Polycyclic aromatic hydrocarbons contamination in Amazonian environments: a systematic review.

Area of Science:

• Environmental Science
• Ecotoxicology
• Analytical Chemistry

Background:

• The Amazon River basin faces significant organic pollutant contamination, notably polycyclic aromatic hydrocarbons (PAHs).
• PAHs pose risks to aquatic ecosystems and potentially human health.
• Understanding PAH distribution and impact is crucial for environmental management.

Purpose of the Study:

• To systematically review and evaluate environmental samples (water, sediment, biota) as monitoring tools for PAHs in the Amazon.
• To assess the extent and geographical distribution of PAH contamination in the Amazon ecosystem.
• To identify key areas and sources of PAH pollution.

Main Methods:

• Comprehensive literature search of four databases (PubMed, ScienceDirect, Web of Science, Scopus) from January 2013 to June 2024.
• Inclusion of 25 studies that analyzed PAHs in environmental samples from the Amazon.
• Systematic review and synthesis of PAH concentration data across different matrices and locations.

Main Results:

• Widespread and significant PAH contamination confirmed across the Amazon ecosystem.
• Sediments emerged as the most affected environmental matrix.
• Highest PAH levels were found in Ecuador (Aguarico and Napo Rivers) and Brazil (São Raimundo Harbor, Barcarena), linked to oil extraction and industrial activities.
• PAHs in water ranged from 4 to 5,363,000 ng L⁻¹, and in sediment from 5 to 711,100 ng L⁻¹.
• Biomarkers in fish indicated ecotoxicological effects, including oxidative stress and genotoxicity.
• Research is heavily concentrated in Brazil (84% of studies).

Conclusions:

• Environmental samples, especially sediments, are effective indicators of PAH contamination in the Amazon.
• PAH pollution is a pervasive issue in the Amazon, with specific hotspots linked to anthropogenic activities.
• Ecological impacts are evident, but human health risk data are limited.
• There is a critical need for expanded research in underrepresented Amazonian regions to understand the full scope of PAH contamination.