Merging science into community adaptation planning processes: a cross-site comparison of four distinct areas of the Lower Mekong Basin

Climate change is increasingly affecting rural areas worldwide. The Lower Mekong Basin (LMB) is at particular risk due to heat stress, changing rainfall patterns, rising sea levels, and more frequent and extreme climatic events. It is imperative that local-level adaptation plans are developed in a manner that builds resilience to these growing threats. Strategies for developing adaptation plans tend to comprise predominantly science-led or predominantly community-led processes. This study examines an approach that balances inputs from both processes in characterizing community vulnerability as a component of the adaptation planning workflow. Evaluation sites are located within four distinct sub-regions of the LMB: the Vietnam Mekong Delta, the Annamite Mountains of Lao PDR, the Cambodia central lowlands, and the mid-elevation forests of northern Thailand. Our results indicate that by merging science-based data with community-level perspective, knowledge gaps from both sides are filled and a more comprehensive understanding of vulnerability is factored into adaptation planning.     

Energy balance in urban Mexico City: observation and parameterization during the MILAGRO/MCMA-2006 field campaign

The parameterization of the energy balance from a residential and commercial neighborhood of Mexico City was investigated using direct measurements of radiative and heat fluxes carried out during the MILAGRO/MCMA-2006 field campaign as a reference. The measured fluxes were used to evaluate different models of the energy balance based on parameterizations that require standard meteorological observations: ambient temperature, relative humidity, atmospheric pressure and cloudiness. It was found that these models reproduce with reasonable accuracy the diurnal features of the radiative and heat fluxes. The largest differences between modeled and observed fluxes correspond to the incoming longwave radiation, mainly due to errors in the cloudiness data. This paper contributes to the understanding of the energy partitioning in (sub)tropical urban environments, particularly in the developing world, where energy balance models have not been evaluated.     

Glass-bearing plutonic fragments from ignimbrites of the Okataina caldera complex, Taupo Volcanic Zone, New Zealand: remnants of a partially molten intrusion associated with preceding eruptions

Glass-bearing plutonic fragments occur as rare accessory lithics within the ca. 64 ka Rotoiti and Earthquake Flat ignimbrites that were erupted from Okataina caldera complex, Taupo Volcanic Zone, New Zealand. Granitoid lithic fragments are only found in the Rotoiti ignimbrite and fall into two groups. Group 1 granitoids have textures consistent with a period of slow cooling followed by rapid quenching, and were excavated by the Rotoiti eruption from a single incompletely solidified magma body. Although isotopic ratios for the Group 1 granitoids are similar to the host ignimbrite, they are not cognate, having different chemistry, mineralogy, mineral chemistry and crystallisation history. It is more likely that they represent fragments of a separate incompletely solidified magma chamber that was intercepted by the erupting Rotoiti ignimbrite magma. Low LILE and high HFSE abundances favour a comagmatic link with the ca. 0.28 Ma Matahina ignimbrite and it is suggested they are derived from an isolated cupola of the Matahina magma chamber that remained at depth (between 3.5 and 5 kbar pressure) after eruption of the Matahina ignimbrite. Migration toward the surface probably accompanied development of the Rotoiti magma system in the upper crust. Most geochemical variation in Group 1 granitoids is related to the abundance of biotite, the concentration of which is controlled by differential shear. REE abundance is controlled by light REE-enriched accessory minerals preferentially included within biotite. Although Eu_n remains constant in the Group 1 granitoids, Eu/Eu^* varies systematically with (La/Yb)_n and is controlled by variations in Sm and Gd rather than in Eu. Group 2 granitoid fragments have a wide range of composition, comparable to many Okataina rhyolites, including those found as lithic fragments in the Rotoiti ignimbrite. Rare microdiorite fragments occur in both Rotoiti and Earthquake Flat ignimbrites and typically contain vesicular interstitial glass indicating that they were incompletely solidified prior to eruption. Those from the Rotoiti ignimbrite are comparable to the (>64 ka) Matahi basaltic tephra and probably represent part of the same magmatic event which generated the Matahi tephra.     

In situ U-series dating by laser-ablation multi-collector ICPMS: new prospects for Quaternary geochronology

The capabilities and potential applications of in situ dating of Quaternary materials using laser ablation-MC-ICPMS are explored. ²³⁴U/²³⁸U and ²³⁰Th/²³⁴U can be measured with precision sufficient for dating at a spatial resolution of 100 μm or better in samples that contain as a little as 1 ppm uranium. Moreover, U and Th concentrations and U-series isotope ratios can be continuously profiled to determine changes in age that occur with sample growth (e.g. in speleothems). These capabilities additionally permit the dating of bones, teeth and possibly molluscs, which are subject to post-mortem open-system behaviour of U-series isotopes, and can be employed to elucidate processes of U-series migration during weathering and diagenesis. A drawback of laser ablation-MC-ICPMS is that it cannot in general provide U-series age estimates with the high precision and accuracy of conventional TIMS or solution MC-ICPMS methods. However, sample preparation is straightforward, the amount of sample consumed negligible, and it can be used to rapidly characterise or screen and select samples from which more precise and accurate dates can be obtained using conventional methods. Given further instrumental developments and the establishment of suitable matrix-matched standards for carbonates and other materials, we foresee that laser ablation-MC-ICPMS will play an increasingly important role in Quaternary dating research.     

Geographic EducationResearch and the Changing Institutional Structure of American Education

Professional geographers are paying increasing attention to the development of a research agenda concerning geographic education. In doing so, it is essential that geographers pay close attention to fundamental changes in the structure of education itself. Traditional educational methods and procedures associated with industrial society are being replaced by new and innovative modes of education that are linked to post-industrial social organization. This article explores the implications of these changes for understanding the teaching and learning of geography in the future.     

Estimating aquifer channel recharge using optical data interpretation

Recharge through intermittent and ephemeral stream channels is believed to be a primary aquifer recharge process in arid and semiarid environments. The intermittent nature of precipitation and flow events in these channels, and their often remote locations, makes direct flow and loss measurements difficult and expensive. Airborne and satellite optical images were interpreted to evaluate aquifer recharge due to stream losses on the Frio River in south-central Texas. Losses in the Frio River are believed to be a major contributor of recharge to the Edwards Aquifer. The results of this work indicate that interpretation of readily available remote sensing optical images can offer important insights into the spatial distribution of aquifer recharge from losing streams. In cases where upstream gauging data are available, simple visual analysis of the length of the flowing reach downstream from the gauging station can be used to estimate channel losses. In the case of the Frio River, the rate of channel loss estimated from the length of the flowing reach at low flows was about half of the loss rate calculated from in-stream gain-loss measurements. Analysis based on water-surface width and channel slope indicated that losses were mainly in a reach downstream of the mapped recharge zone. The analysis based on water-surface width, however, did not indicate that this method could yield accurate estimates of actual flow in pool and riffle streams, such as the Frio River and similar rivers draining the Edwards Plateau.     

Methods for Evaluation of Geodetic Data and Seismicity Developed with Numerical Simulations: Review and Applications

In this work we review the development of both established and innovative analytical techniques using numerical simulations of the southern California fault system and demonstrate the viability of these methods with examples using actual data. The ultimate goal of these methods is to better understand how the surface of the Earth is changing on both long-and short-term time scales, and to use the resulting information to learn about the internal processes in the underlying crust and to predict future changes in the deformation and stress field. Three examples of the analysis and visualization techniques are discussed in this paper and include the Karhunen-Loeve (KL) decomposition technique, local Ginsberg criteria (LGC) analysis, and phase dynamical probability change (PDPC). Examples of the potential results from these methods are provided through their application to data from the Southern California Integrated GPS Network (SCIGN), historic seismicity data, and simulated InSAR data, respectively. These analyses, coupled with advances in modeling and simulation, will provide the capability to track changes in deformation and stress through time, and to relate these to the development of space-time correlations and patterns.     

Complex speleothem growth processes revealed by trace element mapping and scanning electron microscopy of annual layers

Closely-spaced transects measured by excimer laser ablation inductively-coupled plasma mass spectrometry (ELA-ICPMS) at 5 and 32 μm spatial resolution are used to generate trace element composition maps (Ba, Sr, Mg, U, Na, P and Al) from MND-S1, a previously studied modern stalagmite from southwest Australia (Treble et al., 2003: EPSL216: 141). Rainfall at the site is highly seasonal, and trace elements in MND-S1 show strong seasonal variation. Trace element maps show that Ba, Sr, U and Na concentrations coherently follow annual growth layers identified from Scanning Electron Microscopy (SEM) images. The SEM images also reveal that stalagmite growth did not proceed uniformly: growth layers vary in thickness and locally pinch out. Highly preferential crystal growth, determined by nucleation sites left by the previous year’s growth, may be responsible for this uneven growth layering. Differential crystal growth apparently causes variability of trace element concentrations along each annual layer, although additional disequilibrium processes affect Mg, which is less distinctly banded than Ba, Sr, U and Na. Uneven and discontinuous growth layers influence the number of annual cycles, their wavelengths and seasonal amplitudes measured in any one transect. This has clear implications for studies that use annual trace element cycles as chronological markers, growth rate or seasonality proxies.