Trace element distribution in pristine Patagonia River sediments using multivariable analysis

Abstract

Surface sediments may serve as a metal sink that can release metals to the water body causing negative effects to the ecosystems. The analysis of trace-level metals in sediments allows detect pollution that might not be detected in water samples. In this study, the distribution and concentration of selected elements in surface sediment samples were determined in Pichileufu River in Patagonia, Argentina, to corroborate their pristine characteristic. The surface sediment samples from 6 points along the river were collected using the method across and throughout the waterway. All of them were analyzing first by X-ray fluorescence (XRF) determining the major element concentrations. Then, they were acid digested and the selected trace element (V, Cr, Ni, Cu, Mo, Cd and Pb) concentrations were determined by inductively coupled plasma mass spectrometer (ICP-MS). The correlation analysis and principal component analysis indicated that the major and minor elemental compositions allowed quickly identified specific sample that differ from the rest and understood the reason. The obtained results show that all the selected element concentrations were below the PEL of the sediment quality guidelines. There were no significant differences between the selected element contents in the surface sediments of the Patagonia River among the years. The observed differences in the 3-site samples may be related to that it is a stream of the main river. Therefore, this study result could work as reference pristine site. The study highlights the need to make tremendous efforts to monitor and control trace elemental pollution in the Pichileufu Patagonia River to avoid their future contamination from both anthropogenic and natural sources. Among the natural factors, it is very important to consider the desertification process suffered by these steppe areas. In this context, the presented results could be used as background concentrations or as starting point for these studies.