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From ancient times until recently, mining and metallurgical activities in the greater Lavrion area, Greece, have resulted in the production of large amounts of metal wastes that enrich the surrounding soils with toxic metal(loid)s. Since the area is inhabited, soil dust inhalation, consumption of vegetables grown on the contaminated soils, and of dairy products from small ruminants grazing in the area, may impose a real threat for the health of the local residents. After more than 3,000 years of mining history, this study is the first report on the chemical partitioning and behavior of Zn, Cu, Ni, Cr, Cd, Pb, and As in the topsoils (0–15 cm) of Lavrion. Community Bureau of Reference (BCR) sequential extraction was applied to 29 topsoil samples and 4 chemical fractions of the studied elements were defined (a) exchangeable/acid soluble (F1), (b) reducible (F2), (c) oxidisable (F3), and (d) residual (RF). Total concentrations of all elements were above the geochemical background. Zinc, Pb, Cd, and As median total concentration values were 4, 9, 1.4, and 17 times higher than the respective intervention thresholds, indicating severe soil pollution. Most of Cd (78.2%), Pb (69.7%), and Zn (53.3%) were found in F1 + F2 sum, suggesting high availability under modified conditions that periodically can occur in soils. Copper, Ni, As, and Cr were mainly associated with the residual fraction. Principal component analysis results showed that F2 fraction of all studied elements was associated to Fe oxides, confirming the crucial role of Fe oxides in metal(loid)s sequestration in the soil matrix.

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The ability of fertilizer phosphates to desorb arsenates from soils is not yet adequately studied especially in cases of mining lands severely contaminated with arsenic (As). In this study, two soils with different physicochemical properties and heavily contaminated with As equilibrated with solutions containing various rates of phosphates either in the form of triple superphosphate fertilizer (TSP) or as NH4H2PO4 using NaNO3 as background electrolyte. A treatment with TSP in water was also applied to mimic agronomic practices. In general, increased P rates resulted in higher As release and to lower P sorption. Depending on the P rate, desorbed As ranged between 8 and 64.4 mg/kg for soil 1 and between 16.5 and 35.3 mg/kg for soil 2, corresponding to more than 50% of the potentially available As, as defined by the sum of the two first fractions of Wenzel sequential extraction scheme. Arsenic desorption patterns substantially differ between the two soils, mainly affected by active carbonates, organic matter and Fe and Al oxides contents. Though the differences between P treatments were not always significant, the presence of NaNO3 increased the desorbing strength of the solutions. Phosphorus sorption capacity was high for both soils, but excess P addition led to high P concentrations in the equilibrium solutions, implying leaching hazard.

A pot experiment was conducted to evaluate the effect of Na 2 -EDTA 0.01 M (E) and olive mill wastewater 15% (OMW) on As, Pb, and Zn uptake by Pteris vittata L. grown in a soil highly contaminated by mining activities. A two-factor experimental design was followed; 3 treatments (E, OMW, and E + OMW) × 2 batches (single or double dose). Six weeks after the P. vittata transplanting, all pots received the selected dose of each treatment (Batch I). At 8 weeks, in half of the pots, a second dose of the same treatments was added (Batch II). Plants were harvested after 10 weeks and As, Pb, and Zn concentrations were determined in fronds and roots. Depending on the element, both treatment and batch effects were significant. In Batch II, EDTA application resulted in a 55% increase of As and 9-and 4-fold of Pb and Zn concentrations in the fronds, while OMW treatment substantially reinforced plant uptake when combined with EDTA. Roots to fronds translocation of the metal(loid)s highly increased in Batch II. After harvest, composite soil samples of all treatment-batch combinations were subjected to sequential extraction, but no significant differentiations of As, Pb, and Zn partitioning in soil phases were detected.