Dynamic of contaminants and basis for remediation of the Matanza-Riachuelo basin (Buenos Aires, Argentina).

A. FABRIZIO DE IORIO; LAURA DE CABO; J. MORETTON; A. RENDINA; O. SANTANATOGLIA

Foz de Iguazú, Brasil

Congreso; VII IAHS Scientific Assembly; 2005

International Association of Hydrological Sciences

The Matanza-Riachuelo river, main collector of a basin of 2300 km2, flows throughone of the more densely populated areas in the country, and it is one of the most pollutedrivers in the world. There are very few hydrometric measurements. In the upper basin theagricultural activity prevails, while the demographic density and industrial activities areconcentrated in the middle and lower basins. The main pollutants are generated by feedlots,agriculture, urban runoff, dump leachates, domestic and industrial wastewater effluents thatdischarge (generally without previous treatment) to the river or its tributaries. It is importantto assess the pollutant dynamics to elaborate sustainable and effective strategies of control.Also, the study of the attenuation of the anthropogenic environmental impacts on ecosystemsis relevant to the remediation plans for the area. The aim of this project is to analyze thedynamics of pollutants and nutrients in the water-sediment system, the relative stability ofcontaminants, their toxicity variations on different organisms and the bioaccumulation insome of them, in order to generate environmental strategies for appropriate management ofthe river and its alluvial plain. Sampling sites will be located in different areas of the Matanzariver basin, considering low and high contamination sites related to land use. Physical andchemical variables will be determined in the water, in sediments and in the alluvial plainunder different hydrological conditions. Changes in the mobility of heavy metals andnutrients due to modifications in the system oxidation state; variations that take place by theassimilation of different organisms; genotoxic effects in sediments and water related to thechemical forms of heavy metals and persistent organic compounds in the sediment; and thetoxicity level in different organisms will be studied under laboratory controlled conditions.Assimilation and bioaccumulation factors in vegetal and bacteria will be evaluated to settledown alternatives of bioremediation. The results of this research will offer a better knowledgeof the processes that control the mobility and bioavailability of pollutants, it will provideevidence on the key role of some organisms in the biogeochemical cycle of heavy metals andnutrients and a base for their use in bioremediation strategies. This work will offer acontribution to establish guidelines for future legislation and will allow the design ofremediation programs for the different sites of the basin.