Nowadays, Seoul city has brought about many public nuisances, such. as air pollution, stream pollution, noise and vibration due to the increase of urban population, traffic, and industrial development. This research has been conducted in order to grasp the degree of pollution of this year and to obtain basic data necessary for the future preventive measures against public nuisances of air pollution noise and stream pollution of Han-river in Seoul area as well as in other urban areas from June 1, 1969 to January 31, 1970. Six sampling areas for air pollution and noise level, seven sampling sites of main stream and three of tributaries of the Han-river for stream pollution and 25 sampling points for pollution due to industrial wastes were selected and the samples were analyzed against region and season in Seoul area.
The main findings obtained are summarized as follows ;
1. The directions of seasonal main winds are WSW, W, WNW in spring, ENE, WSW, WS in summer, ENE, WNW, E in autumn, ENE, WNW, NW, in winter and the wind velocities of 1.1-2.0 m /sec. are 33.7 per cent, of above 3.1 m/sec. 31.4 per cent, of 2.1-3.0 m/sec. 22.8 per cent, of below 1.0 m/sec. 12.1 per cent in 1969.
2. Dustfalls range from 4.4 tons/㎢/mon. at the residential area to 95.3 at the intersectional area with the mean value of 37.2 in Seoul and dustfall at the park area is 15.5, at the commercial area 25.1, at the industrial area 48.4 and at the semi-industrial area 54.6.
3. The mean value of SO₃concentration, by lead peroxide cylinder method, is 1.91 mg. SO₃/day/ 100 ㎠. PbO₂. cylinder(0.070 ppm), the range is 0.65(0.026 ppm) 5.52(0.221 ppm), 2.91 (0. 116) at the industrial area, 2.08 (0.0$3) at the semi-industrial area, 1.82 (0.073) at the commercial area, 1.70 (0.068) at the intersectional area, 1.48 (0.059) at the residential area, and, 1.05 (0.042) at the park area. The concentrations of SO, are in order of 2.66 in January 1970, 2.29 in November, 2.28 in December, 1.72 in Octor, 1.32 in. September and 1.21 in August in 1969.
4. Concentrations of particles in the air are 2.38 mg/㎥ at the industrial area and 2.73 at the commercial area.
5. The mean value of noise level is 65.9 dB ranging from 37.3 at the residential area to 85.2 at the intersectional area and the level at the industrial and commercial areas are respectively 65.1 and 65.9.
6. Daily peaks of the concentrations of particles in the air, sulfer dioxide and nitrogen dioxide are found twice at 8 : 00 to 1Q : 00 in the morning end at 18 : 00 to 22 00, afternoon.
7. The noise level increases up to 74.0 dB at 10 : 00 and decreases to 43.0 dB at 24 : 00 after keeping more or less constant level.
8. The highest concentration of all pollutants are found on Wednesdays followed by Mondays and Sundays except the noise level and the particles concentration in the air of which the highest level are on Sundays.
9. Reaction rate constants, k, of Han-river near Chunggae-stream and Anyang-stream were 0.24 per day and 0.18 while self-purification rate, f, are 2.3 at the Chunggae and 2.6 at: the Anyang.
10. Theoretical maximum D.O. deficit time is 2.3 days with 7.8 ppm at the confluence of Chungwhile 2.8 days with 10.8 ppm at the confluence of Anyang-stream.
11. Theoretical maximum recovery time is 5.0 days with 5.8 ppm of D.O. at the confluence of Chunggae-stream and 6.1 with 8.0 ppm at the confluence of Anyang-stream.
12. Of water quality of main stream of Han-river:
① Average turbidity is 8 units with the range of 3 to 13 and its peak is 13 at Yeomchang dong from where industrial wastes from Yongarea come into the Han-river.
② Dissolved oxygen contents D.O., are 2.0 to 8.4 ppm and D.O. at up sites of the Han-river are higher, with 7.6 at Walker-Hill boating place, 5.1 at the second Han-river bridge and 5.7 at the first Han-river bridge than at down sites with 3.6 at Yeomchang dong.
③ pH values are 6.4 to 7.5 with the mean value of 7.1 and with slight acid value of 6.7 at Yeomchang dong.
④ Biochemical oxygen demand, B.O.D. at down sites is higher 40.7 ppm at Yeomchang dong, than at up sites, 12.4 at Walker-Hill boating place, and the mean value is 27.7 and the range is 10.2 to 50.5.
⑤ Suspended solids, S.S, are from 14.0 to 531.0 ppm with the mean value of 145.9 ppm. The S.S at Yeomchang dong is 313.7, at the second Han-river bridge 205.0 while 77.3 at Duk-do and 54.2 at Walker-Hill boating, place.
⑥ Coliform colonies range 1.6×10⁴to 1.2×10^(6)/ 100ml. of water with the mean value of 1.9×10^(5). The largest number of colonies are counted at the second Han-river bridge with 6.2×10^(5) while the smallest at Walker-Hill boating place with 1.6×10⁴.
⑦ The highest turbidity is shown in June and October with 8 units each, 7 units are shown in July, September and November and 6 are in August.
⑧ Dissolved oxygen D. O. is 5.5 ppm in June and D.O. in July, August, September, October and November are 5.8, 5.9, 6.0, 6.7 and 6.8 respectively.
⑨ High B.O.D. are shown in September and October with 34.8 ppm and 31.9 respectively and 28.9 in November, 26.5 in June and August 17.8 in July are found.
⑩ High suspended solids are detected in October and November with 249.3 ppm and 245.0 respectively while low are in July and August with 93.3 and 64.1 respectively.
⑪ The highest colony count is shown in August with 3.6×10^(5)/100ml. of water while the lowest in November with 7.6×10⁴, and 27.5×10⁴, 18.7×10⁴, 15.6× 10⁴, 8.2×10⁴are shown respectively in July, September, June and October.
13. In industrial wastes:
① pH values are 5.1 to 8.9 and acid values ofindustrial wastes are shown at chemical, papermill, metal and machine industry, and textileindustry while alkali value at leather factoryand chinaware.
② High suspended solids are detected at leather factory, paper mill and chemical plant with 1,793.0, 1,750.3 and 1,670.8 while low are at Textile and chinaware with 236.7 and 244. 0 ppm respectively.
③ The highest values of B.O.D.,C.O.D., are shown atleather factory with 1,210.5 ppm and 1,315.0 while the lowest at chinaware with 196.7, 535.7 respectively.
14. Of water qualities of tributaries of Han-river:
① pH values are slight alkali at Sungdong bridge and Wonhyo bridge while slight acid at Yangwha bridge.
② The highest suspended solids are shown at Yangwha bridge with 678.5 ppm while 582.0 at Sungdong bridge and 552.0 at Wonhyo bridge.
③ The highest value of B.O.D. is 295.6 ppm at Wonhyo bridge while 290.8 at Yangwha bridge and 281.4 at Sungdong bridge.
④ The highest C. O. D. value is shown at Yangwha bridge with 401.6 ppm and the lowestat Sungdong bridge 301.0.
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