Atmospheric and Climate Science Directorate

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Monitoring Acid Rain Control Strategies

The National Atmospheric Chemistry Database and Analysis Facility NAtCHEM

In the 1970s and 1980s lakes and rivers in eastern Canada and the U.S. were becoming more and more acidic. Sensitive fish species and other aquatic plants and animals were disappearing and forests were starting to die back. Acid rain was the cause and sulphuric acid from sulphur dioxide (emitted into the air from coal fired power plants and metal smelters) was the main culprit. Extensive networks were set up by different agencies and have been operating over 2 decades in both Canada and the U.S. to monitor acid forming chemicals in both air and precipitation. The data from all these networks have been pulled together to map the extent of the acid rain problem, and to determine the effectiveness of pollution control strategies in reducing the impact of acid rain on ecosystems.

However, merging datasets from many networks using different measurement techniques, sampling frequencies and calibration standards is extremely difficult and presents a serious obstacle to the international management of air quality issues. Turning these disparate data into useful information required a mechanism to improve data exchange standards, data analysis procedures and visualization tools.

To address these problems, scientists at the Meteorological Service of Canada MSC created the National Atmospheric Chemistry Database and Analysis Facility NAtCHEM. NAtChem archives and analyses precipitation chemistry, particulate matter and toxic chemical data from major North American monitoring networks. The results have been so successful that the United States and other countries are turning to NAtChem for analysis of air chemistry data.

Forest dieback as a result of acid rain.

The NAtChem program includes a new Data Exchange Standard (DES) and a new Research Data Management and Quality Control Software System (RDQM^tm). The scientific community recognizes DES as a major breakthrough in preserving the value of atmospheric data for long-term use, and the RDQM^tm as a powerful system for quality controlling and managing environmental datasets.

NAtChem, with its supporting analytical tools of DES and RDQM^tm, has enabled Canada to retain a leading-edge understanding of acid rain and other air quality issues. It has shown that despite reductions in SO₂ emissions over the past decade, over 500,000 square kilometres of eastern Canada still exceeds the critical load for sulphate – meaning that lakes and forests are still at risk of further damage. Additional emission reductions are needed to protect these sensitive ecosystems from acid rain.

By pulling data together from diverse air quality monitoring networks, the NAtChem program is able to examine the link between pollution control strategies and their impact on health and ecosystems.

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These two maps generated by NAtChem show how the extent of acidic rainfall has decreased over eastern North America as a result of the implementation of sulphur dioxide control strategies in Canada and the United States between 1980 and 1998.

“RDQM^tm is an enormous time saver and invaluable foro quality controlling global precipitation chemistry data sets.Without it we would be lost.” Volker Mohnen Head, Qualiy Assurance Science Activity Center of the Americas

“NAtChem is invaluable in understanding the chemical climatology of North America.”
Richard Artz Deputy Director
Air Resources Laboratory
National Oceanic and Atmospheric Administration USA

The Green Lane^TM,
Environment Canada's World Wide Web Site.