Dübendorf, Switzerland
This groundwater sampling site is quite unique among the GReG site. It is set in a highly urbanized area and eDNA is collected from the aquifer through a borehole.
Why here?
In 2024, a new High-Temperature Borehole Thermal Energy Storage (HT-BTES) system was installed at the Empa and Eawag (https://www.eawag.ch/en/) campus in Dübendorf, Switzerland. The facility aims at advancing the current understanding of geothermal energy storage technologies. Particularly, the system consists of 144 boreholes of 100 m depth each, and it is integrated with the campus's district heating networks.
From a biological perspective it is a interesting case example for a groundwater habitat in an urban setting. A detailed lithology for the observation site is available, revealing two main layers, a lower Molasse consisting of sandstone, marl, and siltstone, overlain by a layer of Moraine with a thickness of up to 5 m, consisting mainly of silt and lenses of sandy gravel. On top there are glacial lake deposits with gravel lenses and Low-terrace gravel. The facility also hosts the ARTS project (Aquifer Reaction to Thermal Storage: https://www.arts-energystorage.ch/en/). Different research groups study the aquifer's response to the shifting temperature regime induced by the HT-BTES system.
The ARTS sampling borehole is covered with a box containing scientific equipment.
An integrative approach
For GReG, samples were taken from depths of 6 (glacial deposits) and 45 meters (Molasse). These samples integrate well into the ongoing microbial and faunistic samplings for the ARTS project, taking place every two weeks. Since the facility is equipped with online monitoring devices for physical and chemical parameters (many openly available here: https://data.arts-energystorage.ch/), the resulting biological parameters can be directly linked to abiotic variables. Overall, this site provides data on groundwater fauna from an urban setting that is currently undergoing major anthropogenic changes, with baseline data available.
Sampling eDNA is straightforward. The box contains measuring devices, pumps and technical equipment. The blue pipe shows the borehole, reaching a depth of 45 meters.
Words by Giulia Zecchin, Roman Alther & Florian Altermatt
Photos by Roman Alther