Mercury in the Delta Where does it come from and what can we do - PowerPoint PPT Presentation

Mercury in the Delta Where does it come from and what can we do about it? Laura McLellan , Environmental Scientist, Central Valley Water Board Laura.McLellan@waterboards.ca.gov; 916-464-4646 Janis Cooke , Environmental Scientist, Central Valley Water Board Janis.Cooke@waterboards.ca.gov; 916-464-4672

Outline • What is mercury? • Where does it come from? • What can we do to clean it up in the Delta? 2

Mercury (Hg) http://spock.fcs.uga.edu/ext/housing/images/mercury2.jpg 3

Where mercury comes from Mercury-rich soils Atmosphere Legacy mining http://bellona.org/assets/sites/6/Coal-Fired-Power-Plant.jpg Oakland Museum of California 4

5 Source: USGS Fact Sheet 2005-3014

Methylmercury (MeHg) • Byproduct of the metabolism of sulfate- and iron- reducing bacteria • Typically produced in sediment MeHg Hg MeHg bacterial methylation 6 21 April 2009 Delta Mercury Control Program Stakeholder Meeting Slide 6

What can we do to clean up mercury in the Delta? In other words, How can we reduce MeHg in Delta fish & waters? • Reduce inorganic Hg in Delta sediment • Control activities that affect MeHg production and loss 7

Reducing inorganic mercury in sediment In-Delta Sources (~3%): Watershed Sources (~97%): • Wastewater treatment • Wastewater treatment plants plants • Atmospheric deposition • Atmospheric deposition • Urban runoff • Urban runoff • Historic mining activities • Naturally mercury- enriched soils • Geothermal springs 8

Upstream Mercury Control Programs are being developed

Image: Dept. Water Resources Cache Creek Settling Basin in Yolo Bypass - A source and solution to mercury inputs

What can we do to clean up mercury in the Delta? In other words, How can we reduce MeHg in Delta fish & waters? • Reduce inorganic Hg in Delta sediment • Control activities that affect MeHg production and loss 11

Control activities that enhance methylmercury production and loss Urban Ag Wastewater Open Water Tributary Inputs Wetlands Methylmercury Sources to the Delta 12

Managed Wetlands Test wetland • Polishing pond pilot test • Vegetation removal (baling, disking, grazing) 13 Graphic credit : USGS

Methylmercury Sources to the Delta Urban Ag Wastewater Open Water Tributary Inputs Wetlands 14

Multi- Layered System 15

Layer 1: Tributary Watersheds to the Delta 16

Layer 2: Wetlands and Open Water 17

Layer 3: Wastewater Treatment plants 18

Layer 4: Agricultural Areas 19

Layer 5: Urban Areas in the Delta Region 20

Layer 6: It is dynamic! Video provided by Moss Landing Marine Laboratories 21

Thank you . Questions? Laura McLellan , Environmental Scientist, Central Valley Water Board Laura.McLellan@waterboards.ca.gov; 916-464-4646 Janis Cooke , Environmental Scientist, Central Valley Water Board Janis.Cooke@waterboards.ca.gov; 916-464-4672