In order to assess the impact of anthropogenic activities on carbon and nutrient accumulation, total organic carbon (TOC), nitrogen (TN), and phosphorus (TP) accumulation rates were examined in a 210Pb-dated mangrove sediment core from Sepetiba Bay, Brazil, a coastal region impacted by multiple environmental changes during the previous century.
Materials and methods
A 50-cm length sediment core was collected from a mangrove forest in Sepetiba Bay. Sediment subsamples were analyzed to measure TOC, TN, δ13C, and δ15N using an elemental analyzer attached to an isotope ratio mass spectrometer Thermo Finnigan Model Delta Plus XP, whereas colorimetric analysis were used to measure TP. For 210Pbex analyses, gamma-ray measurements were performed in a semiplanar intrinsic germanium high purity coaxial detector, coupled to a multichannel analyzer, whereas the sediment accumulation rate (SAR) was calculated according to the constant initial concentration (CIC) method. Also, carbon and nutrient fluxes were calculated using SAR and TOC, TN, and TP contents, whereas statistical differences were evaluated by ANOVA + Tukey HSD analysis with previous data normalization.