Spatial sedimentary distribution, seasonality and the characteristics of organic matter on Fernando de Noronha insular shelf

• Published in: Brazilian journal of oceanography 2018-01, Vol.66 (1), p.131-156
• Main Authors: Barcellos, Roberto Lima, Oliveira, Liza Ellen Eurico de, Flores-Montes, Manuel de Jesus
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Archipelagoes; Atlântico Sul; Bioclastos; Calcium; Calcium carbonate; Calcium carbonates; Carbonates; Evaluation; Geochemistry; Grain size; Gravel; Human influences; MARINE & FRESHWATER BIOLOGY; Matéria orgânica sedimentar; Morphology; Nitrogen; OCEANOGRAPHY; Organic carbon; Organic matter; Organic phosphorus; Phosphorus; Plataforma insular; Ratios; Razão δ13C; Seasonal variation; Seasonal variations; Seasonality; Sediment; Sediment distribution; Sediment samplers; Sediment samples; Sedimentos marinhos; Sediments; Spatial distribution; Spatial variations; Total organic carbon; Wave action
• ISSN: 1679-8759; 1982-436X; 1982-436X
• DOI: 10.1590/s1679-87592018146206601

Abstract The present study was conducted in the Fernando de Noronha archipelago (4°S/32°W). The objective is the evaluation of the spatial distribution and seasonal variations in the sediments and sedimentary organic matter in the northern insular shelf of Fernando de Noronha ("Mar de Dentro"). Nineteen surface sediment samples were collected between December 2013, July 2014 and November 2014. The studied methods included analysis of the grain size, coarse fraction, morphoscopy, total organic matter content, calcium carbonate, organic carbon, total nitrogen, sedimentary phosphorus (organic, inorganic and total), elemental ratios (C/N, C/P) and stable isotopic ratios (δ13C-δ15N). The results allowed to infer that there is no seasonal variation in sediment distribution. Whereas, the shelf sediments present a calcareous sandy sedimentary cover (CaCO3≈ 88.3%), predominantly of well-sorted fine sands, with low organic matter content (TOM