Where are the largest aquifers in South America?

Have you already checked which countries are in your assignment or do you need all of South America? The Guaraní is the most well-known and it's under Argentina, Brazil, Paraguay and Uruguay, but there's also the Amazon aquifer which is huge and spans several countries, and the Orinoco Basin one in Venezuela and Colombia. If you're gonna do a decent job, most sources are gonna talk about those three as the main ones, even though the Guaraní tends to be the one that shows up most in the texts.