Research On The Biotoxicity And Bioaccumulation Of Some Kinds Of Organic Chlorine Pollutants To The Protozoan Tetrahymena Thermophila BF₅

The persistent organic pollutants (POPs) are harmful to humanbeings and ecosystem. In the recent years, more and more funds from the national and provinces'supports indicate the lack of the studies on POPs'issue. The environmental beheavior of POPs, as well as their biotoxicity and controlling, is the key projects in this research area. In this dissertation, the biotoxicity and bioaccumulation of HCB, 2,4-DCP, 2,4,6-TCP to the protozoan Tetrahymena thermophila BF5 were studied. The main conclusions were as follows:1. In PPYS culture medium, low concentration (50μg/L) of HCB slightly promoted the growth of the protozoan, while with 250μg/L and 1000μg/L HCB, the number of protozoan decreased, and showed a short and acute biotoxicity to Tetrahymena thermophila BF5. In inorganic salt culture medium, with 50μg/L, 250μg/L and 1000μg/L of HCB, the number of protozoan decreased, which revealed an inhibition to the growth and an acute and short toxicity.So the presence of the nutrition could slow down the biotoxicity. By making use of dose-effect equation, the EC50 of HCB at 24, 48, 72 and 96h exposed were 364, 514, 296 and 117μg/L, respectively. The results showed that the concentration diffusion played an important role in the bioaccumulation of HCB by Tetrahymena thermophila BF5. Tetrahymena thermophila BF5 had a certainin bioaccumulation ability to HCB. In PPYS culture medium, the BCF varied from 36 to 493. And in inorganic culture medium, BCF varied from 147 to 1328.2. In PPYS and inorganic salt culture medium with 800μg/L and 1000μg/L of 2,4-DCP, 2,4,6-TCP, they displayed an inhibition to the numbers of the protozoan. By making use of dose-effect equation, the EC50 of 2,4-DCP at 24, 48, 72 and 96h exposed were 693, 1849, 1122 and 955μg/L, respectively. The EC50 of 2,4,6-TCP at 24, 48, 72 and 96h were 347, 916, 18661 and 1262μg/L, respectively. Tetrahymena thermophila BF5 had a certainin bioaccumulation ability to 2,4-DCP and 2,4,6-TCP. In PPYS culture medium, BCF varied from 32 to 67. And in inorganic culture medium, BCF varied from 42 to 85.3.According to the average EC50 of HCB, 2,4-DCP and 2,4,6-TCP, the order of single biotoxicity was HCB> 2,4,6-TCP> 2,4-DCP. The results showed the more substituent Cl, the higher toxicity. With the mixture of HCB and 2,4-DCP, HCB and 2,4,6-TCP, HCB and 2,4-DCP and 2,4,6-TCP at 24,48,72,96h, AI was negative.So an antagonistic effect was obtained to explain the joint toxicity. The antagonistic effect could be explained by the competitive site theory, which still needed a further reaserch.