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101.
Climate change is already affecting rural communities along the high Andean plateau, but it is just one of many stresses that Andean people experience on a regular basis. This paper examines the experiences of quinoa farmers in Southwestern Bolivia as they faced the overlapping crises of protracted drought and market disruption in 2017. Drawing on political ecologies of resilience, this paper argues that the ability of rural people to cope with this double exposure was already compromised by ecological and social vulnerabilities produced through the development trajectories of the previous two decades. These development strategies generated three overlapping processes: 1) neoliberal entanglements involving specialization in quinoa production, marketization, and individualization of livelihoods in ways that undermined collective action; 2) new relationships of debt that tied households to monetized response paths and undermined flexibility; and 3) the degradation of soils through extensification, overproduction, and industrialization of quinoa production. This paper argues that while climate and market disruptions are not to be dismissed, we must historicize the double exposure to also ask how resilience and vulnerability to such challenges are generated in the first place.  相似文献   
102.
This paper examines the suitability of the PBRM, a mapping tool based on the perceptions of local stakeholders, for assessing the connection between land uses and health issues. The area, rural Laos around Luang Phabang city, between the Mekong River valley and mountains, seems to have overcome the formal territorial organization based on exposure risks towards an organization based on access to health and medical facilities. In addition, differential access to safe drinking water has been quite solved by the implementation of private can distribution networks. However, these rapid changes accentuate the social gap between well-connected lowlands and valleys on one hand, and mountain areas on the other hand, increasingly sidelined from this transition. Methodologically, PBRM method explores broader issues at a broader scale but does not give an easy access to non-spatial criteria. Plus, the limits of the SHUs (Spatial Homogeneous Unit) the PBRM establishes are geographically precise regarding topology but not spatiality. These results are action-oriented towards local and development-oriented issues.  相似文献   
103.
超积累植物对重金属的区隔化作用能有效降低细胞质内金属离子的浓度,是对重金属重要的解毒机制之一,而细胞内各组织的区隔化作用大小并未取得一致性结论。本文研究了胁迫浓度和胁迫时间对超积累植物印度芥菜(Brassica juncea)细胞及亚细胞中镉分布的影响。印度芥菜幼苗分别用0.5、1.0、2.0、3.0、5.0mg/L镉胁迫1、5、7、10、14天后收获,采用电感耦合等离子体质谱法测定印度芥菜根系和叶片亚细胞中镉的含量。结果表明:镉在细胞壁中的比例占50%~64%,细胞液占22%~38%,细胞器占7%~17%,镉在细胞壁中所占比例显著高于细胞液和细胞器,证明细胞壁区隔化在镉的解毒机制中具有重要的作用。随着胁迫时间和胁迫浓度的增加,根系和叶片中亚细胞各组织中镉含量持续增加,超过7天,镉含量显著升高,说明镉对植物的危害是一个缓慢过程。印度芥菜对镉胁迫浓度的最大耐受量为1.0 mg/L,超过此浓度,植物细胞的破坏症状加重;细胞超微结构研究也表明,镉胁迫浓度超过1.0 mg/L后,细胞结构发生了不同程度的损坏,出现质壁分离、液泡增大甚至空泡化、质膜粗糙等现象,继而影响到细胞的正常功能。因此,在考察重金属对植物的危害时,要充分考虑时间和浓度梯度两个参数的协同作用。  相似文献   
104.
《水文科学杂志》2013,58(6):891-897
Abstract

Precipitation measurement by raingauges is biased by the systematic error resulting from deformation of the local wind field due to the presence of the gauge itself. To correct for this error, it is necessary to know the degree of site exposure. Four measurement methods are dealt with to determine site exposure. It is shown how statistical techniques developed by Grubbs can be used to select the most precise measurement method.  相似文献   
105.
《自然地理学》2013,34(3):285-302
Uluru is an inselberg shaped in arkosic sandstone located in the arid plains of central Australia. The indigenous people believed it rose out of a sand hill and has since remained unchanged. The various minor landforms represented mythological animals, people, and events of the Dreamtime. Later investigators interpreted the residual as remaining after long-distance scarp retreat, or as due to scouring by the wind or by the waters of a huge lake. The inselberg and its decorations have been construed in terms of climatic variations. Uluru also has been interpreted as a compressed and resistant compartment that was exposed as a low rise in the latest Mesozoic. The initial rise shed runoff. The steep flanks were shaped in the Eocene by deep subsurface weathering followed by stripping of the regolith and exposure of bedrock forms. Large tafoni and breaks of slope were formed on the southern side where permeable sediments abutted the residual. Following their exposure, basal flares and footcaves were shaped during a later period of subsurface weathering. The inselberg has grown as a relief feature not by uplift, but by the lowering of the surrounding plains. The morphology of Uluru is an expression of episodic exposure.  相似文献   
106.
In this paper,we proposed a framework for evaluating the performance of ecosystem strategies prepared for enhancing vulnerability reduction in the face of hazards due to climate change.The framework highlights the positive effects of human activities in the coupled human and natural system(CHANS) by introducing adaptive capacity as an evaluation criterion.A built-in regional vulnerability to a certain hazard was generated based upon interaction of three dimensions of vulnerability:exposure,sensitivity and adaptive capacity.We illustrated the application of this framework in the temperate farming-grazing transitional zone in the middle Inner Mongolia of the northern China,where drought hazard is the key threat to the CHANS.Specific indices were produced to translate such climate variance and social-economic differences into specific indicators.The results showed that the most exposed regions are the inner land areas,while counties located in the eastern part are potentially the most adaptive ones.Ordos City and Bayannur City are most frequently influenced by multiple climate variances,showing highest sensitivity.Analysis also indicated that differences in the ability to adapt to changes are the main causes of spatial differences.After depiction of the spatial differentiations and analysis of the reasons,climate zones were divided to depict the differences in facing to the drought threats.The climate zones were shown to be similar to vulnerability zones based on the quantitative structure of indexes drafted by a triangular map.Further analysis of the composition of the vulnerability index showed that the evaluation criteria were effective in validating the spatial differentiation but potentially ineffective because of their limited time scope.This research will be a demonstration of how to combine the three dimensions by quantitative methods and will thus provide a guide for government to vulnerability reduction management.  相似文献   
107.
Action is increasingly being taken in New Zealand and elsewhere to restore ecological function to streams through planting of riparian zones. We used simulation modelling to explore the relative performance of three strategies to restore the riparian zone of a pastoral stream to native forest by: (1) passive regeneration; (2) planting then abandonment of a Pinus radiata plantation; and (3) active restoration by planting selected native trees. We linked the forest model LINKNZ with a shade and temperature model (sWAIORA), and a wood model (OSU_STREAMWOOD) to simulate recovery trajectories for key forest stream attributes in hypothetical streams (1.3–14.0 m channel width) in the central North Island, New Zealand. Both active restoration strategies outperformed passive regeneration in shade, temperature and stream wood volume for most of the simulation time (800 years). Although the abandoned pine plantation provided greatest shade initially (<100 years), active native planting provided the greatest benefits overall. In general, recovery of stream shade (and temperature) is expected within decades, is accelerated by deliberate planting, and is fastest in small streams in which thermal stress from sunlight exposure is greatest. However, full recovery of stream and riparian function may take centuries, being dependent on large trees providing wood to structure the channel.  相似文献   
108.
In 2001, a small H4 chondrite, Frontier Mountain (FRO) 01149, was found on a glacially eroded surface near the top of Frontier Mountain, Antarctica, about 600 m above the present ice level. The metal and sulphides are almost completely oxidized due to terrestrial weathering. We used a chemical leaching procedure to remove weathering products, which contained atmospheric 10Be and 36Cl in a ratio similar to that found in Antarctic ice. The FRO 01149 meteorite has a terrestrial age of 3.0 ± 0.3 Myr based on the concentrations of the cosmogenic radionuclides 10Be, 26Al and 36Cl. This age implies that FRO 01149 is the oldest stony meteorite (fossil meteorites excluded) discovered on Earth. The noble gas cosmic ray exposure age of FRO 01149 is ~ 30 Myr. The meteorite thus belongs to the 33 Myr exposure age peak of H-chondrites.The bedrock surface on which FRO 01149 was found has wet-based glacial erosional features recording a former high-stand of the East Antarctic ice sheet. This ice sheet evidently overrode the highest peaks (> 2800 m a.s.l.) of the inland sector of the Transantarctic Mountains in northern Victoria Land. We argue that FRO 01149 was a local fall and that its survival on a glacially eroded bedrock surface constrains the age of the last overriding event to be older than ~ 3 Myr. The concentrations of in-situ produced cosmogenic 10Be, 26Al and 21Ne in a glacially eroded bedrock sample taken from near the summit of Frontier Mountain yield a surface exposure age of 4.4 Myr and indicate that the bedrock was covered by several meters of snow. The exposure age is also consistent with bedrock exposure ages of other summit plateaus in northern Victoria Land.  相似文献   
109.
The objective of this study was to identify spatial variability in exposure to outdoor traffic-related air pollution with specific emphasis on comparing exposure estimates for working females and males across a metropolitan area. A spatial exposure simulation model was used to estimate annual average exposure to traffic-related nitrogen dioxide for males and females reporting regular work in census tracts other than that of their residence, in Vancouver, British Columbia. The model produced estimates of annual average exposure in six microenvironments (home indoor, work indoor, other indoor, outdoor, in-vehicle to work, and in-vehicle other) using time-activity patterns and work flow data, for males and females in each of 382 census tracts. This allowed for the identification of spatial variations in exposure estimates for each gender, due to mobility within the study region. Indoor sources of nitrogen dioxide were not included in the simulation. No significant differences in estimated total exposure were found between working females and males in general. Small but observable spatial differences, however, were found between working females and males at the 90th percentile of the exposure distributions associated specifically with the work indoor microenvironment. These were highest in suburban areas (+3 μ g/m3 for females, relative to total exposures in the range of 26 to 37 μ g/m3 annual average hourly nitrogen dioxide). These results identify specific geographic locations in the study area where personal monitoring studies might be warranted and suggest that the inclusion of workplace locations in multivariate modeling could be useful to further understand differences in estimated exposures.  相似文献   
110.
郭文伯  张艳  柴彦威 《地理研究》2015,34(6):1310-1318
利用2010年北京两个典型郊区社区(天通苑、亦庄)居民出行的GPS数据与活动日志调查数据,测度了不同交通方式环境下居民每日出行过程中PM2.5和CO空气污染暴露度,并分析了不同人群PM2.5和CO空气污染暴露度的差异性,进而构建结构方程模型分析郊区社区居民PM2.5和CO空气污染暴露度的影响因素。研究表明:① 机动化出行率对空气污染暴露程度的直接影响最大,其次是出行次数与出行时间,即机动化出行率越大,出行次数越多、出行时间越长空污染暴露程度越高;机动化出行率通过影响出行时间和出行次数间接影响空气污染暴露度;职住距离对居民空气污染暴露度也存在影响,职住分离程度越高空气污染暴露度越高,职住距离通过增加出行时间进而增加空气污染暴露度。② 不同社会经济属性群体的出行空气污染暴露度存在一定差异性,中等收入群体显著高于低收入群体和高收入群体,租房者显著低于购房者;未婚群体的PM2.5污染暴露度显著高于已婚群体,驾照持有群体的CO污染暴露度高于无驾照群体。  相似文献   
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