Abstract
PurposeInformation on the geochemical composition of suspended sediments in rivers is crucial to identify sediment source type or area. In large river basins, however, the relation between sediment composition and its controlling factors is often obscured. This study aims to assess and improve the conceptual understanding on the factors and mechanisms that control the composition of suspended sediments in the River Rhine, one of the large European rivers, and to identify the dominant source types of elements.Materials and methodsWe performed log-linear regression analysis and principal component analysis (PCA) on bi-weekly monitoring data of suspended sediment composition, supplemented with daily measurements of suspended sediment concentrations (SSC) and discharge at the Lobith monitoring station near the German-Dutch border for the period 2011–2016.Results and discussionThe statistical analyses show a consistent grouping of elements that display contrasting temporal variation or different responses to increased discharge. The contrasting behaviour also becomes manifest in the results from the PCA. A first component that explains about the half of the total variance in the entire dataset reflects the variation in clay content in the suspended sediment. A second component reflects anthropogenic pollution and explains about a quarter of the total variance. A third component probably reflects variation in sediment provenance.ConclusionsThe majority of the temporal variation in suspended sediment composition can be attributed to variations in grain size (clay content), organic matter content, and anthropogenic pollution. Only a minority of the variation can be attributed to variations in the contributions from different upstream source areas. This variation represented by the third and higher components from the PCA can potentially be used for sediment provenance analysis.
Highlights
The transport of sediment through the river system to seas and oceans is a fundamental process in the denudation of continents and the formation of deltas and coasts (Walling 2006)
The majority of the temporal variation in suspended sediment composition can be attributed to variations in grain size, organic matter content, and anthropogenic pollution
This study examined the temporal variation of suspended sediment composition at the Lobith monitoring station in the Rhine River in the Netherlands
Summary
The transport of sediment through the river system to seas and oceans is a fundamental process in the denudation of continents and the formation of deltas and coasts (Walling 2006). J Soils Sediments (2020) 20:1754–1770 variety of elements other than silicon, the transport of fine suspended sediments contributes significantly to global elemental cycles and the transfer of pollutants from terrestrial to coastal and marine systems (Owens et al 2005; Walling 2006). The load of sediments and associated substances in rivers is strongly controlled by discharge, because the load is the product of concentration and discharge, and because the sediment concentration generally increases with discharge (Van der Perk 2013). Discharge events are very important for sediment transport and geochemical fluxes. Ollivier et al (2015) found that discharge events that represent less than 12% of the time were responsible for 69 to 91% of the annual sediment-associated element fluxes in the Rhône River in France
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