Sedimentary record of hydrocarbons and sewage inputs from a highly populated region in South-Eastern Brazil.

The environmental impacts of the urban expansion in Rio de Janeiro was evaluated based on the historical accumulation of black carbon (BC), aliphatic (AHs) and aromatic hydrocarbons (PAHs) and sterols in a sediment core retrieved from Botafogo Cove. BC related to oil combustion sources increased significantly since the 1990s. AHs were associated with petroleum inputs and revealed a high level of contamination. Multivariate statistical methods (a Principal Component Analysis associated with a linear multiple regression - PCA/LMR) applied to PAHs suggests changes in the sources in recent years. This can be ascribed to a reduction in pyrogenic emissions over the last four decades and to an increase in petrogenic inputs since the 1990s. The sterol dinosterol registered the increased eutrophication over the last three decades, but the sewage marker coprostanol was present at relatively low concentrations (0.40 to 1.16 µg g-1) probably caused by enhanced bacterial activity in the sediment.