키토산 및 아연을 활용한 수경재배 내 Microcystis에 의한 녹조현상 제어효과 연구 = Study on the control of Algal Bloom by Microcystis in Hydroponics using Chitosan and Zinc

다국어 초록 (Multilingual Abstract)

This study was conducted to evaluate the feasibility of controlling algal bloom caused by the cyanobacteria Microcystis in hydroponics using chitosan and zinc. The control effect of Microcystis by chitosan and zinc was investigated through batch reactor and hydroponic system on Microcysits in BG-11 medium solution and nutrient solution widely used in hydroponics. In addition, the acute toxic effects of chitosan and zinc on aquatic ecosystems were investigated using the Daphnia Magna test.
The removal efficiency of Microcystis by the flocculation and precipitation reaction of chitosan reached about 90% within 24 hours, but the removal efficiency tended to be partially reduced due to the resuspension of the precipitated Microcystis over time. The removal efficiency of zinc against Microcystis was found to increase with increasing zinc concentration, and unlike chitosan, the removal efficiency gradually increased with reaction time without Microcystis resuspension, resulting in a Microcystis removal rate of more than 90% after 72 hours at zinc concentrations above 0.5 mg/L. An acute toxicity test for chitosan with Daphnia Magna showed 0 TU at concentrations below 1 mg/L, and an acute toxicity test for zinc showed 0 TU at concentrations below 0.7 mg/L.
The combined use of chitosan and zinc resulted in greater removal of Microcystis than either of them alone, which is thought to be due to the simultaneous action of the physical flocculation and precipitation of chitosan and the biochemical photosynthetic inhibitory effect of zinc on Microcystis. Control experiments with Microcystis in nutrient solution used in actual hydroponics under conditions of 0.5 mg/L and 0.7 mg/L, which were identified as the optimal concentrations of chitosan and zinc for Microcystis control, showed that the combination of chitosan and zinc resulted in a Microcystis removal rate of over 90% after 72 hours without Microcystis resuspension.
Appropriate concentrations of chitosan and zinc were added to a hydroponic system for growing lettuce to determine the control potential of Microcystis by examining the population of Microcystis in the nutrient solution tank, water circulation channels, and roots of lettuce. A large proportion of Microcystis cultured in the hydroponic system were located in the water circulation channels and near lettuce roots, and were found to decrease in the nutrient solution tanks. This is likely due to Microcystis overgrowth at the bottom of the channel or near the roots during operating hours when water circulation is suspended in hydroponic operations. Microcystis control increased with increasing reaction time after chitosan and zinc were added to the nutrient solution tank, with the greatest reduction in Microcystis population occurring under reaction conditions of 5 hours. These results suggest that the combination of chitosan and zinc can effectively eliminate Microcystis produced in the hydroponic system.

목차 (Table of Contents)

• 목 차 ⅰ
• List of Tables ⅲ
• List of Figures ⅳ
• 1. 서론 1
• 1.1 연구의 배경 1
• 1.2 연구의 목적 4
• 2. 이론적 고찰 7
• 2.1 녹조현상의 원인과 문제점 7
• 2.2 남조류의 특성 8
• 2.3 녹조현상 제어방식 11
• 2.4 수경재배와 녹조현상 12
• 2.5 키토산의 응집·침전 14
• 2.6 아연의 광합성 저해 반응 15
• 3. 연구 재료 및 방법 17
• 3.1 연구재료 17
• 3.1.1 Microcystis 배양 17
• 3.1.2 상추(lettuce) 재배 20
• 3.2 연구방법 22
• 3.2.1 키토산에 의한 Microcystis 영향분석 22
• 3.2.2 아연에 의한 Microcystis 영향분석 23
• 3.2.3 키토산 및 아연을 이용한 Microcystis 영향분석 23
• 3.2.4 키토산 및 아연을 이용한 수경재배 양액 내 Microcystis 제어효과 24
• 3.2.5 키토산 및 아연을 이용한 수경재배 시스템 내 Microcystis 제어효과 24
• 3.3 분석방법 27
• 3.3.1 현미경 계수법 27
• 3.3.2 물벼룩 급성독성시험법 28
• 4. 연구결과 및 고찰 29
• 4.1 키토산에 의한 Microcystis 침전효과 29
• 4.1.1 키토산 농도별 Microcystis 응집·침전효과 29
• 4.1.2 시간 경과에 따른 키토산의 응집·침전 후 재부상 거동 31
• 4.2 아연에 의한 Microcystis 제거효과 35
• 4.3 키토산 및 아연에 의한 Microcystis 제거효과 40
• 4.4 키토산 및 아연에 의한 수경재배 내 Microcystis 제어효과 44
• 4.4.1 수경재배 양액 내 Microcystis 성장거동 44
• 4.4.2 키토산 및 아연을 이용한 수경재배 양액 내 Microcystis 제어효과 45
• 4.4.3 키토산 및 아연을 이용한 수경재배 시스템 내 Microcystis 제어효과 48
• 5. 결론 59
• 참고문헌 61
• Abstract 65