For introducing the groundwater quality assessment using background concentration of groundwater, several methods had been studied to estimate the background concentration of groundwater and to suggest the background concentration of study area. Some methods such as Box whisker plot, Percentile and Cumulative probability distribution had been adopted to estimate background concentration, and it was evaluated that the Cumulative probability distribution method presents more reasonable background concentration because it can consider the data distribution. So we estimated the background concentration of study area using cumulative probability distribution method. We suggested the background concentration for each hydrogeology respectively in case hydrogeological water quality similarity is very low.

본 연구에서는 울릉도 온실기체 관측장비(CRDS)에서 관측된 CO2와 CH4 농도를 정형화된 QA·QC 처리절차를 통해 온실기체 평균 배경대기 농도값으로 활용하기 위한 정확도를 향상시켰다. QA·QC 처리절차는 총 3단계로 구성되었다. 첫 번째는 관측자료의 시간별 평균값을 구하기 위한 물리적 한계검사, 기후범위 검사 및 1시간 측정 자료수가 50% 이하인 자료는 제외시키는 과정으로 이루어져 있다. 두 번째는 일평균자료 산출을 위한 단계검사, 앞뒤로 같은 값일 경우는 제외, 하루 중 관측횟수가 15회 이상 및 일관측 자료의 표준편차가 일표준편차 평균의 3배 이하인 자료만 허용하는 과정이다. 세 번째는 기후적 특성분석 활용을 위한 Curve-fitting methods를 이용한 FFT 적용단계이다. 이상의 QA·QC 절차에 의한 CO2 및 CH4의 월평균농도 값을 안면도 지구대기감시센터 자료와 일본 료리 관측자료와 비교 분석한 결과 CO2에 있어서는 울릉도 관측자료 누락에 의한 영향이 다소 크게 나타나 안면도 관측값이 배경대기 평균농도 값으로 유효하였고, CH4는 안면도 보다 오히려 울릉도 관측값이 한반도 배경대기 평균농도 값으로 더 적절한 것으로 추정되었다.

동아시아에서 일산화탄소의 지역적 배경 농도 수준을 분석하기 위해, 1991년부터 2004년까지 장기간 중국 Waliguan(WLG), 몽골이아의 Ulaan Uul(UUM), 한국의 태안반도(TAP), 일본의 Ryori(RYO)에서 관측한 일산화탄소 농도를 분석하였다. 연평균 일산화탄소 농도는 WLG(135±22ppb), UUM(155±26ppb), RYO(171±36ppb), TAP(233±41ppb) 순서로 높은 농도를 보이고 있었다. WLG를 제외하고 전체적으로 봄철에 높고 여름철에 낮은 계절 변동의 특징은 동아시아 다른 지점들에서도 공통적으로 나타나고 있다. TAP는 WLG, UUM, RYO와 비교하여 전체 계절에 높은 일산화탄소 농도를 보이고 있으며 히스토그램에서 넓은 농도 분포를 보이는데 동아시아 대륙, 특히 중국의 가까운 풍하측에 위치하고 있어 광역적 대기 오염의 영향이 크기 때문이다. TAP는 중국 동부 지역을 경유하는 RPC가 봄, 가을, 겨울에서 높은 농도를 나타내었고, 여름철에는 저위도 북태평양으로부터의 OBG에 의해 낮은 일산화탄소 농도를 갖고 있는 해양성 기단의 영향을 받고 있다. NOAA 위성 영상과 GEOS-CHEM 모델 시뮬레이션은 중국 남동부 연안으로부터 황해를 거쳐 한반도와 동해로 확산하고 있는 광역적 대기오염 이동 사례를 확인하고 있다.

The spatial and temporal variations of CO2 concentrations and radiative forcing (RF) due to CO2 were examined at urban center (Yeon-dong) during 2010-2015 and background sites (Gosan) during 2010-2014 on Jeju Island. The RF at the two sites was estimated based on a simplified expression for calculating RF for the study period. Overall, annual mean CO2 concentrations at the Yeon-dong and Gosan sites have gradually increased, and the concentrations were higher at Yeon-dong (401-422 ppm) than at Gosan (398-404 ppm). The maximum CO2 concentrations at the two sites were observed in winter or spring, followed by fall and summer, with higher concentrations at Yeon-dong. The RF at Yeon-dong (annual mean of up to 0.70 W/m2 in 2015) was higher than that at Gosan (up to 0.46 W/m2 in 2014), possibly because of higher CO2 concentrations at Yeon-dong resulting from population growth and human activities (e.g., fossil fuel combustion). The highest monthly mean RFs at Yeon-dong (approximately 0.92 W/m2) and Gosan (0.52 W/m2) were observed in spring 2015 (Yeon-dong) and spring 2013 (Gosan), whereas the lowest RFs (0.17 and 0.31 W/m2, respectively) in fall 2011 (Yeon-dong) and summer in 2012 (Gosan).

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan site, which is known as background area in Korea, from January to September 2011. The temporal variation and the size distribution of aerosol number concentration have been investigated. The entire averaged aerosol number concentration in the size range 0.25∼32.0 ㎛ is about 252 particles/㎝3. The number concentration in small size ranges(≤ 0.5 ㎛) are very higher than those in large size ranges, such as, the number concentration in range of larger than 6.5 ㎛ are almost zero particles/㎝3. The contributions of the number concentration to PM10 and/or PM2.5 are about 34%, 20.1% and 20.4% in the size range 0.25∼0.28 ㎛, 0.28∼0.30 ㎛ and 0.30∼0.35 ㎛, respectively, however, the contributions are below 1% in range of larger than 0.58 ㎛. The monthly variations in the number concentration in smaller size range(<1.0 ㎛) are evidently different from the variations in range of larger than 1.0 ㎛, but the variations are appeared similar patterns in smaller size range(<1.0 ㎛), also the variations in range of larger than 1.0 ㎛ are similar too. The diurnal variations in the number concentration for smaller particle(<1.0 ㎛) are not much, but the variations for larger particle are very evident. Size-fractioned aerosol number concentrations are dramatically decreased with increased particle size. The monthly differences in the size-fractioned number concentrations for smaller size range(<0.7 ㎛) are not observed, however, the remarkable monthly differences are observed for larger size than 0.7 ㎛.

Emission reduction program for in-use diesel vehicles(ERPDV) has been enacted since 2004 over the Seoul metropolitan area, and diesel emission reduction is forced to fulfill this regulation. This study was performed to evaluate the ERPDV using PM10 concentrations of both road-side monitoring and national background network during the period of 2004-2010. In order to assess the pure road emission, we first eliminated the long range transport effect by deducting the trend of annual national background concentrations from the road-side PM10 concentrations, and then analyzed the time series of the resultant PM10 concentrations over Seoul metropolitan area. The annual rates of variations of road-side PM10 with the deduction of trend of background level show -3.2, +0.4, and -2.4㎍/㎥/year, in Seoul, Incheon, and Gyonggi province, respectively. There are steadily decreasing trend in Seoul with all of statistic parameters such as mean, mediam, 5%ile, 10%ile, 25%ile, 75%ile, 90%ile, and 95%ile concentrations. Incheon shows some fluctuations with positive with no significant trend, and Gyonggi province shows overall decreasing but not consistent. Student-t test shows 95% significant level of ERPDV effect in Seoul, but there exists no significant level greater than 90% in both Incheon, and Kyonggi province. Total annual averaged trend over the whole Seoul metropolitan area is estimated to lie in approximately -2.9㎍/㎥/year in this study, implying the intimate involvement of ERPDV to a large extent. This is also suggesting that the further research cost-effectiveness of ERPDV with consideration of the long range transport process would be needed over the Seoul metropolitan area.

Since November 1990, the observations of methane (CH_4) level have been carried out at Tae-ahn Peninsula (TAP) in Korea. Analysis on atmospheric data obtained in the period from November 1990 to August 1992 is carried out and the results are included in this study. We note that CH_-4 does not have a clear seasonal cycle with a minor maximum in August September and with a minimum in June-July. The variations in monthly average level are much larger with 1765.01∼1857.21 ppb (amplitude 92.20 ppb). The occurrence of a minimum in June-July is due to the inflow of the North Pacific air, an increase of OH radical and due to a decrease in CH_4 emission from rice paddy. A maximum in August and September appears to result from an increase in organic materials in agriculture (rice paddy) and forests, inputs of local sources due to weak airflows, stagnation of the warm and moist air and from a decrease in OH radical. The present analysis indicates that according to CH_4 data from Mongolia and from several sites in North Pacific TAP is influenced as much as 31 ppb in average from the inputs of Chinese emission. When the atmospheric CH_4 of TAP is compared with data observed at Korea National University of Education (KNU), the values of KNU are higher (127 ppb) than those of TAP. It is clear that air samples taken at KNU are influenced strongly by local sources in central Korea than those at TAP. According to analysis of trajectories and airflows, we find that there are 4 types in classification. Firstly, when an air flow is originated mainly in China values of CH_4 gas are in medium ranges. Secondly, when an airflow is from both local (Korea) and China we find higher values. Thirdly, with an airflow from both local (Korea) and Japan origins medium values are recorded. Fourthly, when an airflow of maritime origin arrives low values of atmospheric CH_4 are observed at TAP.