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Application of organic carbon and nitrogen stable isotope and C/N ratios as source indicators of organic matter of Nova Viçosa-Caravelas estuarine complex, southern Bahia, Brazil

2014; Sociedade Brasileira de Geologia; Volume: 44; Issue: 1 Linguagem: Inglês

10.5327/z2317-4889201400010003

2317-4889

Saulo Spanó, André Belem, Rafael Nunes Doria, Maria do Rosário Zucchi, José Roberto Bispo de Souza, Alexandre Barreto Costa, Carlos A. D. Lentini, Antônio Expedito Gomes de Azevedo,

Marine Biology and Ecology Research

This study characterized the elementary ratio and isotopes (δ 13 C, δ 15 N and C/N) of surface sediments and suspended solids in surface water of 20 sample points in the estuarine complex of Nova Viçosa-Caravelas, southern Bahia, Brazil .The d 13 C DIC of the dissolved inorganic carbon (DIC), the δ 18 O and δD and physicochemical parameters of water was analyzed to estimate the contribution of continental sources, marine and anthropogenic interference in the study area.The area is characterized by the influence of adjacent coastal area through the main channel of Caravelas Estuary entrance and the Peruípe River in Nova Viçosa Estuary, as the main freshwater intake.The highest values of δ 13 C in sediment and DIC in water were found in the Caravelas bar and higher values of total organic carbon and C/N ratio found within the two channels that interconnect the estuaries of Caravelas and Nova Viçosa.The isotope ratios of carbon and nitrogen indicate that the analyzed organic matter has terrestrial origin with strong signature of mangroves, characteristic of estuarine regions.Although the values of C/N indicate an anthropogenic contribution at some sampling points, the δ 15 N found, compared with the literature, suggests that processes of N series cycling in the estuary are sufficient to keep the impact of human activity in the region at low levels.The results may serve as a baseline for future monitoring and environmental studies in estuarine complex of Nova Viçosa-Caravelas.