가스 크로마토그래피를 이용한 대기와 물시료의 CFCs(chlorofluorocarbons) 분석법의 실험적 평가 Experimental Evaluation of an Analytical Method for Chlorofluorocarbons (CFSs) in Air and Water Using Gas Chromatography원문보기
대기와 물에서의 CFCs(CFC-12, CFC-11, CFC-113)를 분석할 수 있는 시스템을 자체 제작된 퍼지-트랩 추출 장치와 전자포획검출기가 설치된 가스 크로마토그래피를 이용하여 구축하였다. 대기와 물에 대한 시료 채취방법도 확립되었다. 분석 시스템은 실험적으로 최적화되어 최근 대기 시료는 2% 이내, 제주도의 지하수 시료 (CFC-12 농도가 $160{\sim}180pg/kg$)는 5% 이내의 삼중복시료에 대한 재현성을 보였고, 미국지질조사소(USGS)의 분석시스템과 교차 분석을 실시하였으며, 10% 오차 범위내에서 일치하였다. 한반도 중부 지역의 세 지점에 대해 19개월에 걸쳐 대기 중의 CFCs를 관측하여 이 지역에서 국지적인 CFCs 근원이 크지 않음을 확인하였다. 제주도의 한 농업용 공공 관정에서 2개월 간격으로 1년 동안 지하수의 CFCs를 관측한 결과 8월까지 지하수의 CFCs 농도가 감소하고 10월 이후에 다시 증가하는 계절적인 변동을 보여 주었다. 이것은 여름철 우기에 발생한 지하수 함양이 수 개월 지연되어 나타난 결과로 볼 수 있으며, 제주도 현무암 대수층의 높은 투수성을 지시한다.
대기와 물에서의 CFCs(CFC-12, CFC-11, CFC-113)를 분석할 수 있는 시스템을 자체 제작된 퍼지-트랩 추출 장치와 전자포획검출기가 설치된 가스 크로마토그래피를 이용하여 구축하였다. 대기와 물에 대한 시료 채취방법도 확립되었다. 분석 시스템은 실험적으로 최적화되어 최근 대기 시료는 2% 이내, 제주도의 지하수 시료 (CFC-12 농도가 $160{\sim}180pg/kg$)는 5% 이내의 삼중복시료에 대한 재현성을 보였고, 미국지질조사소(USGS)의 분석시스템과 교차 분석을 실시하였으며, 10% 오차 범위내에서 일치하였다. 한반도 중부 지역의 세 지점에 대해 19개월에 걸쳐 대기 중의 CFCs를 관측하여 이 지역에서 국지적인 CFCs 근원이 크지 않음을 확인하였다. 제주도의 한 농업용 공공 관정에서 2개월 간격으로 1년 동안 지하수의 CFCs를 관측한 결과 8월까지 지하수의 CFCs 농도가 감소하고 10월 이후에 다시 증가하는 계절적인 변동을 보여 주었다. 이것은 여름철 우기에 발생한 지하수 함양이 수 개월 지연되어 나타난 결과로 볼 수 있으며, 제주도 현무암 대수층의 높은 투수성을 지시한다.
CFC(CFC-12, CFC-11 and CFC-113) analytical system for air and water was constructed using a customized purge and trap extraction device and a gas chromatograph with an electron capture detector. Sampling methods of air and water for CFCs were also established. The analytical system was experimentall...
CFC(CFC-12, CFC-11 and CFC-113) analytical system for air and water was constructed using a customized purge and trap extraction device and a gas chromatograph with an electron capture detector. Sampling methods of air and water for CFCs were also established. The analytical system was experimentally optimized to result in reproducibilities of triplicates less than 2% for current air samples and less than 5% for groundwater samples with CFC-12 concentration of 160 to 180 pg/kg, and verified with respect to the CFC system in USGS, which showed analytical results were in agreement within 10%. CFCs in air were monitored at three sites over 19-month period in the central part of South Korea, and the result indicates no significant local sources of CFCs in those areas. For groundwater in Jeju Island, CFCs were measured over a year with a two-month interval. The time-series data showed seasonal fluctuations which could be interpreted by the effect of recharge pulse derived from large amount of rainfall during monsoon period with a few month delay, which indicates high permeability of basaltic rocks in Jeju Island.
CFC(CFC-12, CFC-11 and CFC-113) analytical system for air and water was constructed using a customized purge and trap extraction device and a gas chromatograph with an electron capture detector. Sampling methods of air and water for CFCs were also established. The analytical system was experimentally optimized to result in reproducibilities of triplicates less than 2% for current air samples and less than 5% for groundwater samples with CFC-12 concentration of 160 to 180 pg/kg, and verified with respect to the CFC system in USGS, which showed analytical results were in agreement within 10%. CFCs in air were monitored at three sites over 19-month period in the central part of South Korea, and the result indicates no significant local sources of CFCs in those areas. For groundwater in Jeju Island, CFCs were measured over a year with a two-month interval. The time-series data showed seasonal fluctuations which could be interpreted by the effect of recharge pulse derived from large amount of rainfall during monsoon period with a few month delay, which indicates high permeability of basaltic rocks in Jeju Island.
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문제 정의
This study is for the establishment of CFC analytical system for water and air to apply to hydrological studies. Analytical characteristics of CFC-113 as well as CFC-11 and CFC-12 were evaluated using the modified method of Bullister and Weiss (1988) which had been originally designed for measurement of CFC-11 and CFC-12.
가설 설정
3) Relative solubility in water normalized to that of CFC-12 at 25℃. Solubility data from Warner and Weiss (1985) for CFC-11 and CFC-12, from Bu and Warner (1995) for CFC-113.
제안 방법
An analytical system for CFC-12, CFC-11 and CFC-113 in air and water samples was constructed using a customized purge and trap extraction system and a gas chromatograph with an electron capture detector. Air samples were collected using pressurized metal canister method.
CFCs in groundwater were determined for a irrigation well of the eastern area (well A) in Jeju Island which was collected every two or three months for one year to investigate seasonal variation of groundwater ages (Fig. 9). Uncertainties of measured concentrations of CFCs in the groundwater samples are less than 5% for mo마 of measurements (Table 6).
Because these bubbles are lost during introduction of water sample to the extraction system, CFCs in the bubbles should be compensated in final analytical results. Volume of the bubble was determined from the measured diameter of the bubble using the equation, experimentally derived in this study, relating diameter and volume of the bubble (Fig. 2). Because flowing water is not pressurized during the collection of water sample, total pressure is assumed 1 atm in the bubble.
대상 데이터
The site of Yesan is surrounded by agricultural land use and small scale of residence and the site ofBoeun is in the forest with negligible human influence which belongs to conservation area for drinking water protection zone. The sampling site in Daejeon is located in the Daedeok Science Complex, north the downtown area. Uncertainties of measured atmospheric mixing ratios of CFCs were less than 2% (Table 5).
To set a criterion for reliability of low-level analysis, a groundwater sample with low level CFCs was analyzed for seven replicates (Table 3). The sample has low 3H concentration of 0.
이론/모형
An analytical system for CFC-12, CFC-11 and CFC-113 in air and water samples was constructed using a customized purge and trap extraction system and a gas chromatograph with an electron capture detector. Air samples were collected using pressurized metal canister method. For groundwater samples, glass bottle method with metal lined caps was employed, which is much simpler than flame-sealed ampoule method and correction method for the loss of gas bubbles was also established.
The extraction system for water samples was constructed on the basis of the purge and trap system of Bullister and Weiss (1988). The apparatus for water sample introduction was modified from Busenberg and Plummer (1992) and bottle adapter (Teflon) fitted to a glass bottle was installed to minimize atmospheric contact of water sample though the inside N2 pressure is higher than ambient conditions.
성능/효과
For air samples, differences in results were less than 5% for CFC-12 and CFC-11 and 10% for CFC-113, The differences in results for water samples were less than 10% except for the samples with negligible CFCs.
5). To confirm that CFC-113 enters quantitatively the GC main column at the determined IS time, the peak area was compared to that with no backflush. The difference of two measurements was less than 5%, which suggests the determined IS time is appropriate.
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