The ecological and social context of mammal hunting in the coastal savanna of Ghana

This article argues that insufficient attention has been paid in the recent literature to the social and environmental factors which regulate hunting in Ghanaian savannas, and to how this may influence the sustainability of their livelihoods. Despite the vital significance of this issue, the emphasis in the literature and media has been on the destructive impacts of hunting and the bushmeat trade on wildlife. Taking a case study from the coastal savanna of Ghana, a region commonly regarded as a degraded relict of former deciduous forest with a richer wildlife past, it investigates the hypothesis that structure/actor dualities, manifested by socio-cultural change, local environmental knowledge and livelihood activity options, are the primary regulators of hunting intensity and possible sustainability. Such an evaluation is effective if done from a structuration perspective. The integrated methodology incorporates social surveys, GIS based time series image analysis, ecological field methods and statistical analysis. The results provide evidence that the direct and indirect regulatory functions of the socioenvironmental context provide a core feature of the sustainability of hunting. It is concluded that local strategies of resource management may provide an effective complement to conservation policy.     

浙东沿海城镇化对河网水系的影响

我国东南沿海地区,近年来由于城镇化的快速发展,河网水系结构遭到了较大破坏,导致了洪涝、干旱和水质恶化等一系列生态环境问题。为此以浙东沿海鄞东南平原区为例,以GIS技术作支撑,利用航空遥感图像作为信息源,采用河网水系分级量算统计和图形叠加对比等方法,通过城镇化过程中河网形态结构的变化,分析了鄞东南地区河网水系的变化情况,揭示了城镇化的发展与河网演化之间的联系,并定量预测了研究区在目前城镇化速度下的河网结构变化趋势;在此基础上探讨了遏制这种发展趋势的措施,即在城镇化过程中应多保留现有的河道水系,尤其是村镇级中小河道,重视河网结构与功能的恢复,才能改善河网水质和水生态环境。     

The development and control of the seawater intrusion in the eastern coastal of Laizhou Bay, China

Seawater intrusion was observed in China’s coastal aquifers as early as 1960s. At present, it covers an area of more than 2,000 km² in China. In 2002, the seawater intrusion area was increased to 1773.6 km² in Shandong Province, China, and it is continuing to extend in the coastal area of Laizhou Bay. In order to study the characteristic of the seawater intrusion and the pattern of the saltwater/freshwater interface, we set the China’s first three-dimensional seawater intrusion observation network in Longkou City of Shandong Province in 1989. In order to control the development of the seawater intrusion, in 1995, a continuous underground concrete wall, by the method of high-pressure jet grouting, was constructed in the downstream plain area of the Huangshuihe river in Longkou City. The average depth of the 5,842 m long concrete wall is 26.7 m, and the maxim depth is 41 m. It forms a coastal underground reservoir with the total storage capacity of about 5,359 × 10⁴ m³. In the past 10 years, the reservoir obtained great economic benefit, social benefit and ecosystem benefit.     

The application of P–T–X(CO2) modelling in constraining metamorphism and hydrothermal alteration at the Damang gold deposit,Ghana

Orogenic gold mineralization at the Damang deposit, Ghana, is associated with hydrothermal alteration haloes around gold‐bearing quartz veins, produced by the infiltration of a H₂O–CO₂–K₂O–H₂S fluid following regional metamorphism. Alteration assemblages are controlled by the protoliths with sedimentary rocks developing a typical assemblage of muscovite, ankerite and pyrite, while intrusive dolerite bodies contain biotite, ankerite and pyrrhotite, accompanied by the destruction of hornblende. Mineral equilibria modelling was undertaken with the computer program thermocalc , in subsets of the model system MnO–Na₂O–CaO–K₂O–FeO–MgO–Al₂O₃–SiO₂–CO₂–H₂O–TiO₂–Fe₂O₃, to constrain conditions of regional metamorphism and the subsequent gold mineralization event. Metapelites with well‐developed amphibolite facies assemblages reliably constrain peak regional metamorphism at ~595 °C and 5.5 kbar. Observed hydrothermal alteration assemblages associated with gold mineralization in a wide compositional range of lithologies are typically calculated to be stable within P–T–X(CO₂) arrays that trend towards lower temperatures and pressures with increasing equilibrium fluid X(CO₂). These independent P–T–X(CO₂) arrays converge and the region of overlap at ~375–425 °C and 1–2 kbar is taken to represent the conditions of alteration approaching equilibrium with a common infiltrating fluid with an X(CO₂) of ~0.7. Fluid‐rock interaction calculations with M–X(CO₂) diagrams indicate that the observed alteration assemblages are consistent with the addition of a single fluid phase requiring minimum fluid/rock ratios on the order of 1.     

~(210)Pb和~(137)Cs测年在中国海岸带古环境演变研究中的应用

海岸带地处陆地和海洋交界地区,是物质和能量交换的中心地带,沉积环境复杂。而对其沉积记录古环境信息的正确理解和解释在很大程度上依赖于年代框架的建立。210Pb和137Cs年代学的问世,解决了高速沉积环境中时间量程为百年或更短的沉积物的定年,近年来得到广泛的应用。在实际应用中,我们应该根据研究目的、范围等因素,选择合适的测年手段测年。此外,由于每种方法还存在不足,且可能同时会有几种方法适用,所以为了增加测年数据的准确性和可靠性,我们应尽量选择多种适当方法进行对比测年。     

山东滨海盐碱地柽柳林下微生物量变化特征及其影响因素

以山东昌邑国家级海洋生态特别保护区内柽柳林下土壤微生物为研究对象, 测定了其微生物量变化. 结果表明: 研究区细菌、真菌及古菌基因平均拷贝数分别为8.24×10⁶ copies·g^-1、1.51×10⁴ copies·g^-1和2.85×10⁴ copies·g^-1, 微生物量碳、氮平均值分别为140.54 mg·kg^-1和29.19 mg·kg^-1. 自密集区经稀疏区到边缘区, 随植被盖度的降低, 微生物量呈现降低的趋势. 相关分析表明, 不同植被盖度所造成的有机质输入的差异是造成这种变化规律的主要因素.     

The transfer of agricultural technology and the development of small-scale farming in rural Africa: Case studies from Ghana, Sudan, Uganda, Zambia and South Africa

In many developing countries, research institutions or centres have been established to develop and/or adapt technologies that would help agricultural development. This is particularly true in Africa where national efforts have been supplemented with international research institutes. Although some modest progress has been achieved in improving agricultural technology, on the whole, the improvement record is not quite encouraging among the small-scale farmers. In many areas, either there are no improved technologies, or where they exist, are unacceptable by farmers. However, where useful technologies exist, their spread has been very limited and where they have been adapted, the benefits only accrue to a small segment of the community. The logical question posed is: why and how do we find ourselves in the current situation? This paper considers the view that to understand fully why the available technologies have remained largely at the research centres, there is need to examine the whole process of research, development, dissemination and utilization of agricultural technology. It is significant to investigate the structural constraints and prospects under which those involved in the process work, their motivations and the interactions between different groups. The traditional ‘top-down’ of development strategy should be supplemented with farmers' indigenous knowledge, and programmes encouraging transfer of agricultural technology should include institutional support. Only by the identification of farmers' environmental and resource utilisation, preferences, socio-economic circumstances and constraints can a development programme of optimum meaning to farmers be devised and implemented with success.     

AMS ~(14)C测年揭示的渤海湾沿海低地第Ⅱ海相层年龄

在渤海湾沿海低地地区获得4个机械钻孔,结合AMS14C测年方法,对Ⅱ海的年龄进行了研究。结果显示,在Ⅱ海所在层位获得的14C样品年龄均大于43.5ka BP,说明渤海湾沿海低地地区Ⅱ海形成于MIS 3早期或MIS 5,而不是前人认为的23~39ka。建议在前人地层结构研究成果的基础上,系统开展Ⅱ海年龄研究。     

AMS ^14C测年揭示的渤海湾沿海低地第Ⅱ海相层年龄

在渤海湾沿海低地地区获得4个机械钻孔,结合AMS 14C测年方法,对Ⅱ海的年龄进行了研究。结果显示,在Ⅱ海所在层位获得的14C样品年龄均大于43.5ka BP,说明渤海湾沿海低地地区Ⅱ海形成于MIS 3早期或MIS 5,而不是前人认为的23-39ka。建议在前人地层结构研究成果的基础上,系统开展Ⅱ海年龄研究。     

美国海岸带自然资源与生态损害评估及修复工作对中国的启示

海岸带是位于海陆结合部的复杂环境系统,是人类活动最集中的地区。中国大陆海岸线约18000km,涉及沿海11个省,由于经济社会高速发展,海岸带地区的人口、资源、环境矛盾日益突出,面临海岸带资源无序开发、水土污染、滨海湿地退化、海岸侵蚀、地面沉降等一系列生态环境与灾害地质问题,已成为影响生态文明建设的主要问题之一。因此中国持续加大海岸带生态环境保护力度,并提出实施重要生态系统保护和修复重大工程、强化湿地保护和修复等政策措施。美国国家海洋和大气管理局主导的海岸带损害评估及修复计划已实施了近30年,并取得了显著效果,其完善的法律制度体系、规范的损害评估和修复程序、数据集成管理和共享应用等成功经验值得学习借鉴。建议加快完善中国海岸带生态环境损害评估与修复的技术方法体系和制度体系、有序开展海岸带自然资源和生态环境调查、加强海岸带及滨海湿地等重要生态系统的演化和修复技术研究与示范,并构建统一的海岸带基础调查数据库、建立海岸带监测预警体系。     

Brutal presence or convenient absence: The role of the state in the politics of flooding in informal Accra,Ghana

This paper argues that human vulnerability to flood hazards in urban slums in developing countries is greatly affected by the positioning and activities of their city governments. As a result, the paper explores the central role of city authorities in the production of flood vulnerability in selected informal settlements in Accra, Ghana. Using a case study research design, the study draws on multiple qualitative methods to gather evidence including: document review, focus group discussions, flood victims’ interviews, institutional consultation and field observation. The paper reveals two main positions of state and city authorities in Accra’s perennial floods: first, being present and complicit in informal urbanization through their involvement in the politics of land management in flood prone zones; and second, being absent through their inaction in informal growth in flood-risk areas. To each of these positions of the urban state, there are emerging responses from residents and other non-state actors operating within and outside these informal communities. The paper proposes a re-examination of the current structure and processes of urban governance, state-community engagements and urban citizenship in informal communities.     

The Oyambre coastal terrace: a detailed sedimentary record of the Last Interglacial Stage in northern Iberia (Cantabrian coast,Spain)

A detailed study is presented of a 15.3-m-thick Pleistocene coastal terrace located on the Cantabrian coast (northern Spain). Stratigraphic, sedimentological, topographic and micropalaeontological information is combined with a chronology based on luminescence dating to characterize the deposits. The sedimentary succession records: (i) a basal transgressive system, consisting of a wave-cut surface covered by a lower layer of beach gravels and upper beach pebbly sands; and (ii) a thicker upper highstand system (aggrading), comprising medium to very fine aeolian sands interbedded with thin palustrine muds. Luminescence dating involved a detailed sampling strategy (36 samples and two modern analogues) and the use of both quartz optically stimulated luminescence (OSL) and feldspar post-infrared infrared stimulated luminescence single aliquot regeneration protocols; feldspar results were used to confirm the completeness of bleaching of the quartz OSL signal. The quartz OSL luminescence age–depth relationship shows significant dispersion, but nevertheless two rapid phases of deposition can be clearly identified: one at ~130 ka [Marine Oxygen Isotope Stage (MIS) 5] and one at ~100 ka (MIS 5c). The top of the succession is dated to ~70 ka. The MIS 5e marine maximum flooding surface is identified at an elevation of 6.85 m above mean seal level. This elevation provides evidence of a regional sea-level highstand for this sector of the Cantabrian coast.     

The role of geoarchaeology in the interpretation of fragmented buildings and occupation surfaces: The case of coastal settlements in northeast Scotland

Around the world, poorly preserved buildings and occupation deposits often represent the primary evidence for archaeological structures and settlements. Integrated geoarchaeological methods, such as soil chemistry and micromorphology, can be used to maximise the information obtained from such deposits regarding site preservation and the use of space. However, archaeologists are often reluctant to apply these methods if they suspect that preservation is poor or stratigraphy is not visible in the field. To assess the role that geoarchaeology can play in the interpretation of fragmented and poorly preserved structures, this paper presents the results of two case studies in which multiple geoarchaeological methods (microrefuse analysis, pH, electrical conductivity, magnetic susceptibility, loss-on-ignition, portable XRF and micromorphology) were applied to poorly preserved occupation deposits and fragmented buildings in early medieval coastal settlements in northeast Scotland. Micromorphology proved to be fundamental for recognising and understanding the composition of occupation deposits that had formerly been floor surfaces. It also aided interpretations for the use of space and maintenance practices and improved an understanding of the post-depositional processes that had affected stratigraphic visibility at the macroscale. When subjected to principal component analysis, the geochemical, magnetic and microrefuse data were able to provide new details about activity areas, and successfully identified and filtered out the effects of post-medieval contamination. Most significantly, the integrated approach demonstrates that fragmented buildings and poorly preserved occupation surfaces can retain surviving characteristics of the use of space, even if the floor surfaces were not preserved well enough to be clearly defined in the field or in thin section.     

挥发份对高硅岩浆演化趋势的制约:以东南沿海白垩纪晚期花岗岩类岩石为例SCIEI北大核心CSCD

东南沿海分布大面积的白垩纪晚期侵入岩。这些岩石可分为两期:其中115~100Ma以钙碱性系列岩石为主,岩石组合为辉长岩-闪长岩-花岗闪长岩-二长花岗岩-碱性长石花岗岩;而100~86Ma的岩石为碱性系列,岩石组合为石英二长斑岩-正长斑岩-碱性长石花岗岩。115~100Ma的辉长岩以角闪辉长岩为主,具有极高的CaO、MgO和Al_(2)O_(3)含量,具有极低的SiO_(2)(42.9%~53.8%)、全碱(K_(2)O+Na_(2)O:0.86%~5.28%)、Ba、Nb、Th、Rb和Zr含量,也具有极低的FeO^(T)/MgO、La/Yb和Zr/Hf比值,较高的Eu/Eu^(*)、Sr/Y比值和Sr含量,为基性-超基性堆晶岩。与辉长岩同期的闪长岩和细粒暗色包体具有较高的SiO_(2)(50.34%~63.68%),较低的CaO、P_(2)O_(5)、MgO、Al_(2)O_(3)含量,相对低的Eu/Eu^(*)和Sr/Y比值,变化较大的La/Yb和Zr/Hf比值,代表了从基性岩浆储库中抽取的富硅熔体。115~100Ma的花岗闪长岩和二长花岗岩类岩石为准铝质岩石,SiO_(2)含量变化较大(61.7%~75.3%),具有较低的FeO^(T)/MgO、Ga/Al比值和Nb、Zr及Nb+Zr+Ce+Y元素含量,显示出典型I型花岗岩的特征。这些花岗岩具有相对高的La/Yb、Eu/Eu^(*)和Zr/Hf比值和高的Sr、Ba和Zr含量。结合岩相学特征,这些花岗岩为堆晶花岗岩。而115~100Ma的碱性长石花岗岩具有极高的SiO_(2)含量(大于75%),低的Eu/Eu^(*)、La/Yb、Zr/Hf和Sr/Y比值,具有低的Ba、Sr和Zr含量和高的Rb、Nb、Y和Th含量和Rb/Sr比值,表明这些花岗岩是由富硅岩浆储库中抽离的高硅熔体侵入地壳形成。100~86Ma期间形成的二长斑岩和正长斑岩具有极高的全碱含量,可以达到8%~12%,其SiO_(2)主要集中在60%~70%,具有极高的Zr、Sr和Ba含量和Eu/Eu^(*)、La/Yb和Sr/Y比值,显示出堆晶花岗岩的特征。而100~86Ma期间形成的大部分碱性长石花岗岩具有极高的SiO_(2)含量(大于75%),并显示出A型花岗岩的特征,具有高的Rb/Sr比值和高的Rb、Y和Th和低的Ba、Sr含量和低的Zr/Hf、La/Yb、Eu/Eu^(*)和Sr/Y比值,表明它们是由富硅岩浆储库抽离的高硅熔体侵入浅部地壳形成。东南沿海高硅花岗岩的形成和穿地壳岩浆系统密切相关,高硅花岗岩是由浅部地壳内晶体-熔体分异产生的熔体侵入地壳所形成,而高硅花岗岩的地球化学特征与岩浆储库的水及挥发份含量密切相关。115~100Ma期间,从富水的岩浆储库抽离的熔体形成具有低高场强元素含量和低Rb/Sr比值的高硅花岗岩,这一过程与古太平洋板块俯冲有关;100~86Ma期间,从富挥发份的岩浆储库抽离的熔体形成碱性特征、富含高场强元素和具有高的Rb/Sr比值的高硅花岗岩,这一过程和古太平洋板块回撤软流圈上涌有关。     

The role of western Mediterranea tectonic evolution in the geometry of a karstic domain in the Betic Cordilleras (Sierra Gorda,Spain): importance of a tardy extensional regime

Abstract

Located in the central part of the Betic Cordilleras, the large carbonate Sierra Gorda Massif provides an example of a west-Mediterranean karstic aquifer. In spite of a complex polyphased tectonic history, the fracturing presents, from aerial views and at outcrop scale a quite organised geometry. Four fracture directions are found over the massif. N000—010, NOS0-070, N090–100 and N140–170. The statistical and geostatistical approach allows the characteristics (lengths, orientations) and the spatial structure for each fracture set to be determined. The N000–010 and N140–170 sets are grouped in packets whereas the two other sets are grouped in bands. The microtectonic study describes the evolution of the massif in the geodynamic context of this part of Mediterranea, distin guishing three recent stages of brittle tectonic activity in t e massif: a WNW-ESE Middle Miocene compression, then a NNW-SSE to NW-SE compression with a poorly wrenching regime, and finally a probably pre-Quaternary N-S radial distension. This last stage is essential for the karstification of the massif and groundwater circulation. From the combined analysis of fracture network geometry and palaeostresses a multiple porosity model in agreement with hydrological observations made inside the massif can be proposed: in particular, the hectometric N090–100 (and N050–070) fractures which are essential for the network connectivity, and have a major drainage role at aquifer scale, while the N000–010 and N140- 170 ones have a more local drainage role. This extensive tardy regime, which is for the first time described separately from the internal zones of the Cordilleras, must be considered as a significant phenomenon on a regional scale, and henceforth integrated in future geodynamic schemes of this part of Mediterranea. © Elsevier, Paris     

The structural role of Ti in aluminosilicate liquids in the glass transition range: insights from heat capacity and shear viscosity measurements

The shear viscosities and 1 bar heat capacities of glasses and melts along the 67mol% silica isopleth in the system SiO₂-Al₂O₃-Na₂O-TiO₂ have been determined in the temperature ranges 780-1140 K and 305-1090 K respectively. Anomalous behaviour of both these properties is observed for compositions rich in TiO₂ and/or Al₂O₃, an observation attributed to liquid-liquid phase separation followed by anatase crystallization. For samples which do not show anomalous behaviour, it is found that the partial molar heat capacity of the TiO₂ component previously determined in Al-free compositions reproduces our heat capacities to within 1.3%. Viscosity data show that addition of TiO₂ tends to increase viscosity and melt fragility at constant temperature. Furthermore, heat capacity and viscosity data may be combined within the framework of the Adam-Gibbs theory to extract values of the configurational entropy of the liquids and qualitative estimates of the variation of the average energy barrier to viscous flow. Configurational entropy at 900K is inferred to decrease upon addition of TiO₂, in contrast to previous results from Al-free systems. The compositional limit separating normal from anomalous behaviour, as well as the data for homogenous melts have been used to constrain the structural role of Ti in these samples. Our data are consistent with a majority of Ti in five-fold coordination associated with a titanyl bond, in agreement with previous spectroscopic studies. Furthermore, we find no evidence for a Ti-Al interaction in our samples, and we are led to the conclusion that Al and Ti are incompletely mixed, a hypothesis consistent with the observed reduction of configurational entropy upon addition of TiO₂, suggesting an important role of medium range order in controlling the variations in thermodynamic properties.