Toxicity Effect Of Trimethyltin Chloride On Three Kinds Of Aquatic Organisms

Trimethyltin chloride (TMT) is an important organictin compound. It is widely used as plastic stabilizers, wood preservatives, anti-corrosion coatings, pesticides, and kill snails, as well as applied by chemical disinfector and sterilization, which is closely related to industry and agriculture. TMT could be released to environment following the factory effluent and surface runoff. With the rapidly development of organictin plastic and plastics reprocessing, TMT existed widely in the ocean, river, reservoir, groundwater and aquatic organism. Because of the TMT having both hydrophilic and lipophilic, it could enter organism through digestion and skin easily, generate toxicity to aquatic organisms and be accumulated in the body. However, the effects of TMT on ecological toxicity of aquatic organisms are still not clear. The present study is to determine the toxicity of TMT to aquatic organisms and ecosystem and evaluated the environmental safety. Chlorella pyrenoidosa, Daphnia magna, Danio rerio are the typical organisms of plankton, zooplankton and fish in the aquatic ecosystem. The toxicity effects of TMT on Chlorella pyrenoidosa, Daphnia magna, Danio rerio were studied in this research. Moreover, the effects of TMT on physio-biochemical characteristics of Danio rerio were conducted in this present study. The main results were listed as following:1. The growth of Chlorella pyrenoidosa was inhibited by TMT, and showed a significantly dose-response relationships. During the experiment, the growth of Chlorella pyrenoidosa in 0.1, 0.38, and 1.14 mg/L was inhibited to some extent, but still had a slowly growth trend; in 5.31 mg/L, the growth was completely inhibited. In 20 mg/L, the growth had a strong inhibition, the algae cells became transparent gradually from the beginning of the experiment on, in which most of them were disintegrated under the microscope and lethal. The TMT concentration and chlorophyll a content had a dose-response relationship, and the chlorophyll a content decreased slowly with the increase of TMT concentration. The algae cell density showed similar tendency. TMT had the highest toxicity for Chlorela pyrenoidosa, the 96 h-LC₅₀ concentration was 2.45 mg/L.2. The inhibition rate and mortality of Daphnia magna increased with the increase of TMT concentration and the test time. When the concentration of TMT was 0.05 mg/L, Daphnia magna activities were partly suppressed at 48h, but no dead; while the concentration of TMT was 0.185 mg/L, the mortality and inhibition rate was 60% and 80% respectively, and up to 100% at 48 h. The 24 h-LC₅₀ and 48 h-LC₅₀ concentration was 0.15 and 0.087 mg/L, respectively. TMT had the highest toxicity to Daphnia magna.3. TMT was high-toxic to Danio rerio, and the 96 h-LC₅₀ was 2.35 mg/L. The activities of Na⁺,K⁺-ATPase in gill was inhibited significantly by TMT. When the concentration≥0.78 mg/L, the Na⁺,K⁺-ATPase activity was inhibited significantly, and the inhibition rate≥32%. The activities of the low concentration group (0.39 mg/L) was inhibited first and then recovered after 24 h. With the increase of TMT concentration and exposure time, the inhibition of AchE activity in head was increased . Due to the high instability, only the highest concentration group was inhibited significantly. The SOD activity in muscle of Danio rerio showed the trend of increasing at first, and then decreased. When the concentration of TMT was higher, the SOD activity was decreased and activated fasterly. The SOD activity of 0.39, 0.78 and 1.17 mg/L group activated to the maximum level at 48 h, 24 h and 12 h, the activation rate was 153%, 145% and 153% of control, respectively. The above results showed that TMT was high-toxic to Danio rerio, the gill Na⁺,K⁺-ATPase and muscle SOD are targets of TMT.4. The Danio rerio embryos were significantly affectted by TMT. The hatching decreased significantly, but the deformity and mortality increased obviously. When the concentration of TMT≥0.5 mg/L, the hatching rate at 96 h was less than 50%, the deformity and mortality were≥35% and 25%, respectively. It showed that TMT could obviously inhibit the embryo development of Danio rerio.5. According to the acute toxicity test results(EC₅₀ and LC₅₀) of TMT on algae, daphnia and fish, when the evaluation factor was 1000, the quotient method was adopted to assess the ecological risk of TMT, which obtained that the concentration value 0.087μg/L of TMT was no-effect concentration to aquatic organisms.