23 rd Annual NARPM Training Program Passive sampling methods (PSMs) for organic contaminants in sediments: State of the Science Keith Maruya Southern California Coastal Water Research Project Authority

23 rd Annual NARPM Training Program 1

2 Bulk concentration can be misleading Contaminant analyses for bulk (whole) sediments are used to support decision-making; however… −C s,bulk is often a poor predictor of exposure and subsequent risk since contaminant bioavailability ignored 2 TISSUE BAF = C b /C s,bulk SEDIMENT

23 rd Annual NARPM Training Program 3 Equilibrium partitioning helps… Equilibrium (“EqP”) models to predict freely dissolved concentrations in sediment porewater provide a step forward… Documented for regulatory acceptance in Di Toro et al. (1991) Ankley et al. (1996) for metals Burgess et al. (2013) ESBs for both These models identified a controlling sorptive phase Total organic carbon (TOC), acid volatile sulfide (AVS) But these models do not account for heterogeneity within these sorptive phases… 3

23 rd Annual NARPM Training Program 4 …but only indirectly estimates bioavailable contaminant in porewater (“C free ”) From Lydy et al. (2014); courtesy of P. Mayer and B. Escher

23 rd Annual NARPM Training Program 5 PSMs can provide more clarity  SETAC Technical Workshop – Nov 2012  Sponsors: Exxon-Mobil, SCCWRP, SERDP- ESTCP, Univ. CA Riverside, (SETAC)  Ten-member Steering Committee  50 invited participants  equally divided among academia, govt and industry  international representation  Held at SCCWRP (CA) in Nov 2012  Six articles published in IEAM (Apr 2014)

23 rd Annual NARPM Training Program 6 Two types of PSMs Chemical activity based methods that measure the freely dissolved concentration in sediment porewater (C free ) Desorption based methods that measure total contaminant pool, e.g. the fraction that is rapidly desorbed from sediment using an “infinite sink” sorbent (e.g. Tenax, XAD resin) 6

23 rd Annual NARPM Training Program 7 We focused on PSMs that target C free for hydrophobic organics Methods that quantify bioavailability based on diffusion and partitioning of contaminants from sediment to a polymer phase (passive sampler) −Rely on the concept of chemical activity which aims at determination of freely dissolved concentrations (C free ) in sediment porewater −Methods targeting desorbable pool (“Tenax extractions”) not considered as part of this workshop 7

23 rd Annual NARPM Training Program 8 Organic contaminants of interest  Hydrophobic organic compounds (HOCs)  PAH  PCBs  Organochlorine pesticides DDTs chlordanes mirex  PBDEs

23 rd Annual NARPM Training Program 9 Passive sampler designs Sampling Phase or MediaConfiguration Polydimethylsiloxane (PDMS-SPME)Coated fiber, vial Polyethylene (PE)Film/sheet, tube Polyoxymethylene (POM)Film/sheet Ethylvinylacetate (EVA)Coated vial Silicone rubberSheet, Ring 9

23 rd Annual NARPM Training Program 10 Modes of Operation  Kinetic [C p (t) = C free K pw (1-e -kt )]  Requires time dependent calibration  Does not take advantage of full polymer capacity  Equilibrium (C free = C p /K pw )  Requires polymer-water partition coefficients (K pw )  Realizes full potential of sorptive phase (i.e. lower RLs)  Equilibrium mode is preferred

23 rd Annual NARPM Training Program 11 Applications  Lab-based assessment (“ex situ”)  Accelerated, worse-case estimate of C free  Allows for manipulation and experimentation  Field-based assessment (“in situ”)  Actual field conditions  Longer deployments needed to achieve equilibrium fouling, damage  Lab-based measurements likely quicker/cheaper, but less relevant

23 rd Annual NARPM Training Program 12 SPME samplers in lab and field settings

23 rd Annual NARPM Training Program 13 C free provides more relevant exposure metric than bulk sediment chemistry or EqP Estimates of C free from PSMs better predict endpoints of management relevance, e.g. bioaccumulation & toxicity State of the Science for Organics 13 Lu et al (2011) ET&C 30, Adapted from Kreitinger et al., 2006; 2009

23 rd Annual NARPM Training Program 14 Technical challenges  Consensus on calibration parameters (K values)  Demonstration of agreement among practitioners  Very little intercalibration data available  Correction for non-equilibrium conditions  Appropriate use of performance reference compounds (PRCs)

23 rd Annual NARPM Training Program 15 Regulatory Challenges Lack of understanding by practitioners and managers of advantages and limitations relative to traditional analytical methods −What is the theoretical basis for PSMs? −What is the uncertainty in C free measurements? −How is C free translatable to site assessment models? Plethora of different methods and formats reported in the literature Limited experience by commercial laboratories Cost versus benefit? 15

23 rd Annual NARPM Training Program 16 Breaking barriers by building consensus Establish a theoretical basis for PSMs Activity-based PSMs are relatable to endpoints of interest Provide practical guidance for PSM selection and standardization to achieve measurement/application goals Define appropriate uses in regulatory decision- making contexts incorporate PSMs into site assessment frameworks 16

23 rd Annual NARPM Training Program 17 Workshop Steering Committee  Thomas Parkerton, Chair(ExxonMobil, USA)  Keith Maruya, Co-Chair(SCCWRP, USA)  Beate Escher(Univ Queensland, Australia)  Upal Ghosh(UMd Baltimore County, USA)  Marc Greenberg(USEPA, USA)  Susan Kane Driscoll (Exponent Inc., USA)  Peter Landrum(Ann Arbor, USA)  Michael Lydy(Southern Illinois Univ, USA)  Philipp Mayer(Aarhus Univ, Denmark)  Willie Peijnenburg(RIVM, The Netherlands)

23 rd Annual NARPM Training Program 18 Workshop Participants