Environment and Resource Management

Air as an ecosystem service

What is an ecosystem service?

Ecosystem services are described as the goods and services provided by natural ecosystems that benefit, sustain and support the well-being of people. They include the provision of productive soils and clean air and water, the production of food and medicines, the regulation of climate and disease, and landscape opportunities for recreation and spiritual benefits.

Ecosystem services are derived from the complex interactions between the components and processes that occur within an ecosystem (ecosystem functions). It is the diversity of the components (i.e. biodiversity) and interactive processes within and between all ecosystems that produce the extensive range of essential services required for humans to survive. In short, ecosystem services are the benefits people obtain from ecosystems.

Why is the service 'air quality' important?

The surrounding air is essential to sustain life. Air quality issues primarily influence the atmosphere where people live and breathe. In its natural state it has a stable composition however this can be compromised by the presence of air pollutants resulting from human (anthropogenic) activity such as motor vehicles, commercial, industrial and manufacturing facilities and from natural events such as bushfires and dust storms.

Air pollutants can cause a variety of health problems including breathing problems, lung damage, reduced lung function, asthma, bronchitis, cancer; and other systemic damage. These health impacts are particularly harmful to the very young, the very old, and those with pre-existing health issues. Impacts from air pollutants can also adversely impact natural ecosystems and reduce amenity and aesthetic environmental values through haze, smog and dust. The effects may be local or global.

Emissions to the atmosphere have also played a major role in changing the global climate by significantly altering the composition of the atmosphere, in particular through the rise in concentrations of greenhouse gases. Greenhouse gases are responsible for temperature increases around the world and through the depletion of the protective ozone layer that surrounds the earth.

How is the ecosystem service 'air quality' derived?

The functions that contribute to the air quality ecosystem service are gas, climate, waste treatment and assimilation and the effects of vegetation regulations. Relative to the other functions gas regulation was identified as most important to the provision of this service. Variations in the composition of air (gas) result from both natural events and anthropogenic activities.

The self-regulation of pollutants in the atmosphere occurs through natural processes such as mixing, dilution and dispersion, the 'scavenging' effect of rainfall and chemical reactions. In some cases this results in a reduction of pollutant concentration to acceptable levels (in the case of dilution and dispersion) or the transformation to another form (acid rain).

Chemical reactions occurring in the lower atmosphere (troposphere) can result in secondary pollution, such as the reaction between volatile organic compounds (VOCs), nitrogen oxides (NOX) and oxygen (O2) which, in the presence of sunlight produces photochemical oxidants (also known as photochemical smog) of which ozone (O3) is the principal component.

Emissions of other substances have been implicated in global issues such as the depletion of the upper atmosphere (stratospheric) ozone layer, particularly by the man-made chlorofluorocarbons, and in the changing of the atmospheric composition resulting in an enhanced greenhouse effect. This is caused by the increasing levels of carbon dioxide (CO2) from combustion processes and methane (CH4) from agriculture.

While emission to the atmosphere can have global implications in the case of ozone depletion and global warming or climate change, local conditions such as topography, microclimate weather patterns and land use (forestry) can have both positive and negative effects on the dispersion and absorption of pollutants.

Air pollutants may be transported by air movement over short or long distances. Vegetation not only impedes the movement of airborne substances such as dust and aerosols (including agricultural chemicals and industrial and transport emissions), enhances air mixing and mitigates noise; but during transport air pollutants may undergo changes in both composition and concentration. Dilution and dispersion may reduce pollutants to acceptable levels, or may bring them into an environment where concentrations rise and adverse chemical reactions occur.

Vegetation is known to have a mitigating effect of air pollutants by absorption, deposition or reaction. While lowering the pollutant levels in the atmosphere, where concentrations are sufficiently high, it may have a detrimental effect on plant life. As air is ubiquitous and essential, any reduction in air quality will have an impact on surrounding ecosystems. Local high concentrations or long-term exposure to lower concentrations will have an adverse effect on fauna and flora.

Are human inputs required to facilitate this ecosystem service?

Local mitigation strategies can be supported by reductions of pollutants' emissions, achievable through community choices in personal transportation and consumer purchasing, regulation or licensing, improved city planning and urban design and the use of infrastructure to remove pollutants prior to emission through filtration, absorption or other techniques.

Large area emissions can be reduced by changes to practices such as green cane harvesting rather than burning and through coordination of agricultural burning such as hazard reduction burns to times when impacts can be minimised.

Are there any barriers to individuals receiving this ecosystem service?

While access to air is universal, there may be areas where the quality is consistently lower due to proximity to industrial processes or heavy motor vehicle activity. For some demographic or socio-economic reasons a portion of the population may be at greater risk from exposure to lower air quality.

How is it known if the ecosystem service is degrading, maintaining or improving?

The established method of assessment of air quality in South East Queensland is through long-term monitoring of the pollutants of concern in carefully selected areas and comparing the results with objectives set out in the Environmental Protection (Air) Policy (2008).

These objectives are derived from national and international standards:

Maintaining a network of monitoring stations identifies trends over time, such as changes that may be due to demographic, climatic, cultural or land-use changes. Results from monitoring can be used to develop strategies to reduce the impacts of air pollutants and measure how effective implementation of such strategies has been.

Last updated 4 October 2011

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