Continuous measurements of ground-level ozone (O_3) were made in five minutes intervals in the rural area of Korea from July 1993 to June 1994. This site is located in Chongwon, near latitude 36.4˚ N, longitude 127.6˚ E. The results show that the one-year mean value was 17 ppb, and monthly mean ranged from 6 to 47 ppb. A pronounced maximum in summer and a minimum in winter were found, and these were related to anthropogenic emission and photochemical reaction. Diurnal variations of ozone concentration showed a normal distribution with a maximum at 15:00 - 16:00 and a minimum at 07:00 - 08:00. During the period when ozone concentration was very high (> 80 ppb), the stable winds were from N and NW; on the other hand, when ozone concentration was very low, air movement in the large scale was from the North Pacific Ocean. This suggests that in the rural area the long range transport of anthropogenic pollutants from distant sources can contribute to the larger contribution than the generation of ozone from local sources in the rural area.

The Daechong dam is located nearby Chongju city, and the population alone in the Chongju- Chongwon area is over one half million. It is found that the number of days for fog occurrence after constructing the dam was much fewer than those before constructing it. It appears that the construction of a large dam did not cause to increase in the occurrence of fog in the Chongju area, and that was the increase due to topographical characteristics and wind direction. Low visibility in the Chongju-Chongwon area occurred frequently. In summer, Chongwon recorded more days of poor visibility than those observed at Chongju. It is thought that TSP. SO_2 and NO_2 were the main constituents of air pollutants causing the reduction in visibility. These air pollutants are produced by vehicles and industrial activities in the region.

At the close of the year 1990, tombs in south Korea will cover the area of 940 ㎢, which is 0.9% of the entire landspace. Annual increase of 200,000 tombs is encroaching on landspace by 10 ㎢. It is estimated that the decrease in the forest area caused by tombs results a decrease both in the production of O_2 by 912,000 tons and in the absorption of CO_2 by 1,254,800tons per year. As a result, there will be an increase in the amount of CO_2, which is one of the factors that cause the greenhouse effect.

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.

A study on acidity in precipitation was carried out during May 1990 - April 1991 at two sites in Chongwon, Choongbook. We observed variations of pH from 4.0 to 7.0. Annual mean value of pH was 5.21 in the area. In particular, strong acidity of rain fall, pH 4.0 were observed during winter to early spring. Neutral values were observed during June to July and were due to wet deposition of atmospheric pollutants by stationary fronts in the rainy season. Interestingly, acidity of snow observed in winter was neutral and it was weaker than the acidity of rain in winter by a value of 2.0. Discussion is made on meteorological and chemical analyses and seasonal variations of acidity of precipitation.