| In this paper, the experiments of toxicity of pesticides on earthworms were performed under laboratory conditions. The experiments include that: (1) the single and binary-combined toxicity of pesticides on earthworms were tested by using the filter paper contact method and we can depict the dosage-response relationship of pesticide. (2) At the same time, we also studied single and binary-combined pollution of carbofuran and monosultap on protein content and SOD enzyme and AChE enzyme activity of the earthworms. (3) The effect of pesticides on the epidermal morphology of earthworm was investigated by using scanning electron microscope (SEM). (4) Based on the statistical analysis for the measurements, we will find the referent of effect of pesticides on biology.1. By adopting filter paper contact method, the acute toxicological experiment shows that the earthworm have different symptoms for different pesticides. When the two pesticides are combined, the earthworms show mainly the symptoms under carbofuran. The monosultap is more poisonous to earthworms than carbofuran. The dosage-response relationship on earthworms demonstrates more complicated under the binary-combined pesticides of carbofuran and monosultap. And the acute toxicology was affect obviously by temperature and it increased under the higher temperature.2. Protein contents of earthworm were increased firstly and then decreased when the earthworms exposed to carbofuran. Along with the increase of the exposed concentration of monosultap, the protein contents of Eisenia foetida under two different temperatures tended to increase at different scales. Low concentration of pesticides increased the protein contents and high decreased it, when earthworms were exposed to the binary-combined pesticides of carbofuran and monosultap. Nevertheless, the changing trends of protein content seem ruleless. The results suggested that temperature had certain influence on the protein content. And the protein content of earthworms can indicated the early pollution of pesticides.3. According to the investigation on SOD enzyme activity of earthworms, we could conclude that carbofuran show the similar change direction in the exposed times. Low concentration of carbofuran increased the SOD enzyme activity, while high decreased the SOD enzyme activity. Results also showed that protein contents of earthworm were increased under 30 mg·L-1 and then decreased with the exposed times and concentrations under 10℃. The SOD activities decreased 32.2 % and 21.2 % under 10℃and 20℃, respectively, when the earthworms exposed to monosultap. Binary-combined pollution of carbofuran and monosultap (30 mg·L-1) showed extraordinary similar change trend with carbofuran, but the tendency wasn't consistent under 20℃. The SOD activity was higher under 20℃. Though the SOD activity of earthworms can indicate the effects of pesticides, it was vertiginous. Therefore, it is suggested that SOD activity should be used with other indicator to reflect the pollution of pesticides.4. The AChE activities of earthworms were significantly restrained by carbofuran but were not restrained by monosultap significantly. It could resume when the exposed experiment was proceeding. The AChE activities of earthworms were also restrained by binary-combined of carbofuran and monosultap obviously but it was not resumed. And the AChE activities of earthworms increased according to the order of carbofuran, binary-combined of carbofuran and monosultap, monosultap. In the lower temperature, the AChE activities of earthworms were higher and resumed easier. As a stable index, the AChE activity of Eisenia foetida can be regarded as the biological monitoring indicator to evaluate the effect of carbofuran contamination on environment.5. The pesticide could cause the change of epidermis' structure of earthworms. The pesticide makes the stratum comeum (SC) around hair follicles loose and the flagellum easy to exfoliate. Meanwhile, the pesticide disrupts the highly ordered lipid structure of SC and makes it loose after a long time. But there are no obvious distinction among different concentration treatments. The investigation on the epidermal morphology of earthworms by using scanning electron microscope (SEM) could offer more information and it can he used as an accessorial indicator to biological monitoring and evaluate the environmental contamination.
|
PDF Full Text Request