Chemical characteristics of fine particulate matters measured during severe winter haze events in Ulaanbaatar,Mongolia

In order to investigate the chemical characteristics of atmospheric aerosol measured during a severe winter haze event, 12-hr PM_2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) samples were collected at an urban site in Ulaanbaatar, Mongolia, from January 9 to February 17, 2008. On average, 12-hr PM_2.5 mass concentration was 105.1 ± 34.9 μg/m³. Low PM_2.5 mass concentrations were measured when low pressure developed over central Mongolia. The 12-hr average organic mass by carbon (OMC) varied from 6.4 to 132.3 μg/m³, with a mean of 54.9 ± 25.4 μg/m³, whereas elemental carbon (EC) concentration ranged from 0.1 to 3.6 μgC/m³, with a mean of 1.5 ± 0.8 μgC/m³. Ammonium sulfate was found to be the most abundant water-soluble ionic component in Ulaanbaatar during the sampling period, with an average concentration of 11.3 ± 5.0 μg/m³. In order to characterize the effect of air mass pathway on fine particulate matter characteristics, 5-day back-trajectory analysis was conducted, using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The haze level was classified into three categories, based on the 5-day air mass back trajectories, as Stagnant (ST), Continental (CT), and Low Pressure (LP) cases. PM_2.5 mass concentration during the Stagnant condition was approximately 2.5 times higher than that during the Low Pressure condition, mainly due to increased pollutant concentration of OMC and secondary ammonium sulfate.

Implications: Mongolia is experiencing rapid rates of urbanization similar to other Asian countries, resulting in air pollution problems by the growing number of automobiles and industrialization. Ulaanbaatar, capital of Mongolia, is inherently vulnerable to air pollution because of its emission sources, topography, and meteorological characteristics. Very limited measurements on chemical characteristics of particulate matter have been carried out in Ulaanbaatar, Mongolia.     

Consultant Guide/1987

ABSTRACT

This study considers the characteristics of ground-level ozone (O₃) in five Korean cities over a time period of 6-8 years. The focus of this study is daily maximum 1-hr and 8-hr concentrations. For all the study cities in the period examined, the mean and most of the percentiles (5, 10, 25, 50, 75, 90, and 95) for the daily maximum 1-hr and 8hr concentrations showed increasing trends, although not all trends were statistically significant. The daily maximum 1-hr and 8-hr concentrations slowly increased during late winter, and peaks were attained during the summer season (from May to September). All the selected cities exhibited a high degree of correlation between their daily maximum 8-hr and 1-hr concentrations. The daily maximum 8-hr concentrations, which were climatologi-cally equivalent to the Korean 1 hr/100 parts per billion (ppb) standard, were higher than the current 8 hr/60 ppb by a difference of 8-16 ppb. Compared with other cities in Korea, Seoul recorded a substantially higher frequency of days and hours with concentrations above 1 hr/100 ppb, and a higher frequency of days with concentrations above 8 hr/60 ppb and 8 hr/80 ppb. Seoul also recorded a substantially higher frequency of hours with concentrations above 1 hr/100 ppb than days with concentrations above 1 hr/100 ppb, implying that on some days severe exceedances persisted for more than one hour per day. During multiple-day episodes a North Pacific High dominated Korea, which is quite typical in Korea during the summer season.     

Polarity effect of pulsed corona discharge for the oxidation of gaseous elemental mercury

The effect of polarity on the oxidation of Hg⁰ was examined in the presence of O₂ via a pulsed corona discharge (PCD). The experimental result showed no difference in the energy yield of Hg⁰ oxidation at both positive and negative PCDs (∼8 μg Hg W h⁻¹ at following conditions: total flow rate = 2 L min⁻¹ (Hg⁰ = 50 μg N m⁻³, O₂ = 10%, and N₂ balance), temperature = 150 °C, and specific energy density = 5-15 W h N m⁻³). This suggests that the positive PCD process used to control gaseous air pollutants may play an essential key role in Hg⁰ oxidation because it consumes enough energy (∼15 W h N m⁻³) but an electrical precipitator could not because it consumes less energy (∼0.3 W h N m⁻³) to oxidize Hg⁰.     

Use of reporter-gene based bacteria to quantify phenanthrene biodegradation and toxicity in soil

A phenanthrene-degrading bacterium, Sphingomonas paucimobilis EPA505 was used to construct two fluorescence-based reporter strains. Strain D harboring gfp gene was constructed to generate green fluorescence when the strain started to biodegrade phenanthrene. Strain S possessing gef gene was designed to die once phenanthrene biodegradation was initiated and thus to lose green fluorescence when visualized by a live/dead cell staining. Confocal laser scanning microscopic observation followed by image analysis demonstrates that the fluorescence intensity generated by strain D increased and the intensity by strain S decreased linearly at the phenanthrene concentration of up to 200 mg/L. Such quantitative increase and decrease of fluorescence intensity in strain D (i.e., from 1 to 11.90 ± 0.72) and strain S (from 1 to 0.40 ± 0.07) were also evident in the presence of Ottawa sand spiked with the phenanthrene up to 1000 mg/kg. The potential use of the reporter strains in quantitatively determining biodegradable or toxic phenanthrene was discussed.     

Accelerating preliminary eco-innovation design for products that integrates case-based reasoning and TRIZ method

While the innovativeness and market potential of a new product is normally emphasized, its environmental impact is often neglected. Despite their ability to help designers reduce the environmental impact of products throughout their life cycle, many eco-design methods focus on the redesign of existing products, necessitating a more innovative design capacity. This work describes a novel model to accelerate the preliminary eco-innovation product design by integrating the advantages of case-based reasoning and the TRIZ method. Previous cases from a database support a novel design to satisfy functional performances under the CBR framework. The innovative principles and evolution patterns of the TRIZ method can enhance the design level of new products to achieve eco-innovation. Four eco-innovation concepts for a PC mouse demonstrate the effectiveness of the proposed model.     

Oil spreading in instantaneous and continuous spills on rotating earth

The effect of the Coriolis force on the oil spill spreading in the gravity-viscous regime is examined. A new shallow water model for the transport and spreading of oil slick of arbitrary shape is described in which the Coriolis force is included in the momentum equations and the oil–water friction is parameterized in a frame of the boundary layer theory including the Ekman friction. The numerical Lagrangian method based on smoothed particle dynamics is described. New similarity solutions of the model equations are obtained for unidirectional and axisymmetric spreading in gravity-viscous, gravity-turbulent and gravity-viscous-rotational regimes for instantaneous as well as continuous releases. The numerical simulation extends these results for the case of continuous release in the presence of currents. It was shown that Coriolis term in the momentum equation can be omitted if slick thickness is much less of the laminar Ekman layer thickness. However, the Ekman friction should be retained for slicks of any thickness for larger times. The Ekman friction results in the essential slowdown of the spreading as well as in the deflection of the oil spreading velocity at 45° from the direction of velocity in the non-rotation case. Numerical simulations of large-scale spills showed that after the 2?days the slick area with the Coriolis effect was approximately less than half of that without rotation. Therefore, the earth rotation can be also important in the oil weathering.     

Development of a high-efficiency rotary dryer for sewage sludge

A rotary drum dryer having an internal rotating body was designed and tested in this study. It was shown that the developed dryer is effective for drying sewage sludge. The best operating conditions in the dryer were low energy input and almost 10% moisture content. The conditions are 255°C for the rotary drum temperature, 17 min for the sludge residence time, and 55 kg/m³ h for the dryer load. Under these conditions, the drying efficiency was 84.8%. The average diameter of dried sludge was less than 8 mm, and the weight reduction rate was 80%. Parametric screening studies achieved the following results. The drying efficiency increased with the increase of the internal temperature and the sludge residence time in the rotary drum, while the drying efficiency decreased when increasing the dryer load. In addition, it was shown that NH₃ and CO₂ were the primary components released from the sewage sludge drying process. The amounts of both of these components increased when the rotary drum temperature was increased.