Particle-bound mercury in Saharan dust-loaded particulate matter in Cabo Verde

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Public Health

Background:

• Mercury is a toxic heavy metal with significant environmental and health impacts.
• Particulate matter (PM) can bind mercury, forming particle-bound mercury (PBM), which affects air quality and human health.
• Cabo Verde is susceptible to atmospheric dust events, influencing local air pollution.

Purpose of the Study:

• To quantify particle-bound mercury (PBM) concentrations in PM10 and PM2.5 during dust and non-dust events in Cabo Verde.
• To identify the sources of PBM and assess associated health risks.
• To determine the contribution of dust events to PBM levels in different particulate matter fractions.

Main Methods:

• Collected PM10 and PM2.5 samples during dust and non-dust events at urban and rural sites.
• Measured PBM concentrations using established analytical techniques.
• Analyzed air mass trajectories and elemental markers to identify PBM sources.
• Conducted health risk assessment based on inhalation, dermal, and ingestion pathways.

Main Results:

• PBM concentrations were substantially higher during dust events (2.21-fold for PM10, 13.3-fold for PM2.5) compared to non-dust events.
• The PM10/PM2.5 PBM ratio was higher during non-dust events, indicating a greater role of coarse particles when dust is absent.
• Sources of PBM were linked to mineral dust, mining, oceanic emissions, and biomass burning.
• Dust events significantly enriched PBM in fine PM2.5 (84-94%), increasing inhalation exposure risks.

Conclusions:

• Dust events are a major contributor to elevated PBM concentrations in Cabo Verde, especially in fine particulate matter.
• Inhalation of PBM during dust events poses a significant health risk.
• Understanding PBM sources and transport is crucial for managing air quality and health impacts in the region.