Geochemical Signatures of Recent Holocene Estuarine Sediments of the Jaboatão River, Pernambuco, Brazil
The Jaboatão River Basin, northeastern Brazil, is characterized by urban and industrial land uses, although it includes extensive sugarcane plantations with a marked deterioration of the native forests. Heavy metal (HM) concentrations in estuarine sediments of the river have been measured to assess possible historical sources of pollution. The trace metals were investigated based on samples from a drill core taken 4 km from the mouth of the river. The sediments of the core were analysed for chemistry, particle size, and organic matter (OM) content. The chemical species analysed (As, Cr, Pb, Hg, Ni, and Zn) show higher concentrations in the 30–35 cm interval of the core. This indicates that the accumulation of HMs has been constant over the last few decades and confirms the existence of two well-differentiated compartments, one above and one below the 30–35 cm horizon. The partitioning of the sedimentary and geochemical profiles highlights varying environmental conditions in the estuary. This behaviour is marked by a conspicuous dichotomy in the C/N ratio, specifying signatures dependent on the geochemistry of the sediments and on hydrodynamic variations, in an essentially organo–siliciclastic depositional context. The OM present in the sediments indicates a progressive evolution of continental environment conditions at the bottom to more estuarine conditions at the top, which could indicate a small and progressive drowning of the Jaboatão River mouth, probably related to sea-level rise in the range considered.
KeywordsHeavy metal Organic matter Environmental geochemistry
- Hu, J., Peng, P., Jia, G., Mai, B., & Zhang, G. (2006). Distribution and sources of organic carbon, nitrogen and their isotopes in sediments of the subtropical Pearl River estuary and adjacent shelf. Southern China Marine Chemistry,98(2–4), 274–285.Google Scholar
- Lima E. A. M. (2008). Avaliação da Qualidade dos Sedimentos e Prognóstico Geoquímico Ambiental da Zona Estuarina do rio Botafogo, Pernambuco. PhD, Brasil, UFPE, p. 172.Google Scholar
- Usui, T., Nagao, S., Yamamoto, M., Suzuki, K., Kudo, I., Montani, S., et al. (2006). Distribution and sources of organic matter in surficial sediments on the shelf and slope off Tokachi, western North Pacific, inferred from C and N stable isotopes and the C/Nratios. Marine Chemistry,98, 241–259.CrossRefGoogle Scholar