Journal of the Chilean Chemical Society
On-line version ISSN 0717-9707
CHIRINOS, LUIS R et al. CHEMICAL PROFILES IN LAKE SEDIMENTS IN LAGUNA CHICA DE SAN PEDRO (BIO-BIO REGION, CHILE). J. Chil. Chem. Soc. [online]. 2005, vol.50, n.4, pp. 697-710. ISSN 0717-9707. http://dx.doi.org/10.4067/S0717-97072005000400010.
Metal profiles in lake sediments could provide historical environmental information on impacts caused by human activities and natural events, with view to the formulation of effective environmental policies. This paper presents data on sedimentary metal profiles in Laguna Chica de San Pedro (LCSP) lake, located in the Bio Bio Region in Southern Chile, where important industrial activities are concentrated. Sediment properties (organic and inorganic matter, grain size, particle distribution, biogenic silica, Mn/Fe ratio), major (Al, Ca, K, Mg, Ti, Na), trace (V, As, Co, Cu, Zn, Ni, Cr, Pb, Sr), and mobile (Fe, Mn, P, S) elements, as well as mineral profiles (plagioclase, quartz, clays, amorphous material) are presented, up to 65 cm depth. In general, relatively constant concentration profiles are observed in the sedimentary core mid section, for most elements. Most changes in composition are seen at the top (recent industrial period) and bottom (before human intervention) sections. Variable redox conditions, generated by biological activity at the sediment-water interface are likely to account for composition profiles at the sediment-water interface. On the other hand, physical processes seem to be mostly responsible for concentration changes in Pre-industrial sediments. Mineral content profiles, such as plagioclase, clay and quartz, as well as total clay content remain fairly constant in most of the core, showing significant changes at its bottom part. High excess V, As, and S values, especially at the upper sediment, arise as a consequence of redox conditions in the lake. Certainly, such metal enrichment is mainly associated with natural sedimentary matter supply from the watershed