and selenium using the California Air Pollution Control Officers Association Guidelines. No significant non-cancer effects are found due to the emissions. The maximum calculated risk is 1.197×10-5 and is an extremely conservative value. Analysis shows that the use of realistic assumptions for exposure duration and unit risk factors during the risk calculations could reduce the zone of impact to 0 km2. 相似文献
86.
The diethyl ether, chloroform, acetone and methanol extract of Nerium indicum leaf were evaluated for their piscicidal activity against common freshwater air breathing predatory fish Channa punctatus. The rank of order of toxicity (LC50) of the leaf extract was, diethyl ether extract (17.34 mg/l)>acetone (40.01 mg/l)>chloroform (40.61 mg/l)>and methanol (106.37 mg/l). There was a significant negative correlation between LC50 values and exposure periods. Thus increase in exposure period, LC50 decreases from 17.34 mg/l (24 h) to >13.58 mg/l (96 h) in the diethyl ether extract. Similar trends were also observed in acetone, chloroform and methanol extracts. Exposure of sub-lethal doses (40% and 80% of LC50) of the diethyl ether extract of N. indicum leaf (which has maximum piscicidal activity) for 24 or 96 h caused significant alteration in the level of total protein, total free amino acid, nucleic acid, glycogen, pyruvate, lactate and activity of enzyme protease, phosphatases, alanine aminotransferase, aspartate aminotransferase and acetylcholinesterase in liver and muscle tissue. The alterations in all the above biochemical parameters were significantly (P<0.05) time and dose dependent. There was a significant recovery in all the above biochemical parameters, in both liver and muscle tissues of fish after the seventh day of the withdrawal of treatment. Thus, the leaf extracts of N. indicum have potent piscicidal activity against fish C. punctatus and also significantly affect both aerobic and anaerobic pathway of respiration in fish. 相似文献
87.
88.
Poorti?Varshney Renuka?Saini Ajay?TanejaEmail author 《Environmental geochemistry and health》2016,38(2):593-605
Exposure to airborne particulate matter results in the deposition of millions of particle in the lung; consequently, there is need for monitoring them particularly in indoor environments. Case study was conducted in three different microenvironments, i.e., urban, rural and roadside to examine the elemental bioavailability in fine particulate matter and its potential health risk. The samples were collected on polytetrafluoroethylene filter paper with the help of fine particulate sampler during August–September, 2012. The average mass concentration of PM2.5 was 71.23 µg m?3 (rural), 45.33 µg m?3 (urban) and 36.71 µg m?3 (roadside). Elements in PM2.5 were analyzed by inductively coupled plasma atomic emission spectroscopy. Percentage bioavailability was determined to know the amount of soluble fraction that is actually taken across the cell membrane through inhalation pathway. Cadmium and lead were found to have cancer risk in a risk evaluation using an Integrated Risk Information system. 相似文献
89.
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
90.
Iron in its familiar form exists in the +2 and +3 oxidation states, however, higher oxidation state of iron +6, ferrate(VI) (Fe(VI)O(4)(2-)) can be obtained. The high oxidation power of ferrate(VI) can be utilized in developing cleaner ("greener") technology for remediation processes. This paper demonstrates the unique property of ferrate(VI) to degrade almost completely the cationic surfactant, cetylpyridinium chloride (C(5)H(5)N(+)(CH(2))(15)CH(3).H(2)O Cl(-), CPC). The Rate law for the oxidation of CPC by ferrate(VI) at pH 9.2 was found to be: -d[Fe(VI)]/dt = k[Fe(VI)][CPC](2). Ferrate(VI) oxidizes CPC within minutes and molar consumption of ferrate(VI) was nearly equal to the oxidized CPC. The decrease in total organic carbon (TOC) from CPC was more than 95%; suggesting mineralization of CPC to carbon dioxide. Ammonium ion was the other product of the oxidation. This is the first report in which Fe(VI)O(4)(2-) ion opens the pyridine ring and mineralizes the aliphatic chain of the organic molecule giving inorganic ions. 相似文献