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51.
Hard rock aquifer system, as it lacks in primary porosity, is complex because of heterogeneity, and hence its performance solely depends on secondary factors such as weathering, fractures, joints and lineaments, etc. As a result, there is no uniformity in behavior of such aquifer system which varies with the intensity of factors causing secondary porosity. In view of this aquifer system of hard rock, particularly multilayered aquifer system such as basalt, the targeting of deeper aquifer system becomes uncertain. Under this situation, mapping of lineament assumes great importance particularly for targeting the deeper aquifer. In view of this, a small watershed WGKKC-2 falling in Nagpur District of Central India has been studied in detail to understand the significance of lineaments on governing deeper aquifer system. The study has been carried out by deploying remote sensing technique for delineation of hydro geomorphology and lineaments vis-à-vis performance of bore wells. The results are encouraging which mainly emphasize the role of lineament mapping in hard rock aquifer system for identification of groundwater potential zones.  相似文献   
52.
Emerging environmental issues related to heavy metal contamination in rice draw great concern about the soil quality of paddy farming lands irrigated with groundwater. Investigating the functioning of soil microorganisms exposed to heavy metal contamination is imperative for agricultural soil manipulations. The current study accentuates the influence of heavy metals on microbial activity and community composition in arable soil of West Bengal State of India. The result revealed that the fertility indicators (activity of all soil enzymes) and growth-limiting factors (soil N and P) were negatively correlated with the heavy metal stress except the soil total organic content which demonstrated significant positive correlation with the heavy metals. In case of functional diversity of soil, all the considered diversity indices exhibited no specific pattern along with the availability of heavy metals. Further, despite the heavy metal contamination, we observed a very complex and indifferent pattern of bacterial community composition along the heavy metal contamination sites. Overall, we found that γ-Proteobacteria had been the most abundant bacterial community followed by Actinobacteria, Firmicutes, β-Proteobacteria and α-Proteobacteria. Commemorating all the results, we can infer that arsenic and other heavy metal contamination is deteriorating the soil quality and hence warrants immediate attention of concerned soil scientist and agronomists.  相似文献   
53.
Drainage reorganization on restricted temporal and spatial scales is poorly-documented. We attempt to decode the relatively complicated mechanism of drainage realignment involving two small rivers that show structurally controlled, highly anomalous channel networks. We provide geomorphic and shallow subsurface evidence using ground-penetrating radar (GPR) for the presence of a buried paleo-valley flowing northward through the wind gap and surface faulting along the range bounding Katrol Hill Fault (KHF) which correlates with the previously known three surface faulting events in last ~30 ka bp . Most of the present river channels and the KHF zone are occupied by aeolian miliolite (local name) which is stratigraphic and lithologic equivalent of the Late Quaternary carbonate rich aeolianite deposits occurring in several parts of the globe. The history of drainage evolution in the study area comprises pre-miliolite, syn-miliolite and post-miliolite phases. Geomorphic evidences show that the paleo-Gangeshwar River flowed north through the wind gap and paleo-valley, while the short paleo-Gunawari occupied the saddle zone to the east of Ler dome prior to and during the phase of miliolite deposition which ended by ~40 ka bp . Southward tilting of the Katrol Hill Range (KHR) due to surface faulting cut off the catchment of the paleo-Gangeshwar River. The abandoned catchment stream extended its channel eastward along the strike through top-down process while the paleo-Gunawari River extended its course westward by headward erosion (bottom-up process). As the channels advanced towards each other they joined to produce the “S”-shaped bend which formed the capture point. We conclude that multiple surface faulting events along the KHF in the last ~30 ka bp , resulted in uplift and tilting of the KHR which caused drainage realignment by river diversion, beheading and river capture. Our study shows that the complexity of drainage reorganization processes is more explicit on shorter rather than longer timescales.  相似文献   
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55.
Complex organic materials may exist as haze layers in the atmosphere of Titan and as dark coloring agents on icy satellite surfaces. Laboratory measurements of optical constants of plausible complex organic materials are necessary for quantitative evaluation from remote sensing observations, and to document the existence of complex organic materials in the extraterrestrial environments. The recent Cassini VIMS and CIRS observations provide new constraints on Titan’s haze properties in the mid-infrared wavelength region. Here, we present the optical constants (2.5–25 μm) of Titan tholins generated with cold plasma irradiation of a N2/CH4 (90/10) gas mixture at pressures of 0.26 mbar, 1.6 mbar, and 23 mbar. Our new optical constants of three types of Titan tholins suggest that no single Titan tholin in this study fulfills all the observational constraints of the Titan haze material. The discrepancy remains a challenge for future modeling and laboratory efforts that aim toward a better understanding of Titan’s haze material.  相似文献   
56.
We present two dark energy (DE) models with an anisotropic fluid in Bianchi type-VI 0 space-time by considering time dependent deceleration parameter (DP). The equation of state (EoS) for dark energy ω is found to be time dependent and its existing range for derived models is in good agreement with the recent observations. Under the suitable condition, the anisotropic models approach to isotropic scenario. We also find that during the evolution of the universe, the EoS parameter for DE changes from ω>−1 to ω=−1 in first model whereas from ω>−1 to ω<−1 in second model which is consistent with recent observations. The cosmological constant Λ is found to be a positive decreasing function of time and it approaches a small positive value at late time (i.e. the present epoch) which is corroborated by results from recent type Ia supernovae observations. The cosmic jerk parameter in our derived models is also found to be in good agreement with the recent data of astrophysical observations. The physical and geometric aspects of both the models are also discussed in detail.  相似文献   
57.
58.
The Hyperspectral Imager for the Coastal Ocean (HICO) was used to derive chlorophyll-a (chl-a) based on the normalized difference chlorophyll index (NDCI) in two Gulf of Mexico coastal estuaries. Chl-a data were acquired from discrete in situ water sample analysis and above-water hyperspectral surface acquisition system (HyperSAS) remote sensing reflectance in Pensacola Bay (PB) and Choctawhatchee Bay (CB). NDCI algorithm calibrations and validations were completed on HICO data. Linear and best-fit (polynomial) calibrations performed strongly with R2 of 0.90 and 0.96, respectively. The best validation of NDCI resulted with an R2 of 0.74 and root-mean-square error (RMSE) of 1.64 µg/L. A strong spatial correspondence was observed between NDCI and chl-a, with higher NDCI associated with higher chl-a and these areas were primarily located in the northern PB and eastern CB at the river mouths. NDCI could be effectively used as a qualitative chl-a monitoring tool with a reduced need for site-specific calibration.  相似文献   
59.
We present chemical abundance measurements from medium-resolution observations of eight subdamped Lyα (sub-DLA) absorber and two strong Lyman-limit systems at   z ≲ 1.5  observed with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5-m Magellan II Clay telescope. These observations were taken as part of an ongoing project to determine abundances in   z abs≲ 1.5  quasar absorption line systems focusing on sub-DLA systems. These observations increase the sample of Zn measurements in   z abs≲ 1.5  sub-DLAs by ∼50 per cent. Lines of Mg  i , Mg  ii , Al  ii , Al  iii , Ca  ii , Mn  ii , Fe  ii and Zn  ii were detected and column densities were determined. Zn  ii , a relatively undepleted element and tracer of the gas-phase metallicity is detected in two of these systems, with  [Zn/H]=−0.05 ± 0.12  and  [Zn/H] > +0.86  . The latter one is however a weak system with   N H  I < 18.8  , and therefore may need significant ionization corrections to the abundances. Fe  ii lines were detected in all systems, with an average Fe abundance of  〈[Fe/H]〉=−0.68  , higher than typical Fe abundances for DLA systems at these redshifts. This high mean [Fe/H] could be due to less depletion of Fe on to dust grains, or to higher abundances in these systems. We also discuss the relative abundances in these absorbers. The systems with high metallicity show high ratios of [Mn/Fe] and [Zn/Fe], as seen previously in another sub-DLA. These higher values of [Mn/Fe] could be a result of heavy depletion of Fe on to grains, unmixed gas, or an intrinsically non-solar abundance pattern. Based on cloudy modelling, we do not expect ionization effects to cause this phenomenon.  相似文献   
60.
Catastrophe risk models are used to assess and manage the economic and societal impacts of natural perils such as tropical cyclones. Large ensembles of event simulations are required to generate useful model output. For example, to estimate the risk due to wind-driven storm surge and waves in tropical cyclone risk models, computationally efficient parametric representations of the wind forcing are required to enable the generation of large ensembles. This paper presents new results on the impact of including explicit representations of extra-tropical transitioning in parametric wind models used to force storm surge and wave simulations in a catastrophe risk modelling context. Extra-tropical transitioning is particularly important in modelling risk on the Japanese coastline, as roughly 40 % of typhoons hitting the Japanese mainland are transitioning before landfall. Using both a historical and idealized track set, we compare maximum storm surge and wave footprints along the Japanese coastline for models that include, and do not include, explicit representations of extra-tropical transitioning. We find that the inclusion of extra-tropical transitioning leads to lower storm surge (10–20 %) and waves (5–15 %) on the southern Japanese coast, with significantly higher storm surge and waves along the northern coast (25–50 %). The results of this paper demonstrate that useful risk assessment of coastal flood risk in Japan must consider the extra-tropical transitioning process.  相似文献   
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