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
제10권 제4호 (2001년 8월) 10건
1.
2001.08
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A macroeconomic minimodel was simulated to suggest the public policy for sustainable use of Nakdong River Basin. The minimodel for the simulation shows the interrelationships between natural environment and economic activity. Topsoil, water, economic assets, and money stock are plotted for 300 years, beginning with 1996 in each simulation.
The computer simulation runs suggest that the Nakdong River Basin system in the near future may strongly be influenced by the favorable availability of outside resources, while the economic assets and money stock may be declined by indigenous environmental stock depletion. The simulation run made under the constant decrease in systems purchased inputs with investment ratio of developed country and for sustainable use. The results of simulation shows the recover of natural environment and decrease of economic activity under these condition.
Therefore, the economic structure of Nakdong River Basin should be transformed from the present industrial structure to the social-economic structure based on an ecological-recycling concept which depend on renewable resources rather than industrial structural which depend on outside resources.
2.
2001.08
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Investigations were carried out to observe the seasonal succession of phytoplankton, and viable counts of bacteria from the mid to lower reaches of Nakdong River. An intensive monitoring was conducted from May to December 1999 biweekly at 6 sites in a main channel and 3 tributaries. Although there are several sites with high nutrient loading from the basin, all of study sites showed mesotrophic states owing to high discharge(June∼September). Relatively low algal biomass and CFUs(mean of chl. a, 12.3±11.5 ㎍/ℓ, CFUs : 1.8×10 7) were observed during the rainy season. The diatom population was dominant(over 85% of total community) year-long with peaks (Stephanodiscus hantzschii) in the fall and winter. Dominance of blue-green algal groups during the summer was not observed in the summer. Microorganisms peaked in the summer and fall (June∼September), affected mainly by the inputs of phytoplankton and nutrients. Biomass of phytoplankton and CFU counts were higher in the Kumho River than the other tributaries and main channel.
3.
2001.08
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Biosorption of Pb was evaluated for plants, Persicaria chinensis, Oenanthe javanica and Salvinia natans. The adsorption equilibrium was reached in about lhr for Pb and the highest adsorption capacity was 150㎎ Pb/g biomass at S. natans. Pb adsorption process showed a pseudo second order irreversible reaction. The highest initial adsorption rate was 2000㎎ Pb/g biomass/hr at O. javanica. In spite of pH variation, Pb adsorption capacity by P. chinensis was maintained uniformly. When light metals concentrations were increased in the solution, Pb was selectively adsorbed. The selectivity of mixture solution showed the adsorption order of Pb>Cu>Cr>Cd. The Pb adsorption capacity of P. chinensis pretreated with NaOH was increased by 30% in comparison with that of no treatment.
4.
2001.08
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In an attempt to evaluate the possibility of producing an organic fertilizer using sediments from coastal farming areas, the chemical composition, bacteriological quality and heavy metals in the sediments alkalized by quicklime and magnesium hydroxide were analyzed. The optimum reaction was obtained from the following conditions : a 1:4 mixture of dry sediment to food wastes and the addition of 30% quicklime to the mixture. According to the classification standard for compost constituent by Higgins, all composts had a low or intermediate grade in T-N and K2O content, a low grade in P2O5 and a high grade in CaO and MgO content. Stabilization by quicklime and magnesium hydroxide is likely to inhibit the bacterial decomposition of organic matter and the activity of pathogenic organisms. Raising the pH of stabilized sediments to 12 for 2 hours(PSRP criteria of EPA) allowed 99.99% of the coliform group, fecal group and viable cell count to be reduced. The results suggested that the crude fertilizer produced by alkaline stabilization method was innoxious and thereby the sediments from coastal farming areas could be used as organic fertilizer.
5.
2001.08
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Wastewater from the pigment industry has high levels of organics and is known as hardly biodegradable. The objective of this study is to evaluate the applicability of aerobic fixed-bed biofilm reactor packed with ceramic support carrier for the pigment wastewater treatment. Orange 2(widely used azo pigment) adsorption experiment onto biofilm and activated sludge, and continuous treatment experiments were performed. In batch adsorption experiment, maximum adsorption quantity of biofilm was at least two times higher than that of activated sludge. In continuous experiment using aerobic fixed-bed biofilm reactor, the influent concentration of COD and Orange 2 were 75∼500㎎/ℓ(0.45∼3.00㎏ COD/㎥.day), 5∼50㎎/ℓ (0.03-0.30㎏ Orange 2/㎥.day), respectively. At a COD loading rate of 2.5㎏ COD/㎥.day and Orange 2 loading rate of 0.18㎏ Orange 2/㎥.day, removal efficiency of COD and Orange 2 were over 95%, 97%, respectively.
6.
2001.08
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A packed bed of volcanic rock was used as deodorizing material to remove hydrogen sulfide(H2S) from air in a laboratory-scale column, and was inoculated with Thiobacillus sp. as H2S oxidizer. The effects of volcanic rock particle size distribution on system pressure drop were examined. Various tests have been conducted to evaluate the effect of H2S inlet concentration and EBCT(Empty Bed Contact Time) on H2S elimination. The pressure drop for particles of size range from 5.6 to 10 ㎜ was 14 ㎜H2O/m at a representative gas velocity of 0.25m/s. Biofilter using scoria and Thiobacillus sp. could get the stable removal efficiencies more than 99.9% under H2S inlet concentrations in the range from 30 to 1,100ppm at a constant gas flow rate of 15.2 ℓ/min. H2S removal efficiencies greater than 99% were observed as long as EBCT was longer than 8sec at the 250ppm of H2S inlet concentration. When EBCT was reduced to 5.5 sec, H2S removal efficiency decreased by about 12 percent. The maximum H2S elimination capacity was determined to be 269g-H2S/㎥·hr.
7.
2001.08
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The toxicity values of various heavy metals were evaluated by acute immobilization and chronic reproduction impairment tests, using Daphnia magna. Acute tests were evaluated by the inhibition of their mobilization after 24hrs without food addition. The tests of reproductive impairment were investigated for 21 days by food addition and exchange of water. The effect of each concentration was assessed by Probit analysis and t-test.
The results obtained from this study were as follows : 1) The change of pH and DO was not significant in the acute tests, while, in the reproductive tests, pH was increased by 0.3∼1.4 and DO also increased. 2) The EiG50 values of immobilization to Daphnia magna in artificial fresh water were 0.030㎎/ℓ(Cu), 0.054㎎/ℓ(Cd), 0.12㎎/ℓ(Cr), 0.74㎎/ℓ(Pb), 3.4㎎/ℓ(As) and the NOEiC values were 0.010㎎/ℓ(Cu), 0.018㎎/ℓ(Cd), 0.010㎎/ℓ(Cr), 0.10㎎/ℓ(Pb), and 1.8㎎/ℓ(As). 3) The EiC50 values of reproductive impairment to Daphnia magna were 13.8㎍/ℓ(Cu), 2.9㎍/ℓ(Cd), 15.5㎍/ℓ(Cr), 61.7㎍/ℓ(Pb), 759㎍/ℓ(As), and NOErC values were 0.95㎍/ℓ(Cu), 0.54㎍/ℓ(Cd), 1.2㎍/ℓ(Cd), 7.4㎍/ℓ(Pb), 110㎍/ℓ(As).
The results of tests using OECD artificial culture water were more sensitive than natural water for culturing. The presented data show that an artificial culture water is suitable in the experiment of bioassay for assessing the toxicity of materials.
8.
2001.08
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For the remediation of the contaminated soil with heavy metals, Cd, Cr, Cu, and Pb, the reaction parameters were optimized. Tartaric acid (TA) and oxalic acid(OA) as a washing agent were evaluated as a function of concentration, reaction time, mixing ratio of washing agent and recovery of metals. The optimum washing conditions of TA and OA were in the ratio of 1 : 20 between soil and acid solution during 2 hr reaction under unbuffered pH solutions. At the optimized reaction conditions, the removal efficiencies were compared with that of 0.1 M HC1 and ethylenediamine tetraacetic acid(EDTA). TA showed higher efficiency on the removal of Pb than that of EDTA, which established for the remediation of contaminated soil with Pb and Cd metals.
The recovery of metal ions from washing solution was achieved by adding calcium hydroxide and sodium sulfide by forming the precipitation of metal hydroxide and metal sulfide. Optimum amounts of sodium sulfide and calcium hydroxide were Cd = 25g/ℓ, Cu = 5∼10g/ℓ and Pb = 5∼10g/ℓ for the washing solution of OA and 2∼5g/ℓ for the washing solution of TA, respectively. The amounts of Na2S and Ca(OH)2 for the tartaric acid was less than that of oxalic acid.
9.
2001.08
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pH(H2O), pH(KCl), CEC(cation exchange capacity), O.M.(organic matter) and exchangeable cations(K, Na, Ca, Mg) of paddy soil, upland soil and forest soil in Kumi city were investigated for the purpose of knowing soil acidification and the correlation between soil acidification and leaching of inorganic salts.
The mean pH(H2O) values of paddy soil were 5.23(surface soil) and 5.69(subsoil), and those of upland soil were 6.37(surface soil) and 6.11(subsoil), and those of forest soil were 4.67(surface soil) and 4.74(subsoil). The mean pH(KC1) values of paddy soil were 4.59(surface soil) and 4.98(subsoil), and those of upland soil were 5.48(surface soil) and 5.04(subsoil), and those of forest soil were 3.82(surface soil) and 3.89(subsoil). The acidification of forest soil was more rapid than that of paddy soil and upland soil.
The total mean amounts of exchangeable cations(K, Na, Ca, Mg) in paddy soils were 6.14me/100g(surface soil) and 5.64me/100g(subsoil), and those in upland soils were 6.86me/100g(surface soil) and 6.65 me/100g (subsoil), and those in forest soils were 4.06me/100g(surface soil) and 3.34me/100g (subsoil). The contents of inorganic salts in forest soil were much less than those of paddy soil and upland soil.
The correlation coefficients(r) between pH(H2O) values and the total amounts of exchangeable cations in soils were 0.6635** (surface soil) and 0.6946** (subsoil), and those between pH(KCI) values and exchangeable cations in soils were 0.6629** (surface soil) and 0.5675**(subsoil).The correlation between soil acidification and leaching of inorganic salts in soil was positively significant at 1% level.
10.
2001.08
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The asphalt mixture with CRM(Crumb Rubber Modifier) is known to show a better performance in resisting thermal cracking, fatigue cracking and rutting compared with the conventional mixture. The laboratory tests on the physical characteristics of indirect tensile strength, density, flow and Marshall value of the CRM asphalt were conducted. The test results show that CRM asphalt has better physical characteristics than that of conventional asphalts. And the analysis on the noise reduction effect, penetration capacity from the field test on the national road in Haksan of Chungbuk, and recycling of tire waste were conducted. From this study, the results show that 1% CRM asphalt has higher the noise reduction effect and penetration capacity than those of conventional asphalts. And, optimal contents of crumb rubber modifier in the asphalt binder is one percent. In this case, crumb rubber modifier were used 10 ㎏ to make the asphalt binder of one cubic meter. So it was named as Eco-asphalt.
