isnotalwaysaneasytask.However,forcertainelementsthathave stable isotopes, such as Pb, it is more feasible because anthro- pogenic and natural sources often exhibit different isotopic com- positions, and Pb isotopes are not fractionated by industrial processesorbiologicalrecycling,retainingtheisotopicfingerprint of their source (Shirahata et al., 1980; Véron et al., 1994; Chiaradia et al., 1997; Monna et al., 2000; Bindler et al., 2001a; Brännvall et al., 2001; Renberg et al., 2001, 2002; Bindler, 2006; Soto-Jimenez et al.,2006;Yang et al., 2007). While many studies on elemental and lead isotopic geochem- istry of lake sediments have been undertaken in the Northern Hemisphere (Carignan and Nriagu, 1985; Hermanson, 1993; Graney et al., 1995; Farmer et al., 1996; Branvaall et al., 1997; Von Gunten et al., 1997; Schettler and Romer, 1998; Rasmussen et al.,1998;Kober et al.,1999;Outridge,2000;Eades et al.,2002; Outridge et al.,2002;Renberg et al.,2002;Yang et al.,2002a;Ng and King, 2004; Schettler and Romer, 2006; Grahn et al., 2006; Introduction Chemostratigraphy of lake sediments has been used in a number of studies as a tool to reconstruct natural environmental changes, andtoassesstheextentofhumanactivitiesintracemetaldeposi- tion. However, the interpretation of the palaeoenvironmental recordprovidedbysedimentgeochemistryisoftenambiguous.As pointedoutbyearlierauthors,thesurfaceenrichmentofmetalsin lakesedimentsmaybeattributednotonlytoanthropogenicactiv- ities, but also to natural processes such as postdepositional remo- bilization caused, for instance, by different degrees of metal affinityfororganicmatter(Ramussen,1998;ElBilali et al.,2002; Yang et al., 2002a; Outridge et al., 2005; Sanei and Goodarzi, 2006).Thus,tracingthesourcesoftraceelementsinlakesediments Abstract: A 72 cm long core was collected from Lagoa da Viração (LV), a small pond in the Fernando de Noronhaisland,northernBrazil.Sedimentsfromthelowersectionofthecore(20–72cmdepth)containessen- tially mineral matter, while in the upper section (0–20 cm depth) mineral matter is mixed with organic matter. Lithogenic conservative elements – Si, Al, Fe, Ti, Co, Cr, Cu, Ba, Ga, Hf, Nb, Ni, Y, V, Zn, Zr and REE – exhibitremarkablyconstantvaluesthroughoutthecore,withconcentrationssimilartothoseofthebedrock.The vertical distribution of soluble elements – Ca, Mg, Na, K, P, Mn and Sr – is also homogeneous, but these ele- ments are systematically depleted in relation to the bedrock. LOI, TOC, Br, Se, Hg and Pb, although showing nearlyconstantvaluesinthelowersectionofthecore,aresignificantlyenrichedintheuppersection. Thecon- centrationprofilesofBrandSesuggestthattheymaybeaccountedforbynaturalprocesses,relatedtotheslight affinityoftheseelementsfororganicmatter.Ontheotherhand,theelevatedlevelsofHgandPbinrecentsed- iments may be explained by their long-range atmospheric transport and deposition. Furthermore, the isotopic composition of Pb clearly indicates that anthropogenic sources contributed to the Pb burden in the uppermost pond sediments. Key words: Geochemistry, lake sediments, Fernando de Noronha, mercury, lead isotopes. The Holocene 19,3 (2009) pp. 433–442 © 2009 SAGE Publications 10.1177/0959683608101393 *Author for correspondence (e-mail: soniaoli@usp.br) A geochemical and lead isotopic record from a small pond in a remote equatorial island, Fernando de Noronha, Brazil Sonia Maria Barros de Oliveira, 1 * Luiz Carlos Ruiz Pessenda, 2 Suzy Eli Marques Gouveia, 2 Marly Babinski 1 and Deborah Ines Teixeira Favaro 3 ( 1 Institute of Geosciences, University of São Paulo, rua do Lago, 562, São Paulo 05508-080, Brazil; 214 C Laboratory, Centre for Nuclear Energy inAgriculture, University of São Paulo, Caixa Postal 96, Piracicaba SP 13416-000, Brazil; 3 Institute of Nuclear and Energetic Research, IPEN, Caixa Postal 11049, São Paulo, Brazil) Received 3 December 2007; revised manuscript accepted 28 August 2008 08-101393-Oliveira:HOL-Template 1/21/2009 7:26 PM Page 433 PROOF ONLY