Post on 07-Aug-2019
Advancing the use of passive sampling in risk assessment and management of
contaminated sediments: Results of an international passive sampling ring test
Michiel T.O. Jonker, Stephan van der Heijden, Yongju Choi, Yanwen Wu, Loretta Fernandez, Robert M. Burgess, Upal Ghosh,
Mehregan Jalalizadeh, Jennifer Apell, Phil Gschwend, Rainer Lohmann, Mohammed Khairy, Dave Adelman, Michael Lydy,
Samuel Nutile, Amanda Harwood, Keith Maruya, Wenjian Lao, Amy Oen, Sarah Hale, Danny Reible, Magdalena Rakowska,
Foppe Smedes, and Mark Lampi
Acknowledgments
Cefic-LRi; ECO22 project
Bruno Hubesch
Mark Lampi
ILSI-HESI
Michelle Embry
ECETOC
Malyka Galay Burgos
Various funding agencies participants
Background (1)
• Numerous sediments & soils are contaminated with organic contaminants,
such as PAHs & PCBs
• Current risk assessment based on total, solvent-extractable concentrations
• Not the total, but only the ‘bioavailable’ concentration is available for
uptake in organisms and causing effects
• Improved risk assessment (less false positives) is possible, based on
bioavailable concentrations
Background (2)
• Several methods have been developed for measuring bioavailable
concentrations
• Most attention currently paid to ‘passive sampling’, i.e., using polymer
samplers to determine ‘freely dissolved concentrations’ in sediments/soils
• Passive sampling is a mature technique in science, but not yet fully
accepted in the regulatory community: there is no scientific consensus on
which technique to apply (range of methods available)
• Need for:
• Scientific consensus: comparison study of different methods
• Information on robustness (variability/accuracy)
• Standardization of method(s)
Objectives
• Map the state of the science of passive sampling (performance) in
sediments: Quantify intermethod and interlab variability
• Investigate how any (unacceptable) variation can be reduced
• Recommend standard method(s)
Setup (1)
General setup
• 11 labs participating in ring test; 1 coordinating lab (UU)
• 14 passive sampling formats
• 3 different sediments
• 25 target compounds
Participants
• Established track record in passive sampling with sediments
• Netherlands, Norway, Czech Republic, Korea, USA
Setup (2)
Setup (3)
Passive sampling formats
• Polyethylene (PE): 6 suppliers; 2 thicknesses (25 and 50 µm)
• Polydimethylsiloxane (PDMS): 5 different SPME fibers (suppliers and
coating thicknesses – 10, 30, 100 µm)
• Polyoxymethylene (POM): 2 suppliers and 3 thicknesses (17, 55, 77 µm)
• Polyacrylate (PAc): 30 µm coated SPME fibers
• Silicone rubber (SSP): 100 µm thickness
Compounds
• 13 PAHs (3-6 rings) and 12 PCBs (tri- to heptachlorinated)
• Range in hydrophobicity, partitioning behavior, freely dissolved concs
Setup (4)
Setup (5)
Sediments
3 sediments differing in complexity:
1. Spiked sediment (SP): high concentrations
spiked; low background; sandy; TOC=1.4
2. Field contaminated sediment (Dutch;
Biesbosch area; BB): homogeneous; low
concentrations PAHs and PCBs; TOC=4.3
3. ‘Composed’ sediment (FD): 2 field sediments
mixed.
- French, sandy sediment; low-high PCB
levels (no PAHs)
- Dutch, clayey sediment; moderate PAH
levels (no PCBs); NAPLs (diesel) present;
TOC=2.3
Setup (6)
Experiments
1. ‘Own procedure’: Participants followed their own approach
2. ‘Standardized procedure’: Participants followed standard protocols (UU)
3. Standardized procedure, but extracts analyzed by UU
4. ‘All @ UU’: all 14 formats applied (standardized) and analyzed by UU
5. Additional tests:
- analysis of analytical standard and weighing test (all participants)
- solvent extraction and recovery tests, homogeneity test (UU)
- Partition coefficients (Kpw’s) for all compd’s and polymers (UU)
Results (1)
1. Own procedure (State of the science in passive sampling)
Without PCB-77
Chemical-averaged variation range factor (95% percentile / 5% percentile)
10 29 9
10 9
BB FD SP
All chemicals
Results (2)
1a. Own procedure (Effect of standardizing Kpw’s)
BB FD SP
Without PCB-77
Chemical-averaged variation range factor (95% percentile / 5% percentile)
12 21 10
10 9
All chemicals
Results (3)
2. Standard procedure (Effect of standardizing protocols & Kpw’s)
BB FD SP
Without PCB-77
Chemical-averaged variation range factor (95% percentile / 5% percentile)
7 9 4
4 5
All chemicals
Results (4)
3. Standard procedure, analyzed @ UU (Impact of analytical chemistry)
BB FD SP
Chemical-averaged variation range factor (95% percentile / 5% percentile)
2.4 2.4 2.6
Results (5)
Standard analytical solution
2.8
Averaged variation range factor (95% percentile / 5% percentile)
Results (6)
4. All @ UU (Intermethod variation)
BB FD SP
Chemical-averaged variation range factor (95% percentile / 5% percentile)
1.6 1.7 1.7
Summary (BB sediment)
Intralab / intermethod
Interlab + intermethod
protocol
s
1.6
10 10 4 2.4
Kpw analytics
Conclusions
• Variation in passive sampling results (current practice) is rather (too) large
• Important contribution to the variation by analytical chemistry!
Identification, integration, calibration
• Variation can be significantly reduced by standardizing protocols
Standardization: polymer washing procedures, polymer/sediment ratio,
sediment/water ratio, way and time of mixing, extraction solvent and procedure
• Standardizing Kpw’s does not reduce variation, but is essential for precision of
Cfree
• Different polymers yield very similar results: Intermethod variability is small
(within a factor of 1.6)
• Passive sampling is a robust method - ready for use within regulatory
applications, provided that standard protocols are used and analytical
chemistry is quality controlled