The water detective

Geologist Charlotte Sparrenbom could be called a water detective. In her research, she searches for facts about underground water and its age in order to investigate and minimise the risk of pollution in groundwater. She is very concerned about insufficient monitoring of water quality by Swedish authorities.

Charlotte Sparrenbom

Senior lecturer Charlotte Sparrenbom is participating in the new research project TRUST, which aims to expose conditions underground. Photo: Peter Kroon

Sweden has insufficient national monitoring of groundwater quality. The few surveys that are carried out show that roughly one third of Swedish groundwater samples are polluted with pesticides.

“Sweden needs to act now to gain control of the situation regarding our drinking water resources”, says Charlotte Sparrenbom, a senior lecturer at the Department of Geology.

Together with other researchers and water experts working outside academia, she recently wrote a widely talked-about opinion piece in Dagens Nyheter. Last autumn she was also in charge of Grundvattendagarna, a two-day conference in Lund that brought together researchers, civil servants, local authority employees and individual companies to discuss water issues. This involvement has led to Charlotte Sparrenbom having contact with the Swedish Government Offices in connection with the ongoing drinking water inquiry that the Government appointed last year.

In her day job, she conducts research on various aspects of groundwater quality, for example the science of dating the water. When searching for pollutants in the ground, it is relevant to know the residence time (age) of the groundwater. Groundwater can vary in age depending on how deep underground it is, the porosity of different soil and rock layers in the area, the presence of cracks in the bedrock, etc. When drilling into the ground, it is possible to find several separate groundwater stores of different ages.

“A lot of the water we drink today is 20, 30 or 40 years old. It contains traces of the types of chemical that were common in society at that time”, says Charlotte Sparrenbom.

Dating groundwater is also important, for example for a government agency following up the effects of a chemical ban. They need to know how long it may take before the effects of the ban become noticeable, i.e. the time it takes for the chemicals to reach the groundwater and the time it takes for the polluted groundwater to be transported down through the ground from the pollution source to drinking water sources.

In Sweden, half of the drinking water comes from the groundwater and the other half from surface water. Charlotte Sparrenbom observes that the groundwater that is formed in the ground today will be drunk by our children, grandchildren and future generations. Groundwater can reach an age of thousands of years.

“What we do today forms a kind of footprint that is reflected in future drinking water”, she says.

Charlotte Sparrenbom is also participating in a new research project called TRUST. Using new geophysical methods, researchers from Lund and Aarhus will search for pollutants underground in urban environments. The aim is to expose the pollutants in order to avoid unpleasant – and expensive – surprises in new property developments. The research project is funded by Formas and is run in collaboration with partners in the construction industry, including Skanska, the Swedish Transport Administration and Tyréns.

An old industrial site here and a depot there. Chemical waste from such sites may have entered the groundwater and therefore needs to be investigated before development begins. However, to avoid having to do too much test drilling, TRUST aims to find other methods of obtaining data. There is namely always a risk that drilling may spread any pollution. In the TRUST project, the researchers will instead use geophysical methods that involve sending down electrical signals or measuring sound waves in the ground.

“Different pollutants can travel in different directions in the ground depending on density, solubility, etc. It can be extremely tricky to find them”, says Charlotte Sparrenbom.

The signals from the geophysics measurements are picked up and interpreted to provide information on underground conditions that the developers need to assess the situation. Charlotte Sparrenbom finds it very inspiring to conduct research in a field with such strong relevance to society. She also values the opportunity to have an influence.

“Dialogue with external partners is very time-consuming, but that is also how you gain inspiration for what problems we need to consider more closely in our research”, she says.

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