Cd^2＋对红裸须摇蚊Propsilocerus akamusi的急性毒性研究

Acute Toxicities of Cd^(2+) on Propsilocerus akamusi (Diptera: Chironomidae)

采用急性毒性实验方法,研究了水环境中常见污染物Cd2+对红裸须摇蚊Propsilocerus akamusi的急性毒性,结果表明,Cd2+对红裸须摇蚊在24h、48h以及72h的半致死浓度(LC50值)分别为235.63(95%CI:160.96～418.82)、165.17(95%CI:140.65～198.35)及94.12(95%CI:81.93～108.78)mmol·L-1Cd。Cd2+对红裸须摇蚊幼虫的毒性与对其他摇蚊物种幼虫有明显不同,该物种对Cd2+急性毒性不敏感,有非常强的耐受能力。同一时间不同浓度的Cd2+处理对CAT活性影响的LSD法多重比较检验结果显示,24h与48h的各浓度Cd2+对CAT活性都没有明显差异,只是在72h时CAT活性在对照组与其他处理浓度组之间的差异达到了显著性水平。时间因子对CAT活性的影响则主要表现为Cd2+浓度在400mmol·L-1时,72h处理组与48h处理组的活性表现出显著差异,CAT活性在72h时被显著抑制。

Acute toxic experiments were carried out to test the toxicity of Cd^2＋ on Propsilocerus akomusi （Diptera： Chironomidae）. Median lethal concentrations （LC50 values） were obtained using Probit method. For Propsilocerus akamusi （Tokuna） exposed to cadmium, the 50% lethal concentrations （LC50） in 24, 48 and 72 h were observed respectively to be 235.63 （95% CI： 160.96～418.82）, 165.17 （95% CI： 140.65～ 198.35）, and 94.12 （95% CI： 81.93～108.78） mmol·L^-1Cd. Cadmium toxicity to Chironomids larvae presented differed from the results found for other Chironomids species. Apparently, this species was very tolerant to Cd^2＋ during the short-time experiments. LSD test results presented that the treatment-effect on CAT activity was only showed significant differences after 72 h treatment. CAT activity did not change significantly at 24 h and 48 h courses. A longer exposure time （72 h） resulted in significant differences in Chironomids between the control and all six treatments （LSD test, P〈0.05）. The time-factor effect on CAT activity was only presented between 48 h and 72 h. CAT activity did not change significantly at 24 h and 48 h. A longer exposure time （72 h） resulted in significant differences in Chironomids in CAT （LSD test, P〈 0.05）. CAT activity was significantly lower after 72 h compared with 48 h when the larvae were exposed to higher concentration of Cd （400 mmol·L^-1） （P〈0.05）.