A historical evaluation of anthropogenic impact in coastal ecosystems by geochemical signatures

Anthropogenic activities in Brazilian coastal areas were successfully used as a support for ²¹⁰Pb dating (Guarapina Lagoon, Marambaia Sound and data previously published on Guaratuba Bay). The calculated ²¹⁰Pb sedimentation rates were 1.4 ± 0.27, 6.1 ± 0.54 and 4.7 ± 0.21 mm/year, respectively. In the Guarapina Lagoon, an increase in the organic matter concentration was well correlated with a construction of an artificial channel in the 1950's. In Marambaia Sound, temporal changes in grain-size and heavy metal concentrations corresponded to hydrological diversions in the 1950's and the beginning of industrial activities since the 1960's. In Guaratuba Bay, a 1963 ¹³⁷Cs fallout peak was found and Hg fluxes throughout the sediment profile that were correlated with human activities within the drainage basin, such as building of reservoirs and intensification of agricultural practices since the 1960's.