Determination of the chemical properties of water and sediments in agricultural land use by using energy dispersive X-ray fluorescence spectrometry

Abstract

The energy dispersive X-ray fluorescence spectrometry (EDXRF) methodology was applied in 29 samples on a year (Jun/2012 to Jul/2013) of monitoring program to assess freshwater quality of Lajeado Pardo River, the main tributary of a water supply reservoir, and 4 samples of soil from the surrounding forest and 6 samples of river and lake sediments were analyzed. High levels of Fe and Mn have a natural relationship with the soils of the region, while Cu, Zn, Ba and Cr, although natural soil micronutrients, may have enrichment from the use of fertilizers and pesticides. According to the Canadian Sediment Quality Guidelines for the Protection of Aquatic Life and CONAMA nº 344/2004 regulations, the concentration of Cr and Cu found in the sediments can cause severe effects on aquatic life. In freshwater, the concentration of Fe, Zn, Cu and Mn was higher than the maximum indicated by the Canadian Water Quality Guidelines for the Protection of Agriculture and the Canadian Water Quality Guidelines for the Protection of Aquatic Life. The elements Al, V, Zr, Sr, Cr, Y and Nb were not detected in fresh water, being restricted to soils and bottom sediments. Mean annual solid discharge in Lajeado Pardo River was estimated in 9.59 ton/year.km2 . But, on a rainy day, the observed yield was 7.38 m³/s and the specific solid discharge was estimated in 8.09 ton/day.km2 , that is 307 times more than the daily mean discharge