In order to investigate the influence of shrimp farming activities on carbon and nutrient accumulation, sediment cores were collected from two areas at different distances from shrimp farms within a Peruvian mangrove ecosystem. In both areas two sediment cores were collected in a transect, one from a mangrove-covered site and one from a mudflat site. At both study sites, the isotopic values of carbon and nitrogen as well as the C:N molar ratios suggest that the highest carbon accumulation rates were linked to terrestrial-derived organic matter, with higher carbon stocks and fluxes within mangrove-covered zones. The historical records indicate that since the mid-1970's, the areas nearest to the shrimp farming activity have been accumulating higher proportions of algal derived organic matter, which were likely triggered by the high nutrient influx derived from shrimp farming effluents. The...

Phosphorus is an essential element for life and, when scarce, this macronutrient is a limiting factor for primary production. Phosphorus (P) is a widely used element in the composition of fertilizers, besides being present in large quantities in domestic effluents. Its accumulation in the springs is related to the proliferation of algae and cyanobacteria. In excess, P is a pollutant that contributes greatly to the eutrophication, development of reduced conditions and deterioration of water bodies. In order to understand how the anthropogenic action affected the accumulation of P in the freshwater reservoir of Salto Grande, Americana City (São Paulo State, Brazil), the evaluation of a temporal sedimentary record was carried out. For this purpose, a sediment core collected in the reservoir of Salto Grande was studied. The sediment core recorded the reservoir history since its filling in 1...

Purpose 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 Pb-210-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, delta C-13, and delta N-15 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 (210)Pbex analyses, gamma-ray measurements were performed in a semiplanar intrinsic germanium high purity coaxial detector, coupled to a multichannel analyzer, whereas the sediment accumu...