Weathering patinas on the medieval (S. XIV) stained glass windows of the Pedralbes Monastery (Barcelona, Spain)

Background, aim, and scope  The first step in the restoration of a medieval stained glass window is the evaluation of its degree of degradation. This implies the study of the chemical composition of the stained glass as well as the new mineral phases developed on its surface (patinas). Patinas are clearly related to glass composition, time, environmental conditions, microenvironments developed in local zones, bioactivity, physical and chemical factors, etc. This study was carried out on patinas developed in selected Na-rich stained glass of the Santa Maria de Pedralbes Monastery (Barcelona, Spain). The location of this monument in the city (about 5 km from the shoreline and close to the Collserola hill flank) helped to determine the environmental conditions in which patinas developed. The aim of our study was to characterize the patinas formed on the surface of the selected glass of this monastery in order to understand the role of the chemical composition of the original glass (Na-rich) as well as the environmental conditions in which they developed. Materials and methods  Powdered samples of two different color-type patinas (ochre-orange and brownish) were collected in the external and internal parts of the stained glass windows of the Prebystery and Chapter House of the Pedralbes Monastery by using a precision (odontological) drill. These patinas were subsequently analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Results  XRD analyses evidenced the presence of sulfates (gypsum and thenardite), calcite, Ca-oxalates (whewellite and weddellite), and quartz forming part of the patinas. Although these mineral phases can be found in both color-type patinas, whewellite and thenardite are more common in the ochre-orange patinas. The results obtained were validated by the FTIR measurements. It has been observed, when thenardite is present, that gypsum occurs as traces. Thenardite is in most of the cases associated with whewellite and mainly occurs in the internal parts of the glass. In contrast, weddellite is limited to the absence of thenardite and whewellite and to the external parts of the stained glass. Quartz is present in all the patinas independent of their location and color. Calcite also occurs in many samples. It appears in both color-type patinas and, in some cases, is associated to the presence of weddellite but not to whewellite and/or thenardite. Discussion  Glass composition together with environmental conditions and location of the patinas (internal or external parts of the stained glass window), as well as the provenance of the glass within the monastery, are the main factors that define the development of the new mineral phases. Moreover, the action of microorganisms, when present, can also strongly influence the development of some mineral phases. For example, the formation of calcite in the external parts of the stained glass (associated with the presence of oxalates) is related to the action of microorganisms. When calcite is formed in the internal parts of the glass and it is not associated with the presence of Ca-oxalates, an inorganic origin can be invoked. The presence of weddellite requires a very humid microenvironment with very little exposure to sunlight. In fact, this mineral phase has only been observed in the external parts of some glass located in the humid and shady side of the monastery. Whewellite (which only appears in the internal parts) needs a low degree of relative humidity. It has been observed that sulfur precipitating in basically one mineral phase (thenardite or gypsum) depends on the microenvironmental conditions of the moment and the glass composition. When thenardite occurs, it can be maintained that the original glass is of Na composition. The occurrence of quartz in all samples is interpreted as being due to the deposition of atmospheric particulate matter. The color of the patinas can be originated by different processes (presence of carotenes, organic pigmentation, atmospheric contamination, etc.). Conclusions  In the case of moderately weathered stained glass windows, the combination of XRD and FTIR techniques is very useful to obtain a fast preliminary evaluation of the degree of weathering of a stained glass window. The presence of specific mineral phases in the patina (e.g., thenardite) confirms the Na composition of the original stained glass. This is important since Na-rich glass underwent a lesser degree of weathering than K- or K-Ca-rich glass. However, their absence cannot preclude other possibilities. It has been extensively evidenced through time that environmental conditions play an important role on the formation of the different mineral phases which form part of the patinas. Recommendations and perspectives  The first step in the restoration of a stained glass window is the evaluation of the degree of deterioration of the glass. This evaluation includes a chemical analysis of the glass as well as a characterization of the patinas developed on their surfaces. The obtained results will be essential in order to define the best restoration practices to be followed.     

Black layers on historical architecture

Background, aim and scope

The external surface of any building in urban polluted environment is unavoidably destined to be covered with layers that assume a grey to black colour and are generally called ‘black crusts’. These, according to standard protocols and glossary, are deteriorated surface layers of stone material; they can have variable thickness, are hard and fragile and can detach spontaneously from the substrate, which, in general, is quite decayed. Plain visual examination may lead to consider ‘black crusts’ all similar, whilst only a careful diagnostic investigation can distinguish ‘black crusts’ and the consequences of their formation on stone substrates. In this paper, various black layers on marble are studied and compared and the morphological and compositional characteristics discussed according to the related mechanisms of formation. Differences between old (hundred years) and recent crusts (30 years) are investigated and pointed out.

Materials and methods

Samples of black crusts collected from the Milan Cathedral façade (Candoglia Marble) have been studied and compared with the careful and synergic employ of traditional techniques: optical (transmission and reflected VIS light) and electron microscopy, X-ray spectrometry and micro-Fourier transform infrared spectroscopy.

Results

Visual examination of loose fragments does not allow to point out outstanding differences amongst the various samples; black layers have similar main mineral components, gypsum and airborne particles, with different spatial distribution. The microscopic studies allowed to point out the porosity differences, the gypsum crystallisation habit, different amount of embedded particles, level and progress of marble decay.

Discussion

The observations lead to define three main types of black crusts: black crust deriving from marble sulphation, compact deposit and encrustation due to exogenic materials deposition. Black crusts show evidence of sulphation in progress, without a clear continuity solution between crust and marble; the lack of separation is particularly evident in ‘recent’ crust, where the sulphation process is more active. Black compact deposits show a higher porosity than black crusts because gypsum is not coming from the chemical corrosion of the substrate but from outside; actually, in the former case, the substrate is sound. Encrustations show a highly regular crystal organisation of gypsum (close packed tabular crystals) that cannot be traced back to casual atmospheric deposit or to corrosion of the substrate but rather to the crystallisation of a solution coming from an external source. Also in this case, the marble is sound; evidence of the effect of some protection treatment is pointed out.

Conclusions

In spite of the apparent similarity of the examined samples, analytical results have evidenced three main types of black crusts: black crust with decayed substrate, compact deposit and black encrustation showing a sound substrate underneath. Experimental evidence of calcite grains sulphation in progress, taking place according to a model recently proposed, has been observed. Sulphation process is prevented where particular conservation treatments had been applied in the past.

Recommendations and perspectives

New experimental studies can be focussed to understand the specific conditions (measurements of micro-climatic and thermodynamic parameters) and mechanisms for black crusts formation in situ. The problem of the kinetic of the sulphation process of marble, the assessment of black layers formation in the case of different carbonate stone materials and the study of acid attack in presence of surface protecting layers deserve further investigation.     

Greenwashed sports and environmental activism: Formula 1 and FIFA†

ABSTRACT

Formula 1 motor sport and the Men's World Cup of association football, two major sporting events on our calendars, are indirectly and directly responsible for environmental despoliation. They serve as advertisements for heavy industry, are designed for elite as much as mass consumption, and provide sponsors with dubious social licenses to operate. This occurs through the very mechanisms of the events themselves (engines in Formula 1, tourism in the World Cup) as well as their promotional externalities. I look at greenwashing claims made about these two sporting events and examine counter-discourses, then investigate economic and ecological citizenship. I suggest that a progressive agenda can be forwarded if Greenpeace, which runs campaigns related to these sports, works with its fellow elites, in the case of Formula 1, and with fans in the case of football. Doing so may be more effective than business-as-usual direct action.     

世博会展馆内的空气微生物污染控制

文章研究了世博会展馆内空气微生物污染的控制问题。研究表明,参观人数为400人／小时的情况下,展馆内微生物气溶胶产生量达到44000cfu／h·m^3。空调过滤系统若采用中效过滤,展馆内空气微生物浓度可至4406cfu／m^3,仍超过《室内空气质量标准》2500cfu／m^3的浓度限值,需使用消毒技术净化展馆内空气。增加中效过滤器能够有效去除可吸入颗粒物,有助于降低室内空气微生物浓度。     

上海世博会低碳实践及对中国低碳旅游发展启示

以低碳经济和低碳旅游为视角,全面总结上海世博会在低碳旅游规划、低碳场馆、低碳旅游交通、新能源利用、碳交易机制和平台的建立、城市最佳实践区的设置等方面的经验,以探索符合中国低碳经济特征的低碳旅游发展模式.     

Bolder science needed now for protected areas

Recognizing that protected areas (PAs) are essential for effective biodiversity conservation action, the Convention on Biological Diversity established ambitious PA targets as part of the 2020 Strategic Plan for Biodiversity. Under the strategic goal to “improve the status of biodiversity by safeguarding ecosystems, species, and genetic diversity,” Target 11 aims to put 17% of terrestrial and 10% of marine regions under PA status by 2020. Additionally and crucially, these areas are required to be of particular importance for biodiversity and ecosystem services, effectively and equitably managed, ecologically representative, and well‐connected and to include “other effective area‐based conservation measures” (OECMs). Whereas the area‐based targets are explicit and measurable, the lack of guidance for what constitutes important and representative; effective; and OECMs is affecting how nations are implementing the target. There is a real risk that Target 11 may be achieved in terms of area while failing the overall strategic goal for which it is established because the areas are poorly located, inadequately managed, or based on unjustifiable inclusion of OECMs. We argue that the conservation science community can help establish ecologically sensible PA targets to help prioritize important biodiversity areas and achieve ecological representation; identify clear, comparable performance metrics of ecological effectiveness so progress toward these targets can be assessed; and identify metrics and report on the contribution OECMs make toward the target. By providing ecologically sensible targets and new performance metrics for measuring the effectiveness of both PAs and OECMs, the science community can actively ensure that the achievement of the required area in Target 11 is not simply an end in itself but generates genuine benefits for biodiversity.     

庐山

探讨庐山形成发展过程，描写庐山奇峰、名瀑、绿色植被和宜人气候等优美的自然风光；介绍庐山悠久的历史文化和丰富的人文景观。容地学知识于迷人的山水景色之中，从而增加人们对庐山的认识和旅游的兴趣。庐山于１９９６年被联合国教科文组织批准为“世界文化景观”，列入《世界遗产名录》。     

WTO规则对西部开发的风险及机遇浅探

随着中国加入WTO进程的加快和西部大开发战略的实施，依法治国无疑是改善投资环境、促进西部开发的最有效手段之一。本文根据WTO基本原则与法制经济的相互关系和影响深入浅出地论述了WTO对西部开发的风险及机遇，并提出了针对性的策略和措施。     

Mapping convergence points in the initial emergency response to 9/111

In response to extreme events, researchers have recognised the convergence of volunteers, emergency responders, and other individuals and organisations. In 2000, geographer Paul Routledge presented the concept of convergence spaces as a theoretical means to explain social movements. In applying this concept, this paper explores the geographic space in which organisations and individuals converged immediately following the 11 September 2001 attacks on the World Trade Center. The paper begins to answer the question of whether there were in fact any patterns of convergence among the locations utilised by organisations responding to the attacks. Using data collected from field documents, these geographic locations are mapped over 12 days to help identify possible patterns of clustering. Results of this analysis will begin to provide researchers, policy makers and practitioners with a better understanding of how emergency response evolves geographically following an event.     

Capital allowance schemes for mining projects in LDCs

The capital allowance structure for mining projects in developing countries affects the supply price of investment by determining the payback period, reinvestment and the timing of government receipts. Using the capital allowance structures of Sierra Leone, Tanzania, Zambia, Botswana, Papua New Guinea and Malaysia, the article develops a financial model and examines the effect of capital allowances on foreign investor and host government cash flows under various cost-price conditions. The study stresses the importance to governments of making accelerated depreciation a flexible tool to trade off against other elements in the fiscal package. From the government viewpoint, faster write-offs of capital are preferable to a tax holiday. The article places particular emphasis on evaluating the relationship between capital allowances, income tax and a rent resource tax.