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151.
There is increasing concern about environmental impacts of acidic drainage from acid sulphate soils on Holocene estuarine flood plains. Acidity derives from oxidation of iron pyrite in the sediments. Natural factors determine concentrations and distributions of pyrite accumulations, but human activities have reduced pyrite accumulation in the Pearl River Delta with land use practices increasing terrestrial sediment discharge. Large freshwater discharges and management techniques have enabled sustainable use of these soils. High concentrations of pyrite occur in many estuarine flood plains of Australia because of relatively greater marine inputs. Drainage of these soils enhances pyrite oxidation and estuarine acidification, which is associated with fish-kills. For sustainable development, the problems of acid sulphate soil drainage must be recognised and overcome. 相似文献
152.
Acid sulphate soils form when iron pyrite oxidises to sulphuric acid on atmospheric exposure, lowering soil pH below 4. In the Richmond River estuary, northern New South Wales, flood mitigation, drainage works and floodplain excavations have augmented acid sulphate soil formation by increasing pyrite availability for oxidation. These engineering works have facilitated the transport of acidified water and have impeded recovery from tributary acidification. The increased frequency and duration of acidification are associated with elevated concentrations of inorganic monomeric aluminium and dissolved iron, and major iron hydroxide precipitation, with deleterious effects on exposed aquatic biota and habitat. Fish kills and an outbreak of epizootic ulcerative syndrome (EUS) have been recorded from acidified sites in the estuary. 相似文献
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Bénédicte Zimmermann 《European Review of History》1998,5(1):9-23
Concepts of unemployment or of the labour market are not abstract, but develop from each society's own particular logic. Taking the examples of Germany and France at the end of the nineteenth century, it is possible to see how these concepts were constructed in specific national contexts, and how they were then used in practice. This analysis leads us to rethink current ideas about work and unemployment, and to ask what their future will be in a united Europe. 相似文献
158.
Cultural resource management (CRM) work accounts for most of the archaeology conducted in the United States. A diverse and
somewhat fragmented field, CRM has nonetheless achieved a degree of institutional and organizational maturity. CRM archaeology
has produced important contributions to archaeological methodology and has established and refined knowledge of regional cultural-historical
sequences and settlement and subsistence patterns. The current florescence of historical archaeology is attributable to CRM.
Yet the maintenance of high quality in CRM is a pervasive and enduring problem. Academic institutions need to reestablish
alliances with the CRM community. The future viability of CRM archaeology depends on factors both internal and external to
the discipline: regulatory and statutory “reform,” agency funding levels, looting and other destructive forces, and Native
American and other public involvement. 相似文献
159.
John T. Ishiyama 《Nations & Nationalism》1998,4(1):61-85
Abstract. In postcommunist politics many of the ‘new national right’ political formations in Eastern Europe and the former Soviet Union have joined forces with the communist successor parties. Such a combination is, on the surface, a baffling mixture; how is it possible that two fundamentally different ideological approaches (nationalism and internationalist socialism) can coexist and actively cooperate to form such a potent political force? What are the conditions under which such political cooperation emerges? This article attempts to answer the above questions by, first, empirically testing the effects of several factors which might explain postcommunist–nationalist political cooperation. Second, the quantitative analysis is buttressed with a comparison of the Hungarian and Russian cases. The analysis indicates that the most important variable associated with the emergence of postcommunist–nationalist political cooperation is the effect of previous regime type. 相似文献
160.