Uptake of perfluorinated alkyl substances (PFAS) by hydroponically grown lettuce (Lactuca sativa)

Transcription

1 Uptake of perfluorinated alkyl substances (PFAS) by hydroponically grown lettuce (Lactuca sativa) Sebastian Felizeter Earth Surface Sciences University of Amsterdam

2 Outline Introduction Materials and Method Results and Discussion Summary and Conclusions Outlook

3 Introduction Experimental Set-up not to simulate what happens in nature Research question: How much of the bioavailable PFAS are taken up? With soil there is sorption of the PFAS to the soil, which reduces the bioavailability Use of a hydroponic nutrient solution Better comparability than with soil Exact monitoring of the water uptake Good solubility of PFAS in water, therefore the water uptake might play an important role in the uptake of PFAS

4 Introduction Hypothesis: PFAS are taken up with the water and are distributed with the plants water system Accumulation of PFAS takes place predominantly in the leaves

5 Materials and Method Experimental Set-up Lettuces were pre-grown in soil for 2 weeks Transferred to a contaminated hydroponic nutrient solution (Hoaglands) A mixture of 14 PFAS was used (11 PFCAs and 3 PFSAs) Concentrations of PFAS in nutrient solution: 0.01µg/L, 0.1µg/L, 1µg/L and 10µg/L

6 Materials and Method Experimental Set-up 6 replicates of each concentration and 3 blanks 2 buckets with no plants for evaporation control Harvest of the lettuces after 40 days of contamination Nutrient solution was renewed 3 times Samples were stored at -18 C until extraction

7 Materials and Method Sample preparation Homogenization with household-blender Extraction with ion-pairing method using MTBE as extracting solvent Clean-up with SPE using Florisil cartridges and activated carbon Analysis with HPLC-MS/MS

8 Results Recoveries of ISTD in the range of 60-80% Good linear correlation between concentrations found in the plant and the concentrations in the nutrient solution

9 Results PFTeA Conc roots ng/g FW Conc. water ng/ml

10 Results PFTeA 80,000 Conc roots ng/g FW 70,000 60,000 50,000 40,000 30,000 20,000 y = 67,941x R 2 = 0, ,000 0, ,2 0,4 0,6 0,8 1 1,2 Conc Water ng/ml

11 Results Bioaccumulation factor Roots/Water PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUnA PFDoA PFTrA PFTeA PFBS PFHxS PFOS

12 Results Bioaccumulation factor Leaves/Water PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUnA PFDoA PFTrA PFTeA PFBS PFHxS PFOS

13 Results Conc. Leaves / Conc. Roots 10,000 Higher concentrations in leaves 1,000 PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUnDA PFDoDA PFTrDA PFTeDA PFBS PFHxS PFOS 0,100 0,010 Higher concentrations in roots 0,001

14 Results 1 log Accumulation Leaves/Roots 0,5 0-0,5-1 -1,5-2 -2,5 R 2 = 0,9911 R 2 = 0,9992 PFCAs PFSAs Hydrophobicity log k 0 * * from: DETERMINATION OF HYDROPHOBICITY PARAMETERS OF PERFLUORINATED ALKYLATED SUBSTANCES USING REVERSED-PHASE HPLC, P de Voogt et al., in prep.

15 Results 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Mass distribution Leaves Roots PFNA PFDA PFUnDA PFDoDA PFTrDA PFTeDA PFBS PFHxS PFOS PFOA PFHpA PFHxA PFPeA PFBA % of total PFAS amount

16 Results Uptake in percentage of theoretical maximum uptake 200% 180% 160% 140% Leaves Whole plant 120% 100% 80% 60% 40% 20% 0% PFBA PFPeA PFHxA PFHpA PFOA PFNA PFDA PFUnA PFDoA PFTrA PFTeA PFBS PFHxS PFOS

17 Summary Concentration/total amount of PFAS in roots increase with increasing chain length Higher concentrations in roots than in leaves for all PFAS except PFBA and PFPeA PFDA, PFUnA and PFDoA exceed the theoretical maximum uptake with water The transfer from roots to leaves is dependent on the hydrophobicity of the compounds Largest part of mass transferred is in roots Water transport is not sole determinand

18 Conclusions Uptake of PFAS and transfer from roots to leaves inhibited PFAS are not just taken up passively with water Indication that other processes, e.g. sorption, influenced the root concentration. Root vegetables, e.g. carrots, might pose a greater risk.

19 Outlook Hydroponic uptake experiments with Tomato, Cabbage and Zucchini Field experiments with contaminated soil

20 Acknowledgements Thank you for your attention We thank Wellington Laboratories for generously providing us with Internal Standards The study is part of the EU project PERFOOD (KBBE ), and the financial support of the European Union is gratefully acknowledged.