Particle Fluxes and Bulk Geochemical Characterization of the Cabo Frio Upwelling System in Southeastern Brazil: Sediment Trap Experiments between Spring 2010 and Summer 2012

Anais da Academia Brasileira de Ciências

Ana Luiza S. Albuquerque¹  AndrÉ L. BelÉm¹  Francisco J.b. Zuluaga¹  Livia G.m. Cordeiro¹  Ursula Mendoza¹  Bastiaan A. Knoppers¹  Marcio H.c. Gurgel¹  Philip A. Meyers¹  RamsÉs Capilla¹ 

关键词: sediment traps;    bulk geochemical composition;    Cabo Frio Upwelling System;    particle flux;    Southeastern Brazilian shelf;    armadilhas de sedimentos;    geoquímica do particulado;    Sistema de Ressurgência de Cabo Frio;    fluxo de partículas;    Plataforma continental do Sudeste do Brasil;   

DOI  :  10.1590/0001-37652014107212

来源: SciELO

【 摘 要 】

Physical and biogeochemical processes in continental shelves act synergistically in both transporting and transforming suspended material, and ocean dynamics control the dispersion of particles by the coastal zone and their subsequent mixing and dilution within the shelf area constrained by oceanic boundary currents, followed by their gradual settling in a complex sedimentary scenario. One of these regions is the Cabo Frio Upwelling System located in a significantly productive area of Southeastern Brazil, under the control of the nutrient-poor western boundary Brazil Current but also with a wind-driven coastal upwelling zone, inducing cold-water intrusions of South Atlantic Central Water on the shelf. To understand these synergic interactions among physical and biogeochemical processes in the Cabo Frio shelf, a series of four experiments with a total of 98 discrete samples using sediment traps was performed from November 2010 to March 2012, located on the 145 m isobath on the edge of the continental shelf. The results showed that lateral transport might be relevant in some cases, especially in deep layers, although no clear seasonal cycle was detected. Two main physical-geochemical coupling scenarios were identified: singular downwelling events that can enhance particles fluxes and are potentially related to the Brazil Current oscillations; and events of significant fluxes related to the intrusion of the 18°C isotherm in the euphotic zone. The particulate matter settling in the Cabo Frio shelf area seems to belong to multiple marine and terrestrial sources, in which both Paraiba do Sul River and Guanabara Bay could be potential land-sources, although the particulate material might subject intense transformation (diagenesis) during its trajectory to the shelf edge.

【 授权许可】

CC BY   
 All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License