HP9 Environmental Assessment, Environmental Toxicology
D137-140
1:20 PM - 5:20 PM, Thursday
() Development of a methodology for assessing the Aconcagua river watershed pollution.
Valdovinos, C.E1, Sotomayor, P.A2, Mattar, C3, Silva, P4, Rodríguez, M5, Levy, J6, Bruna, M7, Patilo, C8, 1 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile2 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile3 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile4 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile5 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile6 Ecotoxicological Lab. Universidad Mayor, Santiago, Chile7 GIS Lab. Universidad Mayor, Santiago, Chile8 Perception Remote Center, Santiago, Chile
ABSTRACT- Aconcagua river watershed is located in the Valparaiso Region in Chile, whose surface covers 7.200 km2. The river is born in the Andes mountains and flows toward the Pacific Ocean, being its extension 142 km. The objective of the study, was to evaluate the contamination levels of water and soils and the wild fauna in order to propose measures of prevention, control and mitigation, that will diminish the levels of water and soil contamination utilized in the agriculture and livestock production. Surface waters monitorings were carried out between 2001 and 2004, considering flow river seasonal variations. Toxicity bioassays were performed (Daphnia pulex and Selenastrum capricornutum); physical-chemist and microbiological parameters and pesticides were analyzed. Acetylcholinesterasa (AChE) inhibition was assessed in birds, toads and rodents, to detect the effects of organophosphates and carbamates pesticides. Data obtained were entered in a geographical information system (GIS). Being the agricultural activity the more prominent (90.000 hectares) in the watershed, a map was generated to evaluate the environmental impact agriculture, using surveys and photointerpretation based on a satellite image. Global risk was evaluated, including point and nonpoint sources pollution, assigning them different magnitudes of potential risk with emission of heavy metals, hydrocarbons, fecal coliforms, nitrates, sulphates and percolates of home solid residues. For the spatial analysis, mining, oil refineries, slaughterhouses, dairies, dump sites, etc, were considered as risk sources. A methodology was designed to evaluate the nonpointsource pollution, considering ground use, underground water vulnerability, land slopes, infrastructure, in order to zoning the potential contamination risk. A first general risk zoning was created. Later the Integrated Danger Factor was determined, for each active ingredient of the pesticides applied in the watershed. The crops were classified according to the risk. Matrixes were generated, whose resultant values were spatially visualized for all the basin. Human and animal toxicology factors were incorporated as well as ecotoxicological and physical chemist characteristics of the pesticides used in the watershed. Finally, a new risk zoning was obtained that indicates which ways should be taken to manage the watershed in a more sustainable manner, handling an acceptable level of risk.
Key words: Assessment, Watershed, Risk, Bioassays