Autori: Damian Floarea, Damian Gheorghe, Lãcãtuşu Radu & Iepure Gheorghe

Editorial: Carpathian Journal of Earth and Environmental Sciences, V. 3. Nr. 2, p.65-82, 2008.

Rezumat:

The concentration and distribution of Pb, Cu, Zn and Cd in the soils from Zlatna and Copşa Micã (Romania) highly polluted by metallurgical activity, have been studied in the soil profile for different types of soils related with the physical and chemical properties of the soils. In Zlatna area, there have been studied the Aluviosol, Dystricambosol and Alosol types and in Copşa Micã area the Aluviosol and Phaeozem types. Content of humus, pH, cation exchange capacity, base saturation, organic carbon, C/N ratio, nutrient elements, texture and the heavy metals concentration in total and mobile form were determined for each pedogenetic horizon. The heavy metals concentration varies within the soil profiles related with different properties of the soils and with the metal species. The highest concentrations of lead, of 245 ppm to763 ppm, are in relation with the organic horizons, in conditions of acid pH (3.12 – 3.85) of Dystricambosols and of Alosols from Zlatna zone, and of 561 ppm to 2768 ppm in Aluviosols and Phaeozems from Copşa Micã area, in conditions of alkaline pH. Lead contents decrease suddenly, under the maximum allowable limit in C horizons within the soil profiles. The affinity of Pb for surface horizons is emphasized by the excessive contents of global samples of 995 ppm in Z-T, 980 ppm in Z-2 and of 5000 ppm in CM-T. The copper contents of the soil profiles, close to the maximum allowable limit are specific for the surface horizon of Dystricambosols (73.8 ppm), for the global sample Z-T, (99.7ppm) and for the Aluviosols in Copşa Micã area (71.1 to 96.9 ppm). Copper concentrations of 1165 ppm from Zlatna area increase towards the site of smelter in the global sample Z-2. The copper concentration of Copşa Micã global sample, representative for Aluviosols type exceed maximum allowable limit, being of 199 ppm. In conditions of acid pH, Zn presents concentrations of 775 ppm and of 820 ppm at C and B horizons, rich in clay and with a higher content of Fe and Mn in Aluviosol and Dystricambosol types in Zlatna area. In conditions of neutral to alkaline pH (5.03, 7.10, 7.26) in the soils from Copşa Micã, Zn immobilization in quantities of 7500 ppm, 4900 ppm in Aluviosols, 684 ppm in the Phaeozem type and 8591ppm in global sample at the surface horizons it is associated with values of the humus content between 0.48-4.56 percent. The Cd contents of 5.05 ppm exceed the maximum allowable limit in the global sample Z-2. In Bv horizon of Dystricambosols, the content of Cd is of 2.87 ppm in comparison with the contents under 1 ppm from the surface horizons. The increase of Cd content with the depth is related with the increase of the clay content and with acid pH conditions (3.72-4.59). In soils from Copşa Micã, Cd represents a concentration in the surface horizons of the soil’s profiles, between 100-400 ppm in Aluviosols and 17.99 ppm in Phaeozem type. The high concentrations of Cd (175ppm) and of As (1500ppm) are related with the organic horizon of the soils from the global sample in Copşa Micã area. In comparison with lead and copper, cadmium has mobility on the soil’s profile because it maintains the contents over maximum allowable limit values and the intervention limit in the intermediate horizons of the soil’s profiles.

Cuvinte cheie: soil type, heavy metals, pollution, mobility, soil profile

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