Migration in a transitional economy: Beyond the planned and spontaneous dichotomy in Vietnam

Migration is frequently portrayed as a negative force in its relationship with economic and social development. This negative perception is exhibited through describing population movements as either ‘forced’ (e.g. political and environmental refugees) or ‘voluntary’ movements (e.g. economic and uninhibited relocation). This paper examines the limitations of this conceptual dualism. It points out that the dualistic approach, widely used in the context of developing countries, simplifies a highly complex phenomenon by ignoring its essential heterogeneity and spatial and temporal dynamics. As such, it is limited in explaining and understanding the globally diversified, historically and politically contextualised situations. Focusing on the migratory experiences of contemporary Vietnam, the study identifies major patterns and trends of population mobility in the country in the past fifty years. It shows that despite the state’s continued attempts to reshape the spatial distribution of population over recent historical periods, the policy outcomes with respect to population mobility have been swayed as much by individuals and their families in pursuit of their own aspirations and livelihoods as by state plans. The Vietnam case has provided evidence of a much more complicated relationship between migration and livelihoods than the conceptual dichotomy assumes, and the opportunity for a richer set of policy options. We argue that the evidence from Vietnam, and elsewhere, warrants an integrated approach to studying migration, combining analysis at the macro- and micro-levels with the nexus lying at the critical decision-making point of the individual or household.     

Evaluating the anthropogenic impacts on groundwaters; a methodology based on the determination of natural background levels and threshold values

The present work investigates the long-term effects of human intervention on groundwaters based on the determination of natural background levels (NBLs) and threshold values (TVs) for groundwater electrical conductivity, chloride, ammonium, sulphates and nitrates. The methodology adopted is the one proposed in the 6th Framework European Project ??BRIDGE??, which was applied with some adjustments in Rhodope area (Northern Greece). The study area was especially selected because it incorporates two distinct subareas: the northern one which can be safely considered as a pristine area, where NBLs for groundwaters were assessed from; the southern part which forms a typical Mediterranean region, intensively cultivated for the last 40?years. Groundwater TVs were determined considering two types of groundwater receptors: (a) groundwater ??itself?? and (b) groundwater dependent lagoons in the coastal part of the study area. Results showed that groundwater quality is altered seriously from its natural background composition indicating how human activities have affected groundwater quality and showed that chemical status of groundwater has been seriously aggravated. The number and the spatial distribution of monitoring locations exceeding TVs revealed that chloride and nitrates are the most serious threats for groundwater in the study area.     

Calorimetric study of the stability of spinelloids in the system NiAl2O4-Ni2SiO4

Enthalpies of solution in molten 2 PbO · B₂O₃ at 974 K were measured for four spinelloids, phases I (0.75 NiAl₂O₄ · 0.25 Ni₂SiO₄), II (0.60 NiAl₂O₄ · 0.40 Ni₂SiO₄), III and IV (0.50 NiAl₂O₄ · 0.50 Ni₂SiO₄) in the system NiAl₂O₄ · Ni₂SiO₄. The enthalpies (in cal per 4-oxygen mol) of formation from NiAl₂O₄ and Ni₂SiO₄ spinels are: phase I, 945±366; phase II, 1072±360; phase III, 2253±390; phase IV, 3565±544. Using these enthalpy data in combination with phase relations at high pressure at 1373 K, positive entropies of formation of the spinelloids from NiAl₂O₄ and Ni₂SiO₄ spinels were estimated (in cal mol^?1 K^?1): phase I, 1.2; phase II, 1.5; phase III, 2.0–2.3; phase IV, 3.0–3.1. The thermochemical data obtained above suggest that the spinelloids are “entropy-stabilized” phases with partially disordered cation distributions. The configurational entropies of the spinelloids were calculated based on the observed cation distribution in each spinelloid phase. The positive entropies of formation of the spinelloids from the spinel endmembers are due primarily to the configurational entropies although small positive vibrational entropy changes may also exist.     

The quartz-coesite-stishovite transformations: new calorimetric measurements and calculation of phase diagrams

High temperature solution calorimetry of synthetic quartz, coesite and stishovite provides enthalpies of transition. ΔH₉₇₅⁰ for quartz-coesite and ΔH₂₉₈⁰ for coesite-stishovite transition are 320 ± 70 and 11700 ± 410 cal mol^?1, respectively. The present transformation enthalpy data represent a small but significant revision of those of Holm et al. Using the published phase equilibrium data, thermal expansivity, compressibility and heat capacity data, ΔS₉₇₅⁰ for the quartz-coesite and ΔS₂₉₈⁰ for the coesite-stishovite transition are ?1.2 ± 0.1 and ?1.0 ± 0.4 cal K^?1 mol^?1, respectively. These thermochemical data are used to calculate phase boundaries of the transitions. The calculated quartz-coesite transition boundary agrees well with the one determined experimentally by Bohlen and Boettcher. The calculated coesite-stishovite boundary is generally consistent with data by Yagi and Akimoto and by Suito.     

The first post‐injection seismic monitor survey at the Ketzin pilot CO2 storage site: results from time‐lapse analysis

The injection of CO₂ at the Ketzin pilot CO₂ storage site started in June 2008 and ended in August 2013. During the 62 months of injection, a total amount of about 67 kt of CO₂ was injected into a saline aquifer. A third repeat three‐dimensional seismic survey, serving as the first post‐injection survey, was acquired in 2015, aiming to investigate the recent movement of the injected CO₂. Consistent with the previous two time‐lapse surveys, a predominantly west–northwest migration of the gaseous CO₂ plume in the up‐dip direction within the reservoir is inferred in this first post‐injection survey. No systematic anomalies are detected through the reservoir overburden. The extent of the CO₂ plume west of the injection site is almost identical to that found in the 2012 second repeat survey (after injection of 61 kt); however, there is a significant decrease in its size east of the injection site. Assessment of the CO₂ plume distribution suggests that the decrease in the size of the anomaly may be due to multiple factors, such as limited vertical resolution, CO₂ dissolution, and CO₂ migration into thin layers, in addition to the effects of ambient noise. Four‐dimensional seismic modelling based on dynamic flow simulations indicates that a dynamic balance between the newly injected CO₂ after the second repeat survey and the CO₂ migrating into thin layers and being dissolved was reached by the time of the first post‐injection survey. In view of the significant uncertainties in CO₂ mass estimation, both patchy and non‐patchy saturation models for the Ketzin site were taken into consideration.     

The possible hydrologic effects of the proposed lignite open‐cast mining in Drama lignite field,Greece

The present study investigates the possible hydrologic effects of the proposed lignite open‐cast mining in Drama lignite field (north Greece). Recent years have seen a rapid increase in surface mining. This activity has generated a growing concern for the potential environmental impacts associated with large scale surface mining. In order to achieve a safe mine operation and allow extraction of lignite to considerable depths, extensive dewatering by pumping will be necessary, while at the same time it is desirable to avoid presence of overpumping conditions in the broader area. Based on stratigrafic, hydrologic and hydrogeologic data, a three‐dimensional finite difference model was developed in order to simulate the dewatering process of the western part of the lignite open‐cast mine in Drama and to predict both spatially and temporally the decline of ground water level down to the lignite surface. The dewatering of the part of the aquifer which underlies the mine area will influence the hydrological conditions of the broader region. The most important anticipated effects will be the abandonment of shallow wells as well as the decrease of ground water pumping rates of deep wells. Aquifer discharge towards the ditches of the study area will cease and there will be an inversion of ground water flow from the ditches towards the underlying aquifer. Dewatering activities will probably result in minor subsidence of the nearby peat deposits of Drama Philippi marshes. Moreover, sand pumping as well as the presence of gasses is likely to cause local subsidence phenomena, mainly in the pit slopes. Copyright © 2007 John Wiley & Sons, Ltd.