A geochemical study of overbank sediments in an urban area (Madrid, Spain)

Abstract

Overbank and stream sediments have been studied in the Community of Madrid. Four vertical profiles have been sampled corresponding to Guadarrama, Jarama, and finally Manzanares River, where two profiles have been studied upstream (El Pardo profile) and downstream (Rivas profile) Madrid city. Sieved samples (<63 µm) were subjected to total (ICP-MS/ICP-OES and INAA) and partial analysis (ICP-MS). AMS radiocarbon dating techniques revealed a young age (170 ± 40 years BP) at 2.40-2.65 m depth for Rivas profile. It has not been possible to detect pristine or pre-industrial overbank sediments, since in the rest of the studied profiles, anthropogenic wastes were found even in the lower levels. Three main sources of sediment have been detected in the area. Granitic and arkosic geology, located in the northern part of Madrid (U, Th, W, K, Na, or rare earth elements); clays located in the southeast of Madrid (Ni, Cr, or V), and finally an anthropogenic source has been identified (Au, Ag, Pb, Zn, or Sb) in Rivas profile. The influence of the anthropogenic activity has been established based on the contents distribution of contaminant elements in the profile. This can be associated to the growth of industrial activities and population in the city of Madrid during the last decades. The comparison of the profiles by a k-means cluster analysis showed some similarities for these samples that could have analogous sources (anthropogenic and geological).

Application of lead isotopic methods to the study of the anthropogenic lead provenance in Spanish overbank floodplain deposits

“…Lead 206 Pb/ 207 Pb isotope ratios in Madrid Area range from 1.1738 in the river sediment of the Rivas profile Figure 2 shows the analysed Pb contents (Adánez Sanjuán et al 2014a) and 206 Pb/ 207 Pb ratios in the four profiles sampled in Madrid Area. Pb contents are much higher and variable in the Rivas profile, where concentrations range from 120 to 272 ppm (Table 3).…”

“…In the Rivas profile, EF are higher, while in the rest of the profiles they are close to one. In Adánez Sanjuán et al (2014a), there is a comparison between the contents of Pb in these overbank sediments and background values in alluvial soils (De Miguel et al 2002), concluding that only Rivas profile exceeds the background.…”

General concepts of geochemical mapping at global, regional, and local scales for mineral exploration and environmental purposes

“…Orientation surveys for mineral exploration are covered adequately in exploration geochemistry textbooks (Hawkes and Webb, 1962;Levinson, 1974Levinson, , 1980Rose et al, 1979;Thompson, 1986), an outline of which is given below. Even for continental-scale geochemical surveys, orientation surveys, termed pilot or research projects, were carried out for the assessment of (i) overbank sediment in different European countries, Björklund, 1994, 1996;Macklin et al, 1994;Swennen et al, 1994;Bølviken et al, 1996;De Vos et al, 1996;Hindel et al, 1996;Langedal 1996a, b, c;Demetriades and Volden, 1997;Pulkkinen and Rissanen, 1997;Van der Sluys et al, 1997;Swennen et al, , 2000Demetriades, 2008;Adánez Sanjuán et al, 2014), China Xie and Cheng, 1997;, Australia Caritat et al, , 2008aCaritat et al, , 2008b and Mexico (Ridgway et al, 1995), and (ii) soil in the United States of America and Canada (Smith et al, 2005;Morrison et al, 2008).…”