Study On The Response Of Daphnia Magna To The Compound Of Suspended Particulate Matter And Antibiotics In Aquatic Environment

In recent years,the abuse of antibiotics has led them entry into the aquatic environment constantly.Particulate matter which in water can interact with antibiotics and act as carriers,which will have corresponding toxic effects on aquatic organisms and damage the normal functions of aquatic ecosystems.In order to investigate the effects and mechanism of suspended particulate matter and antibiotics on the zooplankton in aquatic environment.We select Daphnia magna?cladoceran?as research object,inquiring into the mechanism of freshwater zooplankton in response to the stress of single and mixed phenicol antibiotics?Chloramphenicol:CAP;Thiamphenicol:TAP;Florfenicol:FLO?,natural particles?NP?,natural nanoparticles?NNP?and the combination of particles and antibiotics by analyzing the survival,growth,reproduction,oxidative stress and damage of D.magna.Our results indicate:?1?The toxicities of single and mixed phenicol antibiotics were increased with temperature increasing from 20?to 25?.Their individual toxicity depicted with an order of 72-h EC₅₀ were as follows:CAP>FLO>TAP and CAP?FLO>TAP under 20?and 25?,respectively.The most toxic groups of the mixed treatments were CAP+FLO?306.3 mg/L?and CAP+TAP?42.1 mg/L?respectively.After long-term exposure to individual phenicol drugs at 25?,the toxic effect of FLO was greater than CAP and TAP.Besides,there is no distinct rule in effects of phenicol antibiotics on the activities of CAT and levels of GSH in D.magna.The MDA content of D.magna was increased after exposure to low concentrations?0.001 mg/L or 0.001+0.001 mg/L?of CAP,TAP+FLO and CAP+TAP treatments.?2?The survival rate of D.magna was inhibited by low concentrations of NP??50 mg/L?.However,high concentrations??100 mg/L?of NP did not affect the normal survival of D.magna.Moreover,acute toxicities of the mixtures of phenicol antibiotics and NP were different.10 mg/L and 200 mg/L NP were able to increase the acute toxicity of CAP and TAP to D.magna.For CAP+TAP exposure groups,low concentration of NP could increase their acute toxicity to the animals,but high concentration of NP was able to reduce the acute toxicity of CAP+TAP to daphnids.The activity of CAT and levels of GSH were significantly inhibited and induced by mixture groups of CAP+NP?10 mg/L?/TAP+NP?200 mg/L?and CAP+TAP+NP?10/200 mg/L?,respectively.Furthermore,the MDA content of D.magna was increased after exposure to mixture of TAP?50 mg/L?/CAP+TAP and NP?10/200mg/L?.?3?The survival rate of D.magna was inhibited by low concentrations of NP??10 mg/L?.However,high concentrations??50 mg/L?of NP did not affect the normal survival of D.magna.10 mg/L NNP could increase the acute toxicity of CAP to D.magna,but 100 mg/L NNP was able to decrease its toxicity.Moreover,low and high concentrations of NNP could increase the acute toxicity of TAP to the animals.For CAP+TAP,10 and 100 mg/L NNP were able to reduce their toxicity to daphnids.Furthermore,the activity of CAT and levels of GSH were significantly induced by mixtures of CAP?0.001 mg/L?/CAP+TAP and NNP?10/100 mg/L?.TAP+NNP compound had little effect on the GSH level of the animals,but the activity of CAT was induced by TAP+NNP?100 mg/L?.As for CAP+NNP,the content of the MDA increased first and then decreased with the increase of CAP exposure concentrations.Besides,the effect of TAP+NNP compound on the content of MDA content was reversed.There was a significant increase in MDA content of D.magna which exposed to CAP+TAP+NNP treatments.