四种重金属暴露对青鳉呼吸行为的毒性效应

研究青鳉对不同重金属污染物的敏感性和响应阈值,为水体污染特别是重金属污染的早期预警监测提供定量基础。青鳉3月龄,体长(1.5±0.1) cm,体重(0.15±0.01) g;4种重金属为Cd、Zn、Cu和Hg。研究结果表明:青鳉对Cu~(2+)、Zn~(2+)、Cd~(2+)和Hg~(2+)的急性致死毒性大小为Hg~(2+)Cu~(2+)Cd~(2+)Zn~(2+);Hg~(2+)、Cu~(2+)和Cd~(2+)暴露下青鳉呼吸频率和呼吸强度先升高再降低(P0.01),呼吸参数与重金属浓度间呈现倒"U"型关系;Zn~(2+)暴露下青鳉呼吸频率、呼吸强度显著下降(P0.01);青鳉呼吸行为对Cu~(2+)、Zn~(2+)、Cd~(2+)和Hg~(2+)4种重金属暴露的响应阈值和响应时间分别为0.15、0.95、0.15、0.045 mg/L和2 h 32 min、4 h 7.5 min、3 h 5.5 min、4 h 37 min,响应阈值与96 h LC_(50)的比值分别为0.43、0.19、0.33、0.77。青鳉对Cd~(2+)、Zn~(2+)、Cu~(2+)、Hg~(2+)污染较为敏感,其呼吸参数可作为突发性水体重金属污染的生物监测指标。

Effect of Heavy Metals on Medaka Respiration

Early warning systems with fish as the bio-indicator have been developed by scholars at home and abroad for detecting accidental release of pollutants. In this study, we investigated the acute respiratory effects of four heavy metals (Cu, Zn, Cd and Hg) on medaka (Oryzias latipes). The objectives were to examine the effect of short-term heavy metal exposure on medaka respiration and provide data to examine the potential of an early warning system using mekada as the bio-indicator. Juvenile medaka (3 month) were selected as the test organism (body length, 1.5?0.1 cm; body mass, 0.15 ? 0.01 g). Lethal toxicity of the heavy metals to medaka followed the order, Hg2+ > Cu2+ > Cd2+ > Zn2+. After exposure to increasing concentrations of Hg2+, Cu2+ and Cd2+, respiratory frequency and intensity initially increased and then decreased, and the differences, compared to controls, were significant (P<0.01). Exposure to Zn2+ decreased respiratory frequency and intensity significantly at all but the lowest concentration (p<0.01). The respective acute toxicity thresholds and response times of medaka after exposure to Cu2+, Zn2+, Cd2+, Hg2+ were as follows: 0.15 mg/L, 2 h 32 min; 0.95 mg/L, 4 h 7.5 min; 0.15 mg/L, 3 h 5.5 min; 0.045 mg/L, 4 h 37 min. The ratios of response threshold to 96 h LC50 were 0.43, 0.19, 0.33 and 0.77, respectively. In brief, the respiration parameters of medaka are sensitive to the heavy metals and could be used as biological indicators in an early warning system for sudden heavy metal release to inland waters.