EAWAG news 52e (Mai 2002)
Tracers: Elements of Evidence in Environmental Research (Entire volume)
Editorial (
en52e_edi_s.pdf,
screen version 62 KB; en52e_edi_p.pdf,
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Bernhard Wehrli (bernhard.wehrli@eawag.ch)
Lead Article
Tracers - Making the Invisible Visible
(en52e_bewe_s.pdf,
screen version 170 KB; en52e_bewe_p.pdf,
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Jürg Beer und Bernhard Wehrli (juerg.beer@eawag.ch,
bernhard.wehrli@eawag.ch)
Tracers are tools used in environmental research both to make processes
more visible and to discover unknown processes. Tracers were used, for example
in marine research, to answer the question about where the Gulf Stream ends.
EAWAG is investigating similar questions about streams and lakes by using
isotope tracers. Trace compounds in environmental repositories can be used
to reconstruct changes in climatic conditions. A relatively recent development
is the use of indicators of biological processes; biomarkers allow us to assess
the effects of various pollutants on organisms.
Research Reports
Determination of the Compound-Specific Isotope
Signature of Chemical Pollutants
(en52e_zwank_s.pdf,
screen version 180 KB; en52e_zwank_p.pdf,
print version 4638 KB)
Luc Zwank (luc.zwank@eawag.ch)
Analytical methods have evolved to a point where it becomes possible to
determine the isotopic composition of individual chemical compounds at low
detection limits. These advances have opened new possibilities for the assessment
of contaminated ground water. EAWAG intends to optimize established analytical
methods for their application in contaminant hydrology.
Biological Tracers in Ecotoxicology
(en52e_eggen_s.pdf,
screen version 152 KB; en52e_eggen_p.pdf,
print version 283 KB)
Rik I.L. Eggen (rik.eggen@eawag.ch)
Biomarkers are biochemical or physiological indicators of physical, biological
or chemical stress on organisms. They are tracers for reactions that can take
place on different biological levels - molecular, cellular, whole organism.
This article discusses molecular biomarkers that are induced by chemical stress.
Their detection enables us to assess very early the potentially negative effects
of chemicals on organisms and ecosystems.
Sedimente – Archive für Detergentien
(en52e_gigald_s.pdf,
screen version 245 KB; en52e_gigald_p.pdf,
print version 645 KB)
Walter Giger und Alfredo C. Alder (walter.giger@eawag.ch,
alfredo.alder@eawag.ch)
In the past, chemicals contained in detergents and cleaning agents were often
very recalcitrant and were deposited in lake sediments. These chemicals can
now be used as tracers to document the history of their release into the environment,
which, in turn, allows us to assess the success of measures taken to reduce
their use. Decreasing concentrations in the sediments can be attributed to
changes in product formulations as well as to improved removal of these chemicals
by wastewater treatment plants.
RNA - A Tracer to Detect Microorganisms
(en52e_zepp_s.pdf,
screen version 181 KB; en52e_zepp_p.pdf,
screen version 253 KB)
Kornelia Zepp (kornelia.zepp@eawag.ch)
The group "Molecular Ecology" at EAWAG in Kastanienbaum uses 16S
rRNA, a structural element of ribosomes, as a tracer in studies on the carbon
cycle in anaerobic sediments. Two examples are presented here. Fluorescence
in situ hybridization was used to identify active bacteria in 150 year old
sediments from Baldeggersee. Two populations of methane-forming Archaea were
characterized in Rotsee sediments; their depth distribution was correlated
with the quality of available organic material.
Silver as a New Tracer for Diatom Production
(en52e_friedl_s.pdf,
screen version 143 KB; en52e_friedl_p.pdf,
print version 323 KB)
Gabriela Friedl (gabriela.friedl@eawag.ch)
Sediments from oceans and lakes contain a record of the history of the water
body itself, of the nearby land masses, and of the climate. The art of paleoceanography
and paleolimnology is to correctly interpret these archives. Metals generally
serve as tracers, yielding information about primary productivity levels as
well as redox conditions at the time of deposition. The use of silver as a
specific indicator for the productivity of diatoms is a new addition to the
arsenal of tracers.
Temperature Microstructure as a Tracer of
Turbulence and Mixing
(en52e_wueest_s.pdf,
screen version 148 KB; en52e_wueest_p.pdf,
print version 213 KB)
Alfred Wüest (alfred.wueest@eawag.ch)
The smallest temperature variations in natural waters extend over fractions
of millimeters. These so-called temperature microstructures can be used as
a tracer of turbulent mixing processes and their small-scale dynamics. This
methodology allows us to differentiate between different effects that cause
mixing in natural waters such as wind and cooling.
Identification of Groundwater Habitats Using
Radon as a Tracer
(en52e_hoehn_s.pdf,
screen version 238 KB; en52e_hoehn_p.pdf,
screen version 525 KB)
Edurad Hoehn (eduard.hoehn@eawag.ch)
Floodplains harbor a complex network of aquatic habitats that are fed by surface
water as well as ground water. With the help of the radon method, it is possible
to identify habitats that are primarily influenced by ground water. In the
"middle floodplain" of Valle di Blenio, we were able to distinguish
three types of ground water by determining radon along with sulfate concentrations.
Each type of ground water is characterized by a different proportion of freshly-infiltrated
surface water.
Conservative Elements on New Trails
(en52e_kipfer_s.pdf,
screen version 113 KB; en52e_kipfer_p.pdf,
print version 178 KB)
Rolf Kipfer (rolf.kipfer@eawag.ch)
A new model describing the physical process of gas exchange between entrapped
soil air and ground water is able to provide an explanation of excess air
in ground water. The model postulates equilibrium conditions between the ground
water and the entrapped air. Based on this model, we can more meaningfully
interpret atmospheric gas concentrations and more accurately quantify radiogenic
helium which, in turn, allows us to more accurately date young ground water.
Forum
Interview with Ruth Gonseth "Emerging Water Contaminants"
(en52e_forum_s.pdf,
screen version 187 KB; en52e_forum_p.pdf,
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Dr. Ruth Gonseth
was a representative of the Green Party in the Swiss National Parliament (Nationalrat)
from 1991 to 2001. In this function, Dr. Gonseth was intensively concerned
about contaminants in water and has submitted two legislative proposals "Research
Need: Chemicals with Endocrine Effects" and "Reduction of Hormonally
Active Substances". Dr. Gonseth has a dermatology practice and is an
active member of the association "Doctors for Environmental Protection".
EAWAG News interviewed Dr. Gonseth about the motives of her involvement in
these issues, Switzerland's role in the international scene, and what she
expects from research.
In Brief (en52e_forum_s.pdf,
screen version 195 KB; en52e_forum_p.pdf,
print version 462 KB)
Publications und books
Please feel free to submit questions or suggestions any time to the editor Martina Bauchrowitz.