Acumulación y Especiación de Altas Concentraciones de Cr, Ni y Zn en un Sistema Acuático Vegetado y no Vegetado.

DI LUCA, G. A.; MUFARREGE, M. M.; HADAD H. R.; MAINE, M. A.

Cancun

Congreso; VI Congreso Iberoamericano de física y Química Ambiental. Sociedad Iberoamericana de Física y Química Ambiental (SiFyQA).; 2011

Sociedad Iberoamericana de Física y Química Ambiental (SiFyQA).

A greenhouse experiment was conducted in order to determine whether the presence of Typha domingensis affects the accumulation and speciation of Cr, Ni and Zn in sediments of an aquatic system. Plastic aquaria of 10 L capacity were used, in which were placed 4 kg of sediment and 2 rhizomes of T. domingensis of 10 cm in length, the same aquarium without plants were arranged, both in duplicate. 5L of solution 100 mg l-1 Cr + 100 mg l-1 Ni + 100 mg l-1 Zn was added. Water, plant and sediment were sampled periodically for 90 days. In each sample were measured pH, redox potential, concentrations of metals in water, plant tissues (leaves, roots and rhizomes) and sediment profile (0-3 cm, 3-7 cm and 7-10 cm) and the fractionation of metals in the surface layer (0-3cm) (Tessier et al., 1979), Relative growth rates  and chlorophyll concentration.. The 3 metals were efficiently removed from the water. The pH was significantly higher and the redox potential was significantly lower in non-vegetated aquaria, compared to aquaria with vegetation. The sediment with plants accumulated significantly higher concentration of the three studied metals. The accumulation of metals was significantly higher in the superficial sediment (0-3 cm). In both treatments, Cr was mainly accumulated in the fraction bound to organic matter, Ni in the fraction of Fe-Mn oxides and Zn in Fe-Mn oxides and carbonates with no significant difference between both fractions. Leaves accumulated high concentrations in some samples exceeding those of roots. The traslocation factor of Cr was higher than that of Ni and Zn. The increase percentage of chlorophyll concentrations was negative in all samples, except at 14 and 21 days, which coincided with an increase in metal concentration in shoot. While relative growth rates were positive, were significantly lower than in the control. We can conclude that in the case of an accidental dump of high concentrations of Cr, Ni and Zn in aquatic systems vegetated with T. domingensis, the species will survive and will promote the accumulation but will not affect the speciation of these metals in the sediment.