Environmental and anthropic variabilities at Guanabara Bay (Brazil): A comparative perspective of metal depositions in different time scales during the last 5,500 yrs

• Published in: Chemosphere (Oxford) 2021-03, Vol.267, p.128895, Article 128895
• Main Authors: Cordeiro, R.C., Monteiro, F.F., Santelli, R.E., Moreira, L.S., Figueiredo, A.G., Bidone, E.D., Pereira, R.S., Anjos, L.C., Meniconi, M.F.G.
• Format: Article
• Language: English
• Subjects: Anthropogenic signals; Bays; Brazil; Environmental Monitoring; Geologic Sediments; Guanabara bay; Holocene; Humans; Metals; Metals, Heavy - analysis; Palaeoenvironment; Sediments; Water Pollutants, Chemical - analysis
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.128895

The determination of age-dated metal sediment accumulation rates in a representative South American bay is able to portray the dimension of human impacts during the colonial occupation and industrial periods. Many studies have assessed metal distribution and chronology at Guanabara Bay, in Brazil. However, understanding natural variabilities associated to paleoclimatic changes and comparing these natural variabilities to anthropogenic processes are not well established to date. Accurate geochronological control integrating ages determined by 210Pb and 14C chronologies through an exponential spline fit model allowed for a precise definition of changes associated to the holocene marine transgression, as well as the colonial period, leading to intense land use changes, and the industrial period. The reference values of the system were defined based on their concentrations and the accumulation rates of ecotoxicologically important metals. Al, Ba, Fe, Cd, Cu, Cr, Li, Ni, Mn, Pb, Si, Ti, V, and Zn distributions were determined in a Guanabara Bay core (BG-28) by the EPA 3051 method. Elemental distribution profile assessment allowed for the identification of variabilities associated to weathering processes, predominantly of lithogenic origin, mainly for Al, Ba, Fe, Li, Si, and V. Weathering processes occurred simultaneously to land use changes in the drainage basin since the colonial period, at 400 cal yr BP, and during the industrial period, mainly after the 1960s, denoted by Cd, Cr, Cu, Mn, Pb and Zn increases. The highest average metal enrichment values metals associated to industrial processes reached 5.95, with 119.1-fold higher accumulation rates than the background accumulation values observed between 4200 and 500 cal yr BP. [Display omitted] •Al, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn, V were determined by EPA method 3051 in a 5,500 year sediment record from Guanabara Bay.•The natural variability of weathering processes, transport and deposition were predominant for Al, Ba, Fe, Li, Si, and V.•Land-use change since the colonial period, at 400 cal yr BP, and industrial period, indicates Cd, Cr, Cu, Mn, Pb and Zn increase.•The highest normalized degree of contamination and average accumulation enrichment reached 5.95 and 119 respectively in 90’s.