Arsenic mobility in sediments from Paracatu River Basin, MG, Brazil

Area of Science:

• Environmental Science
• Geochemistry
• Agricultural Science

Background:

• The Paracatu River Basin in Brazil is characterized by extensive irrigated agriculture and mining operations (gold, lead, zinc).
• The region naturally contains sulfide minerals and high levels of arsenopyrite, a primary arsenic-bearing mineral.
• Elevated arsenic (As) levels in environmental compartments pose risks to ecosystems and human health.

Purpose of the Study:

• To evaluate the distribution, mobility, and transport of arsenic (As) in surface water, groundwater, sediments, and local vegetables.
• To assess arsenic contamination levels against established environmental quality standards.

Main Methods:

• Collection of surface water, groundwater, sediment, and vegetable samples in October 2010 and November 2011.
• Analysis of arsenic concentrations in all collected environmental samples.
• Statistical correlation analysis to determine relationships between arsenic levels in different compartments.

Main Results:

• Sediment samples exhibited high arsenic concentrations (738–2,750 mg kg⁻¹), exceeding environmental standards (5.9 mg kg⁻¹).
• 37% of water samples showed arsenic levels above the quality standard (10 µg L⁻¹), ranging from below detection limit to 110 µg L⁻¹.
• Most vegetable samples contained arsenic within the normal range for plants (below detection limit to 120 mg kg⁻¹), but a correlation with water and sediment arsenic was observed.

Conclusions:

• Arsenic contamination in sediments and water from the Paracatu River Basin significantly exceeds established environmental quality standards.
• A clear correlation exists between arsenic concentrations in water, sediment, and vegetable samples, indicating potential pathways for arsenic uptake.
• The findings highlight the environmental risks associated with mining and agricultural activities in arsenic-rich regions.