Man-Goo Kim

Bisphenol A migration from polycarbonate baby bottle with repeated use

This study was to quantify the migration of bisphenol A (BPA), from new polycarbonate (PC) baby bottle into the water filled in the bottle, with repeated use up to 100 times and extraction by water temperature ranging from 40 degrees C to 100 degrees C. BPA was determined by GC-MS, operated in the selected ion monitoring mode. The concentrations of BPA, migrated from brand-new PC baby bottle, were 0.03ppb and 0.13ppb at 40 degrees C and 95 degrees C, respectively. However, the concentration of BPA from the bottle used for 6months, were 0.18ppb and 18.47ppb at 40 degrees C and 95 degrees C, respectively. The levels of BPA migration were rapidly increased when the water temperature was over 80 degrees C. The variations of BPA level were divided into three regions; lag effect, steady and aging, which showed different increasing rate. PC baby bottle after being utilized 60 times which was correspond to the baby bottle used for 3months started aging. It also showed an increasing rate of 4.9x10(-2)ppbtime(-1). These results are explained by increase in d-spacing of PC baby bottle. The d-spacing of PC baby bottle increases with repeated use from 0.499nm in brand-new bottles to 0.511nm with bottles which had been used for 6months.

Emission characteristics of PCDD/Fs, PCBs, chlorobenzenes, chlorophenols, and PAHs from polyvinylchloride combustion at various temperatures.

Abstract The effect of temperature on polyvinylchloride (PVC) combustion using a downstream tubular furnace was investigated for the formation of polycylcic aromatic hydrocarbons (PAHs) and chlorinated compounds. As the temperature increased, higher levels of PAHs were generated. Chlorinated compounds reached a peak at 600°C, with low emissions recorded at 300 and 900°C. There was a close correlation (R2 = 0.97) among polychlorinated bi-phenyls (PCBs), hexachlorobenzene, pentachloroben-zene, and polychlorinated dibenzo-p-dioxins and poly-chlorinated dibenzofurans (PCDD/Fs). PAHs at all temperatures were analyzed in the gas phase. PCDD/Fs and PCBs were emitted as a solid phase at 300 and 600°C and as a gas phase at 900°C. For some PAHs, chloroben-zenes, and PCDD/Fs, a mathematical equation between the gas and solid phase and the reciprocal temperature in semilog proportion was derived. The proposed equation, which is log (amount in gas phase/amount in solid phase) = −A/T + B, where T is the temperature of the furnace and A and B are constants, for these species relating their gas/solid distributions showed a good relationship.

Emission characteristics of PCDD/Fs in diesel engine with variable load rate.

Emission characteristics of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in diesel engine were studied with variable load rate of the diesel engine with the emission test cycles, US D-13 mode. The load rate is changed from 25% to 50% and 75% at constant speed of 2400 rpm. PCDD/Fs concentration and phase distribution of PCDD/Fs with the isokinetic sampling of exhaust gas is obtained in this study. The average PCDD/Fs concentrations per unit of exhaust gas with 25%, 50% and 75% load rate are 14.5, 6.9 and 6.4 pg-TEQ/N m3, respectively. In all diesel engine runs, PCDFs are more prevalent than PCDDs. As a load rate is increased, the ratio of PCDDs is gradually decreased. The amount of high-chlorinated PCDDs emitted in diesel engine is larger than that of low-chlorinated PCDDs. The significant emission form of PCDD/Fs produced from diesel engines exhaust is a gas phase.

Rapid Time Variations in Chemical Composition of Precipitation in South Korea

Data from a monitoring program on precipitation at four sites in South Korea during the period from 1993 to 1998 were analyzed for determining a time trend relationship in chemical composition of precipitation. The concentrations of nss-sulphate, ammonium and calcium were found to have decreased over time at a statistically significant level in Seoul (p<0.05). The concentration of nss-sulphate had declined by a rate of 12% per year for the period from 1993 to 1998. The concentrations of ammonium and calcium decreased by 11% and 12% per year respectively for the same period. The concurrent reduction of cation offsets the change in strong acid anion, thus the annual mean pH of precipitation has been approximately constant. In contrast to the rapid change of sulphate, the second most abundant anion, nitrate, showed no statistically significant decrease. As a result, the nitrate to nss-sulphate ratio (N/S ratio) has increased rapidly; the N/S ratio in precipitation has increased from less than 0.1 in 1985 to nearly 0.5 in 1998 at Seoul. In spite of the short monitoring period, a significant upward trend in the N/S ratio was also observed at all of the other sites suggesting that the nitrogen species contribute more to precipitation acidity throughout Korea.

Estimation of Dry Deposition by Using a Filter Pack Method at Chunchon, Korea

Atmospheric gases and particulates were collected using four-stage filter-pack in Chunchon from January through December in 1999. Particulate SO42− and NO3−, and gaseous HNO3, SO2 and NH3 were analyzed. Annual average concentration of SO42−(S), NO3−(S), HNO3 (g), SO2(g) and NH3(g) were 5.75µg/m3, 4.98µg/m3, 0.33ppb, 1.52ppb and 7.25ppb, respectively. Annual dry deposition fluxes were estimated using the measured concentration and dry deposition velocity published by other research group. Annual dry deposition of S was 287kg · (km)−2·y−1, which accounted for about 30% of total S deposition. For N deposition, dry deposition is predominant; about 70% of total N deposition was through dry process mostly as forms of NH3 and HNO3.

Emission Characteristics of Volatile Organic Compounds from Air Fresher using Small Emission Chamber

This study investigated the emissions characteristics of air freshener using small emission chamber method. The emission of VOCs from air freshener were determined in the small chambers in the temperature (25, ), relative humidity (), ventilation rate (0.3, 0.5, (), and sample loading factor () in this study. The emission tests from air freshener for sample loading factor resulted in TVOC emission rates of after 5 hours. For most target VOCs such as limonene, -pinene and linalool, higher temperature and ventilation rate levels exhibited increased emission rates.

Evaluation of Precipitation Composition at an Urban and a Rural Area for the Central Korean Peninsula

Precipitation samples were collected using wet-only samplers on a daily basis at Chunchon (rural area) and Seoul (urban area) from January to December in 1998. The pH, electrical conductivity, and the concentrations of major ions were analyzed. The volume-weighted annual average values of pH for both sites were identical. However, for volume weighted average pH of precipitations below 20 mm in Chunchon was significantly (p<0.05) lower than that in Seoul. The value of [NO3−]/[nss-SO42−], calculated from average composition of rainfalls below 20mm, were 0.42 and 0.61 in Seoul and Chunchon, respectively. This supports that acidification of precipitation by nitrogen oxides, a part of which might be transported from the Seoul metropolitan area, caused the difference in pH between Chunchon and Seoul.