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1.
"Longitudinal residential histories are used to examine the extent to which three rural areas in Britain had distinctive migration histories from the 18th to the 20th centuries. Migration flows into and out of the regions are used to examine the extent to which the regions were integrated into the British migration system, and the relative importance of rural to urban migration is assessed.... Analysis reveals a high degree of short-distance mobility within regions and emphasises the dominance of London in longer-distance migration.... It is also suggested that the role of towns in the migration system has previously been overemphasised, with much migration taking place between small settlements and some movement from large cities to smaller towns and villages.... The analysis challenges some accepted notions about migration in the past, and contributes to the debate about the extent to which British regions became part of a national economic and social system from the 18th century." 相似文献
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生活垃圾淋滤液组分的变化特征及其污染机理分析──以长春市为例 总被引:3,自引:0,他引:3
利用室内模拟试验成果对长春市生活垃圾淋滤液的组分特征、变化规律及其对土壤、地下水的污染机理进行了分析;结合野外监测资料运用非确定性模型方法建立模拟模型,对淋滤液的污染组分进行趋势预测,为垃圾堆放场地的设计和垃圾污染的治理提供理论上的依据。同时为解决城市生活垃圾污染问题和寻找垃圾场地奠定了基础 相似文献
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利用合成磷灰石可以从水溶液中除去铅和其它重金属离子,对于含有大约100ppm二价铅的水溶液少量的羟基磷灰石就可以很容易地把铅的浓度减小到ppb级水平,或者到检出水平以下。这一反应取决于溶液中Pb~(2+)的含量和羟基磷灰石的含量,反应可以很快,几分钟内即可完成。通常认为反应机理主要是铅磷酸盐的沉淀作用。在自然界的地球化学条件下,溶液中的铅趋向于沉淀转变成相当难溶和稳定的磷氯铅矿。扫描电子显微镜 相似文献
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Alvarez-Salgado XA Herrera JL Gago J Otero P Soriano JA Pola CG García-Soto C 《Marine pollution bulletin》2006,53(5-7):239-249
Hydrographic data collected during the cruise HIDROPRESTIGE were combined with meteorological and dynamic data provided by remote sensors and drifting/moored buoys, to describe the surface circulation of the Northern Iberian basin in March-April 2003. Sea surface winds transported the floating Prestige oil slicks from the sinking area to the continental slope off the Rías Baixas in 1/2 month: the surface current intensity was 2% of the wind intensity and it was rotated clockwise 5 degrees from the wind direction. Mesoscale cyclonic and anticyclonic structures west of 10 degrees W increased the residence time of oil patches in the Northern Iberian basin, as compared with the expected southwards flow of the Iberian current (IC). On the other hand, the Iberian poleward current (IPC) formed a marked surface front with coastal waters, preventing the entry of fuel oil into the rías. PAHs in the surface layer during the cruise were <0.5 microgL(-1), except in the Galicia bank (approximately 1 microg L(-1); where the Prestige tanker was still leaking) and the vicinity of Cape Fisterra (approximately 1.5 microg L(-1); where the convergence front between the IPC and coastal waters vanished). 相似文献
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New Zealand fur seals in the Kaikoura region breed near a town with expanding tourist and fishing industries and commonly come ashore entangled in nets and plastic debris. However, the rate at which entanglement occurs was previously unknown. A decade of Department of Conservation seal callout data was analysed to determine the level of entanglement in the region and the most common debris type. Monitoring of adult female fur seals released from entanglement provided information on the potential for serious wounds to heal and survivorship of released individuals. Entanglement rates of pinnipeds in Kaikoura are some of the highest reported world-wide (average range: 0.6-2.8%) with green trawl net (42%), and plastic strapping tape (31%) together contributing the most to debris types. Nearly half of the reported entangled seals are successfully released (43%) and post-release monitoring shows that with appropriate intervention the chance of an individual surviving even with a significant entanglement wound is high. Our study demonstrates that while entanglement in the region is high, a successful intervention protocol may help reduce the potential for entanglement-related mortality in the region. 相似文献
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以水文地质化学动力学方程为基础,承压含水层稳定流为例,推演了由水化学指标表示的一维和二维稳定井流的裘布依公式。在讨论化学指标表示的裘布依公式与原公式关系的基础上,结合水文地质、水文地球化学综合模型,讨论和写出不同区带、各种矿物及相应组分化学指标表示的基本方程式。以山西晋城市新矿区抽水试验及相应的水化学指标,讨论了计算步骤和方法。最后讨论了这类公式可以扩展到潜水及非稳定流各种井、渠公式中,以及用水化学指标表示公式的某些实际意义。 相似文献
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Accoroni S Romagnoli T Colombo F Pennesi C Di Camillo CG Marini M Battocchi C Ciminiello P Dell'Aversano C Dello Iacovo E Fattorusso E Tartaglione L Penna A Totti C 《Marine pollution bulletin》2011,62(11):2512-2519
Intense blooms of the benthic dinoflagellate Ostreopsis cf. ovata have occurred in the northern Adriatic Sea since 2006. These blooms are associated with noxious effects on human health and with the mortality of benthic organisms because of the production of palytoxin-like compounds. The O. cf. ovata bloom and its relationships with nutrient concentrations at two stations on the Conero Riviera (northern Adriatic Sea) were investigated in the summer of 2009. O. cf. ovata developed from August to November, with the highest abundances in September (1.3 × 106 cells g−1 fw corresponding to 63.8 × 103 cells cm−2). The presence of the single O. cf. ovata genotype was confirmed by a PCR assay. Bloom developed when the seawater temperature was decreasing. Nutrient concentrations did not seem to affect bloom dynamics. Toxin analysis performed by high resolution liquid chromatography-mass spectrometry revealed a high total toxin content (up to 75 pg cell−1), including putative palytoxin and all the ovatoxins known so far. 相似文献