Ecology and health in risk analysis of polluted soils

Risk analysis can be used as a scientific tool for addressing the health of ecosystems. Here we describe a protocol for characterizing risks in the ecosystems of several polluted soil scenarios in the Madrid Community (Central Spain). Our starting hypothesis was that to recover the health of degraded ecosystems that could affect public health, an ecotoxicological diagnosis of each site is required. The sites we considered were industrial and urban solid waste landfills and abandoned mines. This diagnosis revealed many interacting processes that need to be assessed if we are to realistically address the issue of restoring impacts on ecosystems affected by soil pollution. These processes are: 1) Geo-edaphic processes, requiring the analysis of geomorphologic factors; 2) Chemical–physical processes occurring in the soils, such as the release of anions or cations ; 3) Erosion–pollution processes that require an understanding of the autoecology of plant species that could be used for remediation in scenarios with this dual problem; 4) Bioaccumulation–biodegradation processes, requiring the integration of microbiology and plant biology tools to assess any toxic effects on soil and plant subsystem populations; 5) Edaphic–bioavailability processes, since different ecotypes show a varying response to a given soil; 6) Population–ecopathology development processes, essential for both cultivated and native plant species comprising trophic networks; 7) Secondary–primary ecological succession processes, a commonly observed mechanism in old landfills sealed with soils from the surroundings-ecological knowledge of reference communities is essential for a good ecotoxicological diagnosis.; 8) Climate change–global warming processes, of utmost importance for revegetating polluted soils since success will depend both on the soil seed bank and on stochastic processes.