Environmental Pollutants

While there are innumerable chemicals in our atmosphere, ARQP research focuses on the following chemicals due to their toxicity, persistence, potential for long-range transport and environmental significance. The Environment Canada Fact Sheet on Air Toxics offers an introduction to toxic chemicals in the environment.

Pesticides

Pesticides are a diverse group of chemicals manufactured to kill nuisance organisms. They include herbicides, insecticides and fungicides applied to crops, gardens and lawns as well as compounds used to control the spread of tropical diseases. DDT, the infamous pesticide responsible for eggshell thinning in birds, has been banned from manufacture or use in Canada, along with numerous other dangerous pesticides.

The danger of many pesticides, and other persistent organic pollutants (POPs) of concern, is that they are toxic, bioaccumulative and persistent. Bioaccumulation refers to how concentrations of the chemical in animals get larger as we move up the food chain. Persistence is the ability of a chemical to exist unchanged for years. Persistence allows some chemicals to migrate to colder climates through the process of global distillation.

Air Quality Processes Division Pesticide Research: ARQP scientists are involved in monitoring pesticide concentrations in air in the Great Lakes region as part of the Integrated Atmospheric Deposition Network (IADN). Analysis of IADN samples for pesticides takes place at the Organics Analysis Laboratory of ARQP. Further work includes studying how pesticides and other chemicals partition, or become distributed between the air or water and a lipid phase (such as animals' body fat) for which they have an affinity. It is this partitioning process that causes the bioaccumulation of pesticides such as DDT. Other projects involve studying the movement of currently used pesticides between soil and air and developing new methods of measuring pesticide concentrations in air.

ARQP scientists are also monitoring the concentrations of pesticides that reach the Arctic as a result of their use is southern Canada and the United States. This work is part of a study measuring the concentrations of a number of "new" chemicals in arctic air and water. "New" is used here to indicate that these substances have not been studied in the Arctic until now. Some of these new chemicals have already been identified in air and beluga, indicating they are entering the food chain. Our scientists are also monitoring chlorinated pesticides in the Arctic as part of the Northern Contaminants Program (NCP). In this program, concentrations of contaminants have been measured over several years at Canadian and Russian arctic sites. The data are being used to negotiate international controls on these substances and to test mathematical models of contaminant transport.

Mercury

Mercury is a liquid heavy metal that can volatilize into the atmosphere. In Canada, airborne mercury comes primarily from coal-fired power plants in the United States and from Canadian metal smelting operations and incinerators. Mercury also has natural sources such as the weathering of bedrock and gaseous emissions from soils. Mercury is found in the atmosphere as mercury vapour and attached to airborne particles. When this element combines with carbon, its organic form, methyl mercury, is highly toxic and bioaccumulates in the body fat of animals. For more information, please see the "Mercury and the Environment" brochure.

Air Quality Processes Division Mercury Research: Atmospheric mercury has been measured continuously at Alert, Nunavut, Canada since 1995 as part of the Northern Contaminants Program (NCP), and it is currently being measured both as a vapour and on particles. Researchers are also measuring mercury concentrations in snowfall at Alert, and a new mercury monitoring station is being implemented at Amderma, Russia. These data are used to assess whether arctic mercury concentrations are changing over time, and how much of the airborne mercury is deposited onto the land and water. These measurements at Alert are also part of the Canadian Atmospheric Mercury Measurement Network (CAMNet), which operates monitoring sites across Canada. Mercury is also monitored in the Great Lakes region, along with numerous other chemicals as part of the Integrated Atmospheric Deposition Network (IADN). In another project, researchers are measuring the flux, or movement, of mercury from the arctic ice surface during polar sunrise and melt conditions in the springtime. This study involves collecting samples at three arctic sites and using satellite imagery to determine the extent and characteristics of the ice and open water. Other research including mercury is a MITE study of the evolution of aerosols in power plant and smelter plumes.

PAH

Polycyclic aromatic hydrocarbons (PAH), some of which are known animal carcinogens, are produced whenever something is burned. Human sources range from vehicle exhausts to meat cooking to numerous industrial sources.

Air Quality Processes Division PAH Research: PAH research at ARQP takes many forms. Similarly to the pesticides above, these compounds are being monitored in arctic air as part of NCP and IADN. Scientists are also working to identify the organic chemicals found on atmospheric particulate matter collected in Ontario, Canada. PAH and their oxidized products are prevalent in the gaseous phase of air and on particles.

Another study focuses on carefully controlled reactions of PAH in a Teflon- lined smog chamber. The goal of this research is to unravel the complex transformations that take place when PAH react with other compounds in the air. The chamber is also used to measure the percentage of PAH found in the gas phase of air, versus that found on particles. In co- operation with other researchers, an air sampler called the Integrated Organic Gas and Particle Sampler (IOGAPS) has been developed by an ARQP scientist to collect chemicals in these two phases. By measuring gas-phase and particle-phase PAH separately, we can better understand how these chemicals will move and behave in the environment.

PCNs

Polychlorinated naphthalenes (PCNs) were produced industrially and are also generated by combustion. They behave similarly to PCBs in the environment, and some PCNs are toxic. PCNs were manufactured for use as wood preservatives and in electrical insulation fluids, and their combustion sources include municipal waste combustion and metal smelting. Scientists still have many questions about PCNs' environmental concentrations and impacts.

Air Quality Processes Division PCN Research: PCNs are considered "new" chemicals, meaning that they have not previously been studied in the environment. However, the environmental behaviour of PCNs is currently being investigated, particularly their tendency to partition from air or water to lipid phases. PCNs and other new chemicals are also being measured by ARQP scientists in the Arctic as part of NCP. The presence of a new chemical in the Arctic is considered by Canadian and international agencies to be a cautionary sign, signalling the need for evaluation of persistence and toxic effects under arctic conditions.

PCBs

Before their persistent and bioaccumulative nature was known, polychlorinated biphenyls (PCBs) were produced industrially for use in electrical capacitors and transformers, paints, sealants and other applications. Both Canada and the U.S.A. banned the manufacture of PCBs in the 1970s. Current air concentrations in these countries are therefore due to leaking PCB storage or waste disposal sites or long-range transport from other countries. PCBs highlight the danger of manufacturing persistent environmental compounds.

Air Quality Processes Division PCB Research: Similarly to the pesticides and PAH described above, PCBs are monitored as part of IADN and NCP, and the IADN analyses are completed at the Processes Division Organics Analysis Laboratory. Researchers are studying PCB concentrations in the Arctic because of the chemicals' tendencies to travel north from points of use in temperate areas and to accumulate in arctic food chains. ARQP scientists are also developing new methods to sample PCBs from the atmosphere.

Particulate Matter

Airborne particulate matter (PM) is a major component of smog, and consists of microscopic material in the air. This material can be dust, smoke, or the products of atmospheric chemical reactions. While the coarser particles can be respired, the finer particles known as PM_2.5 (less than 2.5 microns, or 2.5 thousandths of a millimetre in diameter) pose a greater risk by penetrating deep into the lungs. Acidic or toxic chemicals associated with the particles can then irritate the lung tissue, reducing respiratory function.

Air Quality Processes Division PM Research: Please also see the Particulate Matter Program including Air Quality Processes Division PM research.

Ozone and Other Oxidants (SMOG)

Ozone, hydrogen peroxide and other photochemical oxidants are components of smog. In cities, emissions from industry and vehicles combine in the presence of sunlight to form a mixture which irritates our respiratory systems and can pose a risk to the elderly and to people with asthma. Transport by wind also allows smog to affect rural areas and to generate transboundary pollution issues.

Air Quality Processes Division Oxidants Research: ARQP oxidant research activities are described under the Acid Deposition and Oxidants Program.

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Meteorological Service of Canada - Environment Canada - Government of Canada

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