Monitoring the levels of brominated and organophosphate flame retardants in passenger cars: Utilisation of car air filters as active samplers

Filters in residential and office air conditioning(A/C) systems have been used as sampling devices for monitoring different pollutants.However,cabin air filters(CAFs) in the A/C system of passenger cars have not been utilised for this purpose.In this study,we collected22 used CAFs from passenger cars in Hanoi,Vietnam to analyse for 8 polybrominated diphenyl ethers(PBDEs) and 10 organophosphate esters(OPEs).All the analytes were detected in more than 50% of samples with the exception of BDE153 and BDE154.The average concentrations of ∑_(10)OPEs and ∑_8 BDEs in the captured dust were 2600 and 40 ng/g,respectively with Tris(1-chloro-2-propyl) phosphate(TCIPP) and BDE209 as the dominant congener in OPE and BDE groups,respectively.CAFs are a potential tool to qualitatively assess the levels of semi-volatile chemicals in suspended dust in cars as a screening step for exposure assessment of those chemicals.     

Metal speciation in sediment and bioaccumulation in <Emphasis Type="Italic">Meretrix lyrata</Emphasis> in the Tien Estuary in Vietnam

The concentrations of seven toxic metals (cadmium (Cd), nickel (Ni), chromium (Cr), arsenic (As), lead (Pb), copper (Cu), and zinc (Zn)) were determined in sediments and the soft tissues of a bivalve species (Meretrix lyrata) collected from the Tien Estuary in Tien Giang Province, South Vietnam. The total metal concentrations in sediments (mg/kg dry weight) increased as Cd (0.06) < Cu (5.0) < Pb (13.9) < As (16.3) < Ni (24) < Cr (50) < Zn (62). Speciation analysis revealed that these metals existed mainly in the residual fraction (43–94%), followed by the Fe-Mn oxide-bound (5–35%) and organic/sulfide-bound (0.6–9.2%) fractions. The metal concentrations in M. lyrata (mg/kg dry weight) were in the ranges of 1.3–1.9 (Cd), 1.5–2.8 (Ni), 1.8–3.4 (Cr), 11–16 (As), 0.3–0.6 (Pb), 6.9–8.7 (Cu), and 95–128 (Zn), which are safe for human consumption. The order of the mean biota-sediment accumulation factor (BSAF) of the metals in the non-residual fractions of the sediment for M. lyrata was Cd > Cu > As > Zn > Cr > Ni > Pb. The Risk Assessment Codes (RACs) suggest that the highest mobility of Cd (with RAC = 37%) poses greater environmental risk to aquatic biota. Correlation analysis results show that M. lyrata can be used as a biomonitor of Cd and Cu pollution in the exchangeable, acid-soluble, and non-residual sediment fractions.     

The evolving local social contract for managing climate and disaster risk in Vietnam

How do disasters shape local government legitimacy in relation to managing climate‐ and disaster‐related risks? This paper looks at how local authorities in Central Vietnam perceive their social contract for risk reduction, including the partial merging of responsibilities for disaster risk management with new plans for and investments in climate change adaptation and broader socioeconomic development. The findings indicate that extreme floods and storms constitute critical junctures that stimulate genuine institutional change. Local officials are proud of their strengthened role in disaster response and they are eager to boost investment in infrastructure. They have struggled to reinforce their legitimacy among their constituents, but given the shifting roles of the state, private sector, and civil society, and the undiminished emphasis on high‐risk development models, their responsibilities for responding to emerging climate change scenarios are increasingly nebulous. The past basis for legitimacy is no longer valid, but tomorrow's social contract is not yet defined.     

Organic certification for shrimp value chains in Ca Mau,Vietnam: a means for improvement or an end in itself?

Eco-certification has been used as a tool to mitigate adverse effects of aquaculture production and might thus be understood as a private approach to sustainable ecosystem management. In production forests in Ca Mau, Vietnam, where mangrove have suffered degradation despite legal protection, different projects have targeted reversing this trend by means of private certification using the ‘Naturland’ organic standard as a reference. So far the outcomes have, however, been proven unsatisfactory. With the aim to better understand the reasons for these poor outcomes, a survey of forty households was conducted in a production forest in Rach Goc commune, Ngoc Hien District. We evaluated farmers’ perceptions on mangrove management, the drivers guiding shrimp farming, and whether there was a difference between participants and non-participants in a former ‘Naturland’ organic project. To complement the survey, a range of stakeholders involved in shrimp value chains were interviewed to better understand the terms and benefits of certification. The results of this survey suggested that, when applied to shrimp–mangrove farming systems in production forests in Ca Mau, ‘eco-certification’ and associated benefits are not very satisfactory. The survey results revealed that certified farms do not show significant differences to non-certified farms in terms of social and environmental benefits. As far as the implementation process was concerned, the survey results showed that a failure to integrate local farmers as participants consequently resulted in households becoming ‘objects’ for certification and not project partners with equal weight and power. It appears that rather than being a tool for improvement, ‘Naturland’ certification for shrimp–mangrove farming systems in Ca Mau’s production forests has become an end in itself.     

Atmospheric heavy metal deposition in Northern Vietnam: Hanoi and Thainguyen case study using the moss biomonitoring technique,INAA and AAS

Background, aim, and scope  

The moss technique is widely used to monitor atmospheric deposition of heavy metals in many countries in Europe, whereas this technique is scarcely used in Asia. To implement this international reliable and cheap methodology in the Asian countries, it is necessary to find proper moss types typical for the Asian environment and suitable for the biomonitoring purposes. Such a case study was undertaken in Vietnam for assessing the environmental situation in strongly contaminated areas using local species of moss Barbula indica.     

Carbon dioxide capture with concentrated,aqueous piperazine

Concentrated, aqueous piperazine (PZ) has been investigated as a novel amine solvent for carbon dioxide (CO₂) absorption. The CO₂ absorption rate of aqueous PZ is more than double that of 7 m MEA and the amine volatility at 40 °C ranges from 11 to 21 ppm. Thermal degradation is negligible in concentrated, aqueous PZ up to a temperature of 150 °C, a significant advantage over MEA systems. Oxidation of concentrated, aqueous PZ is appreciable in the presence of copper (4 mM), but negligible in the presence of chromium (0.6 mM), nickel (0.25 mM), iron (0.25 mM), and vanadium (0.1 mM). Initial system modeling suggests that 8 m PZ will use 10–20% less energy than 7 m MEA. The fast mass transfer and low degradation rates suggest that concentrated, aqueous PZ has the potential to be a preferred solvent for CO₂ capture.     

The potential environmental risks of pharmaceuticals in Vietnamese aquatic systems: case study of antibiotics and synthetic hormones

Presently, many pharmaceuticals are listed as emerging contaminants since they are considered to be great potential threats to environmental ecosystems. These contaminants, thus, present significant research interest due to their extensive use and their physicochemical and toxicological properties. This review discusses a whole range of findings that address various aspects of the usage, occurrence, and potentially environmental risks of pharmaceuticals released from various anthropogenic sources, with emphasis on the aquatic systems in Vietnam. The published information and collected data on the usage and occurrence of antibiotics and synthetic hormone in effluents and aquatic systems of Vietnam is reported. This is followed by a potential ecological risk assessment of these pollutants. The extensive use of antibiotics and synthetic hormones in Vietnam could cause the discharge and accumulation of these contaminants in the aquatic systems and potentially poses serious risks for ecosystems. Vietnam is known to have extensively used antibiotics and synthetic hormones, so these contaminants are inevitably detected in aquatic systems. Thus, an appropriate monitoring program of these contaminants is urgently needed in order to mitigate their negative effects and protect the ecosystems.     

Long range transport of fine particle windblown soils and coal fired power station emissions into Hanoi between 2001 to 2008

Fine particulate matter (PM_2.5), source fingerprints and their contributions have been measured and reported previously at Hanoi, Vietnam, from 25 April 2001 to 31 December 2008. In this study back trajectories are used to identify long range transport into Hanoi for two of these sources, namely, windblown dust (Soil) from 12 major deserts in China and emissions from 33 coal fired power plants (Coal) in Vietnam and China. There were 28 days of extreme Soil events with concentrations greater than 6 μg m^?3 and 25 days of extreme Coal with concentrations greater than 30 μg m^?3 from a total of 748 sampling days during the study period. Through the use of back trajectories it was found that long range transport of soil from the Taklamakan and Gobi desert regions (more than 3000 km to the north west) accounted for 76% of the extreme events for Soil. The three local Vietnamese power stations contributed to 15% of the extreme Coal events, while four Chinese power stations between 300 km and 1700 km to the north-east of Hanoi contributed 50% of the total extreme Coal events measured at the Hanoi sampling site.     

Leaching from granular cement-based materials during infiltration/wetting coupled with freezing and thawing

Many secondary materials are being considered for use as substitutes for natural aggregates in highway applications due to their suitable engineering and economic properties. During the design life of the application, recycled materials are exposed to freeze/thaw cycles and other aging processes such as carbonation, coupled with intermittent infiltration/wetting by precipitation events. In such scenarios, leaching of material constituents is a primary pathway for environmental impact. This paper presents results of the effect of freezing and thawing on the leaching behavior of major and minor constituents from a laboratory formulated granular cement-based material. Scenarios considered included water percolating through the material (flow-through) and run-off (flow-around), both important leaching pathways in highway environments. The effect of moisture content at the time of freezing, number of freeze/thaw (F/T) cycles, and material size reduction were investigated. F/T exposure and subsequent infiltration/wetting resulted in consolidation and self-cementing of the granular cement-based material. For the flow-around scenario, F/T exposure resulted in a reduction in constituent release with time and increasing F/T cycles. For the flow-through scenario, moisture content at the time of freezing was an important parameter and an increase in the release was initially observed due to preferential flow/cracks and/or constituent redistribution prior to a decrease that resulted from self-cementing during further thawing and percolation.