Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Aquifers suffocate when river beds silt up

03.12.2013
In the course of the last few decades, the oxygen concentration levels in aquifers in the Swiss Plateau have dropped irregularly.

Results of the National Research Programme "Sustainable Water Management” (NRP 61) suggest that the irregular decrease might be related to various degrees of silting in watercourses.

A significant proportion of the water we use comes from aquifers that are fed by infiltration along watercourses. River water temperatures have been rising regularly for several decades. By analysing data from municipal pumping stations, the Eawag researchers Simon Figura, David Livingstone and Rolf Kipfer have observed that this trend also extends to groundwater, where the average temperature increase is 0.3 to 0.6°C every ten years.

Sawtooth decrease
The increase in groundwater temperature is probably having a negative impact on the concentration of dissolved oxygen in ground water by encouraging biological activity and therefore oxygen consumption. At the same time, it is reducing the solubility of the oxygen in the water.

A new analysis by the researchers now confirms that there is a trend towards lower levels of dissolved oxygen. As opposed to water temperatures, this decrease is not continuous but follows a sawtooth pattern: it is regularly interrupted by sudden increases that cannot be solely due to temperature.

By analysing the variations in water flow rate and the pumping volumes, the researchers have developed a new hypothesis: high river discharge and high pumping volumes lead to better river bed infiltration. This, in turn, leads to a swift increase in the oxygen concentration. However, it seems that this only happens after extreme spates that sweep away the silt on river beds. The spates thus clean the natural filter formed by river beds, which facilitates greater renewed infiltration and reoxygenation of the groundwater.

This hypothesis on the effects of the removal of riverbed silting is supported by field observations. During the 1970s, a layer of zebra mussels approximately five centimetres thick formed on the bed of the Rhine near to one of the pumping stations studied by the researchers. Several years later, divers noticed that the layer was no longer there. For this period, measurements indicate a clear increase in dissolved oxygen concentrations in aquifers.

What does the future hold?
Climate forecasts for the 21st century predict an increase in extreme weather. Scorching summers such as that experienced in 2003 are likely to become more frequent. Some aquifers became anoxic in 2003. One of the major consequences of this was the solubilisation of iron and manganese particles, which precipitated out of the water in pumping stations, where they negatively affected the operation of the pumping wells. However, there should also be more spates to clean river beds and encourage groundwater oxygenation. The researchers thus expect the slow decline in oxygen levels to continue, but believe that the spates as well as high discharge and high pumping volumes will prevent continuous aquifer anoxia.
(*) Simon Figura, David Livingstone, and Rolf Kipfer (2013). Competing controls on groundwater oxygen concentrations revealed in multidecadal time-series from riverbank filtration sites. Water Resources Re-search. DOI: 10.1002/2013WR013750

(Available to journalists in PDF format from the SNSF: com@snf.ch)

Contact
Simon Figura
Eawag
Überlandstrasse 133
CH-8600 Dübendorf
Tel.: +41 58 765 55 10
E-mail: simon.figura@eawag.ch
National Research Programme "Sustainable Water Management" (NRP 61)
The National Research Programme “Sustainable Water Management” (NRP 61) develops scientific principles and methods for the sustainable management of water resources, which are under increasing pressure. NRP 61 explores the effects of climate and social changes on these resources and identifies the risks and future conflicts associated with their use. NRP 61 operates with CHF 12 million for a research duration of four years. Website of NRP 61 "Sustainable Water Management": www.nrp61.ch

Weitere Informationen:

http://www.snf.ch/E/media/pressreleases/Pages/2013.aspx
http://www.nrp61.ch

Medien - Abteilung Kommunikation | idw
Further information:
http://www.snf.ch
http://www.nrp61.ch

More articles from Earth Sciences:

nachricht Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>