oa Pyrogenic Carbon Accumulation in the Iberian Margin During the Common Era Revealed by Pah and Black Carbon

This study investigates the accumulation of combustion-derived materials—specifically polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC)—in marine sediments from the Iberian Margin over the past 2,000 years. These materials serve as valuable proxies for reconstructing past fire activity, pollution, and human influence. Sediment cores from offshore Douro (Porto), Tagus, and Algarve were analyzed as part of the ICW3P Project.

The Tagus core showed the highest PAH fluxes, particularly during the Little Ice Age and post-1909, indicating increased industrial and high-temperature combustion. Four- and five-ring PAHs dominated, suggesting strong anthropogenic input. Diagnostic PAH ratios confirmed pyrogenic sources. In contrast, the Porto core showed perylene abundance in deeper layers, hinting at natural sources. PAH data from Algarve was minimal.

Black carbon profiles were consistent across cores but did not correlate with PAH trends. Stable carbon isotope values (δ13C) of BC were similar in Tagus and Douro, suggesting limited use of BC as a combustion marker in these sediments.

The results highlight that PAHs, more than BC, are effective indicators of historical pyrogenic inputs. Continued refinement of core resolution and integration with other proxies will enhance the understanding of past environmental changes on the Iberian Margin.