Polychlorinated dibenzo-p-dioxins and dibenzofurans from food salt samples processed by heat treatment in Korea

Eight samples of processed food salt collected from five plants in Korea were analyzed for 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) using liquid-liquid extraction, clean-up procedures, and high resolution gas chromatography-high resolution mass spectrometry. The study included the analyses of two kinds of salt product sample: bamboo-salt and parched salt. The levels of toxic PCDD/Fs found in the salt product samples were extremely low: the results revealed TEQ levels ranging between the sub pg TEQ/g and sub fg TEQ/g. The differences in the TEQ values of toxic PCDD/F were observed between the salt product samples, which were treated with different frequency of baking using four different fuels (firewood, pine wood, pine resin, and indirect heating by gas) at temperatures from 300 to 2000 degrees C. In bamboo-salt samples, the concentrations and TEQ values of toxic PCDD/Fs ranged between 0.57-66 pg/g and 5.7x10(-5)-0.64 pg TEQ/g, respectively. PCDD/Fs levels in bamboo-salts baked by firewood were found to be higher than those baked by pinewood or pine resin. In parched salt samples, the concentrations and TEQ values of toxic PCDD/Fs ranged between 0.97-3.7 pg/g and 0.0097-0.017 pg TEQ/g, respectively. The data was discussed regarding the concentration and the distribution pattern of congeners.     

Effects of basic oxygen furnace slag and inorganic nutrients on the germination of resting cysts of two toxic dinoflagellates

Effects of basic oxygen furnace (BOF) slag, inorganic nutrients and H2S on the germination of resting cysts of two toxic dinoflagellates Alexandrium catenella/tamarense and Gymnodinium catenatum were studied in batch cultures. The germination rate of the test species has increased by 23-25%, when the concentration of NO3--N or H2S in culture medium has increased to 2.0 ppm. At the treatment of enriched NH4+-N and PO43--p, the germination of resting cyst was increased. Nevertheless, the increased range in germination rates was less than those of NO3--N and H2S. When BOF slag in culture medium increased to 50 mg/ml (or 500 g/m2), the cyst germination rate fell to less than 5%. At higher level of concentrations germination was completely inhibited. Adding BOF slag to the culture medium reduced the concentration of inorganic salts and H2S in seawater and sediments, resulting in the inhibition of cyst germination. These findings demonstrate the potential use of BOF slag on the sediments seed bank of red tide organism because it has an ability to inhibit resting cysts germination.     

Improvement of thermal hydrolysis rate of dichloroacetic acid using alcohol

Dichloroacetic acid (DCAA) is produced during the oxidation of trichloroethylene. It is also produced in drinking water treatment as a disinfection by-product. DCAA is a problem material, because of its toxicity. The objective of this research is to find the final products and the reaction pathway of the DCAA decomposition by hydrolysis, and to increase the hydrolysis rate. The removal of both chlorine atoms in DCAA structure was achieved with hydrolysis at around 75 degrees C, and the final products were oxalic acid and glycolic acid. The reaction pathway was the production of oxalic acid and glycolic acid from two glyoxylic acid molecules by Cannizzaro reaction after the glyoxylic acid production from dechlorination of DCAA with hydrolysis. The hydrolysis rate of DCAA was increased with the use of 90% ethanol solution as solvent. The activation energy of DCAA was about 80 kJ/mol in it, while it was around 105 kJ/mol in water.     

Benefits-based analysis of visitor use of Sorak-san National Park in Korea

Benefits-based management seeks to provide recreation benefits for recreation participants by managing the physical environments in which recreation occurs. This study investigates the relationship between benefits desired by visitors and the physical, social, and managerial characteristics of settings that facilitate realization of recreation benefits. Data such as perceived benefits from recreation experiences, setting attributes that significantly influenced perceived benefits, and sociodemographic variables were collected from 376 visitors to Sorak-san National Park in the eastern part of the Korean peninsula. Cluster analysis was used to group visitors' desired benefits into 12 domains: relationship with nature/scenery, escaping pressure, learning about nature, family togetherness, introspection, exploration, autonomy/achievement, being with friends, leading others, skills/learning, risk taking, and meeting/observing new people. Multiple regression was used to link benefit domains with the characteristics of settings. The social attribute of recreation settings was linked to eight of the ten benefit domains. There were two statistically strong multiple regression correlations: (1) between domain of “relationship with nature /scenery” and the attributes “forest/water,”“attractive nature,” and “facility/maintenance” and (2) between the domain of “escaping pressure” and the attributes “attractive nature” and “social.” The results of this study are useful to managers in their efforts to provide recreation opportunities for visitors to achieve beneficial outcomes.     

Minimum effective release rate of antifoulants. 2. Effects of TBTCI, 2-furyl-n-pentyl ketone and coumaric acid at Snug harbor,Hawaii

Minimum effective release rate (MERR) of three antifoulants was examined at Snug harbor, Hawaii using a dynamic diffusion system. Among the three antifoulants tested TBTCI was found to be effective in preventing the settlement of Hydroides elegans and Crisea sp at 0.5 microg cm(-2) d(-1) flux rate. At a maximum flux rate of 10 microg cm(-2) d(-1) of 2-furyl-n-pentyl ketone larval settlement of both the test species were 32-36% reduced. More or less similar effect was seen at 10 microg cm(-2) d(-1) of coumaric acid. Non-toxic antifoulants, 2-furyl-n-pentyl ketone and coumaric acid exhibit specific activity against target species. MERR obtainedfor the three antifoulants is discussed.     

A Biosurfactant-Enhanced Soil Flushing for the Removal of Phenanthrene and Diesel in Sand

In order to examine the potential of biosurfactants in soil remediation, and to investigate the effects of several operating conditions, such as flow rate, biosurfactant concentration and surfactant type, biosurfactant-enhanced soil flushing was conducted. In the biosurfactant-enhanced soil flushing process, the removal efficiency increased as the flow rate decreased. Rhamnolipid showed no effect on the removal efficiency of phenanthrene and diesel from sand in the concentration range 0.3-0.5%. However, rhamnolipid showed higher efficiencies for the removal of phenanthrene and diesel from sand than Tween 80. Based on total recovery, following an equivalent pore volume flush, it was more difficult to remove diesel than phenanthrene. In order to obtain the specific removal efficiency, more pore volumes of surfactant solution may be required in field applications. Under optimum conditions, the biosurfactant removed as much as 70% of the phenanthrene and 60% of the diesel in the sand. These results indicate that the use of biosurfactants in the flushing process is favorable, not only with respect to the environment, but also on removal efficiencies.     

Removal characteristics of trace compounds of landfill gas by activated carbon adsorption

The removal characteristics of trace compounds and moisture in raw landfill gas (LFG) were studied. The LFG from the extraction well was saturated with water and moisture was eliminated by physical methods including cyclone-type dehydrator and compressor. The moisture removal efficiency of dehydrator and compressor was above 80%. As the moisture contents of LFG decreased, the toxic compounds like aromatics and chlorinated compounds were effectively removed by using the granular activated carbon. The breakthrough time and adsorption capacity of benzene, toluene, and ethyl benzene decreased rapidly when the relative humidity is over 60%. The effect of moisture was more pronounced at lower adsorbate concentrations tested than at higher concentrations. The breakthrough curves for multi-component mixtures show displacement effects. In the course of competing adsorption, adsorbates with strong interaction force to displace weakly bounded substances. Adsorption by activated carbon is in descending order of xylene, ethylbenzene, toluene, tri or tetrachloroethylene, benzene, carbon tetrachloride and chloroform in LFG, respectively.