담수 물벼룩 Daphnia magna의 자외선 B 적응이 자외선과 중금속의 동시노출에 따른 독성반응에 미치는 영향

• 영문명: Effect of Ultraviolet-B Radiation Acclimation to Fresh Water Daphnia magna Simultaneously Exposed to Several Heavy Metals and UV-B Radiation
• 발행기관: 한국환경보건학회
• 저자명: Kim, Jung-Kon Lee, Min-Jung Oh, So-Rin Choi, Kyung-Ho
• 간행물 정보: 『1. 한국환경보건학회지』제33권 제2호, 123~131쪽, 전체 9쪽
• 주제분류: 공학 > 환경공학
• 파일형태: PDF
• 발행일자: 2007.04.30

영문 초록

Many environmental contaminants including several metals, polycyclic aromatic hydrocarbons, and pharmaceuticals, have been identified to be phototoxic in the water environment. Concerns regarding photo-enhancement of toxicity of several environmental contaminants have been increasing because of the increased level of ultraviolet irradiation on the earth surface. However, there exist arguments that there might be certain defense mechanisms taking place in the aquatic ecosystem, which may include behavioral characteristics or genetic acclimation. This study was conducted to understand the potential responses of aquatic receptors to several phototoxic metals in the real environment, where long-term acclimation of such organisms to low dose UV-B may take place. For this purpose, water flea Daphnia magna was acclimated to environmentally relevant dose of UV-B (12 to 18uW/cm2) for >11 generations. The differences in developmental and life history characteristics, and toxicity responses were evaluated. Acclimation did not affect the daphnids growth, longevity, and reproduction characteristics such as time to first brood, and brood size: After 21 d, survival of D. magna was not influenced by UV-B acclimation. When the number of young per female was compared. the daphnids acclimated for 11 generations tend to produce less number of neonates than the un-acclimated individuals but with no statistical significance (p>0.05). Four metals that were reported to be phototoxic elsewhere were employed in this evaluation, that include As, Cd. Cu, and Ni. UV-B level being applied in acclimation did increase the toxicity of Cd and Cu, significantly (p<0.05). However, the toxicities of As and Ni were not affected by irradiation of UV-B. Phototoxic responses were evaluated between the acclimated and the un-acclimated daphnids. For Cu, UV-B acclimation led to reduction of the photo-induced toxicity (p≈0.1) in daphnids. Non-acclimated Daphnia were affected by 50% at 4.18 ug/l Cu. but UV-B acclimated individuals exhibited EC50 of 5.89 ug/l. With Cd, UV-B acclimation appeared to increase phototoxicity (p>0.05). With As and Ni, UV-B acclimation did not influence photo-induced toxicity. This observation may be in part explained by the type of reactive oxygen species that were generated by each metal. Similar to UV-B light, Cu is known to generate superoxide anion by acting as redox cycling toxicant. This is one of the first studies that employed_laboratory based UV-B acclimated test species for photoenhanced toxicity evaluation.

키워드

Daphnia magna, ultraviolet-B, acclimation, photoenhanced toxicity, reactive oxygen species