外出务工对山区农民适应旱灾能力的影响——云南保山的案例

基于在云南省西部保山地区开展的入户问卷调查和关键信息人访谈,探讨在发生旱灾,大量农民外出务工以弥补旱灾给家庭和农业生产带来的损失这一特定背景下,对比外出务工农户和非外出务工农户在收入来源、应对旱灾措施和家庭收入分配上的差异,分析外出务工对农民适应气候变化能力带来的影响。结果表明：外出务工收入给留守家庭的气候变化适应能力带来了积极的影响;另外一方面,大量青壮年劳动力的外出让经济结构仍然以农业为主的村庄出现劳动力缺乏、农业发展后续动力不足等潜在问题。建议在未来针对外出务工人口开展的职业培训中增加诸如家庭财务管理、气候变化等相关内容来加强农村地区和农民的气候变化适应能力,建议政府推广气候智能农业,采取本地化/本土化的适应措施。     

Reductive dissolution of arsenic-bearing ferrihydrite

Ferrihydrites were prepared by coprecipitation (COP) or adsorption (ADS) of arsenate, and the products were characterized using solid-state methods. In addition, the kinetics of reductive dissolution by hydroquinone of these well-characterized materials were quantified. Characterization and magnetism results indicate that the 10 wt% As COP ferrihydrite is less crystalline and possibly has smaller crystallite size than the other ferrihydrites, which all have similar crystallinity and particle size. The results from reductive dissolution experiments show similar reaction rates, reaction mechanism, and activation energy for ferrihydrite precipitated with or without added arsenate. However, a marked decrease in reactivity was observed for 10 wt% As ADS ferrihydrite. The decrease is not attributed to differences in activation energy but rather the preferential blocking of active sites on the ferrihydrite surface. Results demonstrate that arsenic may be released by the reductive dissolution of arsenic-bearing ferrihydrite regardless of whether the arsenic is coprecipitated with or adsorbed onto the ferrihydrite. However, under these reaction conditions, release from materials with adsorbed arsenate greatly exceeds that from materials with coprecipitated arsenate. In fact, a considerable amount of arsenic was released from the 10 wt% ADS ferrihydrite before reductive dissolution was initiated. Therefore, the characterization of arsenate-bearing iron oxide materials to determine the method of arsenate incorporation into structures—perhaps by quantification of Fe-Fe coordination with EXAFS spectroscopy—may lead to improved predictions of the large-scale release of arsenic within aquifer systems under reducing conditions.     

Vulnerability of groundwater in an industrial (Bauxite) valley of Lanjigarh (Orissa), India

Groundwater, particularly in the shallow zone aquifer is an easily available source of freshwater that serves various needs of people around it. Due to rapid growth in the industrial sector, the shallow groundwater regime becomes vulnerable to industrial toxicity and human activity. In the case of bauxite ore processing industry it is not only the groundwater potential that gets affected, but often the quality of groundwater is at risk from the ore processing activity. Bauxite processing plant has been setup in the Lanjigarh (Orissa State), India during 2007. An attempt has been made to evaluate the groundwater regime in the watershed that comprises the plant and its various disposal sites. Although the groundwater has not been found affected due to waste disposals, however, areas vulnerable to pollution have been demarcated.     

Microbial mat-induced sedimentary structures in siliciclastic sediments: Examples from the 1.6 Ga Chorhat Sandstone, Vindhyan Supergroup, M.P., India

This paper addresses macroscopic signatures of microbial mat-related structures within the 1.6Ga-old Chorhat Sandstone of the Semri Group — the basal stratigraphic unit of the Vindhyan succession in Son valley. The Chorhat Sandstone broadly represents a prograding succession of three depositional facies ranging from shallow shelf to coastal margin with aeolian sandsheet. The mat-mediated structures were generated because of plastic or brittle deformation of sand, turned cohesive and even thixotropic because of microbial mat growth. Mat growth also favoured abundant preservation of structures that usually have low preservation potential. Prolific growth of microbial mat in the subtidal to intertidal zone of the Chorhat sea was facilitated due to lack of grazing and burrowing activities of organisms in the Precambrian. It further indicates low rate of sedimentation between the storms, as also attested by frequent superposition of storm-beds, even near the storm wave base. It also reduces erosion and that, in turn, would imply low sediment concentration in flows leading to development of bedforms that are likely to be smaller in size and isolated from each other in a single train in contrast to those that form in mat-free sands.     

Assimilation of Doppler weather radar observations in a mesoscale model for the prediction of rainfall associated with mesoscale convective systems

Obtaining an accurate initial state is recognized as one of the biggest challenges in accurate model prediction of convective events. This work is the first attempt in utilizing the India Meteorological Department (IMD) Doppler radar data in a numerical model for the prediction of mesoscale convective complexes around Chennai and Kolkata. Three strong convective events both over Chennai and Kolkata have been considered for the present study. The simulation experiments have been carried out using fifth-generation Pennsylvania State University-National Center for Atmospheric Research (PSU-NCAR) mesoscale model (MM5) version 3.5.6. The variational data assimilation approach is one of the most promising tools available for directly assimilating the mesoscale observations in order to improve the initial state. The horizontal wind derived from the DWR has been used alongwith other conventional and non-conventional data in the assimilation system. The preliminary results from the three dimensional variational (3DVAR) experiments are encouraging. The simulated rainfall has also been compared with that derived from the Tropical Rainfall Measuring Mission (TRMM) satellite. The encouraging result from this study can be the basis for further investigation of the direct assimilation of radar reflectivity data in 3DVAR system. The present study indicates that Doppler radar data assimilation improves the initial field and enhances the Quantitative Precipitation Forecasting (QPF) skill.     

Spherical Collapse Of A Heat Conducting Fluid In Higher Dimensions Without Horizon

We consider a scenario where the interior spacetime, described by a heat conducting fluid sphere is matched to a Vaidya metric in higher dimensions. Interestingly we get a class of solutions, where following heat radiation the boundary surface collapses without the appearance of an event horizon at any stage and this happens with reasonable properties of matter field. The non-occurrence of a horizon is due to the fact that the rate of mass loss was exactly counterbalanced by the fall of boundary radius. Evidently this poses a counter example to the so-called cosmic censorship hypothesis. Two explicit examples of this class of solutions are also given and it is observed that the rate of collapse is delayed with the introduction of extra dimensions. The work extends to higher dimensions our previous investigation in 4D.     

Advanced application of bem to wave barriers in multi-layered three-dimensional soil media

An advanced application of BEM to the problem of wave screening by barriers is described. The BEM formulation has been developed by utilizing advanced surface modelling, automatic (self-adaptive) error control in the numerical integration. The soil is modelled as a layered, isotropic and linear elastic or viscoelastic medium. The results of the analysis have been compared with full scale test data.     

A new approach to the determination of methane content of coal seams

Summary An approach to the determination of methane content of coal seams is proposed. The method utilizes the transformed Airey's empirical equation on desorption of methane from coals. The methane content values estimated by this method correspond well with actual values from laboratory experiments. In the case of Indian coals, the applicability of the relationship for the calculation of the gas lost from coal lumps during long periods of time loss appears to be limited due to poor agreement with the experimental values.     

Precambrian stromatolite and other structures in the Rajpura-Dariba polymetallic ore deposit,Rajasthan, India

Intimate association of 2 billion years old stromatolite with pyritic lead-zinc ores in the Precambrian polymetallic deposit at Rajpura-Dariba in Rajasthan, which hitherto remained unreported, provides an additional documentation of the syn(-dia)-genetic mineralization. The growth form and petrography of the stromatolite structure have been described and an explanation sought regarding the concentration of sulfides along the siliceous and carbonaceous laminations, as well as in the intercolumnar regions. Consideration of the geologic features noted in the mineralized zone and surrounding region suggests that the stratiform ores were deposited in a near-shore shallow marine environment, developed on basement highs and associated with euxinic conditions. Later, the ores were metamorphosed under conditions reaching upto amphibolite facies during a three-stage deformational history of their enclosing rocks. Some salient features of the secondary structures in the ores have been discussed in relation to this deformation history.     

Combining paleointensity methods: A dual-valued determination on lunar sample 10017,135

A single-heating procedure is presented which makes possible the determination of two partially independent values of paleofield intensity for a given sample, one serving as a check to the other. The approach combines data required for Shaw-type and “ARM-method” determinations and in so doing furnishes a value of the ratio of TRM to ARM acquisition efficiency (f′) corrected for any physicochemical alteration to the magnetic carriers which may have occurred during laboratory heating.

Applicability of the Shaw-method to Fe-bearing samples is favorably demonstrated through simulated paleointensity determinations conducted on synthetic samples containing multi-domain grains. Moreover, coercivity spectra corresponding to anhysteretic remanent magnetization (ARM) are found to be considerably more sensitive to thermally induced alteration when compared with those corresponding to thermoremanent magnetization (TRM).

The combined Shaw-ARM procedure was successfully applied to lunar basalt sample 10017,135 rendering a paleointensity of 0.82 ± 0.11 Oe. The Thellier-Thellier method, however, was not able to provide a meaningful determination on the neighboring chip (number 136). These apparently conflicting findings may be explained by one or more of the following possible interpretations: (1) multiple step-wise heatings cause considerably more damage to the carriers of remanence than does a single-heating procedure; (2) the rock possesses extreme variability in magnetic properties from one sub-sample to the other; (3) the natural remanent magnetization in this lunar basalt is not a simple TRM.