Sediment origin and budget in Sepetiba Bay (Brazil) - an approach based on multielemental analysis

Abstract

Sediment origin and transport were determined in a shallow 447 km 2 coastal lagoon in Brazil, using the distribution of major elements in bottom and suspended sediments. Applying multivariate analysis, the sum of normalized concentrations of Ti, Fe, and Al in sediments was selected to trace the terrigenous influence in bottom sediments, whereas Ca, Si, and K were used as indicators of marine influence. Sepetiba Bay bottom sediments are dominated by up to 80% terrigenous inputs. The open bay sediments are enriched in P, Mg, K, and Ca because of the intensive water column primary production. The inner bay forms an independent circulation cell with a predominance of terrigenous sediments. The results suggest a long residence time for particles in the bay, demonstrated by the magnitude of resuspension flux compared to the total sediment input to the bay.

The Paleo-Environmental Setting of Sepetiba Bay, Rio De Janeiro, Brazil, in the Late Pleistocene: Interpretations From High-Resolution Seismic Stratigraphy

“…Because we do not know the environmental characteristics surrounding Sepetiba Bay, during the Pleistocene, the bankfull condition for calculations is used to approximate the maximum value of river discharge. The highest flood discharges documented for the Guandú River, the largest river in the area, were 190 m 3 /s in the 1940s (Goes, 1942;Barcellos et al, 1997) to 288 m 3 /s during the last 20 years (oral communication, Superintendência Estadual de Rios e Lagoas -SERLA, 1997). The bankfull discharge obtained for the paleo-river is equivalent to or larger than the modern values of Guandú River.…”

Mercury speciation changes in waters of the sepetiba Bay, SE Brazil during tidal events and different seasons

“…Once reaching the bay, Hg, as well as other trace metals associated with suspended particulate matter and transported by rivers, are distributed following tidal currents within the bay. 33,37,49 …”

“…Once reaching the bay, Hg, as well as other trace metals associated with suspended particulate matter and transported by rivers, are distributed following tidal currents within the bay. 33,37,49 Sample collection Four field campaigns (F 1 , F 2 , F 3 and F 4 ) were conducted in the water column at the mouth of Sepetiba Bay, in a fixed point at the main canal of the Bay, during the flood and ebb periods and in the dry and wet seasons ( Figure 1). In each campaign, vertical profiles in the water column were sampled hourly during a half tidal cycle in three different depths: surface, mid water and bottom with water depths of 1, 6 and 12 meters, respectively.…”

Heavy metals in sediment profiles from Sepetiba and Ribeira Bays: A comparative study

“…Despite the presence of several condominiums, marinas, and the Almirante Alvaro Alberto Nuclear Power Plant effluent discharge point, it remains well preserved. Detailed site descriptions of Ribeira and Sepetiba Bays are available in the literature [1][2][3][4][5][6][7][8].…”

“…These comparisons were made to verify whether Ribeira Bay could constitute a reference database for metal concentrations in the neighboring Sepetiba Bay, as proposed by Cardoso et al [1]. It also aims to verify if the changes in the concentration of elements such as aluminum, iron and rare-earth reflect man-made interventions in the Sepetiba Bay drainage system [6]. Due to the actual harbors construction and expansion in Sepetiba Bay, large areas have been dredged and, in order to support the necessary environmental impact assessment studies, metal fluxes and burden will be also presented.…”