Heavy Metal Contamination and Blue Carbon in Puerto Rican Mangroves

Journal of Environmental Quality Article

In this study, Howe et al. (2025) examined the impact of heavy metal pollution on the carbon storage capacity of mangrove ecosystems in Puerto Rico. By measuring concentrations of arsenic, cadmium, chromium, copper, nickel, lead, mercury, and zinc in both soils and mangrove tissues, the team assessed bioconcentration factors (BCFs) and their influence on soil organic carbon retention.

Key takeaways:

• Metal Accumulation: Elevated levels of nickel, copper, and zinc were found in mangrove tissues, indicating strong uptake from surrounding soils.

• Carbon Trade-offs: High metal concentrations were associated with reduced soil organic carbon, suggesting contamination can undermine blue carbon storage.

• Site Differences: Lagoon systems with greater human disturbance exhibited higher contamination levels compared to less-impacted sites.

• Mangrove Response: While mangroves show some resilience to contamination, chronic exposure threatens their long-term climate mitigation potential.

Significance: This research highlights the dual challenge of protecting mangroves as both carbon sinks and pollution buffers. Integrating pollution management into blue carbon strategies is critical to sustaining the climate and ecosystem services of mangroves in the Caribbean and beyond.

Full access to the research article: https://acsess.onlinelibrary.wiley.com/doi/10.1002/jeq2.70078