Avoidance tests with Collembola and earthworms as early screening tools for site-specific assessment of polluted soils

Avoidance tests with earthworms and collembolans were conducted to demonstrate their feasibility as early screening tools for assessing the toxic potential of metal-polluted soils. Four different soils, with different degrees of metal contamination, were obtained from an abandoned mining area. All possible paired combinations were assessed for an avoidance response by the organisms. Data revealed that both species were able to avoid the most contaminated soils at the center of the ore extraction and treatment areas compared to those collected further away from the mine. However, earthworms and springtails differed in sensitivity to metals, especially when testing the two most polluted soils that had different contamination profiles. Earthworms exhibited a more consistent, less variable response than springtails. Overall results showed that avoidance tests with collembolans and earthworms have the potential to be used as screening tools in ecological risk assessment schemes for contaminated land, to trigger other tests in case of concern. However, further method development is needed to reduce variability in the data, particularly in the Collembola assays, and to gain knowledge about the possible effects of soil properties on the outcome of the tests.