Mass Balance Models for Persistent, Toxic Bioaccumulative Chemicals (PBTs) in the Great Lakes: Application to Lake Ontario Joseph V. DePinto LimnoTech Ann Arbor, MI Russell G. Kreis, Jr. U.S. EPA Grosse Ile, MI Great Lakes Research Session 233 rd ACS National Meeting Chicago, IL March 28, 2007

Outline  Overview of PBTs in Great Lakes – Legacy chemicals – Chemicals of emerging concern  Chemical Mass Balance Models  PBT management in Lake Ontario (LaMP) – Development, Calibration/Confirmation of LOTOX2 – Application of LOTOX2

1980s Brought Focus on “Toxic Substances” in the Great Lakes

What is a “Toxic” Substance? PBT  Is Persistent in the environment – Half-life > 8 weeks in any medium (IJC definition)  Tends to be Bioaccumulative – Characteristic of hydrophobic substances – Often not well-metabolized within organism  Elicits a Toxic response in exposed biota

Critical PBTs in Great Lakes Basin – Legacy Contaminants (IJC Virtual Elimination Task Force, 1991)

Typical Great Lakes Legacy Toxic Substance  Historically very high emissions and loadings, followed by significant decrease in loadings through ‘70s and ‘80s  Very Hydrophobic – Strongly associated with particulate matter  Semi-volatile – subject to long-range atmospheric transport  Very Bioaccumulative – Human exposure largely through fish consumption

Typical Historic Pattern of PCB Loadings

Hydrophobic Chemicals Accumulate in Lake Sediments

Typical Great Lakes Toxic Substance  Historically very high emissions and loadings, followed by significant decrease in loadings through ‘80s and ‘90s  Very Hydrophobic – Strongly associated with particulate matter  Semi-volatile – Atmospheric inputs were a significant source of PCBs to Great Lakes in late 1980s – subject to long-range atmospheric transport

Percent Contribution of Atmospheric Deposition of Dioxin to Lake Ontario

Typical Great Lakes Toxic Substance  Historically very high emissions and loadings, followed by significant decrease in loadings through ‘80s and ‘90s  Very Hydrophobic – Strongly associated with particulate matter  Semi-volatile – subject to long-range atmospheric transport  Very Bioaccumulative – Human exposure largely through fish consumption

Food Web Bioaccumulation

Biomagnification in Lake Ontario Food Web (IJC, 1987) BAF for PCBs in Lake Ontario lake trout  6 x 10 6 L/Kg (ww)

Fish Concentrations Responded to Chemical Bans and Load Reductions

Chemicals of Emerging Concern in the Great Lakes  Tend to have similar properties as Legacy Contaminants but with recent and/or ongoing environmental release  Examples: – Polybrominated diphenylethers (PBDEs) – class of chemicals used as flame retardants, plastics in consumer electronics, wire insulation – Perfluoro octane compounds (PFOS/PFOA) – class of chemicals with wide use as surfactants and cleaners, 3M Scotchguard TM, insecticides – Pharmaceuticals and Personal Care Products (PPCP) – tremendous number of human and veterinary drugs  Links to more information: – –

Mass Balance Model Concept Substance X System Boundary External Loading Transport In Transport Out Transformations/ Reactions Rate of Change of [X] within System Boundary (dC X /dt) =  (Loading)   (Transport)   (Transformations) Control Volume

Value of Models for PBT Management  Models can help evaluate and measure the success of load reduction programs – Provide a reference by forecasting the ramifications of no further action – Explain/normalize the small scale, stochastic variability in monitoring data so that longer term, system-wide trends can be seen – Explain time trends of long-term monitoring  Models can aid assessments for which there is no actual environmental experience – Estimate impact of new chemicals – Forecast impact of unusual limnological factors (e.g., ANS invasions, major storm events, climate change) – More localized system responses to watershed load reductions  Models can help guide monitoring programs to be more efficient and effective

Lake Ontario Lakewide Management Plan (LaMP)  GLWQA mandated Lakewide Management Plan (LaMP) in all Great Lakes – Lake Ontario LaMP led by Four Party Secretariat – EPA-Reg 2, NYS DEC, Environment Canada, Ontario MOE  Lake Ontario LaMP identified lakewide beneficial use impairments: – Restrictions on fish consumption – Degradation of wildlife populations – Bird or animal deformities or reproductive problems – Loss of fish and wildlife habitat  Priority LaMP chemicals – PCBs, DDT & metabolites, Dieldrin, Dioxins-Furans, Mirex- Photomirex, Mercury  LOTOX2 model develop to help address several management questions for critical pollutants in Lake Ontario

Toxic Chemical Questions for Lake Ontario Lakewide Management Plan (LaMP) 1. What is the relative significance of each major source class discharging toxic chemicals into Niagara R. and Lake Ontario? 2. What is the role of toxic chemicals existing in sediments of the system? 3. Can changes in major source categories and sediments be quantitatively related to concentrations in the water column and fish? 4. Can observed trends in toxic chemical concentrations over time be explained? 5. How does a regulatory or remediation action affect the water column and fish tissue concentrations at steady-state and over time?

Information Flow in LOTOX2 Model LOTOX2 - Time-dependent, spatially- resolved model relating chemical loading to concentration in water, sediments and adult lake trout Hydraulic Transport Model Chemical Loading Sorbent Dynamics Model Chemical Mass Balance Model Food Chain Bioaccumulation Model In situ Solids Levels

Toxicant in dissolved form Toxicant on suspended particulates desorption sorption Canadian direct sources Deep Sediment diffusive exchange resuspension Atmospheric wet & dry deposition Gas phase absorption Volatilization settling Outflow Dissolved toxicant in interstitial water Toxicant on sediment particulates desorption sorption burial Surficial Sediment Water Column Canadian tributaries Niagara river Hamilton Harbor US tributaries US direct sources Total toxicant in water column Total toxicant in sediment Decay LOTOX2 Chemical Mass Balance Framework

LOTOX2 Segmentation Scheme - plan view Surface water column Deep water column Surface sediment Projection of water column to sediment segments N

Bioaccumulation Model Framework Toxicant Concentration in Phytoplankton (  g/g) (1) Toxicant Concentration in Large Fish (  g/g) (4) Toxicant Concentration in Small Fish (  g/g) (3) Toxicant Concentration in Zooplankton (  g/g) (2) “Available” (Dissolved) Chemical Water Concentration (ng/L) Physical-Chemical Model of Particulate and Dissolved Concentrations Uptake Depuration Predation

PCB Calibration/Confirmation: Historical Simulation

Reconstruction of historical PCB Loading

Model Calibration/Confirmation for Water Column PCB

Confirmation of Average Surface Sediment Concentrations by Segment (1998)

Model Calibration/Confirmation - Lake Trout PCB

Model Confirmation - Lake Trout PCB

Management Application of LOTOX2: Source Category and System Response Time

Sediment Feedback Delays Lake Trout Response (all scenarios start at 2000 and run for 50 years)

Influence of Sediment Feedback

Baseline and Categorical Scenarios (all scenarios start at 2000 and run for 50 years)

LOTOX2 Findings for Management of PCBs in Lake Ontario  Significant load reductions from mid-60s through 80s have had major impact on open water and lake trout rapidly declining trends through that period  Lake is not yet at steady-state with current loads. Time to approximate steady-state with 2000 loads is ~30 years – Slower declines through ‘90s are result of sediment feedback – Ongoing load reductions take 5-10 years to distinguish from no post-2000 load reductions  Point Sources of PCBs are relatively small fraction of current total loading – Major non-point sources are upstream lake and atmospheric gas phase absorption – At present model cannot address problems in localized areas (tributaries, bays, nearshore areas (AOCs)), where PS reductions will have greatest value

Acknowledgements  USEPA – Region 2 for providing most of the funding for this modeling program and for providing guidance and coordination with data collection activities  Lake Ontario LaMP Workgroup members and other Four Party participants for continued support and input, including data collection and sharing  Other collaborative investigators during model development process, especially: – Dr. Joseph Atkinson, University at Buffalo – Dr. Thomas Young, Clarkson University – Dr. William Booty, NWRI – Canada  USEPA – GLNPO for providing funding for the POM-LOTOX2 linkage project and for providing guidance based on experiences with mass balance modeling programs for other Great Lakes systems

Gulls Biomagnify PCBs from Fish