GLOBALTOX considered soils affected by different types of anthropogenic metal contamination (mining, agriculture, and industry) and soil invertebrates with different exposure routes to contaminants (arthropod Folsomia candida; soft-bodied oligochaete Enchytraeus crypticus). Four climate factors (air temperature, soil moisture content, atmospheric CO2 concentrations, and UV radiation) were modulated, individually or in combination, based on the IPCC predictions for the year 2100. Two types of tests were performed: i) avoidance behaviour tests in order to evaluate invertebrates’ survival and avoidance capacity towards anthropogenic metal-contaminated soils; ii) exposure tests of soil invertebrates to anthropogenic metal-contaminated soils in order to evaluate changes in soil parameters (physico-chemical and microbiological) and low biological organisation parameters in soil invertebrates (gene expression, enzymatic biomarkers, and metal(loid) bioaccumulation).
To approach the first specific objective, the climate treatments established were (variations of single climate factors while keeping the rest at control values): Control climate (20 ºC + 50% soil water holding capacity –WHC– + no CO2 + no UV radiation); Air temperature (temperature ramps of 15 – 25 ºC, 20 – 30 ºC, and 25 – 35 ºC); Soil moisture content (75% soil WHC to simulate intense rainfalls/floods; 40-30-25-20% soil WHC to simulate droughts); Atmospheric CO2 (600-800-100 ppm); UV radiation (UV radiation ramp simulating summer UV doses). The main results were:
- Soil parameters (porewater composition and bacterial community structure) of anthropogenic metal-contaminated soils changed under the climate factors range evaluated. The most determinant factors were soil moisture content and air temperature.
- Soil invertebrates’ survival in anthropogenic metal-contaminated soils was affected by the highest air temperatures.
- Soft-bodied oligochaetes were more sensitive to changes induced by single climate factors in anthropogenic metal-contaminated soils than arthropods. Oligochaetes lost their capacity to avoid contaminated soils under extreme water stress situations, but also when contaminated soils showed greater water availability than non-contaminated nearby soils.
- Soft-bodied oligochaetes suffered damage at genetic and (bio)chemical level when exposed to the combined stress of anthropogenic metal contamination and forecasted changes in single climate factors.
To approach the second specific objective, the climate scenarios simulated were: Control climate (20 ºC + 50% soil WHC + no CO2 + no UV radiation); Scenario I (15 – 25 ºC + 30% soil WHC + 800 ppm CO2); Scenario II (15 – 25 ºC + 30% soil WHC + UV radiation); Scenario III (20 – 30 ºC + 25% soil WHC + 1000 ppm CO2); Scenario IV (20 – 30 ºC + 25% soil WHC + UV radiation). For this part we worked with soft-bodied oligochaetes. The main results were:
- Soil invertebrates’ survival in anthropogenic metal-contaminated soils was not affected by the climate scenarios simulated.
- Soil invertebrates were not able to avoid anthropogenic metal contamination under the entire climate scenarios simulated. This response was more pronounced in soils with higher acidity and greater metal(loid) availability, and under the highest temperatures scenarios. Among others, this could be related to the intense soil drought conditions organisms experienced in climate scenarios III and IV and/or the greater toxic effects induced by the anthropogenic metal-contaminated soils.
GLOBALTOX has produced research of high quality, presenting its results at international conferences/workshops/seminars, and it is in the process of results publication. A postgraduate course has been organised in the context of the project, and its team members have been actively involved in outreach activities.
