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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - GLOBALTOX (Toxicity of anthropogenic multi-stressed soils under a global warming perspective)

Teaser

Summary

Global climate change is displayed as a set of stressors potentially impairing the biotic and abiotic components of terrestrial ecosystems. This situation may worsen in environments degraded by anthropogenic activities where soil biota has to deal with already multiple stressors, and the toxicity of the contaminants present may change depending on the prevailing climate conditions. The general objective of GLOBALTOX was to assess how the toxicity of anthropogenic multi-stressed soils may be affected under the current global warming perspective, using soil invertebrates as bioindicators along with soil physico-chemical and microbiological parameters. The specific objectives were: 1) to assess the sensitivity of different invertebrate species to toxicity changes in anthropogenic multi-stressed soils induced by single climate factors (air temperature, soil moisture content, atmospheric CO2 concentrations, and UV radiation) and its relation to changes in soil physico-chemical and microbiological parameters; 2) to assess how the toxicity of anthropogenic multi-stressed soils may be affected under different climate scenarios simulated by climate factors combinations (air temperature, soil moisture content, atmospheric CO2 concentrations, and UV radiation), using soil invertebrates as bioindicators. Increasing toxicity risks of soils degraded by anthropogenic metal contamination were found under forecasted climate conditions for the year 2100, especially when soil dryness was intensified by elevated air temperatures. Worst scenarios were found for soils with acidic conditions and high metal(loid) availability.

Work performed

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 invertebratesâ€™ 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 ÂºC + 50% soil water holding capacity â€“WHCâ€“ + no CO2 + no UV radiation); Air temperature (temperature ramps of 15 â€“ 25 ÂºC, 20 â€“ 30 ÂºC, and 25 â€“ 35 ÂºC); 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 invertebratesâ€™ 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 ÂºC + 50% soil WHC + no CO2 + no UV radiation); Scenario I (15 â€“ 25 ÂºC + 30% soil WHC + 800 ppm CO2); Scenario II (15 â€“ 25 ÂºC + 30% soil WHC + UV radiation); Scenario III (20 â€“ 30 ÂºC + 25% soil WHC + 1000 ppm CO2); Scenario IV (20 â€“ 30 ÂºC + 25% soil WHC + UV radiation). For this part we worked with soft-bodied oligochaetes. The main results were:
- Soil invertebratesâ€™ 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.

Final results

So far, most of the research dealing with climate change and soil ecotoxicology has been focused on how changes in single climate factors may affect the toxicity of individual contaminants, most of the times using standard reference and/or artificial soils. This approach is far from what happens in nature since: reference/artificial soils do not represent real soil conditions; anthropogenic-degraded soils are normally affected by more than one contaminant and/or present multiple stressful conditions for soil biota; multiple climate factors act at the same time. To make a step further, soil ecotoxicology has to consider the emergent suite of stressors driven by global climate change jointly. GLOBALTOX aimed to cover this gap of knowledge by assessing soil ecotoxicity risks under forecasted climate scenarios for the year 2100.

GLOBALTOX findings have an important impact on research, monitoring and management of anthropogenic-degraded soils in the context of global climate change. The higher toxicity risks of anthropogenic metal-contaminated soils found under certain climate scenarios provide clear evidences that support the aim of limiting the increase to 1.5 ÂºC set on the Paris Agreement. Project results will contribute to promote the establishment of a baseline for the development of appropriate tools for identifying which areas may be more vulnerable under which climate conditions (environmental risks assessment), and therefore contribute to improve degraded areas management. Moreover, project outputs might be used to improve the current applicable Portuguese (under discussion) and EU legislation on soil protection.