Designing ambient particulate matter monitoring program for source apportionment study by receptor modeling

Particulate matter (PM) receptor modeling requires specific intensive input data that is always a challenge to produce cost effectively. A well-designed monitoring program is important to collect such PM ambient data in urban areas with diverse and densely distributed sources. This paper presents a general framework for designing such a monitoring program while emphasizing appropriate quality assurance and quality control elements that are particularly applicable where limited resources are available. Topics for discussion include selection of monitoring sites, sampling and analytical techniques, and the uncertainty estimation for ambient concentration input data. The design framework is illustrated by a case study of a monitoring program for PM source apportionment in the Bangkok Metropolitan Region in which 24-h fine and coarse PM samples were collected using two collocated dichotomous samplers. Comparison between black carbon measurements by Smoke Stain reflectometry and Thermal Optical Transmittance method is highlighted.     

Process analysis of ozone formation under different weather conditions over the Kanto region of Japan using the MM5/CMAQ modelling system

We have assessed the contributions of individual physical and chemical atmospheric processes on ozone formation under different weather conditions during a typical summer month (August 2005) using the MM5/CMAQ modelling system. We found that the ozone episodes in the Kanto region are dominated by three major patterns, of which Patterns I and II are regular summertime pressure patterns with a 26% and 16% frequency of occurrence, respectively. A process analysis at two typical sites in the Kanto region – one located in the central region of Tokyo and the other located in the rural areas of Kanto – indicates that ozone formation is mainly controlled by advection, vertical diffusion, dry deposition, and chemical processes. The ground-level ozone concentrations are enhanced mainly by the vertical mixing of ozone-rich air from aloft, whereas the dry deposition and chemical processes mainly deplete ozone. By investigating the effects of each process under different weather conditions, we found that the significant decrease in ozone removal due to the chemical and advection processes under conditions of high stagnation is the most important cause of the enhanced levels of ozone in the central region of Tokyo. The results of this study can contribute to a better understanding of ozone formation in the Kanto region, and they may be valuable for local policy makers for further development planning.     

Species- and tissue-specific accumulation of Dechlorane Plus in three terrestrial passerine bird species from the Pearl River Delta, South China

Little data is available on the bioaccumulation of Dechlorane Plus (DP) in terrestrial organisms. Three terrestrial passerine bird species, light-vented bulbul, long-tailed shrike, and oriental magpie-robin, were collected from rural and urban sites in the Pearl River Delta to analyze for the presence of DP and its dechlorinated products in muscle and liver tissues. The relationships between trophic level and concentration and isomeric composition of DP in birds were also investigated based on stable nitrogen isotope analysis. DP levels had a wide range from 3.9 to 930 ng g⁻¹ lipid weight (lw) in muscle and from 7.0 to 1300 ng g⁻¹ lw in liver. Anti-Cl₁₁-DP and syn-Cl₁₁-DP, two dechlorinated products of DP, were also detected in bird samples with concentrations ranged between not detected (nd)-41 and nd-7.6 ng g⁻¹ lw, respectively. DP preferentially accumulated in liver rather than in muscle for all three bird species. Birds had significantly higher concentrations of DP in urban sites than in rural sites (mean, 300 vs 73 ng g⁻¹ lw). The fractions of anti-DP (f_anti) were higher in birds collected in rural sites than in urban sites. Significant positive correlation between DP levels and δ¹⁵N values but significant negative correlation between f_anti and δ¹⁵N values were found for birds in both urban and rural sites, indicating that trophic level of birds play an important role in determining DP level and isomeric profile.     

Fenton氧化-前置反硝化缺氧好氧池(A/O)处理荧光增白剂废水中试研究

采用Fenton氧化-前置反硝化缺氧好氧池(A/O)对荧光增白剂废水IC出水进行中试实验研究。实验表明,在Fe2+投加量为0.003 mol/L,进水pH值为3,[H2O2]/[Fe2+]为4∶1,反应时间为2 h的条件下,Fenton氧化法对COD的去除率可以达到46%以上,出水BOD5/COD的值由0.26提高到0.58。氧化后废水进入前置反硝化生物脱氮系统进行生化处理,该系统采用间歇式进水,水力停留时间为2 d,实验结果表明,A/O系统对COD、氨氮和总氮的去除率分别达41%、90%以上和86%。该组合工艺对COD的总去除率可达到67%,出水氨氮在20 mg/L以下,总氮在37 mg/L以下。     

Dioxin contamination in soils of Southern Vietnam

Dioxin is the common name for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and is abbreviated as PCDD/Fs. In the case of Southern Vietnam, is of high concern dioxin contamination in the areas affected by past-use chemical defoliants. Our study related to the zone considered as a "hot spot"--Bien Hoa Airbase and surrounding areas (Bien Hung Lake). Although the war ended over 30 years ago, the adverse effects on this territory still continue. Soil and sediment were selected for our research as they act as a sink for PCDD/Fs. The samples were taken and analyzed in CECOTOX laboratory following certified procedures. The total amounts of PCDD/Fs (2,3,7,8 related congeners) in the samples were converted into WHO-TEQ and compared with standard values proposed by Canadian environmental quality guidelines. The obtained data shows a relatively high risk (up to 20.4 times higher than (probable effect level) PEL value for sediment and 46 times higher than standard value for soil). The research is continuing on the assessment of dioxin transport in food chain. Moreover, considering the obtained data a complete solution should be found urgently to solve the problem of dioxin contamination in the studied areas.     

Toxicity of imidazolium salt with anion bromide to a phytoplankton Selenastrum capricornutum: effect of alkyl-chain length

Room-temperature ionic liquids are regarded as environmentally benign alternatives to volatile organic solvents. However, the product designs for this promising group of compounds should take account, not only the technological needs, but also the eco-toxicological hazards. Therefore, this study aimed to evaluate the toxicity of some important ionic liquids on the growth of the freshwater alga, Selenastrum capricornutum. The ionic liquids examined in this study included 1-propyl-3-methylimidazolium [PMIM], 1-butyl-3-methylimidazolium [BMIM], 1-hexyl-3-methylimidazolium [HMIM] and 1-octyl-3-methylimidazolium [OMIM] with a bromide anion. The susceptibility of alga to ionic liquids was strongly dependent on the alkyl-chain length. According to our results, a longer alkyl-chain resulted in stronger inhibition of algal growth. In general, the toxicity could be summarized as decreasing in the following order: [OMIM]>[HMIM]>[BMIM]>or=[PMIM]. Among the ionic liquids examined, [OMIM] [Br] was found to be most toxic to S. capricornutum, with EC(50) values ranging from 26.3 microM to 54.9 microM after an incubating time of 96 h. Although [BMIM] [Br] and [PMIM] [Br] was relatively less toxic than [OMIM] and [HMIM], their toxicity increased as increasing the incubation time from 48 h to 96 h. This fact indicates that these kinds of ionic liquids may become more toxic after being released and contacted to freshwater ecosystem.     

Optimizing the performance of phase-change materials in personal protective clothing systems.

Phase-change materials (PCM) can be used to reduce thermal stress and improve thermal comfort for workers wearing protective clothing. The aim of this study was to investigate the effect of PCM in protective clothing used in simulated work situations. We hypothesized that it would be possible to optimize cooling performance with a design that focuses on careful positioning of PCM, minimizing total insulation and facilitating moisture transport. Thermal stress and thermal comfort were estimated through measurement of body heat production, body temperatures, sweat production, relative humidity in clothing and subjective ratings of thermal comfort, thermal sensitivity and perception of wetness. Experiments were carried out using 2 types of PCM, the crystalline dehydrate of sodium sulphate and microcapsules in fabrics. The results of 1 field and 2 laboratory experimental series were conclusive in that reduced thermal stress and improved thermal comfort were related to the amount and distribution of PCM, reduced sweat production and adequate transport of moisture.     

珠江三角洲一些表层沉积物中多氯联苯的初步研究

本文报导了采自珠江三角洲地区一些水体（包括澳门河口湾）的１７个表层沉积物样品中多氯联苯（ＰＣＢs）的含量、分布特征的初步研究结果,结果表明：①分布于五个地区的１ ７个表表层样品中ＰＣＢs的含量以广州市附近的样品含量最高,澳门内港次之,分别为４８４．４５ｕｇ．ｋｇ＾－１和３３８．５３ｕｇ．ｋｇ＾－１,其余样品均比广州、澳门低一个数量级,而且从珠江干流上游至下游,ＰＣＢs含量具有明显降低的趋势;②广州工     

Arsenic in groundwater and sediment in the Mekong River delta, Vietnam

A study of groundwater and sediment during 2007-2008 in the Mekong River delta in Vietnam (MDVN) revealed that 26%, 74%, and 50% of groundwater samples were above the US EPA drinking water guidelines for As (10 μg/L), Mn (0.05 mg/L), and Fe (0.3 mg/L). The range of As, Fe, and Mn concentrations in the MDVN were <0.1-1351 μg/L, <0.01-38 mg/L, and <0.01−14 mg/L, respectively. Elevated levels of As were found in groundwater at sampling sites close to the Mekong River and in wells less than 60−70 m deep. An inverse relationship was found between As and Mn concentrations in groundwater. Sediment samples from An Giang and Dong Thap had the highest As concentrations (18 mg/kg and 38 mg/kg, respectively). Arsenic sediment occurred mainly in the poorly crystalline Fe oxide phases. Reductive dissolution of the Fe oxide phase is not necessarily the dominant mechanism of As release to groundwater.     

铁炭微电解-Fe~（2＋）/K_2S_2O_8降解甲基橙

针对偶氮类有机物废水具有色度大,难降解的特点,以对二甲基氨基偶氮苯磺酸钠（甲基橙）为模拟研究对象,对水体系中铁炭微电解-Fe2＋/K2S2O8降解甲基橙的方法进行了研究。通过正交实验确定出该方法各因素的影响程度,进一步通过单因素影响实验确定该方法的最佳条件是：铁炭微电解填料、FeSO4和K2S2O8投加量分别为300 g/L、1.3mmol/L和0.7 mmol/L,初始pH值为7.0。在最佳条件下,甲基橙COD和色度去除率分别能达到64.7%和68.2%。