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991.
The present study deals with the slope stability analysis and geotechnical assessment of a part of pilgrimage route to one of the holy shrines of India, i.e. Yamunotri. The route also embraces a proposed site for 204 m high concrete gravity dam across River Yamuna near Lakhwar village with the aim of generation of 300 MW power. Several slide zones were identified and based on the discontinuity orientation, structural features and debris materials, they are recognised as planar, wedge or circular failure types. The morphological dimensions, structural data, orientations and geotechnical parameters of circular failure slides within weathered quartzites, phyllites and shales were evaluated by extensive field work and by laboratory tests for their stability analysis. Internal mechanisms, cohesion and angle of internal friction that resist shear stress in slope materials, obtained from direct shear test are showing minor variation due to relatively consistent grain size distribution and mineralogical composition. General slope is about 40°–43° with sparse vegetation. Materials in and around slide zones are sands with appreciable amount of fines falling in SP–SM category as per Unified Soil Classification System (USCS), except Niste B slide which has clean sands lying in SP group. Factor of safety, computed by requisite parameters of strength, soil and slope properties in circular failure charts, varies from 1.02 to 1.23 in dry conditions while it reduces below unity with increasing saturation, representing stable conditions in dry conditions but with seepage and saturation along the cracks and discontinuities during rainfall make them unstable. Presence of steep slopes, proximity to stream channels and significant weathered and jointed area are causative factors in the route with rainfall and road widening as major triggers initiating the failure. 相似文献
992.
Assessing the bioaugmentation potentials of individual isolates from landfill on metal-polluted soil
S. H. Fauziah P. Agamuthu R. Hashim A. K. Izyani C. U. Emenike 《Environmental Earth Sciences》2017,76(11):401
Heavy metals from leachate are persistent pollutants in soil, especially when landfills lack liners and basic structural system that prevents overflow of leachate beyond restricted areas. It is not ideal to rely only on physical and chemical options for the reclamation/restoration of such contaminated soil. Therefore, it is imperative to adopt bioremediation through the enhancement of microbial potentials. The present study investigated the use of individual isolates for the remediation of soil contaminated by leachate-metals. This is a way to understand the discrete potentials of the gram-positive bacteria species. Environmental isolates taken from contaminated soil were used to remedy soil characterized with various concentrations of metals (Al, Cd, Cr, Fe, Ni, Pb and Zn). Treatments A, B, and C amended with Bacillus sp., Lysinibacillus sp., and Rhodococcus sp., respectively, demonstrated better metal reduction potentials than the control experiment (Treatment D; zero microbial amendment) that depended solely on natural attenuation. With the exception of Ni, the degree of reduction of other metals was less than 50% for all treatments. This study suggests that such result reflects the potential ability of the microbes to metabolize selectively in the presence of metal pollution. However, it is difficult for the individual microbes to attain higher metal reduction efficiency (above 50%) except when blended in the appropriate formulation. 相似文献
993.
Vaibhav Garg S. P. Aggarwal Prasun K. Gupta Bhaskar R. Nikam Praveen K. Thakur S. K. Srivastav A. Senthil Kumar 《Environmental Earth Sciences》2017,76(18):635
The sustainability of water resources mainly depends on planning and management of land use; a small change in it may affect water yield largely, as both are linked through relevant hydrological processes, explicitly. However, human activities, especially a significant increase in population, in-migration and accelerated socio-economic activities, are constantly modifying the land use and land cover (LULC) pattern. The impact of such changes in LULC on the hydrological regime of a basin is of widespread concern and a great challenge to the water resource engineers. While studying these impacts, the issue that prevails is the selection of a hydrological model that may be able to accommodate spatial and temporal dynamics of the basin with higher accuracy. Therefore, in the present study, the capabilities of variable infiltration capacity hydrological model to hydrologically simulate the basin under varying LULC scenarios have been investigated. For the present analysis, the Pennar River Basin, Andhra Pradesh, which falls under a water scarce region in India, has been chosen. The water balance components such as runoff potential, evapotranspiration (ET) and baseflow of Pennar Basin have been simulated under different LULC scenarios to study the impact of change on hydrological regime of a basin. Majorly, increase in built-up (13.94% approx.) and decrease in deciduous forest cover (2.44%) are the significant changes observed in the basin during the last three decades. It was found that the impact of LULC change on hydrology is balancing out at basin scale (considering the entire basin, while routing the runoff at the basin outlet). Therefore, an analysis on spatial variation in each of the water balance components considered in the study was done at grid scale. It was observed that the impact of LULC is considerable spatially at grid level, and the maximum increase of 265 mm (1985–2005) and the decrease of 48 mm (1985–1995) in runoff generation at grid were estimated. On the contrary, ET component showed the maximum increase of 400 and decrease of 570 mm under different LULC change scenario. Similarly, in the base flow parameter, an increase of 70 mm and the decrease of 100 mm were observed. It was noticed that the upper basin is showing an increasing trend in almost all hydrological components as compared to the lower basin. Based on this basin scale study, it was concluded that change in the land cover alters the hydrology; however, it needs to be studied at finer spatial scale rather than the entire basin as a whole. The information like the spatial variation in hydrological components may be very useful for local authority and decision-makers to plan mitigation strategies accordingly. 相似文献
994.
N. N. Rabalais R. E. Turner B. K Sen Gupta D. F. Boesch P. Chapman M. C. Murrell 《Estuaries and Coasts》2007,30(5):753-772
We update and reevaluate the scientific information on the distribution, history, and causes of continental shelf hypoxia
that supports the 2001 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi
River/Gulf of Mexico Watershed Nutrient Task Force 2001), incorporating data, publications, and research results produced
since the 1999 integrated assessment. The metric of mid-summer hypoxic area on the LouisianaTexas shelf is an adequate and
suitable measure for continued efforts to reduce nutrients loads from the Mississippi River and hypoxia in the northern Gulf
of Mexico as outlined in the Action Plan. More frequent measurements of simple metrics (e.g., area and volume) from late spring
through late summer would ensure that the metric is representative of the system in any given year and useful in a public
discourse of conditions and causes. The long-term data on hypoxia, sources of nutrients, associated biological parameters,
and paleoindicators continue to verify and strengthen the relationship between the nitratenitrogen load of the Mississippi
River, the extent of hypoxia, and changes in the coastal ecosystem (eutrophication and worsening hypoxia). Multiple lines
of evidence, some of them representing independent data sources, are consistent with the big picture pattern of increased
eutrophication as a result of long-term nutrient increases that result in excess carbon production and accumulation and, ultimately,
bottom water hypoxia. The additional findings arising since 1999 strengthen the science supporting the Action Plan that focuses
on reducing nutrient loads, primarily nitrogen, through multiple actions to reduce the size of the hypoxic zone in the northern
Gulf of Mexico. 相似文献
995.
996.
Ben K. Greenfield Geoffrey S. Siemering Joy C. Andrews Michael Rajan Stephen P. Andrews David F. Spencer 《Estuaries and Coasts》2007,30(4):627-640
Management actions to control invasive aquatic species can have significant ecosystem-scale effects. We evaluated the water
chemistry and nutrient effects of mechanical shredding to control water hyacinth (Eichhornia crassipes) in an agricultural slough and a tidal wetland on the Sacramento-San Joaquin River Delta, California. Shredding was conducted
with two types of shredder boats in fall of 2003 and another boat in spring of 2004. Shredding measurably affected water quality,
but specific effects varied as a function of shredding site and season. Significant increases were observed for total Kjeldahl
nitrogen and total phosphorus for all experiments. Dissolved oxygen effects varied by site, decreasing after shredding at
the agricultural slough but increasing at the tidal wetland. The increase in dissolved oxygen likely resulted from tidal incursions
from the adjacent river. A year-long time series of dissolved oxygen data indicated a negative relationship between hyacinth
abundance and dissolved oxygen concentrations. Hyacinth contained similar tissue concentrations of mercury to underlying sediments,
suggesting that plant harvesting could aid mercury remediation efforts. Simple mass calculations indicated that Delta-wide
shredding operations could cause between 0.1% and 9.6% increases in the overall abundance of carbon, nitrogen, and phosphorus
in the Delta water column. Results suggest that local effects of management actions to control invasive aquatic plants will
vary widely as a function of site-specific hydrology, but that estuary-wide effects would be limited. 相似文献
997.
998.
M. Sundrarajan Ph.D. G. Vishnu M.Sc. K. Joseph M.Tech Ph.D. 《International Journal of Environmental Science and Technology》2007,4(2):263-270
Exhausted Reactive dye bath samples of Turquoise Blue, Olive Green and Navy Blue shades were collected from cotton knit wear dyeing units in Tirupur. Ozonation was conducted in a column reactor system fed with ozone at the rate of 0.16 g/min to assess its efficiency in reducing the color, chemical oxygen demand and total organic carbon. Complete decolorization of the effluent was achieved in 10 min contact time and ozone consumption of 153 mg/ L for Turquoise Blue, 128 for Olive Green and 143 for Navy Blue shades effluents respectively. The corresponding COD removal was 43%, 44% and 43% for the three shades while TOC removal efficiency was 45%, 45% and 40% respectively. The results from the reusability studies indicate that the dyeing quality was not affected by the reuse of decolorized dye bath for two successive cycles. It is concluded that ozonation is efficient in decolorization of exhausted dye bath effluents containing conventional reactive dyes. However, the corresponding removal of COD from the textile effluent was not significant. 相似文献
999.
Manfred Baer Nicolas Deichmann Jochen Braunmiller John Clinton Stephan Husen Donat Fäh Domenico Giardini Philipp Kästli Urs Kradolfer Stefan Wiemer 《Swiss Journal of Geoscience》2007,100(3):517-528
This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during
2006. During this period, 572 earthquakes and 91 quarry blasts were detected and located in the region under consideration.
Of these earthquakes, two occurred in conjunction with the construction of the new Gotthard railway tunnel and 165 were induced
artificially by the stimulation of a proposed geothermal reservoir beneath the city of Basel. With 20 events with M
L
≥ 2.5, five of which were artificially induced, the seismic activity in the year 2006 was far below the average over the
previous 31 years. Nevertheless, six events were felt by the public, most prominently the strongest of the induced Basel events
(M
L
3.4), which caused some non-structural building damage. Noteworthy are also the two earthquakes near Cortaillod (M
L
3.2), on the shore of Lake Neuchatel, and in Val Mora (M
L
3.5), between the Engadin and Val Müstair, as well as the 42 aftershocks of the M
L
4.9 Vallorcine earthquake, between Martigny and Chamonix, of September 2005.
Editorial handling: Stefan Bucher 相似文献
1000.
Organic carbon isotope composition was studied in the sedimentary cover of the southern Siberian Platform and its surrounding fold systems. The rocks experienced catagenesis, metamorphism, and metasomatism. The chloroform bitumoid (CB) has a stable carbon isotope composition within a wide range of postsedimentation transformations. The average values of δ13C in CB of the sedimentary cover are ?29.5‰. Metamorphism and, especially, ore metasomatism, at the Sukhoi Log deposit caused a 2‰ increase in the heavy carbon isotope concentration of CB as compared to that of the platform deposits. The narrow variations in carbon isotope composition of the bitumoid are defined by their derivation from lipids, whose components are almost insusceptible to changes in the PT conditions. Kerogen from platform deposits is more strongly depleted than CB in the heavy carbon isotope (δ13Cav ? 32.2‰). The insoluble carbonaceous matter (ICM) of the metamorphic shales is significantly enriched in the heavy carbon isotope (δ13Cav ? 21.9‰). The highest changes in carbon isotope composition were found in concentrates of ICM from metasomatically altered rocks of the Sukhoi Log deposit (δ13Cav ? 17.5‰). The heavier carbon isotope composition caused by metamorphism and metasomatism is evidently defined by isotopic exchange between the carbonate carbon and CO2 of metasomatic solutions, on one hand, and ICM of shales, on the other. 相似文献