Passive Sampling for Measuring Freely Dissolved Contaminants in Sediments: Basics, Principles & Applications Robert M Burgess U.S. EPA ORD NHEERL Atlantic Ecology Division Narragansett, RI, USA 25 th 24 th Annual NARPM Training Program
OUTLINE Why use passive sampling methods (PSM) and what they tell us Why do we care about the freely dissolved concentration (C free ) Types of PSM and how they work Preparing, deploying, recovering, and storing PSM Analyzing PSM data Evaluating PSM applications Summary Focus on nonionic organic contaminants (no metals) PAHs Furans Dioxins DDTs PCBs 25 th 24 th Annual NARPM Training Program 1
WHY USE PASSIVE SAMPLING METHODS (PSM) AND WHAT THEY TELL US √ (1) Freely dissolved concentrations (C free ) of contaminants of concern (COC) in water around passive sampler • Surrogate for bioavailable concentrations of COC • Media – Porewater (Interstitial Water) – Water column • Compare to Water Quality Criteria (WQC), other water quality standards, sediment guidelines or water-only toxicity data √ (2) Concentration of COCs in passive sampler • Evidence of correlation with bioaccumulation by aquatic organisms • Serve as surrogates for biomonitoring organisms – Benthic and water column organisms – Especially in situations where mussels or fish cannot be used (e.g., low dissolved oxygen, toxicity, low/high temperature constraints (ice)) 25 th 24 th Annual NARPM Training Program 2
WHY DO WE CARE ABOUT THE FREELY DISSOLVED CONCENTRATION (C FREE )? √ For benthic organisms: What media is an effective surrogate for exposure to bioavailable chemicals? Sediment? Food? = Water column? Chironomus tentans Pore Water = Freely dissolved? √ Adams et al. (1985) addressed this question Two Kepone-amended sediments (same levels) • 1.5% and 12.3% Sediment organic carbon Freshwater midge ( Chironomus tentans ) Flow-through and static 14 day exposures Acute and chronic (growth) endpoints Kepone Exposure-response relationships • Survival and growth versus exposure 25 th 24 th Annual NARPM Training Program 3
WHY DO WE CARE ABOUT THE FREELY DISSOLVED CONCENTRATION (C FREE )? What media is an effective 100 surrogate for exposure to bioavailable chemicals? Midge Survival (%) Sediment 75 Food Water Column 50 1.5% Organic 12.3 % Organic carbon/Kg carbon/Kg sediment (dry) sediment (dry) 25 0 20 40 60 80 Sediment Concentration (mg Kepone/Kg sediment (dry)) 25 th 24 th Annual NARPM Training Program 4
WHY DO WE CARE ABOUT THE FREELY DISSOLVED CONCENTRATION (C FREE )? What media is an effective 100 surrogate for exposure to bioavailable chemicals? Midge Survival (%) Sediment 75 Food Water Column 50 √ Freely Dissolved 1.5% Organic 12.3 % Organic Pore Water carbon/Kg carbon/Kg sediment (dry) sediment (dry) 25 0 12.5 25 37.5 50 Freely Dissolved Concentration (C free ) Pore Water Concentration (µg Kepone/L Pore water) (µg Kepone/L Pore water) 25 th 24 th Annual NARPM Training Program 5
WHY USE PASSIVE SAMPLING METHODS (PSM) AND WHAT THEY TELL US Measuring freely dissolved concentrations (C free ) in the pore waters and water column Why not continue to use conventional sampling methods? Some problems: Is there another sampling method for measuring √ the freely dissolved concentrations (C free ) of Pore Water contaminants? • Centrifugation or squeezing pore water results in limited volumes • Several artifacts including losses to filters and surfaces and contamination by colloids and small particles reduce accuracy of analysis • Collecting large volumes of pore waters is logistically challenging, scientifically dodgy and generally expensive √ Water Column • Logistically and technically difficult to collect and extract large volumes of surface water • Same artifacts as pore water collection • Analytical detection limits are often not sufficiently low 25 th 24 th Annual NARPM Training Program 6
WHY USE PSM AND WHAT THEY TELL US Atmosphere Water Freely Dissolved Concentration (C free ) Freely Dissolved Concentration (C free ) Contaminated Diffusion/Advection Sediments 25 th 24 th Annual NARPM Training Program 7
WHY USE PSM AND WHAT THEY TELL US Bioaccumulation with replacement to maintain equilibrium Passive sampling with replacement to maintain equilibrium Diffusion with replacement to maintain equilibrium In equilibrium systems… there is equilibrium partitioning and there are partition coefficients 25 th 24 th Annual NARPM Training Program 8
WHY USE PSM AND WHAT THEY TELL US For your average contaminated sediment – How does pore water C free behave? Pore water Concentration (C free ) Freely Dissolved Actual C free Resuspension Event (ng/L) (water column intrusion) “Time - averaged” or “time - integrated” measurement Passive sampler-based C free 0 30 Time (days) 25 th 24 th Annual NARPM Training Program 9
TYPES OF PSM AND HOW THEY WORK Atmosphere Atmosphere Water Water Freely Dissolved Concentration (C free ) (C free ) Contaminated Contaminated Sediments Sediments 25 th 24 th Annual NARPM Training Program 10
TYPES OF PSM AND HOW THEY WORK Polyethylene (PE) Polyoxymethylene (POM) PE 25 - 50 µm thick 75 µm thick POM 25 th 24 th Annual NARPM Training Program 11
TYPES OF PSM AND HOW THEY WORK fiber-optic cable 0.25 m cross-section SPMD 2.5 cm SPME triolien layer 50 - 95 um thick polyethylene shell containing synthetic lipid triolien 2.5 cm Solid Phase Semi-Permeable Microextraction (SPME) Membrane Device (SPMD) 25 th 24 th Annual NARPM Training Program 12
TYPES OF PSM AND HOW THEY WORK H H H PCB molecule I I I H H H (a) C I C I C I C C C I I I H H H I I I Polyethylene H H H H H H H Atom Key: I I I I White = Hydrogen C C C C (b) O O O I I I I Black = Carbon H H H H Polyoxymethylene Red = Oxygen “Like Dissolves Like” H Grey = Silicon (i.e., contaminants H H H I I I I dissolve into the polymers) H - C - H Green = Chlorine H - C - H H - C - H H - C - H I I I I Si Si Si Si (c) I I I I O O O H - C - H H - C - H H - C - H H - C - H I I I I H Polydimethylsiloxane H H H 25 th 24 th Annual NARPM Training Program 13
TYPES OF PSM AND HOW THEY WORK Pore water PCB molecule (C free form) Passive Sampler Initial concentration of PCBs in (e.g., PE, POM, SPME) passive sampler = 0 ng/g 25 th 24 th Annual NARPM Training Program 14
TYPES OF PSM AND HOW THEY WORK Equilibrium Sampling (ng/g Passive Sampler) Concentration 0 30 Deployment Time (days) 25 th 24 th Annual NARPM Training Program 15
TYPES OF PSM AND HOW THEY WORK Equilibrium Sampling C Sampler C free K * = Equilibrium Sampler free (ng/g Passive Sampler) Concentration √ C free is the freely dissolved concentration Freely Dissolved of a contaminant (ng/mL), Concentration (C free ) √ C Sampler is the passive sampler concentration (ng/g), √ K Sampler-free is the passive sampler- dissolved partition coefficient (mL/g) 0 30 Deployment Time (days) 25 th 24 th Annual NARPM Training Program 16
TYPES OF PSM AND HOW THEY WORK Number of peer-reviewed publications by PSM 25 25 DGT Polydimethylsiloxane Polydimethylsiloxane Number of Publications Number of Publications 20 20 Polyoxymethylene Polyoxymethylene Polyethylene Polyethylene 15 15 10 10 5 5 0 0 Year Year 25 th 24 th Annual NARPM Training Program 17
TYPES OF PSM AND HOW THEY WORK Superfund sites where PSMs have been used (Updated 2 November 2017): Allegany Ballistics Laboratory (Region 3) Metal Bank (Region 3) Aniston PCB (Region 4) MW Manufacturing (Region 3) Berry’s Creek (Region 2) Naval Station Newport (Region 1) Brodhead Creek (Region 3) New Bedford Harbor (Region 1) Columbia Slough (Region 10) Ordot Landfill (Region 9) Dover Gas Light (Region 3) Pacific Sound Resources (Region 10) Diamond Alkali (Region 2) Palos Verdes Shelf (Region 9) Grand Calumet (GLNPO-Region 5) Portland Harbor (Region 10) Grasse River (Region 2) San Jacinto Waste Pits (Region 6) Lake Hartwell (Region 4) Tennessee Products (Region 4) √ Lower Duwamish Waterway (Region 10) United Heckathorn (Region 9) Manistique River (Region 5) Whitmoyer Laboratories (Region 3) McCormick and Baxter (Region 10) Wyckoff (Region 10) 25 th 24 th Annual NARPM Training Program 18
PREPARING, DEPLOYING, RECOVERING, AND STORING PSM (3) Storage (2) Deployment and (- 4 ˚C wrapped Recovery (~ 30 days) in foil) Passive (1) Solvent Cleaning Sampler (~24 hours) (PE or POM) (4) Solvent Extraction (48 hours) (6) GC/MS Analysis and (5) Volume reduction (~ 1 hour) Data Interpretation 25 th 24 th Annual NARPM Training Program 19
PREPARING, DEPLOYING, RECOVERING, AND STORING PSM Water Column Deployment PE POM PE SPME (in copper mesh envelope) Stainless steel ring Fish trap (NHEERL & MIT) (NHEERL & Brown U) 25 th 24 th Annual NARPM Training Program 20
PREPARING, DEPLOYING, RECOVERING, AND STORING PSM Water Column Deployment 25 th 24 th Annual NARPM Training Program 21
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