城市污水厂尾水对文蛤微核率、溶酶体膜稳定性及解毒酶活性的影响

Effects of Chronic Exposure to Effluent from Municipal Sewage Treatment Plants on Micronuclei Frequency,Lysosomal Membrane Stability and Detoxifying Enzymes in Clams Meretrix meretrix

利用天然海水将取自青岛市团岛污水处理厂的尾水稀释为不同浓度(EVR=1%、5%、10%、20%、30%、40%)的混合液,对文蛤(Meretrix meretrix)进行15d的暴露培养,并测定血细胞中的溶酶体膜稳定性(LMS)、微核率(MNF)以及鳃和内脏中I相解毒酶(7-乙氧基-3-异吩恶唑酮-脱乙基酶-EROD)和Ⅱ相解毒酶(谷胱甘肽转硫酶-GST)随EVR的变化。结果表明,各尾水处理组(即使EVR=1%)的血细胞LMS均明显低于对照水平(P<0.05);EVR≥20%的尾水造成血细胞MNF的显著诱导(P<0.05);然而,鳃、内脏中的EROD、GST活性仅在少数尾水处理组中被激活(P<0.05)。文蛤血细胞LMS对尾水暴露的响应敏感性及其与EVR之间的显著负相关性(R=-0.857,P<0.05),使其适于作为纳污海域尾水污染的生物标志物。

Multiple trace pollutants could not be removed completely by existing A-2O（Anaerobic-AnoxicOxic）treatment process in municipal sewage treatment plants（MSTPs）.With the discharge of the MSTPs effluent,these pollutants are introduced into the surrounding waters and accumulated in the aquatic organisms,which may lead to synthetic toxicity effects such as antagonistic action,additive action,independent effect and synergistic effect.In order to master the sub-lethal toxic mechanisms of sewages on bivalves,and provide feasible biomarkers for polluted seawaters for early-alert,in this experiment,clams（Meretrix meretrix）were exposed to effluent from the Tuandao MSTP in Qingdao City at various concentrations（EVR= 0,1%,5%,10%,20%,30%and 40% v/v）,diluted in natural seawater,for 15 days.Lysosomal membrane stability（LMS）and micronuclei frequency（MNF）in the hemocytes,and phase I detoxifying enzyme（ethoxyresorufin O-deethylase,EROD）and phase II detoxifying enzyme（glutathione S-transferase,GST）in gills and viscera were examined.Results showed that the NRRT in hemocyte of clams exposed to effluents decreases with the increasing of EVR,even if EVR=1%,and hemocyte LMS in all treatment groups are significantly lower than those in controls（P0.05）.Higher MNF values were observed in effluent groups at EVR≥20%（P0.05）.However,both EROD and GST in gills and viscera were activated only by a few concentrations of effluents（P0.05）.Compared to controls,EROD activity in gill of clams was significant induced in EVR20%and EVR30%treatment groups;EROD activity in viscera of M.meretrix only in EVR10% treatments was induced.GST activity in EVR5% and EVR10%treatments was induced dramatically in gills;and that in viscera of clams had an obvious change only in EVR40% groups,which was significant higher than controls.Conclusions：（1）Health adversity of M.meretrix was aggravating after exposed to MSTPs effluents for 15 d,and hemocyte was in severe stress when EVR≥20%;DNA of hemocyte could be damaged by exposed to the effluents.（2）Response of LMS to effluents is sensitive and is significantly correlated with EVR（R=-0.857,P0.05）,making it possible for LMS to indicate levels of polluted seawaters.（3）Individual effluents treatment could induce the activity of EROD and GST in gills and viscera;owing to the hyposensitivity of EROD and GST to low concentration effluents,and has non-significant correlation with EVR mostly,as a result,these two kinds of indicators are not suitable for effluent pollution monitoring in biological ways.