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| Indiana Water Science Center |
U.S. Geological Survey Scientific Investigations Report 2008–5148
By Martin R. Risch and Kathleen K. Fowler
This report is available below as a 76–page PDF for viewing and printing.
Mercury in precipitation was monitored during 2004–2005 at five locations in Indiana as part of the National Atmospheric Deposition Program–Mercury Deposition Network (NADP–MDN). Monitoring stations were operated at Roush Lake near Huntington, Clifty Falls State Park near Madison, Fort Harrison State Park near Indianapolis, Monroe County Regional Airport near Bloomington, and Indiana Dunes National Lakeshore near Porter. At these monitoring stations, precipitation amounts were measured continuously and weekly samples were collected for analysis of mercury by methods achieving detection limits as low as 0.05 ng/L (nanograms per liter). Wet deposition was computed as the product of mercury concentration and precipitation. The data were analyzed for seasonal patterns, temporal trends, and geographic differences.
In the 2 years, 520 weekly samples were collected at the 5 monitoring stations and 448 of these samples had sufficient precipitation to compute mercury wet deposition. The 2-year mean mercury concentration at the five monitoring stations (normalized to the sample volume) was 10.6 ng/L. As a reference for comparison, the total mercury concentration in 41 percent of the samples analyzed was greater than the statewide Indiana water-quality standard for mercury (12 ng/L, protecting aquatic life) and 99 percent of the concentrations exceeded the most conservative Indiana water-quality criterion (1.3 ng/L, protecting wild mammals and birds). The normalized annual mercury concentration at Clifty Falls in 2004 was the fourth highest in the NADP–MDN in eastern North America that year. In 2005, the mercury concentrations at Clifty Falls and Indiana Dunes were the ninth highest in the NADP–MDN in eastern North America.
At the five monitoring stations during the study period, the mean weekly total mercury deposition was 0.208 µg/m2 (micrograms per square meter) and mean annual total mercury deposition was 10.8 µg/m2. The annual mercury deposition at Clifty Falls in 2004 and 2005 was in the top 25 percent of the NADP–MDN stations in eastern North America.
Mercury concentrations and deposition varied at the five monitoring stations during 2004–2005. Mercury concentrations in wet-deposition samples ranged from 1.2 to 116.6 ng/L and weekly mercury deposition ranged from 0.002 to 1.74 µg/m2. Data from weekly samples exhibited seasonal patterns. During April through September, total mercury concentrations and deposition were higher than the median for all samples. Annual precipitation at four of the five monitoring stations was within 10 percent of normal both years, with the exception of Indiana Dunes, where precipitation was 23 percent below normal in 2005.
Episodes of high mercury deposition, which were the top 10 percent of weekly mercury deposition at the five monitoring stations, contributed 39 percent of all mercury deposition during 2004–2005. Mercury deposition more than 1.04 µg/m2 (5 times the mean weekly deposition) was recorded for 12 samples. These episodes of highest mercury deposition were recorded at all five monitoring stations, but the most (7 of 12) were at Clifty Falls and contributed 34.4 percent of the total deposition at that station during 2004–2005. Weekly samples with high mercury deposition may help to explain the differences in annual mercury deposition among the five monitoring stations in Indiana.
A statistical evaluation of the monitoring data for 2001–2005 indicated several statistically significant temporal trends. A statewide (5-station) decrease (p = 0.007) in mercury deposition and a statewide decrease (p = 0.059) in mercury concentration were shown. Decreases in mercury deposition (p = 0.061 and p = 0.083) were observed at Roush Lake and Bloomington. A statistically significant trend was not observed for precipitation at the five monitoring stations during this 5-year period. A potential explanation for part of the statewide decrease in mercury concentration and mercury deposition was a 28 percent decrease in the total estimated annual mercury emissions in Indiana between 2002 and 2005.
Mercury deposition statistically was correlated most closely to precipitation in the 448 samples, 2004–2005, and this relation was demonstrated by statewide maps of annual precipitation and annual mercury deposition based on precipitation data from 127 National Weather Service Cooperative Observer Program stations. However, one area in southeastern Indiana in the vicinity of Clifty Falls exhibited high mercury deposition that might be related more to mercury concentration than to precipitation. This is because areas with the same range of precipitation as southeastern Indiana were mapped with less mercury deposition.
Other data demonstrate a geographic difference for mercury in precipitation in the vicinity of the Clifty Falls monitoring station. The weekly mercury concentrations at Clifty Falls were statistically higher than concentrations at Roush Lake, Fort Harrison, and Bloomington. Clifty Falls data ranked highest among the five monitoring stations for mercury concentration and mercury deposition, 2004–2005, and in the previous 3 years. Episodes of high mercury deposition were recorded most often at Clifty Falls in 2004–2005 and in the previous 3 years. Statistical trends in mercury concentration or mercury deposition were not observed for the Clifty Falls data. A potential explanation for this geographic difference is that annual mercury emissions from sources in the vicinity of Clifty Falls were higher than those at the other stations. Other factors may help explain the differences in total mercury concentrations, such as the types of mercury emissions, mercury transport from stationary sources outside Indiana, and meteorological conditions. Additional data are needed to assign a localized or regional boundary to the area affected by high deposition of mercury near Clifty Falls.
Abstract
Introduction
Purpose and Scope
Description of the Study Area
Mercury in the Environment
Mercury in Fish and Risks to Humans and Wildlife
Mercury in the Atmosphere
The Mercury Cycle
Sources of Mercury
Mercury Monitoring in Indiana
Study Methods
Selection of Monitoring Locations
Instrumentation of Monitoring Stations
Collection and Analysis of Precipitation Samples
Quality Assurance
Data Management and Reporting
Mercury in Precipitation in Indiana
Weekly Samples
Mercury Concentrations and Mercury Deposition
Geographic and Temporal Variability of Mercury in Precipitation
Geographic Variability
Seasonal Patterns
Trends in Mercury Concentrations and Mercury Deposition
Episodes of High Mercury Deposition
Precipitation Normals and Precipitation Distribution
Factors Affecting Geographic and Temporal Variability of Mercury in Precipitation
Summary and Conclusions
Acknowledgments
References Cited
Appendix 1. Weekly precipitation and total mercury at various monitoring stations in Indiana, January 2004–December 2005
Appendix 2. Wind rose plots
1. Schematic of atmospheric mercury and mercury wet and dry deposition.
2. Graphical depiction of mercury cycling in aquatic ecosystems.
3–10. Maps showing:
3. Locations of stationary sources of mercury emissions to the atmosphere
in Indiana and annual mercury emissions
per county in 2002.
4. Locations of National Atmospheric Deposition Program Mercury
Deposition Network monitoring stations in North America,
late 2005.
5. Monitoring locations for mercury in precipitation in Indiana, 2004–2005.
6. Roush Lake monitoring station for mercury in precipitation in Indiana, with nearby stationary sources of mercury emissions.
7. Clifty Falls monitoring station for mercury in precipitation in Indiana, with nearby stationary sources of mercury emissions.
8. Fort Harrison monitoring station for mercury in precipitation in Indiana, with nearby stationary sources of mercury emissions.
9. Bloomington monitoring station for mercury in precipitation in Indiana, with nearby stationary sources of mercury emissions.
10. Indiana Dunes monitoring station for mercury in precipitation in Indiana, with nearby stationary sources of mercury emissions.
11. Photograph of automated precipitation sampler for mercury in precipitation at
monitoring station IN20 at Roush Lake
near Huntington, Indiana.
12. Diagram of automated precipitation sampler at monitoring station for mercury in precipitation in Indiana.
13. Photograph of recording rain gage at monitoring station for mercury in precipitation in Indiana.
14. Boxplot showing distribution of mercury concentrations in weekly samples at five
monitoring stations for mercury in
precipitation in Indiana, January 2004–December 2005.
15. Boxplot showing distribution of mercury deposition in weekly samples at five
monitoring stations for mercury in precipitation
in Indiana, January 2004–December 2005.
16. Scatterplot showing weekly mercury deposition and weekly precipitation at five monitoring stations for mercury in
precipitation in Indiana, 2004–2005.
17–20. Maps showing:
17. National Atmospheric Deposition Program Mercury Deposition Network
monitoring stations with normalized annual
mercury concentrations in 2004–2005 and ranges of mercury concentrations for eastern North America.
18. National Atmospheric Deposition Program Mercury Deposition Network
monitoring stations with annual mercury
deposition in 2004–2005 and ranges of mercury deposition for eastern North America.
19. Annual wet deposition of mercury in Indiana in 2004.
20. Annual wet deposition of mercury in Indiana in 2005.
21. Boxplots showing monthly distributions of mercury deposition, mercury concentration,
and precipitation at five monitoring
stations for mercury in precipitation in Indiana, January 2004–December 2005.
22. Time-series plots showing weekly mercury concentrations at five monitoring
stations for mercury in precipitation in Indiana,
2001–2005.
23. Time-series plots showing weekly mercury deposition at five monitoring
stations for mercury in precipitation in Indiana,
2001–2005.
24. Isopleth maps of annual precipitation at 127 National Weather Service
Cooperative Observer Program stations in Indiana,
January 2004–December 2005.
25. Isopleth maps of annual mercury deposition in Indiana, 2004 and 2005, showing
annual precipitation and estimated annual
mercury emissions per county.
2–1. Roush Lake wind-rose plots, 2004 and 2005.
2–2. Clifty Falls wind-rose plots, 2004 and 2005.
2–3. Fort Harrison wind-rose plots, 2004 and 2005.
2–4. Bloomington wind-rose plots, 2004 and 2005.
2–5. Indiana Dunes wind-rose plots, 2004 and 2005.
1. Stationary sources and estimated annual mercury emissions to the atmosphere in Indiana in 2002.
2. Characteristics of monitoring stations for mercury in precipitation in Indiana.
3. Number and types of weekly precipitation samples from mercury monitoring at five stations in Indiana,
January 2004–December 2005.
4. Mercury concentrations in wet-deposition samples at five monitoring stations in Indiana, January 2004–December 2005.
5. Mercury deposition at five monitoring stations in Indiana, January 2004–December 2005.
6. Five monitoring stations for mercury in precipitation in Indiana ranked by normalized mercury deposition and normalized
mercury concentration, 2004–2005 and 2001–2005.
7. Seasonal Kendall test of statistically significant trends in weekly mercury deposition and mercury concentration at
monitoring stations for mercury in precipitation in Indiana, 2001–2005.
8. Episodes of highest mercury deposition in Indiana, January 2004–December 2005.
9. Precipitation normals, 1971–2000, with annual precipitation and mercury deposition at five monitoring stations for
mercury in precipitation in Indiana, January 2004–December 2005.
1–1. Weekly precipitation and total mercury at Roush Lake monitoring station near Huntington, Indiana,
January 2004–December 2005.
1–2. Weekly precipitation and total mercury, at Clifty Falls monitoring station near Madison, Indiana,
January 2004–December 2005.
1–3. Weekly precipitation and total mercury at Fort Harrison monitoring station near Indianapolis, Indiana,
January 2004–December 2005.
1–4. Weekly precipitation and total mercury at Bloomington monitoring station near Bloomington, Indiana,
January 2004–December 2005.
1–5. Weekly precipitation and total mercury at Indiana Dunes monitoring station near Porter, Indiana,
January 2004–December 2005.
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Whole report (8.14 MB) – 76 pages (8.5" by 11" paper)
Suggested Citation:
Risch, M.R., and Fowler, K.K, 2008, Mercury in precipitation in Indiana, January 2004–December 2005: U.S. Geological Survey Scientific Investigations Report 2008–5148, 76 p.
For more information about USGS activities in Indiana, visit the USGS Indiana Water Science Center home page.
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