Mercury in the Atmosphere Thomas M. Holsen Clarkson University - PowerPoint PPT Presentation

Mercury in the Atmosphere Thomas M. Holsen – Clarkson University

Outline Outline � Sources of Atmospheric Hg Sources of Atmospheric Hg � � Anthropogenic Anthropogenic vs vs natural natural � � Anthropogenic sources Anthropogenic sources � � Forms of Hg in the atmosphere Forms of Hg in the atmosphere � � Hg concentrations in NYS Hg concentrations in NYS � � Hg deposition processes Hg deposition processes � Acknowledgements – – C Driscoll, M Cohen, NY DEC, YJ C Driscoll, M Cohen, NY DEC, YJ Acknowledgements Han, S Lai, J Pagano Pagano, M Milligan , M Milligan Han, S Lai, J

Global Sources of Mercury Global Sources of Mercury to the Atmosphere (in metric tons per year) to the Atmosphere (in metric tons per year) Source Seigneur et Bergan et al. et al. Mason & Source Seigneur et Bergan Mason & al. 2004 al. 2004 1999 1999 Sheu 2002 Sheu 2002 Direct Anthropogenic 2143 2160 2400 Direct Anthropogenic 2143 2160 2400 Recycled Anthropogenic Recycled Anthropogenic 2134 2134 2000 2000 2090 2090 Total Anthropogenic 4277 4160 4490 Natural 2134 1900 2110 Natural 2134 1900 2110 Total 6411 6060 6600 (% of Anthropogenic Origin) (67%) (69%) (68%) from C. Driscoll

U.S. Anthropogenic Emissions of Mercury U.S. Emissions of Mercury 250 Other Non-MACT 210 185 Other MACT 200 Hazardous Waste Incineration 150 118 Chlorine Production TPY Industrial Boilers 100 Municipal Waste Combustors 50 Medical Waste Incinerators 0 Utility Coal Boilers 1990 Emissions 1996 Emissions 1999 Emissions Source: EPA 1990, 1996 NTI and EPA 1999 NEI. Short tons per year.

From M. Cohen

Based on 1999 NEI From YJ Han

Atmospheric Mercury Species Atmospheric Mercury Species � Elemental Mercury (Hg 0 ) Predominant species, Long range transport Globally distributed, 0.5 to 2 years residence time � Gaseous divalent mercury (RGM, Hg 2+, ) Oxidized mercury: Hg(II) : HgCl 2 , other species? Highly water soluble -> short atmospheric life time (0.5-2 days) Local and Regional effects � Particulate Mercury (Hg p ) Species largely unknown – probably Hg(II) Local and Regional Effects (0.5-2 days)

Estimated Speciation Profile for U.S. Estimated Speciation Profile for U.S. Atmospheric Mercury Emissions (1999) Atmospheric Mercury Emissions (1999) RGM

Simplified Mercury Cycle from C. Driscoll

Hg sampling sites in NYS Hg sampling sites in NYS + Potsdam + Sterling + Stockton Potsdam and Stockton funded by NYSERDA, Potsdam and Stockton funded by NYSERDA, Sterling by US EPA Sterling by US EPA

Sterling, NY Sterling, NY Between Oswego and Rochester on a bluff overlooking the lake

Manual Air Sampling Manual Air Sampling TGM: Adsorption into Gold traps RGM: Annular Denuder coated by KCl

Monthly Average TGM Concentrations, ng/m 3 Monthly Average TGM Concentrations, ng/m 12 Stockton site 10 Potsdam site Sterling site 8 TVM Concentrations (ng m -3 ) 6 4 2 0 -2 -4 -6 May 00 July 00 May 01 July 01 Sep 01 Nov 01 Jan 02 Mar 02 May 02 July 02 Sep 02 Nov 02 Jan 03 Mar 03 Date

Daily TGM Concentrations, ng/m 3 3 Daily TGM Concentrations, ng/m TGM Concentration 90.00 80.00 70.00 Concentration, ng m-3 60.00 Potsdam 50.00 Stockton 40.00 Sterling 30.00 20.00 10.00 0.00 12/6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005 10/10/2006 Date

Daily RGM Concentrations, pg/m 3 3 Daily RGM Concentrations, pg/m RGM Concentration 90.00 80.00 Concentration, pg m-3 70.00 60.00 Potsdam 50.00 Stockton 40.00 Sterling 30.00 20.00 10.00 0.00 Date 5/14/2002 7/7/2002 8/30/2002 10/11/2002 12/4/2002 1/27/2003 3/22/2003 5/15/03 7/8/03 8/31/03 10/24/03 12/17/03 2/9/04 Date

Computation of Trajectories - - HYSPLIT4 Computation of Trajectories HYSPLIT4 � NOAA Model NOAA Model � � Predicts history of Predicts history of � air movement air movement

Potential Source Contribution Function Potential Source Contribution Function (PSCF) (PSCF) Sampling site Cell 2 Cell 2 Cell 1 Cell 1 Back-trajectory representing high concentration PSCF value Cell 1 = 2/3 Back-trajectory representing low concentration Cell 2 = 0/2

JP- -PSCF result for TGM measurements taken in Potsdam, PSCF result for TGM measurements taken in Potsdam, JP Stockton, and Sterling in NY Stockton, and Sterling in NY

Tekran Automated Speciation System – highly time resolved concentrations

Hg concentrations obtained with a Hg concentrations obtained with a Tekran Speciation System Tekran Speciation System 3.0 14 Elemental Hg 12 Reactive gaseous Hg 2.5 Particulate Hg RGM & Particulate Hg [pg m -3 ] 10 Elemental Hg [ng m -3 ] 2.0 8 1.5 6 4 1.0 2 0.5 0 0.0 -2 05/14/05 05/18/05 05/22/05 05/26/05 05/30/05 06/03/05 06/07/05 06/11/05 06/15/05 06/19/05 06/23/05 06/27/05 07/01/05 07/05/05 07/09/05

Relationship between Relationship between Hg and SO 2 Hg and SO 2 concentrations in concentrations in Rochester, NY Rochester, NY Data from NY DEC Data from NY DEC

Hg Deposition Processes Hg Deposition Processes � Wet deposition Wet deposition – – Hg associated with rain, dew, Hg associated with rain, dew, � snow, fog (mostly RGM) snow, fog (mostly RGM) � Particle dry deposition Particle dry deposition – – Hg associated with Hg associated with � atmospheric particles (mostly RGM) atmospheric particles (mostly RGM) � Air Air- -surface exchange (water and vegetation) surface exchange (water and vegetation) � � RGM deposition only RGM deposition only � � Hg(0) deposition and emission Hg(0) deposition and emission �

Deposition Processes Air-water exchange Wet Dry Wet and dry deposition, deposition particle RGM, stomata uptake Hg(0) (RGM, deposition Hg(0) Hg(p)) (Hg(p)) RGM → Hg(0) throughfall litterfall

Mercury Deposition Mercury Deposition � Predominant source of mercury in most Predominant source of mercury in most � watersheds is atmospheric deposition (Lindqvisit Lindqvisit watersheds is atmospheric deposition ( et al. 1991; Mason 1994). et al. 1991; Mason 1994). � Deposition of mercury has increased two to three Deposition of mercury has increased two to three- - � fold over the past two centuries, with some fold over the past two centuries, with some locations exhibiting greater than a twenty fold locations exhibiting greater than a twenty fold increase (Meili Meili 2003; 2003; Nriaguand Nriaguand Becker 2003). Becker 2003). increase ( From C. Driscoll

Historical deposition of mercury to sediments in West Pond and Historical deposition of mercury to sediments in West Pond and Little Echo Pond in the Adirondack region (Lorey Lorey and Driscoll, and Driscoll, Little Echo Pond in the Adirondack region ( 1999) 1999)

Regional and Global Contributions to Total Hg Regional and Global Contributions to Total Hg Deposition to the Catskill, NY Receptor Site Deposition to the Catskill, NY Receptor Site 16% USA Canada S. America 13% 60% Europe Africa 2% 5% Asia Natural 2% 2% Seigneur et al. 2002 for NYSERDA

Event- Event -based wet based wet deposition Potsdam, deposition Potsdam, NY, Sept. 2003 – – Apr. Apr. NY, Sept. 2003 2004) 2004) (A) Precipitation Depth (mm) (B) Hg concentration in precipitation (ng L -1 ) (C) Hg wet deposition flux ( µ g m -2 ) Sponsored by NYSERDA and US Sponsored by NYSERDA and US EPA EPA

PSCF result for wet deposition PSCF result for wet deposition PSCF value (max intensity, mean) 0.1 - 0.2 0.2 - 0.3 0.3 - 0.5 0.5 - 0.7 0.7 - 1

Based on 1999 NEI From YJ Han

Dry Deposition Dry Deposition � Difficult to measure � Function of surface type, Hg species, particle size, meteorological conditions � Modeled as product of particle concentration and deposition velocity, Flux = V d × Hg(p) � Generally thought to be equal to or greater than wet deposition � Area that needs additional research

Air- -Water Exchange Water Exchange Air of Hg 0 0 of Hg = K OL (C C d -C C a /H) = K OL ( d - a /H) K OL : mass transfer coeff. C d – dissolved dissolved C d – concentration concentration Ca – – air concentration air concentration Ca H – Henry’s Law constant → RGM - deposition only → Hg(0) - deposition and evasion

Hg Mass Balance for Lake Ontario Hg Mass Balance for Lake Ontario

Conclusions Conclusions � There are significant anthropogenic emissions of There are significant anthropogenic emissions of � Hg – – biggest source in US is utility coal biggest source in US is utility coal Hg combustion combustion � The form of Hg in the atmosphere controls its The form of Hg in the atmosphere controls its � fate and transport fate and transport � There is evidence that North America sources There is evidence that North America sources � contribute significantly to ambient Hg contribute significantly to ambient Hg concentrations and deposition in NYS concentrations and deposition in NYS