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 effect”.

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 pollution threats.

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 analytical techniques.

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.