Persistent and Semivolatile Contaminants in Sediments of Nutrias Lagoon (Uruguay): Historical Trends and Potential Ecological Implications

Why It Matters

The findings reveal that atmospheric transport can contaminate ostensibly pristine coastal ecosystems, prompting policymakers to consider regional monitoring and mitigation strategies. This baseline is critical for assessing future climate‑driven changes in contaminant deposition across South America.

Key Takeaways

• PCB-52 appears sporadically after 1990s, reflecting global trends
• PBDEs absent, indicating negligible regional input
• Mercury stays 65‑85 µg/kg, below sediment guidelines
• PAHs show surface enrichment, occasional ecotoxic thresholds
• Protected lagoon still vulnerable to atmospheric contaminants

Pulse Analysis

Sediment cores act as time capsules, preserving decades of contaminant deposition that surface water samples often miss. In the case of Nutrias Lagoon, the low‑impact, protected setting offers a rare reference point to isolate long‑range atmospheric inputs from local sources. By layering chronological data, scientists can differentiate between historic production peaks—such as the late‑20th‑century rise in PCB‑52—and more recent trends, providing a nuanced picture of how global industrial cycles imprint on remote ecosystems.

The contaminant profile uncovered in the lagoon underscores divergent pathways for different pollutants. While PBDEs were undetectable, suggesting limited use or effective regulation in the region, mercury concentrations remained consistently low, aligning with background atmospheric deposition rates. In contrast, polycyclic aromatic hydrocarbons displayed a clear surface enrichment, with occasional concentrations breaching ecotoxicological thresholds for benthic fauna. This pattern points to episodic inputs, possibly tied to regional biomass burning or distant industrial events, and raises concerns about sub‑lethal effects on the lagoon’s food web.

Beyond the scientific insights, the study carries practical implications for environmental governance. Establishing a paleo‑baseline enables regulators to gauge the effectiveness of international treaties aimed at reducing persistent organic pollutants and mercury emissions. As climate change reshapes wind patterns and precipitation regimes, the frequency and magnitude of atmospheric contaminant delivery may shift, making continuous monitoring essential. Nutrias Lagoon thus serves as both a sentinel and a benchmark for South American coastal management, informing future mitigation strategies and research priorities.