In the footsteps of an industrial past

Ecological risks landfills at Loon op Zand

The village of Loon op Zand has been known for its extensive shoe and leather industry for centuries. Up until the late 90s of the 20th century many well-known shoe brands were produced here. In the past decade the production of shoes and leather products has been moved abroad.

The former shoe and leather industry has left behind, besides the rich artisanal history, other less desirable traces. An area west of Loon op Zand of about 10 hectares served as a sanitary landfill for the wastewater of the leather industry from 1952 to 1994. This has caused contamination of the area with chromium, mainly chromium (III).

At this moment the location is left fallow, completely unpaved and surrounded by forest on three sides.


Trace evidence: mapping risks with the TRIAD approach

The province of Noord Brabant wanted to know if the contamination posed any risks for humans and the environment and if the location was due for immediate remediation.  Therefore, commissioned by the province, Bioclear earth has conducted a TRIAD research of the area. 

The TRIAD research comprises of three distinct approaches to determine the risks namely by applying chemical, toxicological and ecological research methods.

Our tests revealed that the soil contains relatively high amounts of chromium (III), yet is hardly absorbed by the environment and has neither toxic nor ecological effects.

To get to the bottom and further support the conclusions of the TRIAD research iSQ tests with springtails have been performed. Springtails are widespread soil organisms and extremely sensitive to contamination. Springtails exhibit stress symptoms upon exposure to specific toxins. They respond by synthesising specific enzymes to reduce their stress levels. When exposed to metals the stress causes them to produce the enzyme Metallothionein (MT). The synthesis of these enzymes can be measured with molecular analysis techniques.

The performed iSQ test showed that the springtails did not increase their production of Metallothionein. This means that they do not experience stress due to the metal exposure in the soil. The outcome confirmed the results generated by the TRIAD research.

Our research concluded that in spite of high concentrations of chromium (III), this poses no ecological risks to the location. Therefore immediate remediation of the soil is unnecessary. Remediation can be conducted during a more self-evident moment like for example redevelopment of the area.

For more information about risk analysis and management, please contact Freek van den Heuvel.

Freek van den Heuvel
Consultant water quality and phytoremediation