Air Quality Processes Research Division (ARQP)

CANADIAN ATMOSPHERIC MERCURY MEASUREMENT NETWORK (CAMNet)

In 1996, Environment Canada initiated the Canadian Atmospheric Mercury Measurement Network (CAMNet) to provide a better understanding of mercury trends and processes in the environment. Numerous scientific and policy questions regarding mercury as an environmental issue remain to be addressed. Further information on the occurrence, pathways, behaviour and fate of mercury emitted into the atmosphere from both natural and anthropogenic sources is needed. This network works to answer some of these questions. Currently, there are 11 sites participating in this collaborative research effort with locations ranging from approximately 43^o to 82^o N. latitude and 62^o to 123^o W. longitude.

Map of CAMNet sampling sites.

The objectives of CAMNet are:

• 1. to improve the current understanding of the atmospheric transport, transformation and removal processes of elemental mercury and its ecologically significant compounds released into the environment;
• 2. to establish spatial variability and temporal trends in Hg concentrations in the atmosphere and precipitation on a regional/national basis;
• 3. to identify major point and/or regional sources of atmospheric mercury emissions;
• 4. to define representative background ambient air concentrations in various parts of the country;
• 5. to investigate trans-boundary atmospheric transport of this pollutant and to establish how Canadian values compare with those measured elsewhere;
• 6. to provide input to and scientific data for validating numerical models describing the atmospheric pathways and characteristics of mercury species emitted into the environment;
• 7. to provide scientific data for future health-based studies and risk assessments involving atmospheric aspects of mercury in the Canadian environment.

Measuring Atmospheric Mercury:

Ambient mercury vapour concentrations are monitored on a continuous basis using cold vapour atomic fluorescence spectrometric (CVAFS) analysers. Currently, CAMNet uses the Canadian-made Tekran Model 2537A Ambient Mercury Vapour Analyser to monitor total gaseous mercury (TGM) concentrations at each network site. A Standard Operating Procedures Manual has been compiled for TGM measurements and is available upon request. This manual contains guidelines for site selection/establishment and operational protocols. The TGM concentrations are based on one-hour sample integration periods. Precipitation mercury measurements are taken at some of the sites and adhere to the U.S. NADP-Mercury Deposition Network (MDN) sampling protocol where the same contract laboratory performs total mercury and methyl mercury analyses.

QA/QC Procedures:

Both site audit guidelines and data management guidelines have been established for CAMNet. Annual national audits are being undertaken as a way of ensuring the quality, comparability and representativeness of the data collected throughout the network. A data management protocol is also being developed using the Research Data Management and Quality Control System (RDMQ). This system provides a computer-based platform to document, store, format, manipulate, access and quality control the TGM data from the various sites. Precipitation data will be handled in ways similar to NADP-MDN procedures.

CAMNet publications

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