EAWAG news 49e (December 2000)
Ground Water Research in Practice (Entire volume)
Editorial (
en49e_bun.pdf, 50 KB)
Ueli Bundi (ulrich.bundi@eawag.ch)
Lead Article
Ground Water: From Drinking Water Reservoir to a Water Body (
Urs von Gunten (vongunten@eawag.ch)
Ground water plays an important role in Switzerland, both as a source of drinking water and as an integral component of the natural hydrologic cycle. Even though the original practices for protecting ground water have successfully overcome some of the more traditional problems, they must now be extended to include recharge zones in order to insure adequate protection from persistent chemical contamination. As illustrated by comparing water consumption to ground water regeneration in Switzerland’s most densely populated areas, a surplus of drinking water should not be taken for granted. The sustainable utilization of ground water must, therefore, be ensured by employing modern resource management practices.
Research Reports
Ground Water - a Biotope in Obscurity (
Tom Gonser (tom.gonser@eawag.ch)
Since ground water generally resides at a depth where sunlight cannot penetrate, photosynthesis does not occur; consequently, neither organic substances nor oxygen are produced. Energy and oxygen for the ground water ecosystem, therefore, must be provided from the surface. For this reason, hydrological interchange between the surface and the ground water are indispensable to the functioning of ground water ecosystemsSprings - the Forgotten Biotope (
Jens Zollhöfer (jens.zollhoefer@lifescience.ch)
Springs have always been poetically appealing, but they are also fascinating biotopes at the interface between streams and ground water. They harbor innumerable unique organisms, whose environment has thus far been almost completely neglected in Switzerland, both from the scientific and water management points of view. The effective protection of these highly sensitive ecosystems depends not only on tougher legislation, but also on a detailed inventory of all the natural springs that still exist.Ground Water - a Journey Through Time (
Rolf Kipfer (rolf.kipfer@eawag.ch)
New tracer methods show that ground water renewal rates can vary from days to millions of years. Even in Switzerland, the "water tower of Europe", very "old" ground water is substrated from deeper aquifers. Dating back to the last Ice Age, this ground water is not renewable; therefore, the water resource is depleted in terms of mining.Ground Water Quality - the Result of Biogeochemical Processes (
Jürg Zobrist (juerg.zobrist@eawag.ch)
Microbiologically mediated redox processes are regulated by the ratio of accessible oxidizing agents to the amount of available and degradable organic substances in the subsurface. The resulting biogeochemical conditions induce further chemical and microbial transformation of contaminants. The origin of nitrates in ground water may be determined by the isotope ratio d15N to d18OArsenic Contamination of Ground Water: Disastrous Consequences in Bangladesh
(
Stephan Hug (stephan.hug@eawag.ch)
Bangladesh is currently confronted with what is probably the largest case of mass poisoning in the history of humankind. About one third of her 125 million inhabitants are being slowly poisoned by drinking water that contains arsenic. The consequences have already affected tens of thousands: skin discoloration, ulcers, and cancer of the skin, lungs and intestines. Experts both in Bangladesh and at the World Health Organization (WHO) suspect that nearly 20 million people are, to a greater or lesser extent, already suffering from arsenic poisoning. If non-polluted drinking water supplies are not restored soon, arsenic poisoning might soon be the most frequent cause of death in Bangladesh. EAWAG scientists are presently concentrating on the development of a simple solar arsenic-removal-procedure (SORAS).Underground Chemical Spies (
Stefan Haderlein (stefan.haderlein@eawag.ch)
Only rarely under natural conditions do chemical reactions completely decompose organic pollutants; however, abiotic transformation processes can decisively affect the distribution, availability and mobility of ground water contaminants. EAWAG’s innovative approach to research on the interplay between chemical and biological processes in ground water pollutant decomposition heralds novel prospects for decontamination.Ground Water Pollution - the Limits on Biodegradability (
Jan Roelof van der Meer (jan-roelof.van-der-meer@eawag.ch)
Every year in Switzerland about 1500 tons of pesticides, herbicides and fungicides are released into the environment. Traces of these substances have been found in various Swiss ground water samples. Microorganisms can decompose a good many of these chemicals into harmless substances, but to eradicate the remaining contamination, the chemical compounds must be biodegradable. Biodegradability studies suggest that a combination of microbiological and physical-chemical factors determines whether or not pollutants will disappear.Drinking Water Well Catchment Zoning (
Eduard Hoehn (eduard.hoehn@eawag.ch)
To protect the potability of ground water supplies, the revised Water Protection Act in Switzerland now divides inflow into subsurface (ZU) and surface (ZO) zones. In many cases, rough estimates are adequate for dimensioning ZU zones. With regard to the infiltration of river water and subsurface flow from valley slopes into ground water, however, such estimates are inadequate.Drinking Water from Karstic Springs - a Case for Membrane Technology (
Markus Boller (markus.boller@eawag.ch)
Membrane technology opens up new, cost-effective ways of treating spring water in karstic zones. Experimental trials with various membrane processes for treating heavily turbid karstic springwater produced high quality drinking water in all cases; however, membrane life and application scope may be limited by fouling. The most suitable treatment process tested was found to be ultrafiltration, possibly in combination with activated powdered carbon.
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Please feel free to submit questions or suggestions any time to the editor Martina Bauchrowitz.