Santos Felipe R, Bícego Márcia C, Araújo Lígia D, Lourenço Rafael A, Taniguchi Satie, Martins César C, Figueira Rubens C L, Wainer Ilana K C, Rocha Cesar B, Mahiques Michel M
Instituto Oceanográfico, Universidade de São Paulo, 05508-120 Praça do Oceanográfico, 191 São Paulo, SP, Brazil.
Instituto Oceanográfico, Universidade de São Paulo, 05508-120 Praça do Oceanográfico, 191 São Paulo, SP, Brazil.
Mar Pollut Bull. 2025 Oct;219:118299. doi: 10.1016/j.marpolbul.2025.118299. Epub 2025 Jun 19.
The Santos Bifurcation, located off the southeastern coast of Brazil, represents a key mesoscale hydrodynamic system where the southward-flowing Brazil Current diverges, generating complex circulation patterns that influence sediment transport, biogeochemical cycling, and the accumulation of anthropogenic contaminants along the continental margin. The distribution, sources, and deposition dynamics of organic contaminants (including dichloro-diphenyl-trichloroethane (DDTs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs)) were assessed in surface sediments from the Santos Bifurcation (SBF) region, a distinctive oceanographic feature. PCBs, DDTs and PAHs concentrations varied from 0.04 to 0.92 ng g, 0.32 to 1.29 ng g dw, and 57.23 to 276.66 ng g dw, respectively. PCB sources were predominantly associated with long-range atmospheric transport. Historical widespread use of DDTs for agriculture and pest control in continental areas led to their accumulation in the SBF region, where they have undergone slow degradation. The primary sources of PAHs were fossil fuel combustion and petroleum inputs, with latitudinal variations attributed to continental contributions and increased river runoff in southern areas, which are advected northward by coastal currents. Both pyrogenic and petrogenic PAHs are transported by internal shelf currents directed towards the continental slope. All analyzed compounds were detected at higher concentrations in deeper stations (1000 m and 1500 m isobaths) within the SBF region, likely due to regional hydrodynamic processes that enhance the transfer and deposition of contaminants at greater depths.
桑托斯分叉区位于巴西东南沿海，是一个关键的中尺度水动力系统，向南流动的巴西暖流在此处分流，形成复杂的环流模式，影响着沉积物的输送、生物地球化学循环以及大陆边缘人为污染物的积累。对桑托斯分叉区（SBF）这一独特海洋学特征区域的表层沉积物中有机污染物（包括滴滴涕（DDTs）、多氯联苯（PCBs）和多环芳烃（PAHs））的分布、来源和沉积动力学进行了评估。多氯联苯、滴滴涕和多环芳烃的浓度分别在0.04至0.92纳克/克、0.32至1.29纳克/克干重和57.23至276.66纳克/克干重之间变化。多氯联苯的来源主要与远距离大气传输有关。历史上在大陆地区广泛使用滴滴涕进行农业和害虫防治导致其在桑托斯分叉区积累，在那里它们经历了缓慢降解。多环芳烃的主要来源是化石燃料燃烧和石油输入，其纬度变化归因于大陆贡献以及南部地区河流径流量增加，这些径流被沿海洋流向北平流输送。热解成因和石油成因的多环芳烃都通过指向大陆坡的陆架内海流进行传输。在桑托斯分叉区内较深站位（1000米和1500米等深线）检测到所有分析化合物的浓度更高，这可能是由于区域水动力过程增强了污染物在更大深度的转移和沉积。
