Science - March 10, 2005

Snails indicate how dirty soil is

‘Imagine that the levels of zinc, copper and cadmium pollution in the soil are within the limits, but there are still signs that there is something wrong with the nature in an area. We have seen this happen,’ says Dr Jan Kammenga, ‘But now we have found a way of measuring this objectively.’

The method Kammenga is talking about consists of looking at biomarkers in snails, worms, springtails and other soil organisms, rather than measuring the concentrations of polluting substances in the soil itself. By looking at what happens in the organisms, the researchers can study the damage that soil pollution causes. The use of this method is evident, according to Kammenga: ‘Sometimes there is cadmium or zinc in the soil but it is in a compound form that causes little damage. You can see whether this is the case by studying nematodes or earthworms that live in a location where the substances have been found. If the study shows that the pollution is causing no damage, you could decide to wait before clearing the soil.’

The journal Ecotoxicology recently published a special edition devoted to the results of research on the subject from six different countries, and Kammenga was the editor. The studies were carried out under an EU-financed project coordinated by Kammenga from Wageningen, Bioprint 2, which has now come to an end. Kammenga looks back with satisfaction. ‘It was the first time that we looked at biomarkers under field conditions,’ he says. ‘Before the project started we knew nothing. Now we have developed a standard for this kind of research, with a limited but detailed set of biomarkers for a few organisms.’

‘In the follow-up project we will go further,’ continues Kammenga. ‘We will examine gene expression in organisms that live in polluted soil. We will search for universal genes that react in the same way to pollution in all organisms. If we find these it should make it much easier to identify areas with serious pollution.’ / WK