Potentially toxic metals contamination in soils. A comparison of tools to assess their lability (EDTA, SBET, soil solution) I. Popescu 1* , M. Biasioli 2 , F. Ajmone-Marsan 2 and R. Stănescu 1 1 Department of Inorganic Technology and Environmental Protection, “Politehnica” University of Bucharest, 010737, Bucharest, Romania 2 DI.VA.P.R.A. – Chimica Agraria, University of Torino, 10095, Torino, Italy *Corresponding author: iustinapopescu@yahoo.com, Tel +40 761272016 Abstract The risk for receptors (humans, biota, groundwater etc.) from trace metals contaminants from soil is directly related with their lability. In order to prioritize the necessity of remediation it is necessary to evaluate the risk of transfer of these elements from soils to receptors such as humans, plants, or other environmental compartments (atmosphere, groundwater etc). This can be done in a number of ways like implementation of transport models, batch, pot, columns and field experiments, selective or sequential extraction procedures. All these approaches are meant to estimate the quantity of contaminants that might reach the receptors. In the small town of Zlatna, Romania, trace metal concentrations in soils are close to or above intervention limits because of intensive smelting activities that took place in the area until 2004. The National Environmental Protection Agency, in the report State of the Environment - 2009 reveals that the accumulation of metals in the soils of this area caused soil acidification, soil structure degradation, loss of nutrients (especially mobile phosphorus). All these phenomena have led to the degradation of vegetation cover which caused soil erosion and landslides. In this area, the soil is mainly used for gardening, agriculture, and pasture, making the risk of transfer of contaminants from soils into the food chain highly relevant. The extension of the contamination, however, makes it difficult to prioritize interventions and strongly requires studies to assess the transfer of contaminants from soils to receptors. In this study, the lability of lead, cadmium, copper and zinc, in the soils of the area (from urban allotments and pastures) was investigated thorough the application of different tools proposed in the literature. In particular, selective and sequential extraction procedures were applied and compared with results obtained through other methods. First, the soil content of trace metals was quantified by aqua regia extraction and the results showed that in pasture soils the average of pseudo-total concentration of lead, cadmium, copper and zinc in soil are 4000 mg/kg of soil, 9.86 mg/kg of dry soil, 1191 mg/kg and 1564.2 mg/kg of dry soil, respectively. Among the tools selected to assess metals’ lability there are BCR sequential extraction procedure (which is used to evaluate chemical forms of trace metals in soils), EDTA extraction (used to predict the fraction of metals available for plants uptake), SBET extraction (which simulates the fate of the pollutants in gastro-intestinal tract and helps in estimating the bioaccessibility) and soil solution. The methods were applied also for flooded soil, and results reveled that flooding for a short time period (7 days) can increase the lead concentration in soil solution from 727 to 2137 mg/kg of dry soil and cadmium concentration from 7.3 to 8.3 mg/kg of dry soil. Keywords: trace metals contaminants; soil; speciation; availability; lability;