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排序方式: 共有461条查询结果,搜索用时 15 毫秒
381.
The paper describes the results of a laboratory study on the effects of macropore tortuosity on breakthrough curves BTCs and solute distribution in a Forman loam (fine loamy-mixed Udic Haploborolls) soil. BTC were obtained using 2-D columns (slab) containing artificial macropores of five different tortuosity levels. The BTCs were run under a constant hydraulic head of 0.08 m over an initially air dry soil. The input solutions contained 1190 mg l−1 of potassium bromide, 10 mg l−1 of Rhodamine WT, and 100 mg l−1 of FD&C Blue #1. A soil column without macropores served as a control. The displacement of a non-adsorbed tracer was not affected by the tortuosity level. An increase in macropore tortuosity progressively increased the breakthrough time, increased the apparent retardation coefficient (R′), decreased the depth to the center of mass of a given adsorbed tracer, and increased the anisotropy in tracer distribution profile. The relative importance of macropore tortuosity increased with an increase in the adsorption coefficient of the tracer. Compared to macropore continuity, the macropore tortuosity had greater impact on solute distribution profile than in its leaching. 相似文献
382.
Andrew C. Kessler Satish C. Gupta 《Journal of the American Water Resources Association》2015,51(4):1101-1113
Wetland restoration has been proposed as a tool to mitigate excess runoff and associated nonpoint source pollution in the Upper Midwestern United States. This study quantified the surficial water retention capacity of existing and drained wetlands for the Greater Blue Earth River Basin (GBERB), an intensively drained agricultural watershed. Using airborne light detection and ranging, the historic depressional storage was determined to be 152 mm. Individual depression analysis suggested that the restoration of most drained areas would have little impact on the storage capacity of the GBERB because the majority (53%) of retention capacity was in large depressions (>40 ha) which comprised only a small proportion (<1.0) of the observed depressions. Accounting for change in storage and the difference in annual evapotranspiration (ET) between wetlands and the croplands that replaced them, restoration of all depressions in the Minnesota portion of GBERB would provide a maximum of 131 mm additional capacity over and above the modern day capacity (193 mm; 56 mm depressional storage; 60 mm wetland ET; and 77 mm cropland ET). Considering that depressional depths in smaller areas are within the range of uncertainty of the lidar digital elevation models and larger depressions have the most storage, we conclude that efforts to increase the surficial water‐holding capacity of the GBERB would be best served in the restoration of large (>40 ha) depressions. 相似文献
383.
A. Dewan S.K. Gupta J.P. Jani S.K. Kashyap 《Journal of environmental science and health. Part. B》2013,48(4):395-402
Abstract The immunosuppressive effect of lindane was assessed in weanling rats over a period of 5 weeks. Agglutinin titres against S. typhi ‘O’ and ‘H’, S. paratyphi ‘AH’ and ‘BR’ antigens were determined following TAB vaccination in control and lindane‐fed animals. The titres attained in non‐treated controls were higher significantly than those in treated animals indicating a suppressive effect of lindane on humoral immune responses. 相似文献
384.
Michel Mench Jean-Paul Schwitzguébel Peter Schroeder Valérie Bert Stanislaw Gawronski Satish Gupta 《Environmental science and pollution research international》2009,16(7):876-900
Purpose
The term “phytotechnologies” refers to the application of science and engineering to provide solutions involving plants, including phytoremediation options using plants and associated microbes to remediate environmental compartments contaminated by trace elements (TE) and organic xenobiotics (OX). An extended knowledge of the uptake, translocation, storage, and detoxification mechanisms in plants, of the interactions with microorganisms, and of the use of “omic” technologies (functional genomics, proteomics, and metabolomics), combined with genetic analysis and plant improvement, is essential to understand the fate of contaminants in plants and food, nonfood and technical crops. The integration of physicochemical and biological understanding allows the optimization of these properties of plants, making phytotechnologies more economically and socially attractive, decreasing the level and transfer of contaminants along the food chain and augmenting the content of essential minerals in food crops. This review will disseminate experience gained between 2004 and 2009 by three working groups of COST Action 859 on the uptake, detoxification, and sequestration of pollutants by plants and consequences for food safety. Gaps between scientific approaches and lack of understanding are examined to suggest further research and to clarify the current state-of-the-art for potential end-users of such green options. 相似文献385.
Nirankar Singh Ravinder Agarwal Amit Awasthi Prabhat K. Gupta Susheel K. Mittal 《Atmospheric environment (Oxford, England : 1994)》2010,44(10):1292-1300
Aerosol (total suspended particulate) samples collected at three diverse locations (urban-commercial, semi-urban and rural-agricultural) in Patiala, India were analyzed for loss on ignition (LOI) and organic tarry matter (OTM) content in ambient air during crop residue burning (CRB) episodes and non-crop residue burning (NCRB) months in 2006–2007. Results showed high levels of LOI and OTM during wheat and rice crop residue-burning periods at all the sites. Higher levels were obtained during rice crop residue-burning period as compared to the wheat residue-burning period. At semi-urban site, LOI varied between 53 ± 36 μg m?3 and 257 ± 14 μg m?3 constituting 38–78% (w/w) part of the aerosols whereas levels of OTM varied between 0.98 ± 0.11 μg m?3 and 7.93 ± 2.76 μg m?3 comprising 0.42–3.28% (w/w) fraction. At rural-agricultural area site, levels of LOI varied between 86 ± 40 μg m?3 and 293 ± 70 μg m?3 comprising 27–84% (w/w), whereas OTM levels varied between 1.31 ± 0.64 μg m?3 and 10.09 ± 6.56 μg m?3 constituting 0.83–2.42% (w/w) fraction of the aerosols. At urban-cum-commercial site, levels of LOI and OTM varied between 48 ± 23 μg m?3 and 281 ± 152 μg m?3 and 2.53 ± 1.23 μg m?3 and 17.40 ± 8.50 μg m?3, constituting 24–62% (w/w) part of the aerosols, respectively. Results also indicated that OTM and LOI were integral parts of aerosols and their concentrations were influenced by the crop residue burning practices with incorporated effect of vehicular activities in Patiala. 相似文献
386.
387.
Gupta DK Tripathi RD Rai UN Mishra S Srivastava S Dwivedi S Maathuis FJ 《Environmental monitoring and assessment》2007,134(1-3):479-487
Growth and metal accumulation were investigated in two Cicer arietinum L. varieties (var. CSG-8962 and var. C-235) when grown in various combinations of fly ash (FA) amended with garden soil (GS),
press mud (PM) or saw dust (SD). In addition, the levels of photosynthetic pigments, nitrate reductase (NR) activity, cysteine,
non-protein thiols (NP-SH), and ascorbic acid were studied. FA amended with GS or PM led to a 5–10 times increase in biomass
compared to FA control and was most pronounced in the less metal tolerant variety CSG-8962. Amendment of FA with either GS
or PM only moderately increased the contents of some essential metals whereas the non-essential Cd and Cr remained similar
or decreased slightly compared to FA control. FA combined with either GS or PM increased the amount of photosynthetic pigments
and was largely absent when SD was added to FA. Improved nitrogen availability led to increased nitrate reductase (NR) activity
with all amendments but less so with SD. Metal stress indicating parameters were generally reduced (cysteine and non-protein
thiols) or unchanged (ascorbic acid). In conclusion, of the tested ameliorants both GS and PM greatly improved growth of C. arietinum making FA a suitable component of plant growth substrates. 相似文献
388.
Ritesh Vijay Veena K. Sardar Shivani S. Dhage Prakash S. Kelkar Apurba Gupta 《Environmental monitoring and assessment》2010,165(1-4):559-571
The rapid population growth and uncontrolled development in the coastal zone have led to major pollution impacts on creeks, estuarine, and coastal environment. Water quality models are valuable tools to understand the environmental processes for prediction of pollution impacts and evaluate future trends for management. Presently, the Malad creek in west coast of Mumbai receives wastewater and sewage from open drains and partially treated sewage from Malad and Versova treatment plants. The objective of the paper is to assess the environmental quality and estimate the extent of improvement in different parts of the creek by enhancing the collection efficiency and adequate treatment of sewage as well as disposal through ocean outfall. A hydrodynamic and water quality simulation has been carried out for the present condition in the creek and calibrated and validated with two different season data for better representation of the system. Calibrated model has been used to generate future scenarios based on various options. Among scenarios, option of treated effluent diverted to propose outfall and improvement in collection of unorganized flow through sewerage up to 40% and 60% are found most significant for biochemical oxygen demand reduction and increase in dissolved oxygen. Fecal coliform reduction is also found drastically but still very high against standard. To improve the environmental quality of the creek, still upper stretch requires more dilution and flushing due to narrow width and contribution of heavy pollution from open drains. 相似文献
389.
Plants of L. leucocephala were grown in 100%soil (as control), 100% fly-ash and fly-ash amendedwith 50% press mud for 80 days, and analysed withrespect to plant growth, elemental composition andphysiological changes in different parts of the plant.The results revealed that amending fly-ash with pressmud enhanced plant growth as well as otherphysiological responses such as chlorophyll, protein,in vivo nitrate reductase activity compared to100% fly-ash treated plants. The elements Fe, Zn, Cuand Mn accumulated in larger quantities in plantsgrown in 100% fly-ash, and followed the order ofaccumulation Fe > Zn > Cu > Mn. The results of thisstudy indicate that ash amending with press mud mayprovide more favourable conditions for the growth ofthis tree species. 相似文献
390.
P. Rama Chandra Prasad Nidhi Nagabhatla C. S. Reddy Stutee Gupta K. S. Rajan S. H. Raza C. B. S. Dutt 《Environmental monitoring and assessment》2010,160(1-4):541-553
The present study outlines an approach to classify forest density and to estimate canopy closure of the forest of the Andaman and Nicobar archipelago. The vector layers generated for the study area using satellite data was validated with the field knowledge of the surveyed ground control points. The methodology adopted in this present analysis is three-tiered. First, the density stratification into five zones using visual interpretation for the complete archipelago. In the second step, we identified two island groups from the Andaman to investigate and compare the forest strata density. The third and final step involved more of a localised phytosociological module that focused on the North Andaman Islands. The results based on the analysis of the high-resolution satellite data show that more than 75% of the mangroves are under high- to very high-density canopy class. The framework developed would serve as a significant measure to forest health and evaluate management concerns whilst addressing issues such as gap identification, conservation prioritisation and disaster management—principally to the post-tsunami assessment and analysis. 相似文献