Effects of partial capping in the contaminants mobilization and microbial degradat...
Abstract
The Guarani Aquifer System (GAS) is one of the most important transboundary aquifers in the world. Located in parts of four South America countries (Argentina, Brazil, Paraguay and Uruguay), its area is estimated to 1.2 Million km². The GAS is formed by the eolian sandstones of the Jurassic (Botucatu formation) and fluvio-eolian Triassic (Pirambóia formation) periods. In Brazil 1,443 municipalities are located in the SAG area (Borghetti et al., 2004), with growing water demand for urban, industrial and agricultural purposes. Due to the strategic, social and economic importance of this aquifer for the four countries, it is necessary to understand its replenishment. The majority of recharge to the aquifer is hypothesized to occur in the outcrop areas, where the GAS appears as an unconfined aquifer. However few hydrogeologic studies focusing this question are available. The present project is compound of three major foci: 1. A monitoring network installed in the Ribeirão da Onça watershed aiming to understand and quantify the recharge mechanisms at these outcrop areas. A complete water balance can be evaluated, leading to the estimation of the main components of the hydrologic cycle (e.g., precipitation, evapotranspiration, storage, base flow) under agricultural use. The influence of different land uses (e.g. eucalyptus, sugar cane, citrus and grassland) can be quantified. 2. An experimental site under undisturbed dense Cerrado in order to understand pre-deforestation conditions. Canopy interception, throughfall, stemflow, surface runoff, erosion, and water table level are obtained, allowing the evaluation of the impact of soil use changes in comparison to native vegetation. 3. A monitoring network in an abandoned landfill aiming to the evaluation of contamination and transport processes in the Guarani Aquifer. Understanding the hydrological and contamination processes in detail scale is a key step in order to extrapolate local results to the whole aquifer system, providing reliable information for groundwater management and protection purposes. (AU)