Publication Date:
2011-06-27
Description:
A sediment core from Guanabara Bay (Brazil) was analyzed for 210 Pb dating, grain size, total organic carbon (TOC) and total nitrogen, carbon stable isotope ratio (δ 13 C), nitrogen stable isotope ratio (δ 15 N) and the metals Fe, Mn, Ni, Co, Cu, Pb, V and Zn, to assess the influence of land use changes on the aquatic system in a region for which large industrial and urban development is expected in the next few decades. To obtain baseline data for improving the monitoring of the expected increase in anthropogenic impacts from surrounding drainage basins, a multivariate analysis of data from different sediment layers was carried out to evaluate the dated sediment record. The geochemical data suggested three different sedimentary phases along the last 200 years. Before the 1880s, the highest clay and TOC contents were observed, where the C/N ratios and the δ 13 C values suggested a mixture of algal and terrestrial organic matter and the lowest concentrations of Co, Cu, Pb, V and Zn, for which background levels were estimated (4.6, 2.7, 14.9, 24.3 and 70.2 mg kg −1 , respectively). From the 1880s to the 1950s, the metal concentrations and sand particles increased, but no change in organic matter quality was observed, reflecting a period of land use change, still without significant sewage input. After the 1950s, the sedimentation rate increased from 0.42 to 0.77 cm year −1 and increasing urban sewage input was evidenced by lower C/N ratios, higher δ 15 N, decrease of Fe and Mn concentrations and increased fluxes of metals and TOC, which showed a good relationship with population growth data. Content Type Journal Article Pages 1-9 DOI 10.1007/s12665-011-1143-4 Authors Fábio F. Monteiro, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Renato C. Cordeiro, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Ricardo E. Santelli, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Wilson Machado, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Heitor Evangelista, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, Maracanã, Rio de Janeiro, RJ, Brazil Leonardo S. Villar, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Luis C. A. Viana, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Edison D. Bidone, Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, Centro Niterói, Rio de Janeiro, RJ, Brazil Journal Environmental Earth Sciences Online ISSN 1866-6299 Print ISSN 1866-6280
Print ISSN:
1866-6280
Electronic ISSN:
1866-6299
Topics:
Geosciences
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