Tracing contamination in a tropical coastal reserve: A 210Pb-based reconstruction of trace element inputs in Playa La Marinera, Panama

Abstract

Trace element concentrations (V, Cr, Ni, Cu, Zn) were analyzed in surface and core sediments from Playa La Marinera, a protected coastal zone in the Panama Pacific coast that serves as a nesting site for olive ridley sea turtles (Lepidochelys olivacea). ²¹⁰Pb dating revealed increased sediment accumulation from the 1950 s, coinciding with intensified rainfall and watershed land‐use changes (deforestation and livestock expansion). Trace element concentrations peaked recently (2012–2018) and in the ∼ 1950 s. Enrichment factors showed minor enrichment for V and no enrichment for Cr, Ni, Cu, and Zn, suggesting predominantly lithogenic sources. However, Cr and Ni concentrations exceeded the Probable Effect Level (PEL), indicating probable damage to the benthic community. Surface sediments showed spatial variability in trace element concentrations, with the highest levels of V, Cr, Ni, and Zn recorded at the station farthest from the river mouth and local community, possibly due to differential exposure to runoff or sediment resuspension dynamics. Compared to background values reported for other Pacific coastal sites in Panama, such as Coiba Island, most trace element concentrations were higher, except for V, reflecting site-specific environmental and geological conditions. The results establish a geochemical baseline for ongoing and future monitoring, underscoring the influence of both natural and anthropogenic factors on sediment quality in this region of high ecological value. These results establish a historical baseline of sediment contamination in Playa La Marinera, providing essential context for long-term monitoring. Beyond their local relevance, they underscore the need to protect tropical coastal reserves facing increasing land-use pressures and highlight potential implications for biodiversity conservation and risk management in nesting habitats of endangered sea turtles.