Source apportionment of fine carbonaceous particles by positive matrix factorization at Gosan background site in East Asia

Fine particle (aerodynamic diameter <2.5 microm) samples were collected during six intensive measurement periods from November 2001 to August 2003 at Gosan, Jeju Island, Korea, which is one of the representative background sites in East Asia. Chemical composition of these aerosol samples including major ion components, trace elements, organic and elemental carbon (OC and EC), and particulate polycyclic aromatic hydrocarbons (PAHs) were analyzed to study the impact of long-range transport of anthropogenic aerosol. Aerosol chemical composition data were then analyzed using the positive matrix factorization (PMF) technique in order to identify the possible sources and estimate their contribution to particulate matter mass. Fourteen sources were then resolved including soil dust, fresh sea salt, transformed natural source, ammonium sulfate, ammonium nitrate, secondary organic carbon, diesel vehicle, gasoline vehicle, fuel oil combustion, biomass burning, coal combustion, municipal incineration, metallurgical emission source, and volcanic emission. The PMF analysis results of source contributions showed that the natural sources including soil dust, fresh and aged sea salt, and volcanic emission contributed to about 20% of the measured PM(2.5) mass. Other primary anthropogenic sources such as diesel and gasoline vehicle, coal and fuel oil combustion, biomass burning, municipal incineration, metallurgical source contributed about 34% of PM(2.5) mass. Especially, the secondary aerosol mainly involved with sulfate, nitrate, ammonium, and organic carbon contributed to about 39% of the PM(2.5) mass.     

Effect of preparation method of noble metal supported catalyts on formaldehyde oxidation at room temperature: Gas or liquid phase reduction

Formaldehyde (HCHO) is toxic to the human body and is one of the main threats to the indoor air quality (IAQ). As such, the removal of HCHO is imperative to improving the IAQ, whereby the most useful method to effectively remove HCHO at room temperature is catalytic oxidation. This review discusses catalysts for HCHO room-temperature oxidation, which are categorized according to their preparation methods, i.e., gas-phase reduction and liquid-phase reduction methods. The HCHO oxidation performances, structural features, and reaction mechanisms of the different catalysts are discussed, and directions for future research on catalytic oxidation are reviewed.     

Odd-numbered perfluorocarboxylates predominate over perfluorooctanoic acid in serum samples from Japan, Korea and Vietnam

Perfluorooctanoic acid (PFOA) has recently attracted attention as a potential health risk following environmental contamination. However, information detailing exposure to perfluorinated carboxylic acids (PFCAs) other than PFOA is limited. We measured the concentrations of PFCAs (from perfluorohexanoic acid to perfluorotetradecanoic acid) in serum samples obtained from patients in Japan (Sendai, Takayama, Kyoto and Osaka) between 2002 and 2009, Korea (Busan and Seoul) between 1994 and 2008 and Vietnam (Hanoi) in 2007/2008. Total PFCA levels (geometric mean) were increased from 8.9 ng mL(-1) to 10.3 ng mL(-1) in Japan; from 7.0 ng mL(-1) to 9.2 ng mL(-1) in Korea; and were estimated at 4.7 ng mL(-1) in Vietnam. PFCAs of greater length than PFOA were significantly increased in Sendai, Takayama and Kyoto, Japan, and levels of long-chain PFCAs exceeded PFOA levels in serum. Among these PFCAs, perfluoroundecanoic acid (PFUnDA) was the predominant component (28.5%), followed by perfluorononanoic acid (PFNA 17.5%), perfluorodecanoic acid (PFDA 7.9%), perfluorotridecanoic acid (PFTrDA 6.1%) and perfluorododecanoic acid (PFDoDA 1.8%). Odd-numbered PFCAs (PFNA, PFUnDA and PFTrDA) were also observed in Korea and Vietnam and their presence increased significantly in Korea between 1994 and 2007/2008. The proportion of long-chain PFCAs in serum was relatively high compared to reports in Western countries. Further investigations into the sources and exposure routes are needed to predict the future trajectory of these serum PFCA levels.     

Effect of seepage conditions on chemical attenuation of arsenic by soils across an abandoned mine site

The effect of seepage velocity on the As leaching/adsorption by soils collected from abandoned mine sites was evaluated under batch equilibrium and different seepage settings. The breakthrough curves (BTCs) of As leaching from the mine soil column initially displayed the peak export and gradually leveled off over the leaching experiment. A similar As peak was observed after a flow interruption period. Adsorption by downgradient soils was clearly nonlinear, as Freundlich N was <1. In the BTCs of the layered columns, where downgradient soils were overloaded above the mine soil, the extended lag period of As appearance and lower steady-state As concentration observed for slow seepage velocity supported the idea of kinetically limited As attenuation driven by soil adsorption. The perturbation of As concentration was insignificant when the intra-column As concentration gradient was higher. The As concentration drop and time to recovery were greater for less adsorptive soil and fast seepage velocity. Desorption of As from soils retrieved from both batch adsorption and column experiment demonstrate hysteric behavior. The results of this work demonstrated that the risk of As leaching from an abandoned mine site can be greatly attenuated by intermediate downgradient soils via chemical adsorption, which tends to be kinetically limited and energetically hysteric (i.e., non-identical energy pathway).     

Mass transport of organic contaminants through a self-sealing/self-healing mineral landfill liner

The self-sealing/self-healing (SS/SH) liner system is based on the fundamental principle that an impermeable seal is self-formed and self-healed by the pozzolanic reaction at the interface between two adjacent reactive layers. The objectives of this study were to evaluate the effect of contaminants on the performance of an SS/SH liner used as a hydraulic barrier, to understand mechanism of volatile organic compound (VOC) sorption on the SS/SH materials, and to estimate the mass transport parameters of contaminants through the SS/SH liner materials. The hydraulic conductivity of the liner material decreased continuously with time, and stabilized at less than 1 × 10^–7cm/s after approximately 15 days. It is known that the seal at the interface between two reactive layers is self-formed over time, and this contributes to the decrease in the hydraulic conductivity of such a liner system. The retardation of the seven target VOCs tested was greater in the SS/SH liner materials than in a clayey soil specimen owing to the higher sorption capacity. An analytical solution developed to test column equipment could reduce the time required to estimate the hydrodynamic dispersion coefficients of organic compounds by using the data on changes in concentration in the upper reservoir of the column.     

Airborne rice pollen and pollen allergen in an agricultural field: aerobiological and immunochemical evidence

Grass pollens are well known among the health hazardous bioaerosols causing respiratory allergy. Being an important member of the grass family, the rice plants contribute a huge pollen load in agricultural fields during flowering. This results in a seasonal trigger of hay fever and respiratory allergy in the field workers and people living in the vicinity. Studies on the monitoring of airborne rice pollen and the intensity of the released allergen in agricultural fields are largely lacking. The aims of the present study were: (1) daily and hourly monitoring of airborne rice pollen in an agricultural field during the flowering period of plants in a winter crop season by using the Burkard 7-Day Volumetric Sampler and (2) the measurement of hourly airborne allergen intensity in the field in a peak rice pollen period by the double-antibody and chemiluminescence techniques to find out its relationship with the airborne rice pollen concentration. The monthly average concentration of rice pollen was 95 pollen m(-3) and the range of daily average pollen concentration was 0 to 386 pollen m(-3). A bimodal diurnal periodicity showed that the airborne rice pollen concentrations remained high at two different times of the day: between 08:00 h to 12:00 h and 14:00 h to 16:00 h. Deposition of airborne rice pollen allergen showed darker intensities on the immunostained tapes from the Burkard Sampler at the same two positions corresponding to higher pollen counts. These observations provided direct evidence of the allergenicity of airborne rice pollen in field conditions.     

Volumetric assessment of airborne fungi in two sections of a rural indoor dairy cattle shed

There is increasing concern about the exposure to fungal aerosols in occupational environments and associated respiratory allergic diseases and asthma. A large number of people work in cattle sheds around the world, pulmonary function impairments and higher frequency of respiratory symptoms have been reported in dairy farmers; however, it appears that adequate information on the fungal aerosols from the cattle sheds are largely lacking. Volumetric assessment of airborne culturable and nonculturable fungal spores was performed in two sections of a large rural indoor cattle shed of West Bengal, India for 2 consecutive years. An Andersen Two Stage Viable Sampler was used for sampling culturable fungi and a Burkard Personal Slide Sampler was used to collect the total airborne fungal spores including both the culturable and nonculturable types. A total of 31 spore types and 35 types of viable colony-forming units were recorded. Average concentration range of total fungal spores was 233-2985/m(3) and concentration of viable colony-forming units ranged between 165 and 2225 CFU/m(3). Burkard Sampler showed higher frequencies of Aspergilli/Penicilli, Cladosporium, Alternaria, and smut spores. Andersen Sampler showed the prevalence of Aspergillus niger, Aspergillus flavus and Cladosporium cladosporioides colonies. Some recorded fungi were earlier reported as allergenic, toxic, and pathogenic for occupational workers as well as cattle population. Higher concentration levels of airborne total and culturable fungal spores were recorded during the months of November through February (winter) and June through September (late summer and rainy season).     

Temperature and salinity adaptation in the purple shore crab Hemigrapsus nudus: An in vitro physiological study with excised gills

The alkali-soluble polysaccharides of the cell wall from 7 different marine diatoms were shown to contain the monosaccharides rhamnose, fucose, galactose, mannose and xylose. The relative amounts of rhamnose and fucose varied widely from one species to another, from the very rhamnose-rich Chaetoceros affinis to Thalassiosira gravida, where no rhamnose was found. All Chaetoceros species were found to have a high content of rhamnose. Also the proportion of mannose to galactose varied widely from species to species. The observed change in monomer composition from the logarithmic to the stationary growth phase is explained by assuming the alkali-soluble fraction to be a mixture of polysaccharides. The soluble, extracellular polysaccharides from 4 of the diatoms were also investigated. The products from C. affinis and C. curvisetus were homogeneous and composed of only 3 monomers: rhamnose, fucose and galactose. The extracellular polysaccharide composition in all species investigated was quite different from the composition of the cellular alkali-soluble fraction. The ecological aspects of these soluble polysaccharides may prove of considerable interest.     

Studies on hexavalent chromium biosorption by chemically-treated biomass of Ecklonia sp

The biomass of the brown seaweed, Ecklonia sp., is capable of reducing Cr(VI) to Cr(III). However, very little is known about the mechanism of Cr(VI) reduction by the biomass. The aims of the present investigation were to enhance the Cr(VI)-reducing capacity of the biomass using various chemical treatments and to elucidate the mechanisms governing Cr(VI) reduction. Among the various chemical treatments, acid-treatment showed the best performance with regards the improvement of Cr(VI) removal from the aqueous phase, while organic solvent-treatment significantly improved the removal efficiency of total Cr in the equilibrium state. Based on FTIR study, the biomass was subjected to chemical modification of its amino and carboxyl groups, to examine their roles in the Cr(VI) removal from the aqueous phase. Methylation of the amino group significantly decreased the Cr(VI) removal rate, but amination of the carboxyl group significantly increased the Cr(VI) removal rate. Meanwhile, esterification of the carboxyl group and carboxylation of the amino group decreased the Cr(VI) removal rate, but the former showed a more negative effect than the latter. These findings indicated that the amino and carboxyl groups take part in the Cr(VI) removal from the aqueous phase. In conclusion, mechanisms for direct and indirect Cr(VI) removal are proposed, and some aspects for the application of this biomass to Cr(VI) detoxification are discussed.