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81.
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
82.
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
83.
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
84.
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
85.
This study aimed to evaluate the reparative potential of ascorbic acid (AA, 100 mg/kg, orally for 28 days) in sub-acute lead (Pb, 100 ppm in drinking water for 28 days) or cypermethrin (CPM, 50 mg/kg, orally in vehicle for 28 days) poisoning alone and as binary mixture on the basis of oxidative stress parameters in erythrocytes of Wistar rats. Both Pb and CPM produced significant increase in lipid peroxidation along with elevated glutathione-S-transferase and catalase activity individually but not as a binary mixture. Glutathione peroxidase activity was significantly increased but glutathione levels were significantly reduced irrespective of single or co-exposure while the activity of superoxide dismutase and erythrocytic protein content were not significantly affected. Co-exposure led to a comparatively lower level of oxidative stress than that induced by Pb or CPM alone indicating an antagonistic toxicodynamic profile in rat erythrocytes. Co-administration of AA along with Pb and/or CPM significantly restored the oxidative stress parameters to normal values. Overall results indicated that co-exposure induces a lower level of oxidative stress and AA ameliorates Pb- and/or CPM-induced oxidative damage in rat erythrocytes. 相似文献
86.
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
87.
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
88.
Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor 总被引:4,自引:0,他引:4
In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading. 相似文献
89.
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
90.
Raj Singhvi Ajay Taneja Jay Patel Charles Gasser Dennis J. Kalnicky 《Environmental Forensics》2014,15(1):17-24
The United States Environmental Protection Agency/Environmental Response Team (US EPA/ERT), in collaboration with St. John's College, Dr. B. R. Ambedkar University, Agra, India, is conducting a study to determine Hg vapor emission rates resulting from broken compact fluorescent lamps (CFLs) in a residential setting. The overall objectives of the study are to determine Hg vapor emission data and provide homeowners with cleanup procedures and disposal options for broken CFLs. Most of the currently available CFLs in the US market are manufactured in China for US companies. Several different types of CFLs were purchased from local stores and their Hg content was determined. Based on previous studies, such as the 2011 study by Singhvi and colleagues, five popular spiral CFLs were selected for emission studies in an acrylic chamber. This study found that Hg vapor emissions from CFLs may be significantly greater than those from beads of liquid Hg with weights comparable to the Hg content of the CFLs. The average 24-hour Hg loss into the atmosphere from CFLs broken on a plastic surface ranged from 0.6% to 22% of the bulb content, while that for CFLs broken on carpet ranged from 2.6% to 28%. Projections for a 12 foot × 9.33 foot × 8 foot (25.4 m3) room based on the chamber measurements in this study indicate that CFL breakage in some household settings may produce 24-hour Hg concentrations above the 2000 Agency for Toxic Substances and Disease Registry (ATSDR) minimum risk level (MRL) of 0.2 μg/m3, for typical air exchange rates. This study also indicates that Hg emission may not be proportional to exposed surface area based on experiments using liquid Hg with different surface areas. 相似文献