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371.
Emission from field burning of agricultural crop residue is a common environmental hazard observed in northern India. It has a significant potential health risk for the rural population due to respirable suspended particulate matter (RSPM). A study on eight stage size segregated mass distribution of RSPM was done for 2 wheat and 3 rice crop seasons. The study was undertaken at rural and agricultural sites of Patiala (India) where the RSPM levels remained close to the National Ambient Air quality standards (NAAQS). Fine particulate matter (PM(2.5)) contributed almost 55% to 64% of the RSPM, showing that, in general, the smaller particles dominated during the whole study period with more contribution during the rice crop as compared to that of wheat crop residue burning. Fine particulate matter content in the total RSPM increased with decrease in temperature. Concentration levels of PM(10) and PM(2.5) were higher during the winter months as compared to that in the summer months. Background concentration levels of PM(10), PM(2.5) and PM(10-2.5) were found to be around 97 ± 21, 57 ± 15 and 40 ± 6 μg m(-3), respectively. The levels increased up to 66, 78 and 71% during rice season and 51, 43 and 61% during wheat crop residue burning, respectively. Extensive statistical analysis of the data was done by using pair t-test. Overall results show that the concentration levels of different size particulate matter are greatly affected by agricultural crop residue burning but the total distribution of the particulate matter remains almost constant.  相似文献   
372.
Elderly women of a particular socioecological system are considered to be “living encyclopedias” in biocultural knowledge systems. These women play a pivotal role in retaining and passing on biodiversity-related traditional knowledge to the next generations. Unfortunately the fast changing sociocultural values and the impact of modernity have rendered their knowledge somewhat less valuable and they are being treated as “cultural refugia.” Our study on the importance of these women in the conservation of indigenous biodiversity was conducted in 14 randomly selected villages dominated by the Adi tribe of East Siang District, Arunachal Pradesh (northeast India). Data were collected from 531 women (381 elderly and 150 young to middle aged) during 2003–2008 using conventional social science methods and participatory rural appraisal. One innovative method, namely “recipe contest,” was devised to mobilize Adi women of each village in order to energies them and explore their knowledge relating to traditional foods, ethnomedicines, and conservation of indigenous biodiversity. Results indicated that 55 plant species are being used by elderly Adi women in their food systems, while 34 plant species are integral parts of ethnomedicinal practices. These women identified different plant species found under multistory canopies of community forests. Elderly women were particularly skilled in preparing traditional foods including beverages and held significantly greater knowledge of indigenous plants than younger women. Lifelong experiences and cultural diversity were found to influence the significance of biodiversity use and conservation. The conservation of biodiversity occurs in three different habitats: jhum lands (shifting cultivation), Morang forest (community managed forests), and home gardens. The knowledge and practice of elderly women about habitats and multistory vegetations, regenerative techniques, selective harvesting, and cultivation practices contribute significantly to food and livelihood security while sustaining an array of threatened plant species. Basically, knowledge of elderly women on using biodiversity in food and medicinal systems was found in three categories namely: “individual,” “community,” and “refined.” We identified a need to develop holistic policies to recognize and integrate knowledge and practices of elderly women with local level of planning on sustainable conservation of biodiversity as well as community-based adaptations.  相似文献   
373.
The increasing availability of multi‐scale remotely sensed data and global weather datasets is allowing the estimation of evapotranspiration (ET) at multiple scales. We present a simple but robust method that uses remotely sensed thermal data and model‐assimilated weather fields to produce ET for the contiguous United States (CONUS) at monthly and seasonal time scales. The method is based on the Simplified Surface Energy Balance (SSEB) model, which is now parameterized for operational applications, renamed as SSEBop. The innovative aspect of the SSEBop is that it uses predefined boundary conditions that are unique to each pixel for the “hot” and “cold” reference conditions. The SSEBop model was used for computing ET for 12 years (2000‐2011) using the MODIS and Global Data Assimilation System (GDAS) data streams. SSEBop ET results compared reasonably well with monthly eddy covariance ET data explaining 64% of the observed variability across diverse ecosystems in the CONUS during 2005. Twelve annual ET anomalies (2000‐2011) depicted the spatial extent and severity of the commonly known drought years in the CONUS. More research is required to improve the representation of the predefined boundary conditions in complex terrain at small spatial scales. SSEBop model was found to be a promising approach to conduct water use studies in the CONUS, with a similar opportunity in other parts of the world. The approach can also be applied with other thermal sensors such as Landsat.  相似文献   
374.
Various neural networks models are developed and applied for flood forecasting at Sangye station (no. 1) of the Bocheong Stream catchment, which is one of the International Hydrological Program's representative catchments, Republic of Korea. The neural networks models (NNMs) are multilayer perceptron‐neural networks model (MLP‐NNM), generalized regression neural networks model (GRNNM), and Kohonen self‐organizing feature maps neural networks model (KSOFM‐NNM). Data used for model training and testing are divided into two groups: such as floods and typhoon events. Single conventional application and class segregation implementation are applied to evaluate the neural networks models. KSOFM‐NNM forecasts flood discharge more accurately than do MLP‐NNM and GRNNM for the testing data of Methods I and II for single conventional application and class segregation implementation. This study shows that class segregation can capture the dynamics of different physical processes and overcome the difficulties using single conventional application of neural networks models.  相似文献   
375.
Singh J  Singh DK 《Chemosphere》2005,60(1):32-42
Impacts of diazinon, imidacloprid and lindane treatments on dehydrogenase and alkaline phosphomonoesterase enzyme activities were determined in groundnut (Arachis hypogaea L.) field for three consecutive years (1997-1999). Diazinon was applied as both seed and soil treatments but imidacloprid and lindane were used for seed treatments only at recommended rates. Experiments were conducted at Agricultural Research Station Durgapura, Jaipur, Rajasthan, India. Diazinon residues were persist up till 60 days in both the cases. Average half-lives (t(1/2)) of diazinon were found 29.3 and 34.8 days, respectively, for seed and soil treatments. Diazinon seed treatment had no significant effect on dehydrogenase and alkaline phosphomonoesterase enzymes activities. In diazinon soil treatment, there were a significant increase in dehydrogenase and decrease in alkaline phosphomonoesterase activities after 24 h of treatment, which continued till 30 days. In seed treatments, imidacloprid and lindane were present in soil up to 90 and 120 days with average half-lives (t(1/2)) of 40.9 and 53.3 days, respectively. Within 90 days, imidacloprid residues were declined up to 73.17% to 82.49% while decline in lindane residues ranged from 78.19% to 79.86% within 120 days. In imidacloprid seed treated field, both dehydrogenase and phosphomonoesterase activities were increased between 15 and 60 days after sowing. However, a significant decreases in both dehydrogenase and phosphomonoesterase enzyme activities were observed between 15 and 90 days after lindane seed treatment.  相似文献   
376.
Desorption of cadmium from goethite: effects of pH, temperature and aging   总被引:1,自引:0,他引:1  
Mustafa G  Kookana RS  Singh B 《Chemosphere》2006,64(5):856-865
Cadmium is perhaps environmentally the most significant heavy metal in soils. Bioavailability, remobilization and fate of Cd entering in soils are usually controlled by adsorption-desorption reactions on Fe oxides. Adsorption of Cd on soil colloids including Fe oxides has been extensively studied but Cd desorption from such soil minerals has received relatively little attention. Some factors that affect Cd adsorption on goethite include pH, temperature, aging, type of index cations, Cd concentrations, solution ionic strength and presence of organic and inorganic ions. This research was conducted to study the influence of pH, temperature and aging on Cd desorption from goethite. Batch experiments were conducted to evaluate Cd desorption from goethite with 0.01 M Ca(NO3)2. In these experiments Cd desorption was observed at 20, 40 and 70 degrees C in combination with aging for 16 h, 30, 90 and 180 d from goethite that adsorbed Cd from solutions containing initial Cd concentrations of 20, 80 and 180 microM. Following the adsorption step Cd desorption was measured by 15 successive desorptions after aging at various temperatures. At the lowest amount of initially adsorbed Cd and equilibrium pH 5.5, cumulative Cd desorption decreased from 71% to 17% with aging from 16 h to 180 d and the corresponding decrease at equilibrium pH 6.0 was from 32% to 3%. There was a substantial decrease in Cd desorption with increasing equilibration temperature. For example, in goethite with the lowest amount of initial adsorption at equilibrium pH 5.5, cumulative Cd desorption decreased from 71% to 31% with increase in temperature from 20 to 70 degrees C, even after 16 h. Dissolution of Cd adsorbed goethite in 1M HCl, after 15 successive desorptions with 0.01 M Ca(NO3)2, indicated that approximately 60% of the Cd was surface adsorbed. Overall, dissolution kinetics data revealed that 23% to 88% Cd could not be desorbed, which could possibly be diffused into the cracks and got entrapped in goethite crystals. At elevated temperature increased equilibrium solution pH favoured the formation of CaCO3 and CdCO3 which reasonably decreased Cd desorption. Cadmium speciation showed the formation of calcite and otavite minerals at 40 and 70 degrees C due to increase in pH (>9.5) during aging. X-ray diffraction analysis (XRD) of these samples also revealed the formation of CaCO3 at elevated temperatures with aging. While mechanisms such as Cd diffusion and/or entrapment into fissures and cracks in goethite structure with increase in temperature and aging are possible.  相似文献   
377.
Singh KP  Mohan D  Sinha S  Dalwani R 《Chemosphere》2004,55(2):227-255
Studies were undertaken to assess the impact of wastewater/sludge disposal (metals and pesticides) from sewage treatment plants (STPs) in Jajmau, Kanpur (5 MLD) and Dinapur, Varanasi (80 MLD), on health, agriculture and environmental quality in the receiving/application areas around Kanpur and Varanasi in Uttar Pradesh, India. The raw, treated and mixed treated urban wastewater samples were collected from the inlet and outlet points of the plants during peak (morning and evening) and non-peak (noon) hours. The impact of the treated wastewater toxicants (metals and pesticides) on the environmental quality of the disposal area was assessed in terms of their levels in different media samples viz., water, soil, crops, vegetation, and food grains. The data generated show elevated levels of metals and pesticides in all the environmental media, suggesting a definite adverse impact on the environmental quality of the disposal area. The critical levels of the heavy metals in the soil for agricultural crops are found to be much higher than those observed in the study areas receiving no effluents. The sludge from the STPs has both positive and negative impacts on agriculture as it is loaded with high levels of toxic heavy metals and pesticides, but also enriched with several useful ingredients such as N, P, and K providing fertilizer values. The sludge studied had cadmium, chromium and nickel levels above tolerable levels as prescribed for agricultural and lands application. Bio-monitoring of the metals and pesticides levels in the human blood and urine of the different population groups under study areas was undertaken. All the different approaches indicated a considerable risk and impact of heavy metals and pesticides on human health in the exposed areas receiving the wastewater from the STPs.  相似文献   
378.
In atmospheric aerosol studies, it is often required to use two different impactors, namely, the normal pressure and the low-pressure impactor, to measure the mass-size distribution over a wide size range. From the perspective of rendering the system compact for such measurements, it may be more advantageous to combine the two features in a single instrument. In an effort towards exploring this option, a variable configuration cascade impactor (VCCI) comprising of 7 normal pressure and 4 low-pressure stages has been designed and developed. In configuration-1, it operates as a low-pressure impactor, with a sampling flow rate of 10 L min?1 and classifies the particles from 0.1 to 21 μm in eleven size classes. In configuration-2, it operates as a normal pressure impactor, with a sampling flow rate of 45 L min?1, and classifies the particles from 0.53 to 10 μm in seven size classes. As part of performance evaluation of the system, the deposit patterns and the integral performance have been studied. For integral performance, a comparative mass-size distribution measurement between VCCI and standard Andersen impactor was carried out. Its performance was also evaluated against the GRIMM Scanning Mobility Particle Sizer (SMPS) in the common size range of both these instruments and against GRIMM Optical Particle Counter (OPC). In addition to this, VCCI was evaluated for its performance in the PMx configuration obtained by removing a few of the impactor stages sequentially and measuring corresponding size distribution for every stage removed. Changes in the distribution parameters due to spillover of the deposits of previous stage to remaining stages were within 10%. This variation is well within the generally accepted value for all environmental measurement related applications.  相似文献   
379.
The animal, agro-wastes and water hyacinth (Eichhornia crassipes) are a serious problem for the society and ecosystem. The present study carried out the management of water hyacinth and observation of nutritional status like pH, electrical conductivity (EC), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), C/N ratio, total phosphorus and total calcium (TCa) of liquid bio-fertilizer (vermiwash) before and after vermicomposting of feed materials of different combinations of buffalo dung (BD) with water hyacinth (WH) and gram bran (GB). After vermicomposting of different combinations of BD with WH and agro-wastes, significant decrease in level of pH, EC, TOC and C/N ratio was observed, whereas significant increase in TKN, TK, TAP and TCa level in vermiwash of final vermicompost with respect to initial feed material was observed. The pH of initial mixture in all combinations has tended to basic in nature, while in final vermicompost, it becomes neutral/basic. The significant increase was observed in the level of TKN, TK, TAP in BD + GB + WH (1:2:1) and TCa in BD + GB + WH (1:1:2) vermiwash of final vermicompost of combination, whereas decrease was observed in TOC, C/N ratio, pH and EC in BD + WH (1:1), BD + GB + WH (1:1:1), BD + GB + WH (1:2:1) and BD + GB (1:1), respectively.  相似文献   
380.
Present study was carried out to determine pollinators’ diversity and their efficiency with modular approach; foraging behaviour, number of loose pollen adhered on their body and number of pollen deposited on the stigma. The observations explicitly indicate that Megachile spp., Xylocopa tenuiscopa, Amegilla zonata and Nomia sp. were true pollinators and out of these, Megachile spp. were key pollinators of pigeonpea. Among megachilids, Megachile lanata was the most efficient pollinator. Sufficient pollination meticulously accomplished in pigeonpea by true pollinators under this agro-ecological region.  相似文献   
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