NADP: Keeping You Connected, Issue 6

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 NADP: Keeping You Connected March 2016 | Issue 6 

NADP: Keeping You Connected is a quarterly e-newsletter designed to keep you informed about our changing chemical climate and other updates from the National Atmospheric Deposition Program. To offer feedback or submit a suggestion, please email If you were forwarded this notification and would like to receive future newsletters, click here to subscribe.

In this issue:

Calcium Concentration and Deposition Maps

Calcium (Ca2+) is one of the four “mineral dust” cations measured by NADP’s National Trends Network (NTN). Globally, the main source of these cations is soil, where calcium is found as calcium oxide (CaO) and calcium carbonate (CaCO3). Emission processes include windblown (aeolian) erosion, farming and tillage, and traffic on unpaved roads. These sources generally explain the calcium concentration pattern that we observe in NTN data. Calcium is an important nutrient source for vegetation. It also plays an important role in neutralizing acid rain.

   Figure 1: Click to enlarge

Figure 1 shows the Ca2+ concentration in precipitation for 20141, which is highest in the plains of the U.S., where farming, unpaved roads, and windy conditions are prevalent. This is particularly true in the more western states, including areas in and around Utah, where drier conditions lead to higher calcium emissions and therefore higher concentrations in precipitation. During certain years, such as in 2012 when extreme drought dominated much of the West, high concentrations of Ca2+ were also observed in the mountain states (Arizona to Montana). Some urban sites in the East, such as Buffalo, Rochester, and New York City, also experience high Ca2+ concentrations in precipitation. A likely reason may be the heavy amount of salt (sodium and calcium chloride, among others) spread during the big snowstorm in the Northeast in November 2014. However, there are other cities with higher concentrations (Birmingham, Alabama and Orlando, Florida for example) where salting of roads does not explain these high concentrations.

   Figure 2: Click to enlarge

Figure 2 shows the wet deposition of calcium in kilograms per hectare during 2014. The pattern shown in 2014 reflects the pattern of high concentrations in Figure 1, with heavy deposition of Ca2+ in the plains region. However, deposition extends farther into the eastern U.S. compared to the concentration map. Air moving out of the Plains carries the Ca2+ calcium loading farther into the east via west or southwest winds and the Ca2+ is deposited through wet deposition. There are also high deposition rates across the Rocky Mountains where heavy wintertime snow occurs.

A relatively recent paper by Brahney et al. shows an increasing trend in Ca2+ wet deposition using NADP wet deposition measurements. This trend is most pronounced across the western U.S., particularly in the Rockies and in the Plains. The authors point specifically to climate conditions, including drought, as explaining this trend.


Brahney, J., A. P. Ballantyne, C. Sievers, and J. C. Neff. Increasing Ca2+ deposition in the western US: the role of mineral aerosols. Aeolian Research10 (2013): 77-87.

1 NADP concentration maps are shown as PWM concentrations, meaning the concentration of high volume precipitation events are weighted more heavily in the average, and low precipitation volume events are only lightly weighted. The PWM result is an average concertation representing a more typical concentration across all precipitation events.

Long-Term Monitoring is Key to Informing EPA’s Progress in Reducing Emissions

Clara Funk, Biologist, U.S. EPA & David Schmeltz, Senior Analyst, U.S. EPA

For more than three decades, the nation has made great strides in improving air quality and atmospheric deposition, resulting in important improvements to human health and ecosystems. Behind this progress are the long-term collection of observations from the National Atmospheric Deposition Program (NADP) and other complementary long-term monitoring programs upon which scientists and policy analysts continue to rely. The NADP, the Clean Air Status and Trends Network (CASTNET), and the Long-Term Monitoring (LTM) program, along with the continuous emissions monitoring systems (CEMS) are central to the Environmental Protection Agency (EPA)’s emission reduction programs. Consistent, long-term monitoring, along with robust scientific research, provide high quality data that are important for showing how agency programs reduce emissions of sulfur dioxide (SO2), nitrogen oxides (NOx) and other pollutants, and address the ecological and human health problems they drive (e.g., acidification, nutrient over-enrichment, ozone, fine particulate matter, and other concerns).

EPA’s Progress Reports have been an important tool for communicating information from long-term environmental and emissions monitoring programs. Combined with agency programmatic data, EPA evaluates the progress of emission reduction programs and shows the combined effects of agency programs on power sector emissions of SO2, NOx, ozone and fine particles (PM2.5). Recent highlights are described below.

   Figure 3. Click to enlarge

Substantial emission reductions and air quality improvements have been realized since the first nationwide program, the Acid Rain Program (ARP), began in 1995. With the addition of the NOx Budget Trading Program (2003-2008), the Clean Air Interstate Rule (CAIR, 2009-2015), and the Cross State Air Pollution Rule (CSAPR), which began in January 2015, emissions of SO2 and NOx from covered power plants and industrial units have continued to decrease (Figure 3). In 2015, sources covered under these programs reduced annual SO2 emissions by 13.5 million tons (86%) from 1990 levels (before implementation of the ARP) and 8.0 million tons (78%) from 2005 levels (before implementation of CAIR). Similarly, in 2015, sources involved in NOx annual trading programs reduced NOx emissions by 5.0 million tons (78%) from 1990 levels and 2.3 million tons (62%) from 2005 levels. Recent regulatory actions under the proposed CSAPR Update Rule are set to further reduce emissions from the power sector.

   Figure 4:Three-year wet sulfate deposition showing 1989-1991 (left) compared to 2011-2013 (right). Click to enlarge

Regional data from CASTNET through 2013 show declines of 83% in annual mean ambient concentrations of sulfur dioxide, from 8.6 ppb to 1.5 ppb. Similarly, annual mean ambient concentrations of particulate sulfate declined 62%, from 5 ppb to 2 ppb. Over that same period, data from CASTNET and NADP/NTN show a 68% decline in mean total sulfur deposition (wet + dry) nationwide, or 12.8 kg/ha to 4.1 kg/ha (Figure 4). For nitrogen, annual mean ambient concentrations of nitrate declined 46 % from 3 ppb to 1.6ppb (Figure 5). Similarly, over the same period, total inorganic nitrogen deposition (wet + dry) declined nationwide 28 % or 7.6 kg/ha to 5.4 kg/ha.

   Figure 5: Three-year wet inorganic nitrogen deposition showing 1989-1991 (left) compared to 2011-2013 (right)

Significant reductions in emissions and improvements in sulfur and nitrogen deposition have translated into trends towards ecological recovery at some of the country’s most acid impacted systems. Between 1990 and 2013, acid sensitive lakes in the LTM program have experienced significant declines in sulfate concentrations at all 76 monitored sites. However, in the Central Appalachian Mountains, many sensitive streams have yet to experience improving conditions despite decreases in emissions and deposition. In that region, only 21% of the monitored streams have declining sulfate concentrations, while 20% have increasing sulfate concentrations. This increase in sulfate concentrations is attributed to the 30+ year legacy of acid deposition having depleted the buffering capacity in soils and streams.

   Figure 6: Click to enlarge.

Modeling the critical load of sulfates and nitrates to monitored surface waters shows a regional picture of the effects of decreased deposition on ecological recovery and provides a quantitative estimate of whether acid deposition levels resulting from reduction in SO2 and NOx emissions are sufficient to protect aquatic biological resources. NADP’s critical loads science committee (CLAD) has been instrumental in advancing the science and use of critical loads for understanding the effects of atmospheric deposition on ecosystems in the U.S. If acidic deposition is less than the calculated critical load, harmful ecological effects (e.g., reduced reproductive success, stunted growth, loss of biological diversity) are not anticipated, and ecosystems damaged by past exposure are expected to eventually recover. For the period 2011–2013, 20% of all studied lakes and streams show they still receive levels of combined total sulfur and nitrogen deposition in excess of their calculated critical load (Figure 6, red). Although, this is a 42% improvement from 2000-2003 when 34% of all studied lakes and streams exceeded their calculated critical load (red + green).

Despite substantial reductions in the emissions of SO2 and NOx from the power sector and observed environmental improvements, significant challenges persist in the control of nitrogen pollution. In addition to electric power generation, transportation, agriculture, and industrial sources have released unprecedented quantities of nitrogen and related compounds to the environment. Most nitrogen compounds (other than N2 gas) are found in two forms - reduced nitrogen, typically dominated by ammonia species (e.g., NH3 and NH4+), and oxidized nitrogen, composed primarily of nitrogen oxides (NOx). Of these two types of nitrogen compounds, oxidized nitrogen sources are subject to a variety of regulations that limit emissions. In contrast, sources of reduced nitrogen remain largely unregulated. Until NADP launched the Ammonia Monitoring Network in 2010, the extent of the ammonia problem nationwide remained largely unknown. In the future, the ability of long-term monitoring programs to adapt and accommodate new and emerging environmental problems like ammonia will be important to their viability and continued success.

Recent Article Highlights Jacob Lipman’s 1930 Estimate of Atmospheric Sulfur Deposition

David Gay, NADP Program Coordinator

   Figure 7. Click to enlarge

A very interesting article with historically significant connections to NADP was released in March 2015. The article "Ahead of His Time: Jacob Lipman's 1930 Estimate of Atmospheric Sulfur Deposition for the Conterminous United States” by Dr. Edward Landa and Dr. Jamie Shanley of the USGS (active currently in NADP) discusses the early work of Dr. Jacob Lipman and associates in the 1920s and 1930s. Dr. Lipman was a soil scientist and a leader of the New Jersey State Agricultural Experiment Station (SAES)2 and founding editor of the journal Soil Sciences. Dr. Lipman understood that sulfate deposition was an important contributor to sulfur in soils and an influence on agricultural plants that require sulfur for development.

Dr. Lipman estimated the amount of sulfur being deposited (wet and dry) to the soils of the United States, which is what NADP’s NTN and the Clean Air Status and Trends Network (CASTNET, dry deposition) do now on a weekly basis. However, Dr. Lipman realized the importance of sulfur deposition over 40 years before current scientists understood that increasing combustion of coal was increasing sulfuric emissions and causing the acidic precipitation problem. Dr. Lipman put together an early and extensive nutrients balance for U.S. soils, which included sulfur, and accounted for an abundance of both sulfur inputs and losses. He made the first national-scale deposition estimate for sulfur in 1930. To make this estimate, he developed a coal combustion inventory by state, accounted for the sulfur content, and estimated sulfur emissions to the atmosphere. This resulted in an average sulfate deposition estimate for the U.S. of 8.9k/hectare for the year. Landa & Shanley compared Dr. Lipman’s estimates to a 2010 estimate of 1930’s sulfate deposition (Figure 8) and concluded that Dr. Lipman’s estimate was in relatively good agreement to the 2010 work. Landa & Shanley also concluded that the estimates were fairly similar to the earliest NADP measurements and maps from 1979-1985 (Figure 9), where the average sulfate measured would be approximately 8.7 kg/hectare per year for wet deposition.

   Figure 8. Click to enlarge
   Figure 9. Click to enlarge

This early work of a pioneering scientist from the SAES agricultural community is an excellent example of good scientific thinking by our forefathers that links directly to what the NADP does week in and week out. Therefore, the NADP carries on the work of the SAES of the 1970s and the work of the SAES of the 1930s.


Landa, Edward R., and James B. Shanley. Ahead of His Time: Jacob Lipman's 1930 Estimate of Atmospheric Sulfur Deposition for the Conterminous United States. Soil Science 180, no. 3 (2015): 87-89.

2SAES is the founding organization of the National Atmospheric Deposition Program, and currently contributes to 50 sites in the NADP/NTN.

Oregon Operator Retiring After Measuring NADP Data for 35 Years

Molly Woloszyn, NADP Outreach Coordinator
   Figure 10. Click to enlarge

Not many NADP operators can say they have been there from the beginning, but John Moreau of OR10 is one operator who can. Back in May 1980, he installed the equipment for the National Trends Network (NTN) site and worked as the OR10 operator until October 2015 when he retired after a 42-year career with Oregon State University. With 35 years, John currently has the 2nd most years of operation with NADP3.

OR10 is a mountainous site surrounded by 450 to 500 year old Douglas fir trees in the H.J. Andrews Experimental Forest, which is about 45 miles east of Eugene, Oregon. The station has collected samples for the NTN since May 13, 1980. It was also a part of the Mercury Deposition Network (MDN) from December 2002-January 2011.

   Figure 11. Click to enlarge

When asked his favorite part of being an operator, John said he has always enjoyed receiving the NADP annual summaries, which are proof that the data is being used to produce useful deposition maps for the U.S. He also mentioned a memorable moment for him was when NADP used to bring site operators to Champaign, Illinois to see the NADP facilities.

During John’s long career at Oregon State University, he not only served as the OR10 operator, but also built, maintained, and collected data from weather stations at the H.J. Andrews Experimental Forest. He also worked with Dr. Chris Daly from the PRISM Climate Group, helped graduate students with projects, and assisted professors with fieldwork.

John has been busy since retiring last October. He is still working part-time at Oregon State and has been training his replacement, Greg Cohn, who started on January 1st. In retirement, he hopes to spend more time fishing and outdoors, as well as tackle a home remodeling project.

Congratulations John and thank you for your 35 years of operation with NADP!

3 1st place goes to Bob Vande Kopple who is still MI09’s operator after 36 years.

NADP’s 2016 Meeting Information

Spring 2016 Meeting

Madison skyline

The NADP Spring Meeting will take place in Madison, Wisconsin at The Madison Concourse Hotel from Monday, April 25th through Thursday, April 28th. The Madison Concourse Hotel is located right in the heart of Madison, near the State Capitol and University of Wisconsin campus. The committee meetings will take place the first three days and the meeting will end on the 28th with the Executive Committee meeting.

The deadline for the hotel group rate is Sunday, March 27th. Please call the hotel (1-800-356-8293) directly and reference the NADP 2016 spring meeting to receive the group rate.

Meeting flyer:

Fall 2016 Meeting: Save the Date!

Western Scene

Save the date for NADP’s Annual Meeting and Scientific Symposium, which will take place in Sante Fe, New Mexico from Monday, October 31st through Friday, November 4th. The meeting will be held at LaFonda on the Plaza, which is situated in the heart of Sante Fe and provides guests with an authentic New Mexican experience.

The theme of the 2016 annual meeting is “Deposition – What Does the Future Hold?: Exploring the impacts of future scenarios of climate, land use, and environmental policies on atmospheric deposition.”.

This meeting is intended for scientists, policy-makers, resource managers and students interested in air quality, atmospheric deposition and its effects on natural resources and ecosystems. The fall meeting holds NADP subcommittee meetings as well as a scientific symposium, which includes a poster session and reception.

The call for abstracts will be in late spring and registration will be open this summer. Meeting information, including deadlines and registration fees, hotel reservation information and agendas, will be posted on the NADP website as it becomes available.

Meeting flyer:

Recent Publications

New Book Release

The NADP highlights a new book released titled Air Pollutant Deposition and Its Effects on Natural Resources in New York State. The author, Timothy J. Sullivan, is a member of the NADP and its Critical Loads Science Committee.

Ecosystem effects from air pollution in the Adirondacks, Catskills, Long Island Sound, and elsewhere in New York have been substantial. Resource managers, policymakers, and scientists now need to know the extent to which current and projected future emissions reductions will lead to ecosystem recovery. In this book, Sullivan provides a comprehensive synthesis of past, current, and potential future conditions regarding atmospheric sulfur, nitrogen oxides, ammonium, and mercury deposition, surface water chemistry, soil chemistry, forests, and aquatic biota in New York, providing much needed information to help set emissions reduction goals, evaluate incremental improvements, conduct cost-benefit analyses, and prioritize research needs. Sullivan draws upon a wealth of research conducted over the past 30 years, which has categorized, quantified, and advanced understanding of ecosystem processes related to atmospheric deposition of strong acids, nutrients, and mercury, and associated ecosystem effects. An important component of this volume is the new interest in the management and mitigation of ecosystem damage from air pollution stress, which builds on the “critical loads” approach pioneered in Europe and now gaining interest in the United States. This book will inform scientists, resource managers, and policy analysts regarding the state of scientific knowledge on these complex topics and their policy relevance, and will help to guide public policy assessment work in New York, the Northeast, and nationally.

For more information about the author, please visit:

The book is available from Cornell University Press at a discounted price of $26.21 with Promo Code: CAU6.

Journal Publications

A listing of recent journal publications that have used NADP data (the networks used are listed in bold next to the DOI). A publically available online database that lists citations using NADP data is accessible at:

Briggs, John M., John M. Blair, and Eva A. Horne, 2016. Ecohydrological and Climate Change studies at the Konza Prairie Biological Station. Transactions of the Kansas Academy of Science, 119 (1): 5-11.
doi:10.1660/062.119.0103 NTN

Chen, Jiubin, Holger Hintelmann, Wang Zheng, Xinbin Feng, Hongming Cai, Zhuhong Wang, Shengliu Yuan, and Zhongwei Wang, 2016. Isotopic evidence for distinct sources of mercury in lake waters and sediments. Chemical Geology, Vol. 426: 33-44.
doi:10.1016/j.chemgeo.2016.01.030 MDN, AIRMoN

Huang, Suo, Paul Bartlett, and M. Altaf Arain, 2016. Assessing nitrogen controls on carbon, water and energy exchanges in major plant functional types across North America using a carbon and nitrogen coupled ecosystem model. Ecological Modelling, Vol. 323: 12-27.
doi:10.1016/j.ecolmodel.2015.11.020 NTN, AIRMoN

Hundebøl, Nils Randlev and Kristian H. Nielsen, 2015. Preparing for change: acid rain, climate change, and the Electric Power Research Institute (EPRI), 1972–1990s. History and Technology, Vol. 31 (2): 133-159.
doi:10.1080/07341512.2015.1121577 NTN, AIRMoN

Pellerin, Brian A., Beth A. Stauffer, Dwane A. Young, Daniel J. Sullivan, Suzanne B. Bricker, Mark R. Walbridge, Gerard A. Clyde, and Denice M. Shaw, 2016. Emerging Tools for Continuous Nutrient Monitoring Networks: Sensors Advancing Science and Water Resources Protection. Journal of the American Water Resources Association, 1-16.
doi:10.1111/1752-1688.12386 All Networks

Schwab, James J., Douglas Wolfe, Paul Casson, Richard Brandt, Kenneth L. Demerjian, Liquat Husain, Vincent A. Dutkiewicz, Kevin L. Civerolo, and Oliver V. Rattigan, 2016. Atmospheric Science Research at Whiteface Mountain, NY: Site Description and History. Aerosol and Air Quality Research, Vol. 16 (3): 827-840.
doi:10.4209/aaqr.2015.05.0343 NTN

Tulloss, Elise M., and Mary L. Cadenasso, 2016. Using realistic nitrogen deposition levels to test the impact of deposition relative to other interacting factors on the germination and establishment of grasses in the California oak savanna. Plant Ecology, Vol. 217 (1): 43-55.
doi:10.1007/s11258-015-0558-5 NTN, AIRMoN

Weiss-Penzias, Peter S., David A. Gay, Mark E. Brigham, Matthew T. Parsons, Mae S. Gustin, and Arnout ter Schure, 2016. Trends in mercury wet deposition and mercury air concentrations across the US and Canada. Science of The Total Environment.
doi:10.1016/j.scitotenv.2016.01.061 MDN, AMNet