Toxic Effects Of Mercury On Rana Chensinensis And Rana Chensinensis Tadpoles

The present study takes Chinese wood-frog(Rana chensinensis) which is the typical amphibian in the river- forest wetland of eastern region of Jilin Province as the subject of study.This study is undertaken in order to investigate the toxic effects of mercury to wood-frog and its tadpoles as well as the transfer and concentration of mercury throughout the food chain of wood-frog.The experiment mainly includes four parts:the acute and chronic test of Hg² on wood-frog tadpoles;the transfer and concentration of mercury throughout the artificial food chain "corn flour-yellow mealworm-Chinese wood-frog";the survey of field food chain(plants - insects -wood-frog) and comparative analysis with the artificial food chain.The results of this paper as follows:â‘ There was a strong positive correlation between the death rate of tadpole and Hg² concentration,The half lethal concentration(LC50) of 24, 48,72 and 96h was 1.0480,0.8492,0.6091,0.4883 mg·L^-1.The safe concentration(SO was 0.1672 mg·L^-1.â‘¡In the chronic toxicity test,the total mercury concentrations in tadpoles presented undulation within 24h,then decreased gradually until reached the steady value in 25^th day.In the 10 and 20μg·L-1 concentration groups,the bioconcentration factor increased with time,then decreased gradually from 20^th day until reached the steady value.While in the both 30 and 40μg·L-l concentration groups,the bioconcentration factor is big early in the text,then decreased gradually from 5^th day and reached the steady value in 15^th day.â‘¢Artificial food chain enrichment experiments showed that Hg² bioaccumulation factor increased with increasing trophic level.At the same time,Hg² bioaccumulation factor of skin. muscle and viscera increased with time,finally reached balance.â‘£Through the comparative analysis of artificial food chain and the field food chain,under field condition mercury enrichment factor was much higher than the laboratory simulation condition.In field environment wood-frog geted most mercury from environmental media,which exceeded the Hg2 bioaccumulation amount from the food chain.