Resumo

RATTO, SILVIA ELISA; KIRSANOV, NATALIA; MARBAN, LILIANA  e  GIUFFRE, LIDIA. Pedogénesis de sedimentos contaminados y dragados del Río Reconquista-evaluación y diagnóstico. Cienc. suelo [online]. 2016, vol.34, n.2, pp.323-339. ISSN 1850-2067.

A site evaluation was conducted on a landfill of dredged sediment from the Reconquista River on top of a geomembrane with spontaneous willow tree vegetation. Sediment samples were taken up to a depth of 1 m, and were analyzed for potential contaminant presence as well as soil variables. The results showed an incipient pedogenesis and presence of Cd, Ni and Zn metals in the soil solution 7 years after disposal. Organic carbon accumulation, sediments particle size, and color change were detected. Bulk density was found to be less than 1 g cm^-3 and porosity was large, mainly due to cracks. pH was very low, (3.8 in situ, 4.5 in the laboratory), enhancing these elements’ solubility. On surface, total amount of Cd was 1.2 mg kg-^-1; Cr 16.6 mg kg^-1; Cu 43.9 mg kg^-1; Ni 14 mg kg^-1; Pb 32.9 mg kg^-1 y Zn 131,7 mg kg^-1. Volatile organic compounds (PHAs) were identified by mass spectrometry confirming the original sediment contamination. The C distribution in the soil profile suggests a natural attenuation process. The TCLP test (leached quality) was used to evaluate possible metal stabilization techniques. Five treatments were applied: control, two rates of lime-sediment, 1:20 and 1:50; cement with the same two rates and calcium superphosphate fertilizer 1:40. Metals and metalloids found in the soil solution were Al, Cd, Ni and Zn. The TCLP test was applied to the control and to all treatments, stabilized and prevented 100% leaching of Al, Cd and Ni but not for Zn. The fertilizer treatment decreased equilibrium pH throughout the profile increasing Al solubility in the entire soil profile, of Cd and Ni at intermediate depth, while Zn solubility was not modified. Stabilization techniques with calcium amendments would be the best alternative to reduce the biomagnification risk through the entrance of metals in the food chain and could create better conditions for the attenuation of hydrocarbons which could be hazardous for the population´s health.

Palavras-chave : TCLP; Hydrocarbons; Metals; Aluminum.

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