| In the present study, biomimetic sampling was established based on solid phase micro-extraction with polydimethylsiloxane(PDMS) as equilibrium passive sampling polymer to monitor PAHs and OCPs in sediment of mariculture zone. The correlation between PDMS and organisms was calibrated on the basis of two important economic benthic animals(Ruditapes philippinarum and Corbicula fluminea). The results showed that:(1)The method was described for measuring two typical HOCs of pollutants polycyclic aromatic hydrocarbons(PAHs) and organochlorine pesticides(OCPs) in sediments. The method of PAHs as follows: The seven PAHs of sediment samples were extracted used microwave extraction, solvent extraction were 10 m L acetone /exane(V/ V=1:1) mixture, temperature is 80℃,time is 50 min, andpower is 1000 W. Then cleaned up by column chromatography with the purification filler of silica gel and the elution of dichloromethane with 20 m L, then analyzed by high performance liquid chromatography(HPLC). The method of OCPs as follows.The nine OCPs of sendiment samples were extracted used 100 m L acetone/hexane(V/V=1:1) mixture by soxtex system for 24 hours, then cleaned up by column chromatography with the copper powder, anhydrous sodium sulfate and cleanert Florisil and the elution of hexane/dichloromethane(V/V=1:1) mixture with 30 m L, then analyzed by gas chromatograph-mass spectrometer(GC/MS). The percent recoveries respectively added test on 5, 20, 50 and 10, 50, 100ng·g-1for PAHs and OCPs, was over 70%, and the relative standard deviation was under 15% in sediment sample. The method detertion limit of nine OCPs and seven PAHs in biological sample were 0.63~2.70ng·g-1 and 0.10~0.50ng·g-1,which were used for detecting PAHs and OCPs in real sediment sample.(2)Bioaccumulation kinetics about PAHs with Ruditapes philippinarum: we take out organisms after exposed time(16d, 22 d, 28 d, 36 d, 45 d and 56d) to analyse PAHs. The results showed that the concentrations of PAHs in organism trend to equilibrium at 56 d. PAHs bioaccumulation kinetics curve rise in the first stage, then decrease, and then trend to equilibrium. The content of PAHs and OCPs in two organisms have reached a certain degree, which the cumulative amount of Ruditapes philippinarumfor PAHs and OCPs reached 263.6~3500 and 371.9~6832ng/g lipid,respectively, the cumulative amount of Corbicula flumineafor PAHs and OCPs reached 348.2~1667 and 64.2~3507 ng/g lipid,respectively. Besides, the bio-cncentration factors(BCF) of PAHs for Ruditapes philippinarum and Corbicula fluminea were within the range of 1603~2.81×105 and1376~7.67×105, respectively. The bio-cocentration factors(BCF) of OCPs for Ruditapes philippinarum and Corbicula fluminea were within the range of 1632~3.41×105and 669.7~7.28×105, respectively.(3)Determined equilibrium time of solid phase micro-extraction: we take out PDMS after exposed time(7d, 14 d, 21 d and 28d) to analyse PAHs and OCPs. The results showed that the concentrations of PAHs and OCPs in PDMS both trend to equilibriumat 28 d. The freely dissolved concentration of seven PAHs and nine OCPs in marine sediment and freshwater sediment: The freely dissolved concentration of PAHs and OCPs in marine sediment was respectively 2.4ng/L ~ 1791ng/L and 5.7ng/L~ 1341ng/L. The freely dissolved concentration of PAHs and OCPs in freshwater sediment was respectively 4.7ng/L~690.6ng/L and 1.1ng/L~1714ng/L. Besides, freely dissolved concentrations of HOCs in sediment pore-water(Cfree) were lower than total concentrations of HOCs in sediment pore-water(Cwater), and this difference increased with the increase of the hydrophobicity of HOCs.Cwater include Cfree and theconcentration unitedwith dissolved organic carbon(DOC), and the united concentration can not through the cell and became not available to organisms, so Cwater neglet the bioavailability but Cfree refect bioavailability, which lay a basis of solid-phase microextraction on predicting bioaconcentration and bioaccumulation of hydrophobic organic contaminants(PAHs and OCPs) in sediment.(4)Analyzing concentration of PAHs and OCPs in PDMS(CPDMS) and two organisms(Cb,lip),the results indicated that CPDMS were significantly associated with Cb,lip for PAHs and CPDMS were not significantly associated with Cb,lip for OCPs, which indicated that PDMS can be used to caculate PAHs residual in two organisms, but not suit for OCPs.Bwsides, the correlation between CPDMSand Cb,lip of PAHsfor Ruditapes philippinarum is CPDMS =0.122 Cb,lip+0.518(r=0.857,p<0.001), and for Corbicula fluminea is CPDMS=0.180 Cb,lip+0.359(r=0.803,p<0.001). Bio-cncentration factors(BCF) of two organisms and PDMS-cncentration factors(PCF) were significantly correlated with octanol-water partition coefficient(Kow) with similar slopes inregression lines. This indicated that the pathway of uptaking PAHs and OCPs by two organisms was similar to that by PDMS. Significant positive correlation were found between lg BCF and lg PCF, which indicated that PDMS- cncentration can be used to predict bio-cncentration of PAHs and OCPs in two organisms. Bwsides, the correlation between lg BCFand lg PCF of PAHs and OCPsfor Ruditapes philippinarum is respectively lg PCF = 0.930 lg BCF+1.389(r=0.857,p<0.001) andlg PCF= 0.775 lg BCF +1.433(r=0.956,p<0.001), for Corbicula fluminea is respectively lg PCF = 0.978 lg BCF-0.074(r=0.607,p=0.008) and lg BCF +0.710(r=0.839,p<0.001). The PDMS-sediment distribution factors(PSAF)and The biota-accumulation factors(BSAF) of PAHs and OCPs all in a same certain range, that indicated that PDMS-accumulation can be used to predict biota-accumulation of PAHs and OCPs in two organisms.Besides, PSAF is 3 times as large as BSAF of PAHs for Ruditapes philippinarum and 1.5 timesfor Corbicula fluminea. PSAF is 0.9 times as large as BSAF of OCPs for Ruditapes philippinarum and 1.1 timesfor Corbicula fluminea.In conclusion, solid phase micro-extraction with polydimethylsiloxane(PDMS) as equilibrium passive sampling can predict the concentration of HOCs in organisms, BCF and BSAF, which means its can be used as biomimetic sampling to monitor PAHs and OCPs in sediment of mariculture zone. So, solid phase micro-extraction can not only evaluate bioavailability of HOCs in sediment, but also can be used as biomimetic sampling to monitor HOCs in sediment of mariculture zone. In a word, this study provide the theoretical basis for solid phase micro-extraction with polydimethylsiloxane(PDMS)as biomimetic sampling to monitor HOCs in sediment of mariculture zone. |
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