Application and Use of Passive Samplers for Monitoring Organic - - PowerPoint PPT Presentation

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Application and Use of Passive Samplers for Monitoring Organic - - PowerPoint PPT Presentation

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Application and Use of Passive Samplers for Monitoring Organic Contaminants at Superfund Sediment Sites 26 August 2013 1 of x The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites Background Management of

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Application and Use of Passive Samplers for Monitoring Organic Contaminants at Superfund Sediment Sites

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Background

  • Management of contaminated sediments includes source and

institutional controls, remediation, and evaluating effectiveness of selected management actions

  • Contaminant analyses for bulk or whole sediment often serve

as a critical LOE used to support decision-making

− Often provide a poor predictor of exposure and subsequent risk since contaminant bioavailability is ignored − EqP models were developed to predict freely dissolved concentrations in sediment porewater…BUT WITH LIMITATIONS

  • Driven partly by cost of remedial decisions, these challenges

have led to advances in use of passive sampling methods (PSMs)

– Goal: quantify bioavailability of contaminants in sediments

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Variety of PSM phases and configurations

Passive Sampling Phase or Media Configuration Target Analytes

Polydimethylsiloxane (PDMS) Coated fiber, vial HOCs Polyethylene (PE) Film/sheet, tube HOCs Polyoxymethylene (POM) Film/sheet HOCs Ethylvinylacetate (EVA) Coated vial HOCs Silicone rubber (SR) Sheet, Ring HOCs Gels (e.g., DGT) Thin film “DGT” Metals Resin impregnated polyacrylamide gel “Gellyfish” Metals Metal-chelating media Disk/membrane Metals Water-filled equilibration cell “Peeper” Metals

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Cfree estimates from PSMs

  • Measure the equilibrated polymer concentration (Cp)
  • Cfree = Cp / Kpw

where Kpw is the substance-specific polymer-water partition coefficient

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Regulatory “Acceptance” …

  • They are accepted
  • Are being used at several sites, mostly to revise the Conceptual

Site Model

  • Is no formal Superfund acceptance process
  • If passive samplers helps remedial project managers (RPMs)

answer key site questions, they will be used: – Is there a risk, what are the key exposure pathways? – What combination of dredging, capping, MNR? – What are the risk-based goals and sediment cleanup levels? – How to determine remedy effectiveness? – Does the remedy meet performance targets and RAOs ?

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

… So why aren’t PSMs more widely used?

  • Key barriers to more regulatory acceptance and use include:

− Failure of practitioners and decision makers to understand the advantages and limitations of these chemical-based approaches

  • ver traditional analytical methods

− Confusion regarding the plethora of different methods and formats that are increasingly reported in the literature

  • Lack of consensus on:

− Technical guidance for PSM selection and standardization − Use in regulatory decision-making contexts

  • Limited experience in use and analysis of PSMs by commercial

laboratories

  • Uncertainty over cost vs. benefit

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Technical Guidance on Bioavailability & Bioaccessibility Measurements Using Passive Sampling Methods and Partitioning-Based Approaches for Management of Contaminated Sediments

Summary of a SETAC Workshop

Rachel Adams Ian Allan Mayumi Allinson Kim Anderson Sabine Apitz Chris Beegan Todd Bridges Steven Brown Robert Burgess John Cargill Peter Campbell Peter Chapman* Yongju Choi Beate Escher* Will Gala Jay Gan Upal Ghosh* Frank Gobas Todd Gouin Marc Greenberg* Phillip Gschwend Amanda Harwood Steven Hawthorne Paul Helm Michiel Jonker Susan Kane-Driscoll* Peter Landrum* Huizhen Li Michael Lydy* Keith Maruya* Philipp Mayer* Charles Menzie Megan McCulloch Julie Mondon Munro Mortimer Jochen Mueller Amy Oen Thomas Parkerton* Willie Peijnenburg* Danny Reible James Shine Foppe Smedes Jing You Gesine Witt Eddy Zeng* http://www.setac.org/resource/resmgr/publications_and_resources/executivesummarypassivesampl.pdf

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  • Generally accepted that Cfree provides more relevant

exposure metric than total or bulk sediment conc

  • Hydrophobic organic compounds (HOCs)

– Significant literature available detailing calibration and application of PSMs in sediment assessment (>100 papers) – Estimates of Cfree from PSMs shown to better predict measurement endpoints e.g. sediment bioaccumulation and toxicity – Wide range of calibration parameters have been published for the various polymers and/or configurations of PSMs

State of the Science

102 103 104 105 106 102 103 104 105 106

Observed Tissue (µg/kg lipid) Predicted Tissue = Cfree x Kow

in oligochaetes PCBs & PAHs

20 40 60 80 100 0.001 0.01 0.1 1 10 100 1000

Toxic > 41 TU Survival (%) Porewater PAH34 Conc. (Toxic Units) Nontoxic < 5.2 TU

Area of Uncertainty

Probit Analysis of EPA H. azteca 28-day Tests Lu et al (2011) ET&C 30, 1109-16. Adapted from Kreitinger et al., 2006; 2009

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Tissues & Integration of Passive Samplers

Example: Naval Station San Diego

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  • Good correlation between Musculista tissue and

SPME-derived pore water concentrations for PAHs

  • Weak correlation between TOC-normalized bulk

sediment concentration and tissue concentration

  • Benzo(b)fluoranthene, Benzo(k)fluoranthene,

Benzo(a)pyrene

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R² = 0.8723

5 10 15 20 25 30 35 0.0 1.0 2.0 3.0 4.0

Tissue Concentration (ug/kg) Pore Water Concentration (ng/L)

PAH Tissue Correlation with Pore Water Concentration (0-7 cm) R² = 0.2703

5 10 15 20 25 30 35 5000 10000 15000 20000 25000 30000

Tissue Concentration (ug/kg) Sediment Concentration (ng/g)

PAH Tissue Correlation with TOC Normalized Sediment Concentration

21 day PDMS Bulk sediments

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Tissues & Integration of Passive Samplers

Example: Naval Station San Diego

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  • Good correlation between Musculista tissue and

SPME-derived pore water concentrations for PAHs

  • Centrifugation slightly improved predictability
  • ver bulk sediments, but still disturbs samples

and can confuse relationships between porewater and bioaccumulation

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R² = 0.8723

5 10 15 20 25 30 35 0.0 1.0 2.0 3.0 4.0

Tissue Concentration (ug/kg) Pore Water Concentration (ng/L)

PAH Tissue Correlation with Pore Water Concentration (0-7 cm)

21 day PDMS Centrifuged

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Potential Application in Laboratory & Field Settings

  • Consensus that several PSMs ready for application
  • Consider 5 key guiding principles for selection, preparation,

implementation and validation of PSMs

  • 1. Define question(s)

posed by managers to be addressed by measurement of Cfree using PSMs Endpoints addressed by PSMs

  • Sediment toxicity
  • Benthic organism bioaccumulation
  • Transport (i.e., direction of flux,

gradients)

  • Spatial extent delineation
  • Site-specific KOC
  • Model calibration / verification

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Guiding Principles (con’t)

  • 2. Determine pros/cons of ex-situ (bring sediment

sample back to lab) versus in-situ application of PSMs Other Considerations

  • Site accessibility / security
  • Time / Cost
  • Level of expertise required
  • Regulatory considerations
  • Importance of spatial resolution

(heterogeneity; grab vs. fine scale)

  • Temporal resolution

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Guiding Principles (con’t)

  • 3. Perform trade-off of key considerations to select the

most appropriate PSM(s)

Technical Considerations

  • Target analytes (magnitude
  • f Kow, organic/inorganic)
  • Physicochemical conditions
  • Time for deployment
  • Performance specs

(sensitivity, accuracy, precision)

  • Commercial availability
  • 4. Establish QA/QC guidelines for project

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Guiding Principles (con’t)

  • 5. Quantify PSM measurement uncertainty and propagate

through the risk assessment The uncertainty associated with Cfree measurements using PSMs is expected to be only a fraction of the uncertainty associated with the status quo

PSMs uses in sediment assessments and decision frameworks

  • Nature and Extent
  • Flux measurements
  • Evaluating remedial options
  • Exposure and risk assessment
  • Use in tiered assessment approaches

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Fate, Transport and Exposure Processes

  • Characterizing exposure under current

and future conditions

– Mass movement vs phase movement – Getting from contaminant mass distribution to exposure point concentrations and dose – Projecting the effects of remedial actions

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Modeling

  • PSDs are source of input parameters for

models:

– Contaminant mass-balance – Sediment and contaminant transport – Exposure and Dose-Response – Bioaccumulation – Engineering design – Risk/site recovery projection

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Potential Risk Management Applications

  • Cfree gives managers a

better predictor of bioavailability for 3 key exposure pathways:

  • 1. Direct exposure to inverts.

(tox, bioaccum)

  • 2. Flux from sediments to
  • verlying water column
  • 3. Exposures in water

column

Sediment layer 1 Sediment layer 2 Water column

Contaminant flux (CF) CF CF CF CF

DDT DDT DDT DDT DDT DDT Particulate Phase Dissolved Phase DDT DDT

Measurements of Cfree with PSMs can reduce uncertainty in risk assessment and subsequent risk management decisions

1 2 3

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Applications of PSMs in Context of Sediment Management

  • Use in site investigations and risk assessment (these studies

form the technical basis of a clean-up decision)

– Pore water concentration estimates – Moving toward use of PSM measurements as dose metric – Indicator of bioaccumulation and/or bioavailability

  • Use in remedial effectiveness monitoring

– Surface and pore water concentrations—bioavailability trends – Sediment cap and amendment performance – Surrogate for benthic organism bioaccumulation – Indicator for fish bioaccumulation

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Example Profiles

  • 25
  • 20
  • 15
  • 10
  • 5

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 Depth in cap (inches) Pore water concentration(µg/L)

Pore water concentration profile(location 5)

Naphthalene Fluorene Acenaphthane phenanthrene Anthracene Fluoranthene pyrene chrysene B[a]A B[b]F B[k]F B[a]P

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26 August 2013

The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Site Year to Year Comparison

y = 1.2778x R² = 0.9413 0.001 0.01 0.1 1 10 100 1000 10000 0.01 0.1 1 10 100 1000 Concentration Locaiton 4 (2010) Concentration Location 4 (2009)

Site 1

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The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Site Year to Year Comparison

Site 1

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The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Summary of Potential Assessment & Risk Management Applications

  • Improvements from using passive samplers for Cfree

determinations and data collection—increase certainty:

– Ambient or compliance monitoring programs – Quantifying spatial and temporal trends in bioavailable contaminants – Identifying contaminant sources – Dose metric to develop exposure concentration-response relationships – Understanding of risk zones based on likelihood of effects – Modeling (input parameters or verification data) – Evaluating remedial options and designs – Short- and long-term monitoring of chemical bioavailability – Evaluating results of sediment treatment, disposal, or beneficial reuse following management actions – Evaluating remedy effectiveness

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The Use of Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites

Thank you for your attention today

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