Mercury concentration in ecosystem components in water bodies and streams in Khanh Hoa province (Central Vietnam)

Total mercury concentration in water, seston, soils, and muscle tissues of fish in water bodies in Khan Hoa province was determined. Hg concentration in water does not exceed 40 ng/l. It migrates in water mostly in dissolved form. Hg concentration in soils of the examined water bodies varies from 0.01 to 0.05 mg/(kg dry mass) and that in the muscle tissues of fish on the average does not exceed 1.4 mg/(kg dry mass).     

Estimates of the accuracy of vertically extrapolated forecast errors: Isobaric height and temperature

Abstract

Study of vertical extrapolations of the errors in forecast values of pressure‐level heights and temperatures indicates that they do not provide accurate off‐level information. Indeed it appears that, above 850 mb, forecast errors interpolated from observed 1000‐mb values are less accurate than level‐specific monthly mean differences. These results suggest that the de facto function of vertically interpolated single‐level forecast errors, in numerical forecast model updating, is the provision of vertical consistency rather than the injection of time‐specific information – except at the level of observation.     

Geochemistry and petrogenesis of carbonatites from South Nam Xe,Lai Chau area,northwest Vietnam

This paper presents a study of the petrography, mineral chemistry, geochemistry, and Sr–Nd–Pb–C–O isotope systematics of carbonatite dykes and associated rocks from the northeastern part of the Song Da intracontinental rift in South Nam Xe (northwest Vietnam) aimed at constraining the origin of the carbonatite magmas. The carbonatites are characterized by SiO₂ < 12.18 wt.% and by wide ranges in FeO, MgO and CaO content that define them as calciocarbonatite and ferrocarbonatite. On U–Th–Pb isochron diagrams, whole rocks and mineral separates from the ferrocarbonatites form linear arrays corresponding to ages of 30.2–31.6 Ma (Rupelian, Oligocene). The South Nam Xe carbonatites are extremely enriched in Sr, Ba, and light rare earth elements (LREE), and depleted in high field strength elements (HFSE) (e.g. Ti, Nb, Ta, Zr and Hf). The age–corrected Sr–Nd–Pb isotope ratios and C isotope data are relatively uniform (⁸⁷Sr/⁸⁶Sr_(t) = 0.708193–0.708349; ¹⁴³Nd/¹⁴⁴Nd_(t) = 0.512250–0.512267; ε_Nd(t) = ?6.46 to ?6.80; ²⁰⁶Pb/²⁰⁴Pb_(t) = 18.26–18.79; ²⁰⁷Pb/²⁰⁴Pb_(t) = 15.62–15.64; ²⁰⁸Pb/²⁰⁴Pb_(t) = 38.80–39.38; δ¹³C_V-PDB = –2.7?‰ to ?4.1?‰). These isotopic compositions indicate source contamination that occurred before the production of the carbonatite magmas, and did not change noticeably during or after emplacement. The variation in oxygen isotopes is consistent with the change in mineral compositions and trace element abundances: the lower δ¹⁸O values (9.1–11.0?‰) coupled with Sr-rich, Mn-poor calcite, and igneous textures such as triple junctions among calcite grain boundaries, define a magmatic origin. However, the elevated δ¹⁸O values of the ferrocarbonatites (12.0–13.3?‰) coupled with a volatile-bearing mineral assemblages (including REE fluorcarbonates, sulfates, sulfides and fluorite) may be due to interaction with meteoric water during low-temperature alteration. High δ¹³C values and Sr–Pb ratios, and low Rb/Sr (0.00014–0.00301), Sm/Nd (0.089–0.141) and ¹⁴³Nd/¹⁴⁴Nd ratios, coupled with very high Sr-Nd concentrations, suggest the involvement of an enriched mantle component, which probably resulted from metasomatism due to the migration of subducted material. Because of the lack of tectonic data and the limited number of samples studied, this conclusion is still ambiguous and requires further study.     

Imaging with Amber/VLTI: the case of microjets

The engine that powers pre-main-sequence micro-jets is still unknown and remains a fundamental open question in star formation. The engine can be located solely on the inner disk or in the interaction of the inner disk with the star. In order to ease interpretation problems, imaging the jet engine is the ideal probe to disentangle between the old models and shed evidence for new ones. In this paper, we analyse the feasability of imaging bright southern targets, and show that even at low SNR, accurate image reconstructionis still possible with high contrast. However, the small number of ATs requires a fast reconfigurable array. This revised version was published online in July 2006 with corrections to the Cover Date.     

MétéEAU Nappes: a real-time water-resource-management tool and its application to a sandy aquifer in a high-demand irrigation context

The MétéEAU Nappes water-resource-management tool is presented. It is usable on the aquifer or part-of-aquifer scale for real-time observation of the state of the groundwater resource, and it is already operating in France. This online decision support tool is also able to predict the state of the resource in the short- and mid-terms. The paper explains the use of the tool in a case study in the Authion Valley, in the north-west of France, chosen for its context of tension surrounding the groundwater resource resulting from high volumes of abstraction for irrigation. The results of the simulation highlight the advantages of MétéEAU Nappes as a tool for prediction and simulation of the state of the groundwater resource. The results also show the advantages of this type of tool for water resource management, such as supplying local actors with reliable and real-time observations of the aquifer and providing forecasts to anticipate possible water shortage.

     

Three‐dimensional indoor network accessibility auditing for floor plan design

Built environments have played an increasingly important and complex role in contemporary cities in the face of the significant number of discretionary and non‐discretionary event‐based activities that take place indoors, and the great variety of three‐dimensional designs that indoor spaces have grown to assume. However, intelligent tools that can assist designers to achieve high accessibility, particularly for large and complex buildings, are still underdeveloped. This article presents an innovative custom computer‐based design tool, dubbed FloorplanAAU (floor plan accessibility auditing), that couples GIS data modeling, indoor traversable network accessibility analysis, and interactive three‐dimensional visualization for built environments, to interactively evaluate and audit floor plans for high accessibility. The proposed method contributes to the success of applying GIS and transportation geography concepts to establish computational tools toward intelligent design and assessment of built environments.     

Privatization of neighborhood governance in transition economy: a case study of gated community in Phu My Hung new town,Ho Chi Minh City,Vietnam

Literature on common-interest development (CID) in housing, most common in the form of gated communities, has been based largely on the US’s experience, where the interpretation has centered on the interaction between three actors (local government, private developer, and homeowner association) and barely focused on the privatization of neighborhood governance in transition economies. This paper, through a case study of gated community in Phu My Hung new town shows that Ho Chi Minh City, Vietnam—in the context of transition from centrally-planned to market-based economy—has been witnessing this privatized phenomenon of neighborhood governance. It employs both primary data, collected through observation and key informant interview, and secondary data to explain the contextual factors for the rise of gated communities in the city and find out the mechanism of neighborhood governance. In the city, housing privatization reforms, influx of foreign direct investment, and the formation of urban middle class have constituted the supply- and demand-side factors for the rise of gated communities. In addition, the reforms towards grassroots participation created a favorable environment for a privatization of neighborhood governance in which the private developer plays a dominant role in partnership with local government and homeowner association. To a certain extent, this privatization is similar to the case of US’s gated communities, however, it does not threaten the public authority and instead maintains a good collaboration between these three actors. This is an indigenous innovation of gated communities in Vietnam due to its socio-economic conditions and political context.     

Change in carbon flux (1960–2015) of the Red River (Vietnam)

Global riverine carbon concentrations and fluxes have been impacted by climate and human-induced changes for many decades. This paper aims to reconstruct the longterm carbon concentrations and carbon fluxes of the Red River, a system under the coupled pressures of environmental change and human activity. Based on (1) the relationships between particulate and dissolved organic carbon (POC, DOC) or dissolved inorganic carbon (DIC), and suspended sediments (TSS) or river water discharge and on (2) the available detailed historical records of river discharge and TSS concentration, the variations of the Red River carbon concentration and flux were estimated for the period 1960–2015. The results show that total carbon flux of the Red River averaged 2555?±?639 kton C year^?1. DIC fluxes dominated total carbon fluxes, representing 64% of total, reflecting a strong weathering process from carbonate rocks in the upstream basin. Total carbon fluxes significantly decreased from 2816 kton C year^?1 during the 1960s to 1372 kton C year^?1 during the 2010s and showed clear seasonal and spatial variations. Organic carbon flux decreased in both quantity and proportion of the total carbon flux from 40.9% in 1960s to 14.9% in 2010s, reflecting the important impact of dam impoundment. DIC flux was also reduced over this period potentially as a consequence of carbonate precipitation in the irrigated, agricultural land and the reduction of the Red River water discharge toward the sea. These decreases in TSS and carbon fluxes are probably partially responsible for different negatives impacts observed in the coastal zone.     

Delineation of small-scale landforms relative to flood inundation in the western Red River delta, northern Vietnam using remotely sensed data

Flood susceptibility mapping using geomorphologic approaches is effective for delineating flood extent and various degrees of potential flood-affected areas. This approach is useful where the channel system and floodplain morphology change dynamically and in regions where detailed digital elevation models are not available. The first important step in flood zonation using this approach is detailed geomorphologic mapping, also called landform classification. This study aims to describe landform classification using the rule-based method of Ho et al. (Int J Geoinform 8(4):27–38, 2012) adapted to local characteristics in the western plain of the Red River delta, northern Vietnam. The original classification scheme is generally based on the moist condition classification, local land-surface parameters, and relative position indices derived from multi-temporal Landsat data and a shuttle radar topographic mission digital elevation model (SRTM DEM). This study uses average elevations and the standard deviation of elevations as local land-surface parameters rather than local relief, which was used in the study by Ho et al. (Int J Geoinform 8(4):27–38, 2012). Multi-temporal land cover classification was performed using an integrated method to effectively correct the SRTM DEM. The overall classification is consistent with manual mapping by visual comparison. The quantitative comparison between landform units and past flood-affected areas demonstrates a precise boundary delineation of landform objects using this method. The high agreement between the boundaries of landform units and flood-inundated areas suggests the applicability of this method taking advantage of readily available remotely sensed datasets in alluvial floodplains.     

On the potential for CO2 mineral storage in continental flood basalts - PHREEQC batch- and 1D diffusion-reaction simulations

ABSTRACT: Continental flood basalts (CFB) are considered as potential CO2 storage sites because of their high reactivity and abundant divalent metal ions that can potentially trap carbon for geological timescales. Moreover, laterally extensive CFB are found in many place in the world within reasonable distances from major CO2 point emission sources.Based on the mineral and glass composition of the Columbia River Basalt (CRB) we estimated the potential of CFB to store CO2 in secondary carbonates. We simulated the system using kinetic dependent dissolution of primary basalt-minerals (pyroxene, feldspar and glass) and the local equilibrium assumption for secondary phases (weathering products). The simulations were divided into closed-system batch simulations at a constant CO2 pressure of 100?bar with sensitivity studies of temperature and reactive surface area, an evaluation of the reactivity of H2O in scCO2, and finally 1D reactive diffusion simulations giving reactivity at CO2 pressures varying from 0 to 100?bar.Although the uncertainty in reactive surface area and corresponding reaction rates are large, we have estimated the potential for CO2 mineral storage and identified factors that control the maximum extent of carbonation. The simulations showed that formation of carbonates from basalt at 40?C may be limited to the formation of siderite and possibly FeMg carbonates. Calcium was largely consumed by zeolite and oxide instead of forming carbonates. At higher temperatures (60 - 100?C), magnesite is suggested to form together with siderite and ankerite. The maximum potential of CO2 stored as solid carbonates, if CO2 is supplied to the reactions unlimited, is shown to depend on the availability of pore space as the hydration and carbonation reactions increase the solid volume and clog the pore space. For systems such as in the scCO2 phase with limited amount of water, the total carbonation potential is limited by the amount of water present for hydration of basalt.