PROTECTING THE ENVIRONMENT
Assessing ‘Climate Change’
Isotopic measurements can help to
assess the scope of global warming, believed to be caused by the rapid
rise in the atmospheric concentration of carbon dioxide (CO2)
resulting from the burning of coal and other fossil fuels. CO2 traps heat in the atmosphere and causes the so-called “greenhouse
Promoting Energy Alternatives
Geothermal energy uses steam from deep inside the Earth
to drive turbines that produce electricity. The Rio Summit endorsed
it as one of the cleanest ways to generate power. Only pure water vapour
and small amounts of hydrogen sulphide and CO2 are emitted
into the atmosphere.
Geothermal power requires sophisticated science and
technology to monitor the complex processes at work. Isotope
techniques provide an understanding of the water and heat flows
within the reservoir so that a geothermal plant can operate profitably.
Reducing Air Pollution
Atmospheric pollution comes from many sources, including
industrial emissions, car and truck exhausts and coal and wood combustion.
Of special concern to human health are small airborne particles (less
than 10 micrometers) that can penetrate the lungs, causing respiratory
or heart disease and even death. Each pollution source produces a “finger-print”
mixture of airborne particles. A global network has been set up in major
cities to collect air samples and, using nuclear-based techniques,
measure the concentrations of these pollutants. The work aims to build
a composite picture of particulate sources and enable health and environmental
authorities to devise mitigation strategies.
CUTTING TOXIC EMISSIONS
Radiation technology can turn noxious
gases into productive assets. Emissions containing high concentrations
of sulphur dioxide and nitrogen oxides, are the main causes of acid
rain, which damages forests, lakes and farm land. The IAEA supplied
technical expertise for the design, installation and operation of an
electron beam irradiation facility to cleanse plant-flue gases. The
gases are now blended with a small amount of ammonia and then subjected
to electron beam irradiation, which converts them into a solid material
that can be used as a high-grade fertiliser.
Managing Fresh Water Resources
Global demand for fresh water is doubling every 20
years. Meanwhile, renewable water resources available per person are
roughly half of what they were in 1960, a figure that is expected to
drop by half again by the year 2025. Growing scarcity is compounded
by pollution wherever fresh water is used for agricultural, industrial
and domestic purposes.
The IAEA has promoted isotope techniques in hydrology for more than three decades, and is recognised as one of
the leading institutions in this field.
PROMOTING RATIONAL WATER USE
In many regions, most water for human needs is found
in underground aquifers. If water withdrawal from an aquifer exceeds
replenishment, the water may become saline or completely disappear.
Significant amounts of the radioisotope Tritium (3H) were released into the atmosphere during nuclear weapons tests between
1952 and 1963. Hydrologists can calculate the groundwater recharge rate
by measuring tritium levels in the soil at various depths.
Isotopic tracers can also be used to pinpoint water
leaks in dams and reservoirs, thus not only preventing losses, but contributing
to safety. The radioisotope Gold-198 can be introduced into a reservoir,
where it will be drawn toward the leak and absorbed into solid materials
at the site. By tracking the radiation emitted, an isotope hydrologist
can provide the precise coordinates of the leak site to engineers.
Controlling Water Pollution
Surface and groundwater resources are being polluted
by sewage, farm runoff and industrial effluents in many countries. Groundwater
is especially vulnerable and it can take hundreds of years for a deep
acquifer to clear itself of toxic pollutants. Isotopes can trace the origins of groundwater pollution and prevent contamination.
In large aquifer systems, pollution infiltrating at a given point may
emerge in a spring or well up to 100 kilometres away. Intricate systems
must be mapped, and the vulnerability of groundwater to pollution from
surface sources evaluated. Hydrologists use “tracers” to
calculate the “time of travel” of groundwater to assess
CLEANING UP WASTES
Radiation technology is turning some dangerous sold
and liquid wastes into harmless or even useful materials.
With technical advice from the IAEA, sludge will be
irradiated by Cobalt-60 gamma rays to destroy pathogenic
bacteria, and will then be used as fertiliser.
INVESTIGATING HEAVY METALS
The scale of heavy metal pollution is enormous: the
total toxicity of all metals mobilised by human activities each year
exceeds the total of all radioactive and organise wastes combined. The
IAEA is co-ordinating international research efforts on many problems
related to heavy metals – including arsenic, cadmium, copper,
lead and mercury – all of which are easy to detect using nuclear-based
A mercury-pollution survey is being carried out in
Brazil’s Amazon River Basin, where poor people use the toxic substance
to extract small quantities of gold left in mine tailings. People make
no effort to reclaim the mercury but, instead, evaporate it into the
air or dump it in rivers. Anyone consuming fish or using the water for
domestic or agricultural needs is at risk. The IAEA is helping to measure
mercury in human hair, fish and river sediments using sensitive neutron
activation analysis, giving policy makers the information they
need to address this complex problem.