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Distribution of Mercury in USEPA Region Ix R-EMAP Study Areas

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Abstract:Mercury distribution within U .S. EP A Region IX Regional Environmental Monitoring and Assessment Program (R-EMAP) study units is associated with geology and land-use practices. Stream water and sediment data indicate mercury is mobilized from weathering of ore bearing rock, and atmospheric deposition. In the Humboldt River Watershed Total Mercury (HgT) in sediment is detected at 26 of 34 sites ranging in concentration from 0.07 -1.50 fig/Kg. Lowest Effects Level (LEL) for aquatic organisms in sediments of 0.2 fig/Kg is exceeded at 6 sites, which are located downstream from historical mine sites and downwind from current mining activity. Mining facilities in the Humboldt Basin reported, in the 1998 USEP A Toxic Release Inventory (TRI), emitting an estimated 13,560 Ibs. of mercury directly into the atmosphere and over 9 million Ibs. are contained in tailings and waste rock piles. In the Central Valley, CA, irrigation canals, ditches and drains, HgT is found in 15 of 50 sites ranging from 0.1- 0.32 ug/L in water and 0.07-0.66 fig/Kg dry weight sediment. HgT is associated with abandoned mercury and gold mines in the Coast Ranges and Sierras. In the Walker River and Muddy River watersheds, HgT in sediment is found at 7 of28 sites ranging from 0.07- 0.78 fig/Kg, and in 4 of 37 sites ranging from 0.07- 0.80 fig/Kg respectively. One site in the Muddy River has detectable HgT concentration in water of 0.41 ug/L.
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Citation:Hall, R. K., A. R. Olsen, D. T. Heggem, P. Husby, and L. Chambers. Distribution of Mercury in USEPA Region Ix R-EMAP Study Areas. Presented at Environmental Monitoring and Assessment Program (EMAP) Symposium 2004, Newport, RI, May 3-7, 2004.
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Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
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Division: Environmental Sciences Division
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Branch: Landscape Ecology Branch
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Product Type: Abstrct/Oral
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Presented: 05/03/2004
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Related Entries:
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Bullet Item Environmental Monitoring and Assessment Program Western Landscape Pilot
spacer Relationship Reason:   A Project of the Product
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Last Updated on Monday, October 22, 2007
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