Overview of the 20th century impact of trace metal contamination in the estuaries of Todos os Santos Bay: past, present and future scenarios.

This paper discusses the distribution patterns of trace metals in sediments and suspended particulate matter (SPM) in the three main estuaries of the Todos os Santos Bay (BTS), Brazil, during dry and rainy seasons. Data available up to 2012 was also reviewed to assess the status of contamination. For most elements, metal concentrations in sediments decreased from the tidal limits to the lower estuary. Metals in SPM presented more complex distributions along the salinity gradient. Metal variability between rainy and dry conditions was only significant for SPM data. Of the BTS estuaries, the levels of Cd, Zn, Pb and Cu are highest in the Subaé estuary, and they seem to be promoting harmful biological effects in macrofauna, and also may pose potential human health risks. Despite the evidence of important localized contamination, much of the data compiled indicates that the bay and its estuaries are still relatively preserved.