간행물
한국환경과학회지 KCI 등재 Journal of Environmental Science International
- 발행기관 한국환경과학회
- 자료유형 학술지
- 간기 월간
- ISSN 1225-4517 (Print)2287-3503 (Online)
- 수록기간 1992 ~ 2023
- 주제분류 자연과학 > 자연과학일반 자연과학 분류의 다른 간행물
- 십진분류KDC 539DDC 628
권호리스트/논문검색
제3권 제3호 (1994년 9월) 10건
1.
1994.09
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Masan bay is one of the polluted enclosed bays, which has red tides problem and the formation of oxygen deficient water in the bottom layer. Most important factors that cause eutrophication and red tide is nutrient materials containing nitrogen and phosphorus which stem from terrestrial sources and nutrients released from sediment. Therefore, to improve of water quality, reduction of these nutrient loads should be indispensible. At this study, the three-dimensional numerical hydrodynamic and eutrophication model, which were developed by Institute for Resources and Environment of Japan, were applied to analyze the processes affecting the phytoplankton production and also to evaluate the effect of water quality improvement plans on phytoplankton production. in field survey, the range of concentrations of chlorophyll -a at surface area was found to be 29.17 - 212.5㎎/㎥, which were exceeding eutrophication criteria. The constant currents defined by integrating the simulated tidal currents over 1 tidal cycle showed the counterclockwise eddies in the southern part of Budo. The general directions of constant currents were found to be southward at surface and northward at bottom over all the bay. The eutrophicatior model was calibrated with the data surveyed in the field of the study area in June, 1993 The calculated results are in fairly good agreement with the observed values within relative error of 30%. The pollutantI load from the sources such as the input from terrestrial sources and release from the sediment was reduced by the rate of 50, 70, 90, 98% to evaluate the effect of phytoplankeon production. Phytoplankton production was reduced to 50% in case of the 90% reduction of the input loads from terrestrial sources and 8% in case of the 90% reduction of the load from sediment.
2.
1994.09
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Microorganisms capable of utilizing 2,4,5-trichlorophenoxyacetic acid(2,4,5-T) as sole carbon source were isolated from soil by enrichment culture. Among these strains, EL-071P had the highest biodegradability of 2,4,5-T, and according to its morphological and physiological characteristics, it was identified as Pseudomonas sp. This strain was resistant to rifampicin, streptomycin, ampicillin, kanamycin and such metal ions as Zn^+2, Cu^2+, Various compounds of chlorinated phenol and substrate analogs were more easily utilized than 2,4,5-T, but biodegradation rate for each compound was different. The strain easily utilized the compounds of chlorinated substituents on phenol in the order of ortho-, para-, and meta- position. The biodegradability of this strain was very stable.
3.
1994.09
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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.
4.
1994.09
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A Study of the Characteristics of Temperature Inversion During the Cold Half year at Tsukuba , JAPAN
The climatological study of temperature inversion was conducted at the Tsukuba of Japan during the cold half year, the periods of which were both from October 1981 through March 1982 and from October 1982 through March 1983. Meteorological phenomena were observed to appear both from 10m to 200m above the ground and from the surface to 300hPa. The data collected from those phenomena were analyzed in terms of statistics, and investigated from a synoptic point of view. The results are as follow. The dispersion of the surface inversion happens right after sunrise through the whole period. The higher the upper layer is, the later that happens. Up to a height of 200m, the wind speed at a height of 25m has the greatest effect on temperature, but on the other hand the wind speed at a height of 10m has the greatest effect on inversion intensity.
5.
1994.09
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By laying emphasis on the intermediate layer, water property distribution in the Northwest Pacific is studied using the hydrographic data obtained by Japan Meteorological Agency in the period from 1960 to 1986. The scattering of water type in T-S diagram is relatively small in the Kuroshio Region. Both the envelopes of saline side and of fresh side of the scattered data points shifts gradually from saline side to fresh side as the observation line moves from southwest to northeast. In the Mixed Water Region, the scattering of water type increases rapidly as the observation line moves north; The envelope of fresh cold side moves towards fresh cold side much faster than that of saline side. The thermosteric anomaly value at the salinity minimum decreases as the observation line moves from north to south or southwest. This suggests that the water does not advect along the salinity minimum layer, but that the salinity minimun layer is understood as a boundary of two different waters aligned vertically. We defined the typical water masses for the Oyashio Water and the Kuroshio Water. The water mass below the salinity minimum layer may be created by isopycnal mixing of these two water masses with a fixed mixing rate. While, the water mass above the salinity minimum cannot be created simply by isopycnal mixing. The salinity minimum layer may be eroded from upper side due to active mixing processes in the surface layer, while the water of the salinity minimum layer moves gradually southward. This appears to give an explanation why the thermosteric anomaly value at salinity minimum decreases towards south.
6.
1994.09
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Meteorological parameters in the atmospheric boundary layer and the vertical and horizontal dispersion parameters were determined by analyzing the data obtained by the special upper-air observations of one clear day for each season from October 1991 to August 1992. The concentration of the atmospheric pollutants over Taegu was analyzed by using the application of the Gaussian diffusion model. In the diurnal variation of diffusion of atmospheric pollutants, vertical diffusion due to turbulence is active in daytime while horizontal diffusion due to wind is active in nighttime. The mean concentration of pollutants in the side of downwind is higher during the daytime than the nighttime. Thus, the height of the mixed-layer at the nighttime considered as the most important parameter of the mean concentration of pollutants. In the seasonal variation of diffusion of atmospheric pollutants, vertical diffusion due to strong solar radiation is active in summer case day, and horizontal diffusion due to strong wind is active in winter case day. In winter case day, the mean concentration of pollutants in the side of downwind is maximum in the daytime. However, in summer case day, that is maximum in the nighttime.
7.
1994.09
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Chloroform present in the swimming water disinfected with sodium hypochlorite is released to the air of swimming pools. The air chloroform concentrations were measured in two swimming pools A and B which applied both sodium hypochlorite and ozone. Their mean concentrations are 28.0 ㎎/㎥ and 33.6 ㎍/㎥ in the swimming pools A and B, respectively. On the other hand, the mean water chloroform concentrations in the swimming pools A and B were 23.9 ㎍/ℓ and 19.5 ㎍/ℓ, respectively. The air chloroform concentrations were lower in the swimming pools A and B than those reported by previous studies abroad employed the swimming pools which applied sodium hypochlorte only for water disinfection. The water chloroform concentrations were also lower in this study than in the previous studies. The relationship between the air and water chloroform concentrations measured in this study was significant with p=0.002 and R^2=O.42. At similar time to the indoor air sampling, outdoor air samples were collected at two sites near each of the swimming pools A and B. The mean outdoor air chloroform concentrations near the swimming pools A and B were 0.41 ㎍/㎥ and 0.16 ㎍/㎥, respectively. The outdoor air chloroform concentrations measured in this study were equal to or lower than those reported by previous studies abroad. The chloroform dose inhaled for a typical one-hour swim was estimated to be 25.9 ㎍ per person, corresponding to a specific 0.37 ㎍/㎏ body weight. for a reference 70 ㎏ male adult, while the inh lation dose of chloroform from the outdoor air was estimated to be 5.6 ㎍ per person per day, corresponding to a specific 0.08 ㎍/㎏/day for the same reference male adult.
8.
1994.09
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A detachment of biofilm was investigated in an inverse fluidized bed biofilm reactor(IFBBR). The biofilm thickness, δ and the bioparticle density, ρ_pd were decreased by the increase of Reynolds number, Re and the decrease of biomass concentration, b_c. The correlations were expressed as δ=61.6+16.33b_c-0.04Re and p_pd=0.3+0.027b_c- 2.93x10 exp (-5)Re by multiple linear regression analysis method. Specific substrate removal rate, q was derived by F/M ratio and biofilm thickness as q=0,44+0.82F/M-5.1x10 exp (-4)δ. Specific biofilm detachment rate, b_ds, was influenced by F/M ratio and Reynolds number as b_ds=-0.26+0.26F/M+2.17x10 exp (-4)Re. Specific biofilm deachment rate in an IFBBR was higher than that in a FBBR(fluidized bed biofilm reactor) because of the friction between air bubble and the bioparticles.
9.
1994.09
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The primary objective of this study was to examine the toxic effects of PCP on activated sludge and to analyze its metabolic responses while treating wastewater containing pentachlorophenol (PCP) in a sequencing batch reactor (SBR) system operating under different control strategies. This study was conducted in two phases 1 and 2 (8-㏊ and 12-㏊ cycles) Each phase was operated with two control strategies I and II. Strategy I (reactor 1) involved rapid addition (5 minutes to complete) of substrate to the reactor with continuods mixing but no aeration for 2 hours. Strategy II (reactor 2) involved adding the feed continuodsly during the first 2 hours of the cycle when the system, was mixed but not aerated During both phases each reactor was operated at a sludge age of 15 days. The synthetic wastewater was used as a feed. The COD of the feed solution was about 380㎎/ℓ. After the reference response for both reactors was established, the steady state response of each system was established for PUP teed concentrations of 0.1 ㎎/ℓ, 1,0㎎/ℓ, and 5.0 ㎎/ℓin SBR systems operating on both 8-hr and 12-hr cycles. Soluble COD removal was not inhibited at any feed PCP concentrations used. At 5.0 ㎎/ℓfeed PCP concentration and in SBR systems operating on phase 2, the concentrations of MLVSS were dereased; selective pressure on the mixed biomass might be increased, narrowing the range of possible ecological responses; the settleability of activated sludge was poor; the SOURs were increased, showing that the systems were shocked. Nitrification was made to some extent at all concentrations of feed PCP in SBR systems operating on phase 2 whereas in SBR systems operating on phase I little nitrification was observed, Then, nitificaiion will be delayed as much as soluble COD removal is retarded due to PCP inbition effects. Enhanced biological phosphorus removal occurring in the sytem operating with control strategy I during phase I of this work and in the presence of low concentrations of PCP was unreliable and might cease at anytime, whereas enhanced biological phosphorus removal occurring in the system operating with either control strategy . I or II during phase 2 of this work and in the presence of feed PCP concentrations up to 1.0 ㎎/ℓ was reliable. When, however, such processes were exposed to 5.0 ㎎/ℓ PCP dose, enhanced phosphorus removal ceased and never returned.
10.
1994.09
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The objective of this study was to examine and compare to transient response to quantitative and hydraulic shocks which produce equal changes in mass rate of organic feed in aerobic fixed-film process. The general experimental approach was to operate the system at several growth rates under steady-state(pre-shock) conditions, then to apply step changes during day 3 in dilution rate(hydraulic shock), or feed concentration(quantitative shock) at the same organic mass loading rate. Performance was assessed in both the transient state and the new steady-state (post-shock). Shock load of different type did not produced equivalent disruptions of effluent quality for equal increases on mass loading rate. Based on effluent concentrations, a hydraulic and a quantitative shock at the same mass loading caused equal increase in total effluent COD, but the increase was primarily a result of suspended solids the hydraulic shock and COD in the quantitative shock, The time which effluent COD came to peak values were about 32∼48 hours at the low organic loads and 52∼72 hours at the high organic loads, respectively. A quantitative shock produced a much greater increase in effluent COD than did a hydraulic shock at the same mass loading. Mean and peak values of effluent concentration were increased in 2.8∼4.2 times at low organic loading rate, 5.2∼6.6 times at the high organic loading rate respectively.
