From industrial site to recreational area

The contaminated location is an old part of a business area of the former strawboard factory ‘De Eendracht’. The intention is to transform this former industrial site into an attractive area for recreational activities, like hiking and cycling. However, a part of the site (about 3 hectares) is contaminated with heavy metals and is not open to the public. To achieve this willow trees have been planted. The dense cultivation of the trees ensures that people can’t access the area, which prevents direct contact with the contamination.

The beauty of willow trees is that they are capable of accumulating or binding the heavy metals, thereby decreasing the risks and cleaning the soil in a natural way. This method of soil remediation by which plants or trees are used to absorb or break down pollution is called phytoremediation.

After the start of this project in 2016, Bioclear earth conducted monitoring at the contaminated location to evaluate how well the willows are able to extract heavy metals from the soil (phytoextration). In order to do this, we compared the results of the 2018 analyses with those of 2016.

The new data show that the willows retain their ability to absorb heavy metals, even though they are older now. The concentration of copper, cadmium and zinc in the willow samples has increased considerably. This means that the willows slowly but surely contribute to cleaning up the (available) heavy metals at the location.

Despite the increase of heavy metals in the willows, the heavy metal pollution in the soil of the location is still relatively high. However, our springtail test (ISQ test) - developed in collaboration with the Free University of Amsterdam - shows that there is no increase of ecological risk for soil life compared to clean soil.