High Resolution Deterministic Prediction System (HRDPS) Simulations of Manitoba Lake Breezes

The Effects of Lake Breezes On Weather–Manitoba (ELBOW-MB) field project, conducted around Lakes Manitoba and Winnipeg in July 2013, was the first in-depth field study of lake breezes in Manitoba, Canada. Using observational data collected during ELBOW-MB and output from the 2.5?km Canadian High Resolution Deterministic Prediction System (HRDPS), comparisons were made between HRDPS output and observational data to determine whether the HRDPS can simulate Manitoba lake breezes. The model comparisons considered various lake-breeze characteristics, such as depth, inland penetration distance, and initiation and dissipation time. In addition, cross-sections of lake-breeze circulations were analyzed. The results show that the HRDPS was able to correctly simulate lake breezes, or lack thereof, in 78% of cases on Lake Winnipeg and 68% of cases on Lake Manitoba. Modelled lake-breeze initiation and dissipation times were found to be too early in some cases and too late in others when compared with observations. Overall, it was found that the HRDPS was able to simulate most aspects of lake breezes, although inland penetration distance was one characteristic that the HRDPS was not able to simulate realistically.     

Splintered networks: The colonial and contemporary waters of Jakarta

This paper queries the relevance of the ‘splintering urbanism’ thesis to postcolonial cities of the South, and responds to calls for the production of a decentered theory of urbanization through a case study of Jakarta. Drawing on archival and interview data, the paper demonstrates that Jakarta has, since its inception, been characterized by a high degree of differentiation of access to water supply, and of fragmentation of water supply networks. We document the origins of this fragmentation in the colonial era, and trace the legacy of the colonial constructions within the postcolonial city. Moreover, we demonstrate that the introduction of private sector management (in 1988) has not significantly disrupted, and certainly not caused, this pattern. In short, we provide evidence to support our claim that Jakarta’s water supply system is ‘splintered’ rather than ‘splintering’, and demonstrate that this phenomenon was not caused by the rise (or fall) of the ‘modern infrastructural ideal’. In order to explain this sustained fragmentation of infrastructure and access, the paper develops a conceptual framework of postcolonial governmentality that emphasizes the interrelationship between materiality, governmentality, identity, and urbanization, in particular through demonstrating how contested and evolving process of social differentiation are linked to the differentiation of water supply infrastructures and of urban spaces. Although we are wary of any simplistic comparisons between the colonial past and present, we argue that the optic of postcolonial governmentality provides a powerful lens for dissecting the power relations that continue to structure access to water supply and urban space in cities in the South.     

Abiotic reduction of uranium by Fe(II) in soil

Structural Fe(II) has been shown to reduce several oxidized environmental contaminants, including NO₃, chlorinated solvents, Cr(VI), and U(VI). Studies investigating reduction of U(VI) by soils and sediments, however, suggest that abiotic reduction of U(VI) by Fe(II) is not significant, and that direct enzymatic reduction of U(VI) by metal-reducing bacteria is required for U(VI) immobilization as U(IV). Here evidence is presented for abiotic reduction and immobilization of U(VI) by structural Fe(II) in a redoximorphic soil collected from a hillside spring in Iowa. Oxidation of Fe(II) in the soil after reaction with U(VI) was demonstrated by Mössbauer spectroscopy and reduction of U(VI) by the pasteurized soil using U L_III-edge X-ray absorption spectroscopy (XAS). XAS indicates that both reduced U(IV) and oxidized U(VI) or U(V) are present after U(VI) interaction with the Fe(II) containing soil. The EXAFS data show the presence of a non-uraninite U(IV) phase and evidence of the oxidized U(V) or U(VI) fraction being present as a non-uranyl species. Little U(VI) reduction is observed by soil that has been exposed to air and oxidation of Fe(II) to goethite has occurred. Soil characterization based on chemical extractions, Mössbauer spectroscopy, and Fe K-edge XAS indicate that the majority of Fe(II) in the soil is structural in nature, existing in clay minerals and possibly a green rust-like phase. These data provide compelling evidence for abiotic reduction of U(VI) by structural Fe(II) from soil near Fe-rich oxic–anoxic boundaries in natural environments. The work highlights the potential for abiotic reduction of U(VI) by Fe(II) in reduced, Fe-rich environments.     

Advance,deglacial and sea‐level chronology for Foxe Peninsula,Baffin Island,Nunavut

The impact of the Laurentide Ice Sheet (LIS) deglaciation on Northern Hemisphere early Holocene climate can be evaluated only once a detailed chronology of ice history and sea‐level change is established. Foxe Peninsula is ideally situated on the northern boundary of Hudson Strait, and preserves a chronostratigraphy that provides important glaciological insights regarding changes in ice‐sheet position and relative sea level before and after the 8.2 ka cooling event. We utilized a combination of radiocarbon ages, adjusted with a new locally derived ΔR, and terrestrial in‐situ cosmogenic nuclide (TCN) exposure ages to develop a chronology for early‐Holocene events in the northern Hudson Strait. A marine limit at 192 m a.s.l., dated at 8.1–7.9 cal. ka BP, provides the timing of deglaciation following the 8.2 ka event, confirming that ice persisted at least north of Hudson Bay until then. A moraine complex and esker morphosequence, the Foxe Moraine, relates to glaciomarine outwash deltas and beaches at 160 m a.s.l., and is tightly dated at 7.6 cal. ka BP with a combination of shell dates and exposure ages on boulders. The final rapid collapse of Foxe Peninsula ice occurred by 7.1–6.9 cal. ka BP (radiocarbon dates and TCN depth profile age on an outwash delta), which supports the hypothesis that LIS melting contributed to the contemporaneous global sea‐level rise known as the Catastrophic Rise Event 3 (CRE‐3).     

Statistical testing of a new testate amoeba‐based transfer function for water‐table depth reconstruction on ombrotrophic peatlands in north‐eastern Canada and Maine,United States

Proxy reconstructions of climatic parameters developed using transfer functions are central to the testing of many palaeoclimatic hypotheses on Holocene timescales. However, recent work shows that the mathematical models underpinning many existing transfer functions are susceptible to spatial autocorrelation, clustered training set design and the uneven sampling of environmental gradients. This may result in over‐optimistic performance statistics or, in extreme cases, a lack of predictive power. A new testate amoeba‐based transfer function is presented that fully incorporates the new recommended statistical tests to address these issues. Leave‐one‐out cross‐validation, the most commonly applied method in recent studies to assess model performance, produced over‐optimistic performance statistics for all models tested. However, the preferred model, developed using weighted averaging with tolerance downweighting, retained a predictive capacity equivalent to other published models even when less optimistic performance statistics were chosen. Application of the new statistical tests in the development of transfer functions provides a more thorough assessment of performance and greater confidence in reconstructions based on them. Only when the wider research community have sufficient confidence in transfer function‐based proxy reconstructions will they be commonly used in data comparison and palaeoclimate modelling studies of broader scientific relevance. Copyright © 2012 John Wiley & Sons, Ltd.     

Land, ethnic, and gender change: Transnational migration and its effects on Guatemalan lives and landscapes

Migration to the United States of America from Guatemala effects many aspects of Guatemalan life. We document, through extensive ethnographic fieldwork, how migrants and their remittances effect gender relations, ethnicity, land use, and land distribution. Our evidence is drawn from research in four communities. San Pedro Pinula and Gualán represent communities of eastern Guatemala. San Cristóbal Totonicapán is an Indigenous town in Guatemala’s western highlands, and San Lucas is a lowland frontier community in the Guatemalan department of Ixcán, which borders Chiapas, Mexico. Our results reveal that migrants and their remittances, both social and tangible, result in significant changes in land use and land distribution in Ixcán. Migrant money permits the conversion of rainforest into cattle pasture and also results in the accumulation of land in the hands of migrants. In terms of land use, we see in San Pedro Pinula that migrant money also allows the Pokoman Maya to make small entries into the Ladino (non-indigenous) dominated cattle business. In San Pedro Pinula, the migration and return of Maya residents also permits them to slowly challenge ethnic roles that have developed over the last five centuries. When we look at how migration effects gender roles in Gualán and San Cristóbal we also note that migration and social remittances permit a gradual challenge and erosion of traditional gender roles in Guatemala. We point out, however, that migration-related changes to traditional gender and ethnic roles is gradual because migrants, despite their increased earnings and awareness, run into a social structure that resists rapid change. This is not the case when we examine land transformations in Ixcán. Here, migrants encounter few barriers when they attempt to put their new money and ideas to work. Despite the advantages that migration brings to many families, especially in the face of a faltering national economy and state inactivity regarding national development, we conclude that migration and remittances do not result in community or nation-wide development. At this stage migrant remittances are used for personal advancement and very little money and effort is invested in works that benefit communities or neighborhoods. We call for continued studies of the effects of international migration on Guatemalan hometowns that build on our initial studies to better understand the longer-term ramifications of migration in a country where no community is without migrants.     

A 12,000-Year Pollen Record from Lake Maliq, Albania

Pollen data from Lake Maliq, the first from Albania, contribute new information to the discussion of the vegetational, hydrological, and climatological history of the Balkans since 12,000 yr B.P. During late-glacial time, a perennial lake expanded at Maliq. It was surrounded by a complex vegetation association composed of steppe and mixed forest elements. The highly diverse forest flora suggest that late-glacial forest refugia were more developed here at middle altitude, rather than at higher altitude as previously suggested. The forest developed after 9800 yr B.P., while the water level remained high in the Korçë basin until 5000 yr B.P. Different environmental conditions, characterized by lower available moisture and warmer winters, progressively took place after this date. Human activity in the Korçë basin ca. 4500 yr B.P. was coeval with conditions characterized by an increase in winter temperatures and a decrease in summer moisture.