Colloidal rare earth elements in a boreal river: Changing sources and distributions during the spring flood

Variations in the physico-chemical speciation of the rare earth elements (REE) have been investigated in a subarctic boreal river during an intense spring flood event using prefiltered (<100 μm) samples, cross-flow (ultra)filtration (CFF), flow field-flow fractionation (FlFFF), and diffusive gradients in thin films (DGT). This combination of techniques has provided new information regarding the release and transport of the REE in river water. The colloidal material can be described in terms of two fractions dominated by carbon and iron, respectively. These two fractions, termed colloidal carrier phases, showed significant temporal changes in concentration and size distribution. Before the spring flood, colloidal carbon concentrations were low, the colloids being dominated by relatively large iron colloids. Colloidal concentrations increased sharply during the spring flood, with smaller carbon colloids dominating. Following the spring flood, colloidal concentrations decreased again, smaller carbon colloids still dominating. The REE are transported mainly in the particulate and colloidal phases. Before the spring flood, the REE composition of all measured fractions was similar to local till. During the spring flood, the REE concentrations in the colloidal and particulate fractions increased. The increase was most marked for the lighter REE, which therefore showed a strong enrichment when normalized to local till. Following the spring flood, the REE concentrations decreased again and reverted to a distribution similar to local till. These changes in the concentration and distributions of carbon iron and REE are interpreted in terms of changing hydrological flow paths in soil and bedrock which occur during the spring flood.     

Situating local experience of risk: Peripherality, marginality and place identity in the UK foot and mouth disease crisis

Research into exposure to, and experience of, environmental risk that has an explicitly spatial focus can be broadly differentiated into two strands. The first strand focuses on the responses of communities of exposure (or the threat of exposure) to some form of environmental hazard and to the policies put in place by institutional actors to manage the hazard. The second strand addresses social inequalities in exposure to environmental hazards and seeks to correlate uneven spatial distributions of risk across different social groups. It is argued that both strands are limited by their respective understandings of space - and that the way in which vulnerable communities experience environmental risk and its management will be shaped significantly by the complex interactions of different spatialisations or constructions of space. We explore this process by examining accounts of local experience of the UK’s 2001 foot and mouth disease crisis and its management in terms of the interplay of two different spatialisations: socio-cultural marginality and political-economic peripherality. We trace the relationship between these cultural and political-economic spatialisations through an analysis of the discursive mobilisation of contrasting place rhetorics. We conclude that focusing on these rhetorics can enhance our understanding of the spatial processes which are constitutive of place identity and in turn mediate the experience of environmental risk and its management.     

‘Imagineering’ Asian emerging markets: Financial knowledge networks in the fund management industry

This paper examines knowledge production networks in the fund management industry. Focusing on Asian emerging markets (EMs), I explore how fund managers, brokers and research analysts utilise a combination of texts, analytical structures, codified procedures, and social networks to generate interpretations and perspectives on Asian EMs. Utilising a process-based approach, I investigate how ‘EMs’ as an investment category is imagined and practiced by those in the fund management industry through knowledge networks and how such networks are produced and maintained. Discussions are drawn from interviews conducted with 22 EMs specialists in Singapore and London. I argue that Asian EMs have distinct characteristics that are acted upon and reproduced by finance workers in particular ways and that the acquisition and transfer of tacit knowledge takes on increased significance when codified knowledge structures are lacking. Actors in Singapore and London are also embedded in different knowledge networks, which offer different strategic advantages but, when taken together, form a complex and multi-layered knowledge production network of ‘imagineering’ Asian EMs from both within and outside of Asia.     

Monazite–xenotime thermochronometry: methodology and an example from the Nepalese Himalaya

Monazite-xenotime thermochronometry involves the integration of petrographic, geochronological, and geochemical techniques to explore the thermal evolution of igneous and metamorphic rocks containing these accessory minerals. The method is illustrated in this paper by application to an orthogneiss sample from the Everest region of the Nepalese Himalaya that contains leucogranitic segregations produced by in-situ anatexis. Observations of phase relationships and the internal structure of accessory minerals made using both transmitted light and electron microscopy revealed the existence of multiple generations of monazite and xenotime and guided microsampling efforts to isolate grain fragments of Himalayan (Tertiary) and pre-Himalayan age. Nearly concordant U-Pb isotopic ratios for 13 single monazite and xenotime grains ranged in age from 28.37 to 17.598 Ma, making determination of the timing of anatexis difficult without additional information. Presuming that monazite and xenotime were in equilibrium over that entire interval, temperatures estimated from the yttrium contents of dated monazites range from 677-535 °C. Only the highest temperatures are consistent with experimental constraints on the conditions necessary to produce anatectic melts of appropriate composition, implying that the ~25.4-24.8 Ma dates for the grains with high apparent equilibration temperatures provide the best estimates for the age of anatexis. Two monazite crystals yielded ²⁰⁷Pb/²³⁵U dates that are statistically indistinguishable from the ²⁰⁷Pb/²³⁵U dates of coexisting xenotime crystals, permitting the application of both quantitative Y-partitioning and semi-quantitative Nd-partitioning thermometers as a cross-check for internal consistency. One of these sub-populations of accessory minerals, with a mean ²⁰⁷Pb/²³⁵U date of 22.364ǂ.097 Ma, provides inconsistent Y-partitioning (641ᆻ °C) and Nd-partitioning (515-560 °C) temperatures. We suspect the discrepancy may be caused by the high Th concentration (6.12 wt% ThO₂) in this subpopulation's monazite. The Y-partitioning thermometer was derived from experimental data for the (Ce, Y)PO₄ binary and may be inappropriate for application to high-Th monazites. For the other subpopulation (mean ²⁰⁷Pb/²³⁵U date=22.11ǂ.22 Ma), the Y- and Nd-partitioning temperatures are indistinguishable: 535ᇅ and 525-550 °C, respectively. This consistency strongly suggests that the sample experienced a temperature of ~535 °C at 22.11 Ma. This finding is tectonically important because temperatures at higher structural levels were much higher (by ~100 °C) at the same time, lending support to earlier suggestions of a major structural discontinuity within the upper part of the Himalayan metamorphic core at this longitude. An additional finding of uncertain importance is that inherited monazite and xenotime yielded U-Pb discordia with indistinguishable upper intercept ages (465.5NJ.7 and 470ᆟ Ma, respectively) and application of the Y-partitioning thermometer to the inherited monazites produced a restricted range of model temperatures averaging 470 °C. Whether or not these temperatures are geologically meaningful is unclear without independent corroboration of the assumption of equilibrium between the inherited monazites and xenotimes, but it appears that monazite-xenotime thermochronometry may be useful for "seeing through" high-grade metamorphism to extract temperature-time information about inherited mineral suites.     

The Near Infrared Spectrum of Miranda: Evidence of Crystalline Water Ice

A spectrum from 1.2 to 2.5 μm of Uranus' small satellite Miranda obtained in June 1999 reveals strong water-ice signatures. It confirms the existence of a 2.0-μm water feature previously detected on Miranda and shows a strong second broad 1.5-μm water-ice absorption feature. The spectra also reveal a weak absorption band at 1.65 μm that is indicative of crystalline water ice. Reflectance models which combine the new spectra with new photometry indicate that the spectra are characteristic of a mostly water-ice surface, with a large fraction of carbonaceous or silicate contaminates, and the possible presence of ammonia hydrate, as implied by an apparent weak feature near 2.2 μm. The possible presence of other volatiles is also investigated.     

Women in geography in the 21st century. Introductory Remarks: Structure,Agency, and Women Geographers in Academia at the End of the Long Twentieth Century

This paper provides an introduction to the set of articles presented in the focus section Women in Geography in the 21st Century. The paper argues that feminist geographers should view their professional biographies in a structure‐agency context. Such a theoretical perspective views events that are commonly thought to be unique and attributable to individual merit or foible as the outcome instead of interactions between actors and social structures. Creating genuinely equal opportunities in geography departments for women and others who are different from the able‐bodied, middle‐class, white heterosexual male model of “the geographer” depends upon challenges to and transformations of the structures which bear on the discipline, rather than solely upon individual initiative.     

Interpreting the Viking Age to Medieval period transition in Norse Orkney through cultural soil and sediment analyses

The transition from the Viking Age (ca. A.D. 800–1050) to the Medieval period (ca. A.D. 1050–1500) saw the development of widening trade activities that incorporated peripheral North Atlantic polities into mainstream Europe and contributed to the intensification of marineresource exploitation and agricultural production in these localities. As yet, there is only limited understanding of these intensification processes and their interrelationships, particularly at a local, site‐based level. Through the micromorphological analysis of cultural soils and sediments at Quoygrew, Westray, Orkney, we explore the characteristics of farming and fishing activity during the Viking Age–Medieval transition period and establish their chronological relationships. The study demonstrates: (1) that intensification took place from ca. A.D. 966–1162 on an already existing Viking Age settlement, (2) that intensification of fishing activity occurred prior to the intensification of arable agriculture, and (3) that the Quoygrew site continued throughout this period as an economically diverse permanent settlement. When viewed in a wider North Atlantic context, these findings indicate that intensification of different economic activities proceeded at different rates and that intensification of specialized economic activities during the transition from the Viking Age to the Medieval period was dependent on existing knowledge of local environments. © 2005 Wiley Periodicals, Inc.     

‘The forest is our inheritance’: An introduction to Semai Orang Asli place‐naming and belonging in the Bukit Tapah Forest Reserve

The forest realm of the Gòòl‐War watershed of southeast Perak, Malaysia holds much socio‐cultural significance to the Semai Orang Asli communities living along these rivers. Notwithstanding its present‐day location within the Bukit Tapah Forest Reserve, the forest continues to be where Semai conceptions of history and lore are encoded in the geographical particulars of the landscape. A thriving forest‐dependent lifestyle maintains and transmits Semai place knowledge, observed in this research through people's command of ancestral place‐names. This paper provides an introduction to Semai toponymy and considers the implications of indigenous place‐names on the protection of indigenous homelands and ways of life.