Survey of waste water disposal practices at Antarctic research stations

To inform the future practices to be employed for handling waste water and grey water at the Swedish Antarctic station, Wasa, in Dronning Maud Land, the Swedish Polar Research Secretariat took the initiative to survey the practices of the 28 nations with stations in Antarctica. A questionnaire was sent out to all members of the Antarctic Environment Officers Network during the autumn of 2005. Questions were asked about the handling of waste water and grey water, the type of sewage treatment, and installation and operational costs. The response to the questionnaire was very good (79%), and the results showed that 37% of the permanent stations and 69% of the summer stations lack any form of treatment facility. When waste water and grey water containing microorganisms are released, these microorganisms can remain viable in low-temperature Antarctic conditions for prolonged periods. Microorganisms may also have the potential to infect and cause disease, or become part of the gut flora of local bird and mammal populations, and fish and marine invertebrates. The results from 71 stations show that much can still be done by the 28 nations operating the 82 research stations in Antarctica. The technology exists for effective waste water treatment in the challenging Antarctic conditions. The use of efficient technology at all permanent Antarctic research stations would greatly reduce the human impact on the pristine Antarctic environment. In order to protect the Antarctic environment from infectious agents introduced by humans, consideration should also be given to preventing the release of untreated waste water and grey water from the smaller summer stations.     

Memento Mori: The “Death” of Youngtown

Youngtown, Arizona, was founded in 1954 as the nation's first retirement community, presaging the original Sun City (1960) and subsequent proliferation of active-adult communities across America. Youngtown, whose attractiveness waned owing to competition from more upscale, amenity-rich communities, suffered a fatal blow in 1998. Legal issues led to the loss of age restrictions, ushering in a swift and dramatic transformation of Youngtown from retirement enclave to working-class community, as Youngtown was overwhelmed by powerful social currents coursing through the Phoenix metropolitan region: explosive population growth, suburban sprawl, Latinization, and voracious demand for affordable housing. We tell the story of the life and death of Youngtown as a retirement haven, including the response of seniors to the loss in community identity: out-migration, anger, depression, and eventual acceptance among older people who linger. Insular, freeze-frame dreams of community identity and stability common among seniors in retirement enclaves ultimately prove chimerical in the face of urban change. The death of Youngtown as retiree haven, viewed in the sweep of shifting cultural attitudes about aging, may be a harbinger, the opening notes in a requiem for de jure retirement communities.     

(Re)constructing rural–urban spaces: gendered livelihoods,migration, and natural resources in South Africa

Critical approaches to development theory and practice provide alternative perspectives that focus on counterhegemonic and discursive dimensions of the development process. Feminist development is one such approach that opens up new spaces and opportunities to promote socially progressive and sustainable economic strategies. This paper uses feminist development geography as a framework to highlight the intersection of diverse spaces and economic strategies at the household and community levels. The analysis focuses on gendered livelihoods that are linked to circular migration and use of natural resources as a way to understand the integration of rural and urban spaces of development. The empirical section of this paper examines demographic patterns and socio-economic trends in Limpopo Province, South Africa as a context for the case study of two community-based women’s producer groups. These examples illustrate how economic strategies and social identities are embedded in and integrate both rural and urban spaces. This analysis contributes to feminist and post-structural development theory and practice by highlighting the potential for progressive forms of economic and social empowerment.     

NanoSIMS isotopic analysis of small presolar grains: Search for Si3N4 grains from AGB stars and Al and Ti isotopic compositions of rare presolar SiC grains

We report isotopic ratio measurements of small SiC and Si₃N₄ grains, with special emphasis on presolar SiC grains of type Z, and new nucleosynthesis models for ²⁶Al/²⁷Al and the Ti isotopic ratios in asymptotic giant branch (AGB) stars. With the NanoSIMS we analyzed 310 SiC grains from Murchison (carbonaceous CM2 chondrite) separate KJB (diameters 0.25-0.45 μm) and 153 SiC grains from KJG (diameters 1.8-3.7 μm), 154 SiC and 23 Si₃N₄ grains from Indarch (enstatite EH4 chondrite) separate IH6 (diameters 0.25-0.65 μm) for their C and N isotopic compositions, 549 SiC and 142 Si₃N₄ grains from IH6 for their C and Si isotopic compositions, 13 SiC grains from Murchison and 66 from Indarch for their Al-Mg compositions, and eight SiC grains from Murchison and 10 from Indarch for their Ti isotopic compositions. One of the original objectives of this effort was to compare isotopic analyses with the NanoSIMS with analyses previously obtained with the Cameca IMS 3f ion microprobe. Many of the Si₃N₄ grains from Indarch have isotopic anomalies but most of these apparently originate from adjacent SiC grains. Only one Si₃N₄ grain, with ¹³C and ¹⁴N excesses, has a likely AGB origin. The C, N, and Si isotopic data show that the percentage of SiC grains of type Y and Z increase with decreasing grain size (from ∼1% for grains >2 μm to ∼5-7% for grains of 0.5 μm), providing an opportunity for isotopic analyses in these rare grains. Our measurements expand the number of Al-Mg analyses on SiC Z grains from 4 to 23 and the number of Ti analyses on Z grains from 2 to 11. Inferred²⁶Al/²⁷Al ratios of Z grains are in the range found in mainstream and Y grains and do not exceed those predicted by models of AGB nucleosynthesis. Cool bottom processing (CBP) has been invoked to explain the low ¹²C/¹³C ratios of Z grains, but this process apparently does not lead to increased ²⁶Al production in the parent stars of these grains. This finding is in contrast to presolar oxide grains where CBP is needed to explain their high ²⁶Al/²⁷Al ratios. The low ^46,47,49Ti/⁴⁸Ti ratios found in Z grains and their correlation with low ²⁹Si/²⁸Si ratios extend the trend seen in mainstream grains and confirm an origin in low-metallicity AGB stars. The relatively large excesses in ³⁰Si and ⁵⁰Ti in Z grains are predicted by our models to be the result of increased production of these isotopes by neutron-capture nucleosynthesis in low-metallicity AGB stars. However, the predicted excesses in ⁵⁰Ti (and ⁴⁹Ti) are much larger than those found. Even lowering the strength of the ¹³C pocket cannot solve this discrepancy in a consistent way.     

CI-Miner: semantically enhancing scientific processes

The realization of an international cyberinfrastructure of shared resources to overcome time and space limitations is challenging scientists to rethink how to document their processes. Many known scientific process requirements that would normally be considered impossible to implement a few years ago are close to becoming a reality for scientists, such as large scale integration and data reuse, data sharing across distinct scientific domains, comprehensive support for explaining process results, and full search capability for scientific products across domains. This article introduces the CI-Miner approach that can be used to aggregate knowledge about scientific processes and their products through the use of semantic annotations. The article shows how this aggregated knowledge is used to benefit scientists during the development of their research activities. The discussion is grounded on lessons learned through the use of CI-Miner to semantically annotate scientific processes in the areas of geo-sciences, environmental sciences and solar physics: A use case in the field of geo-science illustrates the CI-Miner approach in action.     

An adaptive mesh refinement algorithm for compressible two-phase flow in porous media

We describe a second-order accurate sequential algorithm for solving two-phase multicomponent flow in porous media. The algorithm incorporates an unsplit second-order Godunov scheme that provides accurate resolution of sharp fronts. The method is implemented within a block structured adaptive mesh refinement (AMR) framework that allows grids to dynamically adapt to features of the flow and enables efficient parallelization of the algorithm. We demonstrate the second-order convergence rate of the algorithm and the accuracy of the AMR solutions compared to uniform fine-grid solutions. The algorithm is then used to simulate the leakage of gas from a Liquified Petroleum Gas (LPG) storage cavern, demonstrating its capability to capture complex behavior of the resulting flow. We further examine differences resulting from using different relative permeability functions.     

Effects of seawater carbonate ion concentration and temperature on shell U, Mg, and Sr in cultured planktonic foraminifera

We investigate the sensitivity of U/Ca, Mg/Ca, and Sr/Ca to changes in seawater [CO₃²⁻] and temperature in calcite produced by the two planktonic foraminifera species, Orbulina universa and Globigerina bulloides, in laboratory culture experiments. Our results demonstrate that at constant temperature, U/Ca in O. universa decreases by 25 ± 7% per 100 μmol [CO₃²⁻] kg⁻¹, as seawater [CO₃²⁻] increases from 110 to 470 μmol kg⁻¹. Results from G. bulloides suggest a similar relationship, but U/Ca is consistently offset by ∼+40% at the same environmental [CO₃²⁻]. In O. universa, U/Ca is insensitive to temperature between 15°C and 25°C. Applying the O. universa relationship to three U/Ca records from a related species, Globigerinoides sacculifer, we estimate that Caribbean and tropical Atlantic [CO₃²⁻] was 110 ± 70 μmol kg⁻¹ and 80 ± 40 μmol kg⁻¹ higher, respectively, during the last glacial period relative to the Holocene. This result is consistent with estimates of the glacial-interglacial change in surface water [CO₃²⁻] based on both modeling and on boron isotope pH estimates. In settings where the addition of U by diagenetic processes is not a factor, down-core records of foraminiferal U/Ca have potential to provide information about changes in the ocean’s carbonate concentration.Below ambient pH (pH < 8.2), Mg/Ca decreased by 7 ± 5% (O. universa) to 16 ± 6% (G. bulloides) per 0.1 unit increase in pH. Above ambient pH, the change in Mg/Ca was not significant for either species. This result suggests that Mg/Ca-based paleotemperature estimates for the Quaternary, during which surface-ocean pH has been at or above modern levels, have not been biased by variations in surface-water pH. Sr/Ca increased linearly by 1.6 ± 0.4% per 0.1 unit increase in pH. Shell Mg/Ca increased exponentially with temperature in O. universa, where Mg/Ca = 0.85 exp (0.096*T), whereas the change in Sr/Ca with temperature was within the reproducibility of replicate measurements.     

菲律宾Zambales蛇绿岩套的再研究：对其特提斯来源的启示

A number of geological studies have already been conducted on the Zambales Ophiolite Complex (ZOC), a north-south trending complete ophiolite sequence exposed in the western portion of Central Luzon, Philippines. Previous works recognized the ZOC as being made up of two blocks, the Acoje and the Coto, acting as an arc-back arc pair sometime during the Eocene.