Evidence of anthropogenic and climate-related processes derived from metal contents in sediment cores from a heavily industrialized subtropical estuary

Author(s)

Ferreira, Paulo Alves de Lima ; de Mahiques, Michel Michaelovitch ; Sartoretto, Julie Rosemberg ; Figueira, Rubens Cesar Lopes

• Document type: Journal article
• Source: ENVIRONMENTAL EARTH SCIENCES; v. 84, n. 6, p. 15-pg., 2025-03-01.

Abstract

In this study, the levels of metallic elements (Al, Cr, Cu, Fe, Mn, Ni, Pb, Sc, V, and Zn) and radioactive tracers (excess Pb-210 and Cs-137) were determined in three sediment cores using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and gamma spectrometry, respectively. These samples were collected from the Santos-S & atilde;o Vicente Estuarine System (SSVES) on the western South Atlantic coast. This work, involving multivariate statistics and time-series analysis, discussed how anthropogenic pressures and climate-related processes impact the metal content in sediments deposited in this heavily industrialized coastal system. The sedimentation rate increased during the late 1960s, particularly during the 1970s and 1980s, corresponding to the period of heavy investments in industrial and urban development of the SSVES over the last seven decades. Principal component analysis generated two factors that explained between 57% and 87% of the variance in the elemental content of the sediments in each core. The first component, referred to as the natural component, showed a decreasing trend after 1970. Meanwhile, the second component, the anthropogenic component, correlated with Cu, Pb, and Zn, and increased during the same period. Time-series REDFIT analysis demonstrated that the natural component exhibits statistically significant (alpha = 5%) periodicities associated with local rainfall variability linked to the El Ni & ntilde;o-Southern Oscillation (ENSO), changes in the South American Convergence Zone (SACZ), and solar activity. These forcings drive erosional processes and influence sediment production that contribute naturally to the metallic element content in this tropical humid region where chemical weathering prevails. (AU)

• FAPESP's process: 23/05207-4 - Radiomatric and grain-size analyses in the geological record of the Santos Bifurcation region
• Grantee: Paulo Alves de Lima Ferreira
• Support Opportunities: Scholarships in Brazil - Technical Training Program - Technical Training
• FAPESP's process: 20/14356-5 - The Santos Bifurcation: present and past
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 11/50581-4 - Susceptibility and resilience of urban estuarine systems to global changes: hydro-sedimentologic budget; sea-level rise; response to extreme events
• Grantee: Rubens Cesar Lopes Figueira
• Support Opportunities: Regular Research Grants