Agrowing shortage of water resources will also spell increased conflicts,” UN Secretary- General Ban Ki-moon most recently warned the world community in his address to the UN General Assembly on 24th January. The world moderator (as envisioned by Franklin D. Roosevelt) from South Korea quoted the new International Alert Report, which identifies a potential threat to 2.7 billion people in 46 nations.
Another 56 nations with 1.2 billion inhabitants run a high risk of being destabilised by water crisis, climate change and demographic explosion. Countries and regions as diverse as China, the United States, Spain, India, Pakistan, North Africa and the Middle East will be affected. Such warnings are nothing new. But how consistent and effective are the lessons drawn? Many experts say it is unlikely that the UN Millenium Development Goals, which are primarily related to water, will ever be fulfilled.
It remains to be seen to what extent the International Year of Sanitation 2008 is able to contribute. At the World Economic Forum in Davos in early February, Ban Ki-moon himself subtly criticised the world economies for lacking the necessary determination to help solve the water crisis; he deplored the fact that merely twenty enterprises had so far joined the CEO Water Mandate launched in July 2007.
A discipline drawing less public attention but perhaps more likely to accomplish positive results for water is basic water research. In this context, information on underground water resources is gaining increasing importance. Only by learning more about the direction of groundwater flow, about the interactions of the latter with other aquifers and superficial waters and about the age and the quality of regional groundwater and its replenishment will engineers and decision-makers be able to use the precious resource more sensibly and hopefully in a less conflict-ridden manner.
Conventional methods of gathering this kind of information, such as by measuring precipitation or groundwater tables, will take many years and render only point-source information. Natural and artificial tracers (such as nitrate) are in turn not applicable for long-term monitoring. ÖWAV organised a special seminar on this issue in autumn 2007.
A much more effective and less costly approach consists in collecting information by fingerprinting water through the isotopes contained therein. Isotopes are atoms of the same chemical element that differ in the number of neutrons. The isotopes of hydrogen (such as tritium) and oxygen are probably the best tracers to depict the transport and mixture of water, because they are constituents of a water molecule. Together with the isotopes of noble gases (such as 3He), they are regarded as “ideal tracers”.
Experts use this term to describe trace elements which, apart from the process to be examined, are not subject to any further uncontrollable processes. Added to these are isotopes of anthropogenic origin (such as radiocarbon, CFCs, 85Kr) which are perfectly suited as tracers for “young” groundwater. The time difference between infiltration and sampling can in any case be assessed by measuring the radioactive decay half-time. The same principle applies to age dating of groundwater by means of 14C.
The measurement of natural isotope distribution of hydrogen and oxygen in water also allows to distinguish the processes of groundwater formation according to region and sea level. This is done by using tiny but systematic variations in isotope distribution, as they occur in the rainfalls of different regions. These in turn are based on deviations in evaporation and condensation of water molecules with a different molecular weight. Molecules consisting of 2H, 17O and 18O, for instance, are heavier and more resistant to evaporation than those comprising the isotopes 1H and 16O.
Condensation in clouds and precipitation, however, favours heavier molecules. It is due to these temperature-dependent processes that rainwater contains lighter isotopes than seawater. Depletion is dependent on the distance from the ocean, the altitude of a terrain and the amount of precipitation. There are abundant examples to demonstrate the great importance of water-related (and climate- related) isotope research, which since the 1960s has been mainly boosted by the Isotope Hydrology Section (IHS) of the International Atomic Energy Agency (IAEA).
The discovery of the arsenic groundwater contamination in Bangladesh and investigation of the Nubian Aquifer shared by Libya, Chad, Egypt and Sudan are but a few examples. In addition to mapping the aquifer, experts also seek to identify which groundwater fractions may be used for being replenished by the Nile River and which ones consist of fossil water and are therefore better left untouched. In addition to operating own laboratories and the Global Network of Isotopes in Precipitation (GNIP), IAEA also collaborates with domestic R&D institutions such as Joanneum and ARC Seibersdorf Research.
In conjunction with the latter, the Federal Economic Chamber and the University of Vienna, ÖWAV also hosted a specialised isotope seminar in Vienna in late January, where top-notch methodology was presented and the need to make this know-how increasingly available to companies was underlined.
(Source: aqua press Int. 1/2008, Mag. Christof Hahn)