Emissions. Global Sources of Mercury Primary (smokestacks and mining) Secondary (historical deposition and re emission)

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1 Investigations on the Cycling of Mercury from the Ocean to Fog and Deposition to Land in Coastal California Peter Weiss Penzias, Ph.D. Department of Microbiology and Environmental Toxicology, UC Santa Cruz Mercury in Fog and Its Potential Effects on the Ecosystem Emissions Hg 0 (inert gas) Hg II compounds Global Sources of Mercury Primary (smokestacks and mining) Secondary (historical deposition and re emission) Atmospheric Fate and Transport dilution Bioaccumulation 10 8 concentration factor ppm ppt ppq Oxidation by atmospheric radicals Wet and dry deposition of Hg II compounds Surface mixed layer ~200 m depth Oxygen limited environment Hg II DMHg Hg II MeHg Efficient absorber of water soluble marine emissions DMHg MMHg Iron and sulfate reducing bacteria fog deposition MMHg ppt Marine Fog Ocean Coastal Terrestrial Ecosystem deposition ppm Land Mercury An Amazing But Toxic Metal History of releases of Hg to the atmosphere Reconstructed Emissions History Mercury in Ice Core, Wyoming USA Cinnibar (HgS) and elemental Hg Plant Bowen in Georgia, Coal Fired Power Plant (967 lbs Hg in 2005) Hydraulic Mining Gold and Mercury Mines in California Adding Hg to Amalgamate the Au Artisanal Scale Gold Mining Streets et al., ES&T, 2011 Modern day Hg emissions inventory UNEP,

2 Hg contamination is a problem for California Fish Red = > 0.44 ppm Hg in fish: Recommended No Consumption! Methylmercury: Formed by a many types of microbes, in many types of environments Coastal Ocean Sport Fish CH 3 Hg One model of how Hg becomes bioavailable for microbial methylation Lakes and Reservoirs Podar et al., 2015 SFEI, 2009 SFEI, 2012 Leclerc et al., 2015 Bioaccumulation and Health Risks The Minamata Convention on Mercury is a global treaty to protect human health and the environment from the adverse effects of mercury. Signed by 128 countries in 2013 Ban on new mercury mines and the phase out of existing ones Phase out and phase down of mercury use in products and processes Control measures on emissions to air and on releases to land and water Regulation of artisanal and small scale gold mining. Regulation of interim storage of mercury and its disposal once it becomes waste, sites contaminated by mercury as well as health issues. Mercury in the Environment a Summary Mercury is mobile since it can exist in the gas phase making it a globally dispersed pollutant Mercury is useful for a variety of purposes and is a contaminant in fossil fuels. Mercury current day emissions to the atmosphere are 3 5x higher than preindustrial emissions. Mercury contamination (especially of fisheries) is widespread and difficult to remediate. Emissions controls may lead to lower levels in biota, but mercury cycling is complex and slow. Atmospheric emissions of methylmercury are rare but particularly dangerous. Hypothesis: Marine generated dimethylmercury can evade to atmosphere Depth profiles of DMHg concentrations taken from two cruises on the Pt. Sur in 2014 Coale et al.,

3 Could marine fog absorb methylmercury of marine origin and deliver that methylmercury to coastal terrestrial ecosystems? Fog is a Cloud on the Ground The Salinas Valley In Coastal California, fog arises from marine stratus clouds that advect onto shore. Most common in the summertime. Johnstone and Dawson, PNAS, 2010 High wind speeds along west coast of California result from stationary high pressure over Eastern Pacific Ocean Fog and Upwelling Seasonally Coupled Strong northwest winds and the Coriolis Effect lead to coastal upwelling of seawater. The Marine Atmosphere Influence on Land The hot interior valleys have low surface air pressure and the cold coast has high surface air pressure. Which results in inland penetration of fog banks, especially at night when the dew point temperature is lower. A thermally stable atmosphere above the cold ocean causes the formation of the marine layer and condensation of water droplets. Passive Collector Timelapse Video Monomethyl Hg in Fog Water Compared to Rain Water The University of Arizona Fog and Stratocumulus Evolution (FASE) experiment: 16 flights July Aug 2016 From Mendocino to Morro Bay, km off shore CIRPAS Twin Otter aircraft Naval Postgraduate School/ONR based in Marina, California Sobranes Fire July 26, 2016 Fog water median MMHg concentrations at land sites and ocean locations, summer Weiss Penzias et al., 2016 Cloud water sample MMHg concentrations at locations sampled from aircraft, summer 2016 Mean concentrations of MMHg and THg in samples segregated by air mass type Weiss Penzias et al.,

4 Conceptual Model of how methylmercury gets into fog So what, there s MMHg in fog. Does it matter? Fog Frequencies from Satellite ( ) Coale et al., 2018 Torregrosa et al., 2015 Efforts to assess Hg accumulation in terrestrial food webs 23 ng L ng L 1 and fog waterand lichen 245 ng g 1 14 ng g ng g 1 36 ng g 1 15 ng g ng g 1 14 ng g ng g ng g 1 Wintertime radiation fog 13 ng g 1 Wilmer Lab, UC Santa Cruz Santa Cruz Puma Project 27 ng g 1 26 ng L ng L 1 29 ng g 1 24 ng L ng L 1 Lichen as a Bioindicator of Atmospheric Methylmercury Deposition Sampling Locations and MMHg Concentrations Fog Frequency Final Thoughts Fog drip is significant at many coastal locations in coastal California. Most locations received ~18 L of water per 1 m 2 over a 3 month period when rain inputs were zero. MMHg concentrations in fog water were enhanced ~10x relative to that found in rain and displayed spatial and temporal trends consistent with an ocean source (the atmospheric transport and decomposition of dimethyl Hg). Evidence suggests that plants and animals near the coast have enhanced Total Hg and methyl Hg accumulations relative to those from inland locations, consistent with a significant contribution from fog water. Measuring stable isotopic ratios of mercury in fog water and it plant and animal tissue may be a definitive method for identifying the source of Hg in coastal terrestrial biota. 4

5 Media Reports on Mercury in Fog The Transporter: Cloud Banks Carry Mercury When the fog rolls in off the ocean, so does mercury pollution. Coastal California Fog Carries Toxic Mercury, Study Finds Mercury Dumped in Ocean Returns in Fog Trace amounts of mercury dumped in the Pacific possibly during gold rush days are being carried back on land in fog from the ocean. Armin Sorooshian U. of Arizona Beware the Fog Belle Zheng, Wendy Lin 5