This work presents new results on the arsenic distribution in the groundwater from the SW of Uruguay.
This preliminar y study is based in 28 samples from the Aquifer Systems Chuy, Raigón and Mercedes. The
arsenic concentrations observed exceed some thresholds of the Uruguayan and other (e.g., WHO)
regulations of water quality. The median, maximum and minimum determined have been 16.9, 58.0 and
0.1 μg/l, respectively). There is a horizontal and vertical variation of the concentrations considering all
together the studied aquifers and also within them. The higher values have been observed in the Mercedes
Aquifer in areas near the Uruguay River