Addressing the Big Questions

1. Addressing the Big Questions (Or what do we know and not know?)

2. “There are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know." Donald Rumsfeld Secretary of Defense

3. Management Questions: Impacts • A. Impacts: How are beneficial uses being impaired? • Hg San Francisco Bay and Walker Creek • Delta MeHg TMDL • What are we missing? Are we assessing the important species?

4. Management Questions: Loads • B. Loads of Hg and MeHg • Knowns: watersheds and tributaries • Changing understanding based on flow • Small tributaries vs large • Efficacy of stormwater management practices

5. Management Questions: Loads • B. Loads of Hg and MeHg • Knowns: atmosphere • Knowns: wastewater treatment facilities

6. Management Questions: Loads • What are the unknowns? • Historical sediments • What are the key areas that need to be addressed?

7. Afternoon

8. Management Questions: Processes • C. Processes: Methyl Mercury • What are the primary ecosystems for MeHg production?

9. Management Questions: Processes • What are dominant factors for MeHg production? • What are key processes for transferring MeHg into food web?

10. Management Questions: Processes • What is relative bioavailability of Hg loads entering Bay? • What are biological effects?

11. Management Questions: Process • Is the export of mercury occurring via the water column or the food web?

12. Management Implications • In light of what we know and what we think we don’t know, how do we manage: • Wetlands and wetland restoration? • Reuse of Hg-contaminated sediment? • Uptake of Hg into the foodweb?