MERCURY DEPOSITION IN PENNSYLVANIA:
2006 STATUS REPORT
James A. Lynch, Ph.D.
Professor Emeritus of Forest Hydrology
School of Forest Resources
Kevin S. Horner
Senior Research Technologist
Environmental Resources Research Institute
Jeffrey W. Grimm
Research Assistant
Environmental Resources Research Institute
Hunter C. Carrick, Ph.D.
Associate Professor of Aquatic Ecology
School of Forest Resources
Elizabeth Boyer, Ph.D.
Associate Professor of Water Resources
School of Forest Resources
The work upon which this report is based was supported by funds from the Pennsylvania
Department of Environmental Protection through Contract Number ME359494.
Penn State Institutes of Energy & the Environment
The Pennsylvania State University
University Park, Pennsylvania 16802
November 2007
This publication is available in alternative media upon request.
The Pennsylvania State University is committed to the policy that all persons shall have equal
access to programs, facilities, admission, and employment without regard to personal
characteristics not related to ability, performance, or qualification as determined by University
policy or by state or federal authorities. It is the policy of the University to maintain an
academic and work environment free of discrimination, including harassment. The Pennsylvania
State University prohibits discrimination and harassment against any person because of age,
ancestry, color, disability or handicap, national origin, race, religious creed, sex, sexual
orientation, or veteran status. Discrimination or harassment against faculty, staff, or students
will not be tolerated at The Pennsylvania State University. Direct all inquiries regarding the
nondiscrimination policy to the Affirmative Action Director, The Pennsylvania State University,
328 Boucke Building, University Park, PA 16802-5901; Tel. (814) 865-4700/V, 814-8631150/TTY
Table of Contents
Page
List of Tables ................................................................................................................................ii
List of Figures .............................................................................................................................. iv
Introduction................................................................................................................................... 1
Forms of Mercury ............................................................................................................. 1
Mercury Emissions ........................................................................................................... 2
Mercury Deposition .......................................................................................................... 4
Environmental Concerns................................................................................................... 5
The Mercury Deposition Network ................................................................................................ 9
Network Design and Operation ........................................................................................ 9
Sampling Site Locations ................................................................................................. 11
Sampling Protocols ......................................................................................................... 13
Sample Types.................................................................................................................. 14
Glassware Preparation .................................................................................................... 14
Laboratory Analysis........................................................................................................ 15
The Standard Sampling Period ....................................................................................... 15
Quality Assurance Samples ............................................................................................ 16
Data Completeness Criteria ............................................................................................ 16
Summary Periods ............................................................................................................ 16
Results and Discussions.............................................................................................................. 17
Network Performance ..................................................................................................... 17
Total Mercury Concentrations ........................................................................................ 20
Estimated Wet Total Mercury Depositions..................................................................... 30
Seasonal Total Mercury Deposition Patterns.................................................................. 34
Total Mercury Concentrations ................................................................................... 34
Total Mercury Wet Deposition .................................................................................. 38
Mercury Emissions versus Total Mercury Deposition ................................................... 39
Correlation and Stepwise Regression Analyses.............................................................. 44
Trends in Total Mercury Deposition............................................................................... 50
Summary ..................................................................................................................................... 61
References................................................................................................................................... 68
Appendix I. Weekly Total Mercury Concentrations and Wet Depositions at NADP/MDN
Monitoring Sites in Pennsylvania from January 2005 through April 2007 .......... 72
List of Tables
Table
Page
1. Location of National Atmospheric Deposition Program/Mercury Deposition Network
(NADP/MDN) sites in Pennsylvania in 2005 and 2006 ...................................................... 11
2. Annual summary of weekly sampling periods indicating the number and distribution
of sample types and quality at each Mercury Deposition Network site in Pennsylvania
from 1997 through 2006 ...................................................................................................... 18
3. Maximum and minimum weekly total mercury concentrations (ng/L) and wet
depositions (µg/m2) at eight Mercury Deposition Network (MDN) sites in Pennsylvania
from 1997 through December 2006.................................................................................... 21
4. Mean annual and seasonal volume-weighted total mercury concentrations (ng/L) in
precipitation at eight Pennsylvania Mercury Deposition Network sites from 1997
through 2006. Seasonal means are based on weekly samples collected from DecemberFebruary (winter) March-May (spring), June-August (summer), and September-November
(fall). Annual values are presented for both climatic (December-November) and
calendar years (January-December)..................................................................................... 23
5. Annual and seasonal total mercury wet depositions (µg/m2) at eight Pennsylvania Mercury
Deposition Network sites from 1997 through 2006. Seasonal depositions are based on
weekly samples collected from December- February (winter) March-May (spring), JuneAugust (summer), and September-November (fall). Annual values are presented for both
climatic (December-November) and calendar years (January-December).......................... 31
6. Pearson correlation coefficients (r) between total mercury and the major cation and anion
concentrations in precipitation as measured at eight Pennsylvania collocated mercury
(MDN) and acid rain monitoring sites. All concentrations were log transformed.
Precipitation volume was transformed by taking its square root........................................ 47
7. Summary of stepwise regression analysis with dependent variable log10Mercury
concentrations and log10 transformed major cation and anion concentrations in
precipitation collected at eight Pennsylvania collocated mercury (MDN) and acid rain
monitoring sites. All variables in each model are significant at the 0.050 level ............... 49
8. Pearson correlation coefficients (r) between wet total mercury deposition and cation and
anion wet depositions as measured at eight Pennsylvania collocated Mercury (MDN) and
acid rain monitoring sites. All depositions were log transformed. Precipitation volume
was transformed by taking its square root .......................................................................... 51
ii
Table
Page
9. Summary of stepwise regression analysis with dependent variable log10wet total
mercury deposition and the log10 transformed major cation and anion wet depositions
as measured at eight Pennsylvania collocated mercury (MDN) and acid rain monitoring
sites. All variables in each model are significant at the 0.050 level .................................. 52
iii
List of Figures
Figure
Page
1. Total mercury deposition simulation for the United States and southern Canada using
the Regional Lagrangian Model of Air Pollution (EUEC, 2005) .......................................... 6
2. Fish consumption advisories due to mercury levels in surface waters of the United
States as of December 2004 (U.S. EPA, 2004)...................................................................... 8
3. Location of active and inactive National Atmospheric Deposition Program/Mercury
Deposition Network (NADP/MDN) sites in the United States and southern Canada
as of November 2007 ........................................................................................................... 10
4. Location of active National Atmospheric Deposition Program/Mercury Deposition
Network (NADP/MDN) sites in Pennsylvania in 2005 and 2006 ....................................... 12
5. Volume-weighted mean annual total mercury concentrations (ng/L) and estimated wet
depositions (µg/m2) at all Mercury Deposition Network sites in the United States and
southern Canada that met NADP/MDN’s 75% data completeness criteria in 2005............ 25
6. Spatial interpolation of 2005 volume-weighted mean annual total mercury concentrations
(ng/L) and estimated wet depositions (µg/m2) based on data from Mercury Deposition
Network sites in Pennsylvania and peripheral states ........................................................... 27
7. Volume-weighted mean annual total mercury concentrations (ng/L) and estimated wet
depositions (µg/m2) at all Mercury Deposition Network sites in the United States and
southern Canada that met NADP/MDN’s 75% data completeness criteria in 2006............ 25
8. Spatial interpolation of 2006 volume-weighted mean annual total mercury concentrations
(ng/L) and estimated wet depositions (µg/m2) based on data from Mercury Deposition
Network sites in Pennsylvania and peripheral states ........................................................... 29
9. Seasonal variations in volume-weighted mean total mercury concentrations (ng/L)
across Pennsylvania in 2005 ................................................................................................ 35
10. Seasonal variations in volume-weighted mean total mercury concentrations (ng/L)
across Pennsylvania in 2006 ................................................................................................ 36
11. Seasonal variations in total mercury wet depositions (µg/m2) across Pennsylvania
in 2005. ................................................................................................................................ 40
12. Seasonal variations in total mercury wet depositions (µg/m2) across Pennsylvania
in 2006 ................................................................................................................................. 41
iv
Figure
Page
13. Location of annual mercury emissions (tons/year) at major point sources in Pennsylvania
in 2003 through 2006 ........................................................................................................... 42
14. County summary of annual mercury emissions (tons/year) at major point sources
in Pennsylvania in 2003 through 2006................................................................................. 43
15. Spatial interpolations of volume-weighted mean annual total mercury concentrations
(ng/L) across Pennsylvania in 2003 through 2006 .............................................................. 45
16. Spatial interpolation of annual total mercury wet depositions (µg/m2) across
Pennsylvania in 2003 through 2006..................................................................................... 46
17. Seasonal trends in total mercury concentrations and precipitation at the Hills Creek
State Park MDN site in Tioga County Pennsylvania from 1997 through 2006................... 53
18. Seasonal trends in total mercury wet depositions and precipitation at the Hills Creek
State Park MDN site in Tioga County Pennsylvania from 1997 through 2006................... 54
19. Seasonal trends in total mercury concentrations and precipitation at the Allegheny-Portage
NHS MDN site in Cambria County Pennsylvania from 1997 through 2006 ...................... 55
20. Seasonal trends in total mercury wet depositions and precipitation at the Allegheny-Portage
NHS MDN site in Cambria County Pennsylvania from 1997 through 2006 ...................... 56
21. Seasonal trends in total mercury concentrations and precipitation at the Holbrook MDN
site in Greene County Pennsylvania from 2000 through 2006 ............................................ 57
22. Seasonal trends in total mercury wet depositions and precipitation at the Holbrook
MDN site in Greene County Pennsylvania from 2000 through 2006.................................. 58
23. Seasonal trends in total mercury concentrations and precipitation at the Valley Forge
MDN site in Montgomery County Pennsylvania from 2000 through 2006 ........................ 59
24. Seasonal trends in total mercury wet deposition and precipitation at the Valley Forge
MDN site in Montgomery County Pennsylvania from 2000 through 2006 ........................ 60
25. Trends in total mercury and sulfate concentrations at the Hills Creek MDN site
(PA90) from 1997 through 2006.......................................................................................... 62
26. Trends in total mercury and sulfate concentrations at the Allegheny-Portage MDN site
(PA13) from 1997 through 2006.......................................................................................... 63
v
Figure
Page
27. Trends in total mercury and sulfate concentrations at the Holbrook MDN site
(PA37) from 2000 through 2006. Sulfate concentrations were measured at
the nearby Laurel Hill PADM site ...................................................................................... 64
28. Trends in total mercury and sulfate concentrations at the Valley Forge MDN site
(PA60) from 2000 through 2006......................................................................................... 65
vi