US EPA Office of Research and Development Mercury Modeling Research and Applications

1. US EPA Office of Research and Development Mercury Modeling Research and Applications John M. Johnston National Exposure Research Laboratory Ecosystems Research Division Athens, GA Collaborative Meeting on Modeling Mercury in Freshwater Environments Ontario Ministry of the Environment and International Air Quality Advisory Board of the International Joint Commission January 19 – 20, 2006

2. Talk Overview • Where are we going in NERL / ORD ? • Multimedia problems require integrated approaches and technology to facilitate research • Range of tools for a variety of client needs and applications from assessment to management • Web-based dissemination of information (monitoring data) and methods (models) • Exposure risk characterization and communication • Transport and fate of mercury and its effects on the receptor Although this work was reviewed by EPA and approved for presentation, it may not necessarily reflect official Agency policy. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

3. Primary Agency Role Develop, support and transfer a wide variety of tools and mathematical models that can be used to support watershed and water quality protectionprograms in support of OAR, OW, OSWER, and the Regions

4. Outcomes Outcomes of this research and development program include: • More consistent use of good science and engineering principles in watershed regulatory actions: • TMDLs for sediment, nutrients, toxicants • Watershed protection programs • Regulation of mercury emissions • Superfund site cleanup • More efficient and effective regulation • National program effectiveness

5. Multimedia Challenges • Multiple media models (modules) • atmosphere  watershed and land/air exchanges • Support the use of a range of existing models • empirical, statistical and mechanistic • Multiple receptors (human and ecological) • Fisheries bioaccumulation and exposure of sensitive subpopulations • Broaden the scope and relevance of tools • Multiple pathways and contaminants • NOx, SO2, Hg, PCBs

6. 3MRA/FRAMES First fully integrated comprehensive human and ecological risk assessment technology that combines the science of multi-media modeling into a single technology (FRAMES)

7. Uncertainty Analysis …describing potential differences between model predictions and nature. Uncertainty (UA): due to lack of knowledge and data. • Analysisgiven uncertainty in both models and their inputs, quantify/qualify uncertainty in model output(s). The Three Dimensions of Uncertainty Location Nature Level Communicate Results Adapted from Walker, Harremoes et al., 2003 Sensitivity Analysis & Parameter Estimation …discovering relationships between model predictions and unit changes in input variables. • Sensitivity (SA): finding the subset of input variables that are most responsible for variation in model output. • Analysisrelate importance of uncertainty in inputs to uncertainty in model output(s). • Parameter Estimation (PE): use measured output(s) to back-calculate best estimates of (some) model inputs. Input Space Assessment Techniques Local works intensely around a specific set of input values (i.e., the local condition) Screening quick, simple, ranks input variables and ignores interactions between variables Global quantifies scale & shape of the I/O relationship; all input ranges; assesses parameter interaction Model-Supported Decision Making Under Uncertainty NERL/ERD’s SuperMUSE(a 400-node Windows/Linux Cluster) Supercomputer for Model Uncertainty and Sensitivity Evaluation

8. Model Support and Transfer http://www.epa.gov/athens/wwqtsc/index.html

9. Multimedia ComponentsCenter for Exposure Assessment Modeling

10. Model Development - Mercury • Continue to refine and improve mercury algorithms in GBMM, SERAFM, WASP7, BASS • Continue ERASC evaluation of SERAFM risk/exposure assessment model • Sudbury RiverFish and wildlife exposures with Region 1 (Boston) and BRI (D. Evers) • Cheyenne Sioux RARE Project Region VIII • Host technical session at International Mercury Conference (Madison, WI 2006)

11. Mercury Cycle

12. Mercury Tools

13. Grid-based Mercury Model (GBMM) Model Characteristics • Complete utilization of distributed datasets (e.g. land use, elevation, soil types) for model parameterization and initialization • Simulation of watershed processes at multiple scales to evaluate temporal and spatial changes • ArcGIS technology for manipulating grid-based data

14. Model setup

15. Clip Watershed “Clip watershed”

16. WASP stream network preprocessor

17. Output at user-specified points

18. Optimum grid extent About 2600x2600 cells

19. Mercury hotspotsNLFWA & NLFTS Raw Data of Fish Tissue Samples > .3 ppm (2,283 of 8,598 locations since 1990) <= .3 ppm Source: Tamara Saltman

20. Mercury exposure tool for managersWHAT IF – Watershed Health Assessment Tools Investigating Fisheries (Rashleigh et al., 2005)

21. Site selection and navigation

22. Site selection and navigation (cont.)

23. Simplified exposure tools (BASS model)

24. Watershed mercury loading interaction with impervious cover Simulations using WASP from Clean Air Mercury Rule (Ambrose, 2005)

25. Mercury dynamics in tilled versus untilled soils Calculation using simple spreadsheet derived from IEM-Hg from Mercury Report to Congress (Knightes, 2005)

26. How to achieve collaboration? Common problem/goal + common technology Common datasets comparable model results