Interrelationship between hydrodynamic and hydrochemical conditions and microbiological communities in groundwater, Kappelen, BE

• Forschungsstelle: BAFU
• Projektnummer: 2001.E.10
• Projekttitel Englisch: Interrelationship between hydrodynamic and hydrochemical conditions and microbiological communities in groundwater, Kappelen, BE

Schlüsselwörter (Deutsch)

Grundwasser
Mikrobiologie
Biodiversität

Schlüsselwörter (Englisch)

groundwater
microbiology
biodiversity

Kurzbeschreibung (Englisch)

This document outlines the scope of work to be pursued in support of OFEG funded on-going research by the Laboratoire de Microbiologie of the Université de Neuchâtel (LAMUN) into microbiological communities present in groundwater. Field work will be carried out by researchers from the Centre d'hydrogeologie at the Université de Neuchâtel (CHYN) at the Swiss National Science Foundation (SNF) site of Kappelen, Canton Berne (Kappelen). Activities will consist of hydrodynamic and hydrochemical characterization studies of the aquifer underlying the site. The studies will be integrated into ongoing biological research in a multidisciplinary approach to understanding groundwater biodiversity.

The Kappelen site is located in the central part of the Seeland region, Canton Berne, approximately three km north of the town of Aarberg. The area (90m x 60m) is located in a private forest surrounded by intensely cultivated agricultural land. Porous sand and gravel deposits underlie the area. These deposits form part of the prolific Seeland Aquifer. This aquifer is regionally important and supplies approximately 15 Million cubic meters of water per year to the population in the northern part of the Seeland Region for domestic, industrial and agricultural purposes. Despite it's economic importance, the hydrodynamic and hydrochemical conditions in the aquifer are poorly understood in many areas. Moreover, groundwater microbiological conditions and biodiversity in the aquifer are virtually unknown. Indeed, microbiological aspects of hydrogeology are rarely studied and this area forms an important new branch of research currently developing in groundwater science.

The Kappelen site is an ideal area in which to initiate groundwater microbiological investigations, as it contains a wide variety of potential microbiological habitats. The site is underlain by heterogeneous porous sand and gravel deposits containing groundwater with variable hydrochemistry. Such conditions are representative of a wide range of hydrogeological conditions such as are encountered in the aquifer. Consequently focused studies at particular locations provide a means to develop an understanding of the inter-relationship between microbial populations and their physio-chemical environment.

Projektziele (Englisch)

The goals of this phase of the microbiological study are to obtain a basic understanding of the microbial structure in both the planktonic and benthic (attached) communities across the site. In order to understand the distribution of the various populations across the site, an understanding of their interrelationship hydrochemical and hydrodynamic conditions is essential.
Consequently, the goals of this work are to characterise the following:

1. Vertical and lateral hydraulic variations in flow velocity across the site. This step will be completed by tracer testing using the mobile downhole fluorometer technique recently developed by the Université of Neuchâtel. This approach allows the variations in flow velocity across long screened intervals of wells, such as those present at Kappelen, to be identified and quantified.
2. Vertical and lateral variations in hydrochemistry across the site. Discrete depth sampling, coupled with comprehensive on-site monitoring of well head hydrochemical conditions will be carried out to identify the hydrochemical conditions across the site. Previous preliminary investigations carried out by CHYN researchers showed that the water sampled in some wells is highly reduced and conducive to the formation different biological populations compared to those in shallower, more aerobic wells.
3. The variations in mineralogy across the site. Mineralogical studies of the available mineral substrate across the site will be carried out on currently available borehole cuttings. Existing laboratory based column studies using Kappelen sands has shown that the various minerals in the aquifer can have a variable impact on microbial attachment conditions.

The results of these studies will be integrated with data available from the current OFEG funded microbiology study to provide a more complete understanding of the interactions of the microbial communities in groundwater with their physio-chemical environment.

Umsetzung und Anwendungen (Deutsch)

Erläuterungen zur Gewässerschutzverordnung, Anhang 2. Wird später publiziert.