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경북북부지역 먹는물에서 분리된 대장균군의 항균제 및 염소소독제 감수성
손창규(Chang-kyu Sohn),이춘우(Chun-woo Lee),김태분(Tae-bun Kim),박순길(Soon-geel Park),전찬준(Chan-jun Jeon),이창일(Chang-il Lee),박자영(Ja-young Park),송성복(Sung-bok Song),허완(Wan Huh) 대한환경위생공학회 2008 대한환경위생공학회지 Vol.23 No.2
We examined 165 unchlorinated natural drinking water samples for the presence of E. coli group resistant to antimicrobial agent and chlorine in nothern Gyeongbuk area in 2007. Among 165 water samples, 21 samples(12.7%) were positive to total coliforms and Six genus, 16 strains of E. coli groups isolated from 16 samples showed resistance against more than one antimicrobial agent such as Ampicillin, Tetracycline and Chloroamphenicol. Among 16 strains, 14 strains resistant to Ampicillin, 9 strains resistant to Tetracycline and one strain resistant to Chloroampenicol. but all 16 strains did not contain any integron gene cassettes, which contribute to the spread of antimicrobial resistance alleles by lateral gene transfer of gene cassettes in a variety of enteric bacteria. The minimal inhibitory concentration(MIC) of 14 strains which showed resistant to Ampicillin was between 12㎍/㎖ and 32㎍/㎖, Nine strains resistant to Tetracycline showed between 32㎍/㎖ and 128㎍/㎖ and one strain resistant to Chloroampenicol showed 128㎍/㎖. The chlorine sensitivity of 16 strains isolated from unchlorinated natural water sample didnot show any difference among strains by the concentration of initial free chlorine and elapsed time after chlorine treatment. All 16 strains were killed after 1hr. exposure at 0.2㎎/㎖ of free chlorine per liter or 30minutes exposure at 0.4㎎/㎖ of free chlorine per liter.
포항지역 미세먼지발생에 대한 수용성무기이온의 화학적 특성 및 예측모델 평가
이기창,김보은,이병근,김지훈,박상수,홍경지,류동현,송정한,김태분 대한환경공학회 2023 대한환경공학회지 Vol.45 No.7
Objectives : This study aims to contribute to establishing the regional effective management of fine particulate matter by evaluating the chemical characteristics and contribution of fine particulate matter, and the accuracy of predictive model of fine particulate matter through the measurement of water-soluble inorganic ions (WSIIs) and electrical conductivity for fine particulate matter generated in Pohang. Methods : PM10 and PM2.5 samples were simultaneously collected using a low volume air sampler from April to November 2022. For sample analysis, cations of Ca2+, Mg2+, K+, NH4+, Na+ and anions of Cl-, NO3-, SO42-, and electrical conductivity were measured after pretreatment by ultrasonic extraction. Results and Discussion : The average concentrations of WSIIs for PM10 and PM2.5 in Pohang were 12.1 μg/m3 and 8.5 μg/m3, respectively, accounting for 35.5% and 50.0% of each fine particulate matter. The sum of NH4+, NO3-, SO42- concentration was found to account for the majority of 71% and 78% of WSIIs in PM10 and PM2.5, respectively. The PM2.5/PM10 ratios for NH4+, K+, and SO42- were 95%, 89%, and 81%, respectively, mostly present in PM2.5. The average ratio of PM2.5/PM10 for NO3- was 54%, but it rose sharply to 79% in November when the temperature was low, indicating an increase in contribution to the generation of PM2.5 in winter. During the sampling period excluding April and July, the ion balance for cations and anions was relatively good at a 1:1 ratio and showed chemical properties of fine particulate matter close to neutral. A regression model was evaluated for the measured electrical conductivity of WSIIs and the concentration of fine particulate matter. The MAE and RMSE values for PM2.5 were 1.8 μg/m3 and 2.4 μg/m3, respectively, which were lower than PM10 (MAE 7.5 μg/m3, RMSE 10.3 μg/m3), indicating high precision and accuracy. Conclusion : This study confirmed the origin of fine particulate matter generated in Pohang through WSIIs analysis, and suggested that the measured electrical conductivity of WSIIs could be used as a key parameter for measuring the concentration of fine particulate matter.