Extreme Arsenic Bioaccumulation Factor Variability in Lake Titicaca, Bolivia

Area of Science:

• Environmental Science
• Biogeochemistry
• Ecotoxicology

Background:

• High arsenic (As) levels in surface and groundwater pose significant human health risks globally.
• Latin America faces widespread arsenic contamination, necessitating studies on its environmental cycling.

Purpose of the Study:

• To investigate the biogeochemical cycling of arsenic (As) mediated by periphyton in two South American lakes.
• To quantify arsenic bioaccumulation and speciation in periphyton and associated environmental matrices.

Main Methods:

• Arsenic concentration analysis in water, sediment, and Schoenoplectus californicus.
• Arsenic speciation determination using X-ray absorption spectroscopy.
• DNA analysis to identify potential arsenic-metabolizing taxa.

Main Results:

• Dissolved arsenic concentrations ranged from 5.0-15 μg L⁻¹ in Lake Titicaca to 78.5 μg L⁻¹ in Lake Uru Uru.
• Record-high periphyton bioaccumulation factors (BAFs) up to 245,000 were observed in Lake Titicaca, with As(V) and monomethyl-As (MMA(V)).
• Variable BAFs (1281–11,962) were found at other sites, with diverse arsenic species including arsenosugars.

Conclusions:

• Periphyton play a crucial role in arsenic biogeochemical cycling, with some taxa demonstrating hyperaccumulation potential.
• While current ecosystem and human health impacts appear limited, these organisms offer promise for arsenic bioremediation.
• Further research is needed to isolate and characterize the specific organisms responsible for arsenic hyperaccumulation.