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31.
Ancient copper and lead pollution records from a raised bog complex in Central Wales,UK 总被引:1,自引:0,他引:1
This paper presents records of metal deposition as preserved by a peatland which has accumulated in the lowland coastal zone at Borth, near Aberystwyth, Ceredigion, mid-Wales, U.K. The research objective was to explore the origins and history of metal mining and (or) metallurgy by reconstructing a geochemical record of copper, lead and zinc pollution for the last four millennia. Two cores were extracted from Borth Bog, one from the raised ombrotrophic part of the bog and another from a minerotrophic part of Borth Bog close to the ancient copper workings at Llancynfelin. Although peat stratigraphy and nutrient status have influenced the geochemical record, the results suggest that an early phase of copper and lead pollution occurred at Llancynfelin whilst lead enrichment occurred in the peat core taken close to the centre of Borth Bog during the Bronze Age and the Roman occupation. Therefore the origins of copper and lead mining and metallurgy possibly extend back to the Bronze Age in central Wales. No record of historical pollution exists at either site. The results of this study also provide further evidence that lead and copper are immobile in ombrotrophic peat and that pollution records can be elucidated from minerotrophic peat. Zinc, however, may have suffered from post-depositional mobility. 相似文献
32.
Surendra Singh 《Geographical analysis》2002,34(3):229-244
Important characteristics of spatial agricultural production functions are derived by introducing a non‐negative curvilinear spatial demand function for production input intensities. Given the usual neoclassical rationale assumptions of spatial demand for capital and labor inputs under competitive environment of farming in developing agricultural economies, the optimal production levels are determined by optimizing spatial demand for production inputs. Decreasing price‐to‐transport costs ratio (that is, decrease in the prices of capital goods or increase in freight rates) and increasing wage‐to‐travel costs ratio (that is, increase in labor wages or decrease in the travel rate) expand the limits of the (spatial) optimal boundary of the demand for agricultural capital goods and labor input respectively. These effects occur on account of the operation of (positive) spatial price gradient and (negative) wage‐gradient in the market region. It may be noted that elasticities of demand for production factors are spatially variant and have significant effects on the alterations in the structure of agricultural production. However, the spatial optimal solution of production has a complicated relationship with them. The price elasticity has negative and wage elasticity has positive spatial gradients in the market region. Farmers located in the periphery of the market region are not much affected by the proportionate changes occurring in the prices of agricultural capital goods but are more sensitive to the proportional changes in labor wages. Because of a decreasing trend in capital input demand and increase in labor input with distance from the market, capital‐product diminishes with a decreasing rate and labor‐product increases with an increasing rate in the spatial structure of agricultural production. As a result, capital‐labor ratio falls toward zero, which raises profit rate per unit of capital investment especially in the outer part of the market region. The equilibria of optimal production with price elasticity as well as of capital intensity with labor employment (that is, capital‐labor ratio as unity) determine spatial limits of the optimal production zone which is shifted outward subject to the provision of cheap transportation, stabilizing market prices and/or increasing wage rate at the market center. It will help in extending outwardly the optimal spatial limits of capital investment and will mobilize capital resources of farmers in the periphery for efficient and competitive capital‐dominated farming. 相似文献
33.
Social scientists, geographers, criminologists, and health scientists are often tasked with finding data to best capture the impact of “community context” on individual outcomes, including residential services, physical resources, and social institutions. One outlet for such data in Canada is Digital Map Technologies Inc. (DMTI) Spatial, which offers a national repository of over one million businesses and recreational points of interest. The database is generated through CanMap Streetfiles, which includes geocodes of each point's precise location. These data are available to researchers from their university data library and Esri Canada, but primarily available to private sector and government markets. That said, the goal of the current paper is to encourage researchers to access this rich yet under-utilized data source. Each service, business, or resource in the DMTI Spatial database is assigned to a respective category using Standard Industrial Classification codes and North American Industrial Classification System codes. It is not clear, however, which is the more reliable coding criteria. We provide an overview of our review of DMTI Spatial data and take-away suggestions for using this valuable resource for future research on meso-level residential markers. 相似文献
34.
Shane P. Singh 《Australian journal of political science》2009,44(3):421-437
This project examines the dimensions of politics and voter preferences in Australia. Evidence from an empirical spatial analysis provides that Australian parties and voters are organised along a unidimensional socioeconomic continuum. Numerous individual-level factors, including party identification, ideology and a host of demographic and opinion variables, predict voters' positions along the continuum. Moreover, voter locations are shown to relate strongly to vote choice, demonstrating the importance of socioeconomic positions to voter behaviour in Australia. Finally, because this approach allows for a full examination of voter preference orderings, it is important to the study of voting behaviour and representation under preferential electoral institutions in Australia and elsewhere. 相似文献
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