Can reed beds clean contaminated groundwater?

NARRATOR: This is the Helmholtz Center for Environmental Research in Leipzig, Germany. Scientists here have launched an ambitious project inside this greenhouse. They are using reed beds to extract pollutants from contaminated groundwater. The pilot project is taking place in a mini constructed wetland. In the wetland simulation, the reed beds are filtering high concentrations of toxic substances out of the groundwater. Constructed wetlands really do work - reed beds are able to decontaminate water. This purification effect is largely thanks to microbiological processes. The plants transport large amounts of oxygen to their roots, allowing micro-organisms that decompose toxic substances to thrive. The plants also aerate the contaminated water. At the end of the degradation process only water and carbon dioxide should be left behind.

HOLGER WEISS: "In this project we know exactly how much water goes in and how much comes out. We know exactly which and what quantities of toxic substances are involved at the start and at the end. We can measure all the parameters, and change them if required. At the end of our research project we'll be able to understand these natural processes so well, we'll be able to control them."

NARRATOR: The scientists take samples constantly, as they still need to shed light on many uncertainties. For example: how contaminated do the plants themselves become? Can they be composted afterwards or do they have to be incinerated as toxic waste? And the degree to which the groundwater is contaminated varies. In the laboratory, the researchers use a high-frequency plasma mass spectrometer to check the iron content of the water. The readings fluctuate. There are clearly still many questions to be resolved, but hopes are high that these plants will be able to make an important contribution to purifying our water.