Survey-based inventory for atmospheric emissions from residential combustion in Vietnam

Environmental Science and Pollution Research - Local questionnaire surveys were conducted to collect representative activity data for calculation of annual emissions from residential combustion in...     

Lack of mtDNA and morphological differentiation between two acorn barnacles <Emphasis Type="Italic">Tetraclita japonica</Emphasis> and <Emphasis Type="Italic">T. formosana</Emphasis> differing in parietes colours and geographical distribution

Tetraclita japonica and T. formosana are common intertidal barnacles with similar morphology, which leads to uncertainty in their species status. In the present study, we try to elucidate the taxonomic status of the two taxa using morphology and mitochondrial control region and cytochrome c oxidase subunit I (COI) sequences of the barnacles in their distribution range. The two taxa were found to be morphologically similar; a diagnostic difference between them was only observed in the colour of the parietes and opercular plates. Little genetic differentiation was detected in the control region and COI (Φ_CT < 0.025 for both markers) between two taxa, but differentiation was found between the southern (Taiwan and Hong Kong) and northern (Japan) populations of T. japonica/T. formosana, which might be the result of isolation by distance and upwelling in summer. Our data suggest that the two presently recognized species probably represent two colour morphotypes of the same species exhibiting different geographical distribution. T. japonica is abundant in Japan and southeast coast of China, whereas T. formosana is only abundant in Taiwan. The heterogeneous environment might exert a divergent selection pressure leading to asymmetric distribution of the two colour morphotypes. The different colours might be a result of either phenotypic plasticity adaptive to environmental variables or genetic hitchhiking of local adaptive genotypes. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Assessment of the use of spent copper slag for land reclamation.

The shortage of waste landfill space for waste disposal and the high demand for fill materials for land reclamation projects in Singapore have prompted a study on the feasibility of using spent copper slag as fill material in land reclamation. The physical and geotechnical properties of the spent copper slag were first assessed by laboratory tests, including hydraulic conductivity and shear strength tests. The physical and geotechnical properties were compared with those of conventional fill materials such as sands. The potential environmental impacts associated with the use of the spent copper slag for land reclamation were also evaluated by conducting laboratory tests including pH and Eh measurements, batch-leaching tests, acid neutralization capacity determination, and monitoring of long-term dissolution of the material. The spent copper slag was slightly alkaline, with pH 8.4 at a solid : water ratio of 1 : 1. The batch-leaching test results show that the concentrations of the regulated heavy metals leached from the material at pH 5.0 were significantly lower than the maximum concentrations for their toxicity limits referred by US EPA's Toxicity Characteristic Leaching Procedure (TCLP). It was also found that the material is unlikely to cause significant change in the redox condition of the subsurface environment over a long-term period. In terms of physical and geotechnical properties, the spent copper slag is a good fill material. In general, the spent copper slag is suitable to be used as a fill material for land reclamation.     

Quantum yield study of the photodegradation of hydrophobic dyes in the presence of acetone sensitizer.

The photodegradation of hydrophobic disperse dyes with different chromophores in the presence of acetone (ACE) was investigated. In this study, the photodecay of dyes was carried out in the Rayonet RPR-200 merry-go-round photoreactor, with 253.7 nm monochromatic ultraviolet (UV) lamps. A typical azo disperse dye (CI disperse yellow 7--DY7) and an anthraquinone disperse dye (CI disperse orange--DO11) were used as the probe compounds. The results demonstrate that the addition of acetone increases the solubility of hydrophobic disperse dyes and enhances the photosensitization reaction simultaneously. More than ten times of quantum yield enhancement is observed in the presence of ACE photosensitizer than in water alone. The photodegradation of DY7 and DO11 is dominated by photoreduction, which follows pseudo first-order decay, and the rate constants strongly depend on the solvent system (i.e., ACE/H2O ratios) and the initial pH levels. The decay quantum yields of dyes are normally observed with the increase of the ACE/H2O ratio. The optimum quantum yields of DY7 and DO11 were determined at 0.5 (v/v) and 0.25 (v/v), respectively, in alkaline conditions. A further increase in the ACE/H2O ratio reduces the quantum yields, possibly due to light attenuation by excess acetone.     

2016年夏季南京大气污染特征观测分析

为研究南京夏季大气复合污染的特征,2016年8月15日~9月15日期间开展了强化观测实验,本文利用仙林、鼓楼80m楼顶2个站点的强化观测资料,结合草场门常规监测资料,统计分析了南京不同地区夏季O₃和颗粒物（PM_2.5、PM₁₀）的浓度特征和相关性,以及郊区水溶性离子与其气态前体物的转化率变化特征.研究表明：3个站点O₃平均小时浓度为100.3μg/m³.PM_2.5和PM₁₀浓度分别为41.1和67.8μg/m³,郊区夜间存在颗粒物浓度高值.SO₄^2-、NO₃^-、NH₄⁺浓度总和占PM_2.5浓度的比值达到61%,OC（有机碳）/EC（元素碳）比值范围为0.8~4.0,日均值超过2.0的天数占77%,城、郊均存在二次污染.白天O₃与颗粒物（PM_2.5）浓度呈显著正相关变化,硫转化率（SOR）、氮转化率（NOR）分别与O₃浓度、湿度显著正相关.HONO主要在夜间积累,HCl和HNO₃浓度峰值出现在下午.与其它无机盐相比,NH₄⁺在总氨中所占比例明显偏低,大气中的氨主要以气态NH₃存在.观测期间O₃污染较重,O₃与颗粒物的正相关关系显著,化学反应在颗粒物积累过程中具有重要贡献,此外还可能存在城区向郊区的污染输送.     

Homogeneous and heterogeneous photolysis of nitrate in the atmosphere: state of the science,current research needs,and future prospects

● Recent advances in the photolysis of nitrate/HNO₃ are reviewed. ● Mechanisms and key factors affecting the photolysis of nitrate/HNO₃ are summarized. ● Atmospheric implications and future research recommendations are provided. Nitrate is an important component of atmospheric particulate matter and affects air quality, climate, human health, and the ecosystem. Nitrate was previously considered a permanent sink for nitrogen oxides (NO_x). However, this viewpoint has been challenged in recent years because growing research evidence has shown the transformation of nitrate into NO_x (i.e., renoxification). The photolysis of nitrate/HNO₃, especially in the particulate phase or adsorbed on particles, can be a significant renoxification process in the atmosphere. The formation and photolysis of nitrate in aerosol not only change the diurnal variation of NO_x, but also provide long-distance transport of NO_x in the form of nitrate, which affects local and regional atmospheric chemistry and air quality. This review summarizes recent advances in the fundamental understanding of the photolysis of nitrate/HNO₃ under various atmospheric conditions, with a focus on mechanisms and key factors affecting the process. The atmospheric implications are discussed and future research is recommended.