Enrichment,Metabolism And Transformation Of Typical PPCPs In Different Organisms

Pharmaceuticals and personal care products(PPCPs)are one of the most concerned emerging contaminants.Due to their large use and that they could not be completely removed by traditional sewage treatment processes,PPCPs are discharged into the water environment,resulting in the false persistence in the water environment.At present,a large number of literatures have reported the existence of PPCPs in urban sewage,surface water,groundwater,drinking water and even living organisms.Due to their bioactivity,bioaccumulation and transmission along the food chain,PPCPs may pose potential hazards to aquatic ecosystems.However,there is insufficient understanding of its enrichment and transformation in aquatic organisms,as well as its transmission along the food chain.As a green and emerging technology,microalgae treatment technology is gradually widely used in sewage treatment.Therefore,this paper firstly selected the typical PPCPs as research objects to reveal the physiological response and degradation by microalgae.Then,we explored the enrichment and transmission patterns of the PPCPs along the food chain in Daphnia magna and Danio rerio.The specific contents are list as follows:This study explored the physiological response,removal,degradation products and degradation pathways by microalgae(C.vulgaris and P.tricornutum)to different concentrations of methylparaben(MPB)(0,1,5,10,20,40 and 80 mg/L),which is commonly distributed in water.The results were shown as follows:(1)The growth of C.vulgaris was stimulated by 86.02±0.07% at 1 mg/L of MPB exposure,but it was inhibited by approximately 60.17±0.05% at 80 mg/L of MPB exposure.The growth of P.tricornutum was inhibited by 6.59±0.13% at 1 mg/L of MPB exposure.(2)C.vulgaris could completely degrade different concentrations of MPB,and the degradation rate is up to 100%.However,P.tricornutum only partially degraded different concentrations of MPB,and the degradation rate was between 4.3～34.2%.(3)After 6th day of 20 mg/L MPB exposure,the extracellular enzyme activity of C.vulgaris was 293.64 U/g DCW,while that of P.tricornutum was 32.62 U/g DCW.Therefore,the extracellular enzyme activity of C.vulgaris was significantly higher than that of P.tricornutum.(4)Biodegradation is the main mechanism for the removal of MPB by two microalgae,and there is a small part of bioadsorption and bioaccumulation,indicating that the abiotic removal is negligible.(5)Two different degradation pathways of microalgae for MPB were proposed.The two types of microalgae mainly convert MPB by dehydroxylation,demethylation,dihydroxylation,hydroxylation and ring fission reactions.MPBs can be completely mineralized and detoxified by C.vulgaris,while P.tricornutum only partially removed MPBs and reduced their toxicity.In addition,the enrichment and the transport along the Daphnia magna-Danio rerio food chain of SDZ and TCC were studied.The results of the study are shown as follows:(1)SDZ and TCC did not induce significant acute toxicity to Daphnia magna.Compared with that of the control,the cumulative number of Daphnia magna in the exposure group was delayed by at least 24 h,suggesting that SDZ and TCC adversely affected the reproduction of Daphnia magna.(2)Within 60 h of exposure,the maximum bioconcentrations of TCC and SDZ by Daphnia magna were 305.48±91.22ng/g and 0.99±0.16 ng/g,respectively.The maximum BCF was 554.16±91.21 and1.09±0.13 for TCC and SDZ,respectively.This indicated that Daphnia magna has a strong ability to enrich TCC.(3)The enrichment order of TCC in Danio rerio was gill >muscle > intestine.Water intake is the main pathway for zebrafish to enrich TCC and food intake could also transfer TCC to Danio rerio,though no biomagnification effect has been observed.Moreover,only a small amount of SDZ was enriched in Danio rerio muscle tissue.