Geochronology and heavy metal flux to Guanabara bay, Rio de Janeiro state: a preliminary study

Abstract

Guanabara Bay, located in Rio de Janeiro state. It is surrounded by the second most important metropolitan area of the country. Over recent decades, land disturbance and urbanization in the surrounding area has significantly increased sediment input to the bay and had a negative effect on its overall environmental. This is especially related to high volumes of untreated sewage and industrial effluents. This study evaluates the history of this human impact through detailed examination of a sediment core taken from the northern portion of Guanabara Bay. A geochronology is established using 210 Pb dating and related to organic carbon and heavy metal fluxes to the sediments. This gave a calculated net average sedimentation rate for the core of 0.67 cm.year -1 . The organic carbon and heavy metals flux started to increase at the beginning of the last century and the highest values was observed in the top of the cores.

Phosphorus fractionation distribution in Guapimirim estuary: SE Brazil

“…The region has experienced socio-spatial transformations and population growth, which were generated by the deployment of a large petrochemical complex (COMPERJ) and other activities related to the oil and gas sector (Klink 2013; Baptista Neto et al 2013). …”

“…Over the last 100 years, the catchment area around this bay has been strongly modified by human activities, which have increased river discharge, sediment loads and the amount of waste and untreated sewage entering the bay (Borges et al 2009; Aguiar et al 2011; Fonseca et al 2013; Baptista Neto et al 2013). As the largest contributor of fresh water to Guanabara bay, the Guapimirim estuary also brings in nutrients, especially phosphorus (P), from sewage and various human activities in its catchment area.…”

Sources of Pollutants in the Northern/Northeast Area of Guanabara Bay (Se, Brazil) Since the Late Nineteenth Century Using Lead Isotopes and Metal Concentrations

“…Guanabara Bay (southeastern Brazil) is located between the latitudes 22º24' and 22º57 'S and longitudes 42º33' and 43º19' W. It practically encompasses the entire metropolitan region of Rio de Janeiro and, despite being of incontestable historical, economic, cultural, scientific, social and environmental importance, it is one of the most degraded coastal environments in the country (Baptista Neto et al, 2013). It is a complex ecosystem which includes for instance forests, mangroves, marshes, wetlands, lagoons, dunes, beaches, rivers, estuaries, coves, islands, slabs, pinnacles, rocky outcrops and cliffs (Amador, 1997).…”

Seagrass and Submerged Aquatic Vegetation (VAS) Habitats off the Coast of Brazil: state of knowledge, conservation and main threats

“…These processes have included the conversion of mangrove forests into urban areas, bridge building and the installation of treatment plants ( GRILLO et al, 2013;BAPTISTA NETO et al, 2013a). In and surrounding Guanabara Bay, for example, the catchment area has been greatly modified by human activities over the last 100 years, in particular by the deforestation and uncontrolled settlemen, which have generally increased the river discharges and sediment loads flowing into the bay (BAPTISTA NETO et al, 2013b). Consequently, the average rates of sedimentation are very high (from 0.67 cm y -1 to 2 cm y -1…”