Concentrations,profiles, emission inventory,and risk assessment of chlorinated benzenes in bottom ash and fly ash of municipal and medical waste incinerators in northern Vietnam

Environmental Science and Pollution Research - Concentrations and congener profiles of seven di- to hexachlorinated benzenes (CBzs) were characterized in bottom ash and fly ash samples collected...     

Application of WRF-Chem to simulate air quality over Northern Vietnam

Environmental Science and Pollution Research - The WRF-Chem (Weather Research and Forecasting with Chemistry) model is implemented and validated against ground-based observations for meteorological...     

Administrative Co-management: The Case of Special-Use Forest Conservation in Vietnam

Special-use forests (SUFs) are nature protected areas in Vietnam used to conserve nature and its biodiversity. While the Vietnamese government has managed to increase the size and number of SUFs, biodiversity within these areas continues to decline. To improve protection of these SUFs, co-management has been advocated in Vietnam. Successfully implementing co-management requires decentralization of authority and a certain extent of public involvement in management activities. This paper assesses how and to what extent the governance of Vietnam’s SUFs have taken up the challenge of shifting from conventional government-based management to co-management. Current practices of (co-) management were investigated in 105 of the 143 SUFs. The results show that the type of co-management varies little between different categories of SUFs. Nevertheless, a national ‘style’ of Vietnamese co-management could be identified, labelled ‘administrative’ co-management; fostering interaction between a variety of actors, but final decision-making power on management remaining strongly in the hands of the provincial government.     

长江口潮滩芦苇根表铁膜磁性特征及其环境意义

湿地植物根表铁膜对包括重金属在内的物质迁移转化具有重要作用,其氧化铁组成研究备受重视,但利用环境磁学方法进行表征的研究还未见报道.本文对长江口潮滩植物芦苇根系及周边沉积物进行了磁学分析,并结合沉积物粒度、漫反射光谱等测试,对芦苇根表铁膜的磁性矿物组成进行了系统研究.结果表明,芦苇根表铁膜磁性矿物主要包括磁铁矿和赤铁矿.由于沉积物不同深度氧化还原环境的不同,铁膜磁性矿物组成存在垂向差异.研究柱样24 cm深度以上,由于相对氧化的环境,铁膜磁性矿物除磁铁矿外,还有较多的赤铁矿贡献;24 cm深度以下,因根系处于相对还原的环境,磁性矿物以磁铁矿为主.与沉积物相比,24 cm以上深度铁膜中亚铁磁性矿物含量较低,24 cm深度以下则相反,反映铁膜和沉积物磁性矿物来源不同.本项研究表明,磁性测量方法有助于认识湿地植物根表铁膜的矿物组成,对湿地生物地球化学过程研究具有重要价值.     

Determination of polycyclic aromatic hydrocarbons in dry tea

Twenty-eight different tea samples sold in the United States were evaluated using high-performance liquid chromatography (HPLC) with fluorescence detection (FLD) for their contamination with polycyclic aromatic hydrocarbons (PAHs). Many PAHs exhibit carcinogenic, mutagenic, and teratogenic properties and have been related to several kinds of cancer in man and experimental animals. The presence of PAHs in environmental samples such as water, sediments, and particulate air has been extensively studied, but food samples have received little attention. Eighteen PAHs congeners were analyzed, with percentage recovery higher than 85%. Contamination expressed as the sum of the 18 analyzed PAHs was between 101 and 1337 μg/kg on dry mass and the average contents in all of the 28 examined samples was 300 μg/kg on dry mass. Seven of the congeners were found in all samples with wide ranges of concentrations as follows: fluorene (7–48 μg/kg), anthracene (1–31 μg/kg), pyrene (1–970 μg/kg), benzo(a)anthracene (1–18 μg/kg) chrysene (17–365 μg/kg), benzo(a)pyrene (1–29 μg/kg), and indeno(1,2,3-cd)pyrene (4–119 μg/kg). The two most toxic congeners benzo(a)pyrene and dibenzo(a,h)anthracene were found at high concentrations only in Earl Grey Twinnings, Earl Grey Harney& Sons Fine Teas, and Chai Ultra Spice Black Tea Twinnings. Six PAH congeners are considered as suspected carcinogens (U.S.EPA), formed the basis of the estimation of the toxic equivalent (TEQ), Chai Ultra-Spice Black Tea Twinnings had the highest TEQ (110.9) followed by two grey tea samples, Earl Grey Harney & Sons Fine Tea (57.7) and Earl Grey Twinnings (54.5). Decaffeinated grey teas had the lowest TEQs, decaffeinated Earl Grey Bigelow (9.4) and Green Tea Honey Lemon Decaffeinated Lipton (9.6).     

Kinetics of the reactions of soot surface-bound polycyclic aromatic hydrocarbons with the OH radicals

The kinetics of the heterogeneous reaction of OH radicals with 15 polycyclic aromatic hydrocarbons (PAHs) present in laboratory generated simulated kerosene combustion soot was studied at T = 290 K in a low pressure discharge-flow reactor combined with an electron-impact mass spectrometer. The kinetics of soot-bound PAH consumption in reaction with OH were monitored using off-line HPLC measurements of their concentrations in soot samples as a function of time of exposure to OH. Concentration of OH radicals in the gas phase was measured by mass spectrometry. The first-order rate constants measured for the individual PAH at T = 290 K ranged from 0.02 to 0.04 s^?1 and were found to be independent of the OH concentration ([OH] = (0.34–2.5) × 10¹² molecule cm^?3) and of the molecular structure of the PAH. In addition, the uptake coefficient of OH on soot surface and the diffusion coefficient of OH in He were measured to be 0.19 ± 0.03 (calculated with geometric surface area) and (615 ± 80) Torr cm² s^?1, respectively. Comparison of the results on the PAH + OH reaction to those from previous studies carried out on different carbonaceous substrates, indicates probable dependence of the heterogeneous reactivity of PAH toward OH on the substrate nature. Rapid reaction with OH can be an important potential pathway of the atmospheric degradation of non-volatile PAH present mainly in the particulate phase in the atmosphere.     

Tsunami mitigation by coastal vegetation considering the effect of tree breaking

Damage to vegetation by tsunami moment and reduction of potential tsunami force are discussed based on a numerical simulation. A numerical model based on two-dimensional nonlinear long-wave equations that include drag forces and turbulence-induced shear force due to the presence of vegetation was developed to estimate tree breaking. The numerical model was then applied to a coastal forest where two dominant tropical vegetation species, Pandanus odoratissimus and Casuarina equisetifolia, were considered. The threshold water depth for tree breaking increased with increasing forest width, and the analysis was consistent with the field investigation results that the critical tsunami water depth for breaking is around 80% of the tree height for P. odoratissimus. C. equisetifolia is stronger than P. odoratissimus against tsunami action, but P. odoratissimus can reduce a greater tsunami force than C. equisetifolia due to its complex of aerial root structures. Even if breakage occurs, P. odoratissimus still has high potential to reduce the tsunami force due to its dense aerial root structures. Previous numerical models that do not include the breaking phenomena may overestimate the vegetation effect for reducing tsunami force. The combination of P. odoratissimus and C. equisetifolia is recommended as a vegetation bioshield to protect coastal areas from tsunami hazards.     

Effects of cadmium and chlordane on cellular apoptosis in ecotoxicological test species

Cadmium and chlordane are compounds chosen for a preliminary study on the impact of environmental contaminants on apoptosis in different representative species. These two potentially toxic substances decrease in vitro apoptosis of Daphnia magna cells. This appears to be related to the chemical concentrations and the time exposure. Cadmium was also directly introduced to the cell culture medium of Syrian hamster embryos (SHE) or indirectly via daphnids, which had firstly consumed algae contaminated with cadmium. A very sharp transfer of cadmium toxicity from algae to daphnids is noted and an inhibition of the apoptosis in SHE cells can be observed.     

Compliance of paper-making plants with regulations on wastewater management in Bac Ninh Province,Vietnam

This study investigated the compliance of paper-making plants in Phong Khe Commune of Bac Ninh Province with regulations on wastewater management. According to existing regulations for wastewater management, all paper plants in Bac Ninh province are required to submit an environmental impact assessment report, pay the wastewater charges, and establish a wastewater treatment system. Many paper-making plants in the commune did not, however, comply with these regulations. Although fines were imposed for non-compliance, only a few plants paid the fines due to weak enforcement. As a result, the current costs of compliance of paper-making plants were very small compared with the full costs of compliance. Type of plant, location of the plant, and number of schooling years of the plant owners were found to be significant factors affecting compliance. The main reasons why the plants did not comply with the regulations were the plant owners’ inadequate understanding of environmental regulations, their lack of financial resources, limited space for treatment system installation, small fines, and the limited capacity of the local environment authorities in enforcing the regulations. The option of wastewater treatment for a group of paper-making plants located close to one another was widely accepted. The study proposes collective action for the adoption of this treatment option and policy recommendations.     

Pleistocene speciation of sister taxa in a North Pacific clade of brooding sea stars (<Emphasis Type="Italic">Leptasterias</Emphasis>)

Although numerous coastal marine species show intra-specific lineage splitting and population divergence times that date to the period of glacial cycles during the Pleistocene epoch, reported instances of recent speciation in the coastal marine environment are relatively rare. Marine organisms with brood-protection and other reproductive modes with limited dispersal potential have been suggested to experience more frequent speciation and extinction events than related species with higher dispersal rates, but few studies have actually estimated divergence times of sister species in these organisms. Here, two mitochondrial gene regions (cytochrome oxidase subunit I, putative control region and upstream tRNAs) and a nuclear gene region (Elongation factor 1α subunit intron 4) provide evidence of recent (0.5–1.2 Mya) cladogenetic events in four pairs of putative sister taxa in a predominantly North Pacific brooding subgenus of sea stars (Leptasterias subgenus Hexasterias). Calibration is obtained from a trans-arctic migration in a related clade of sea stars (Leptasterias subgenera Hexasterias and Nesasterias) that is timed to the opening of the Bering Strait at 3.5 ± 0.25 Mya, and uncertainty in the calibration point is accommodated with a normally-distributed Bayesian prior probability. Similar estimates of population splitting times for two of the pairs of putative sister taxa were obtained by a multilocus coalescent analysis. Estimates of mitochondrial mutation rates (0.01/My) were approximately 50% of the values calibrated for sister species pairs in tropical sea stars and sea urchins. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.