Cadmium (Cd) is a trace element that can be highly toxic to biota, and humans are exposed mainly through contaminated food. Knowing the background concentration of Cd in soils is of great importance, as well as assays with plants to identify the effects of the contaminant in soil, which can be a viable alternative for assessing ecotoxicity. Therefore, this research has as main goals: to reassess the background concentration of Cd in soils of the state of São Paulo; to assess ecotoxicological effects of Cd at different levels in plant species; and also to determine the No Observed Effect Concentration (NOEC) and the Lowest Observed Effect Concentration (LOEC) for a few plant characteristics. To determine the background concentration, we will use samples from 150 different soil profiles from the state of São Paulo, collected from the layer between 0-20 cm of depth. The total Cd content will be correlated with the chemical, physical and mineralogical attributes in the soils. For the second experiment, several plant species will be sown to germinate in 100 g of sandy soil contaminated with Cd (0, 10, 40, 80, 160, 320 mg km-1) using solutions of CdCl2. After 120 h, germination, root and shoot growth will be evaluated to determine which parameter was more sensitive to Cd stress. Another experiment will be conducted in a greenhouse with two plant species (found to be most sensitive in the germination assay), in contaminated soil at five levels of Cd. After 30 days, plant growth, dry and fresh weight, leaf protein content, enzymatic activity and Cd content will be determined for both species. From the EC50 values, the NOEC and LOEC values will be calculated.
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