Determination of baseline element composition of lichens using samples from high elevations.

Area of Science:

• Environmental Science
• Geochemistry
• Botany

Background:

• Lichens are sensitive bioindicators of environmental conditions.
• Establishing baseline elemental composition is crucial for pollution monitoring.
• Remote high-elevation areas offer insights into natural elemental deposition.

Purpose of the Study:

• To determine the baseline trace element composition of lichens from unpolluted regions.
• To differentiate between natural and anthropogenic elemental inputs in lichens.
• To propose a method for establishing reference elemental concentrations.

Main Methods:

• Sample collection from high-elevation, low-pollution sites in the Himalayas, Mt. Kenya, and the Alps.
• Multi-elemental analysis of lichen trace elements, primarily using Instrumental Neutron Activation Analysis (INAA).
• Statistical analysis to identify dominant sources of elemental variation.

Main Results:

• Lichen elemental composition is primarily influenced by airborne soil dust (natural occurrence).
• Long-range atmospheric transport of pollutants contributes to elevated levels of volatile elements like Bromine (Br), Cadmium (Cd), and Antimony (Sb).
• The average of the lowest observed concentrations is proposed as a reliable indicator of natural elemental composition.

Conclusions:

• Baseline elemental concentrations in lichens are mainly derived from natural soil dust.
• Anthropogenic pollutants can be detected in remote areas, particularly volatile elements.
• The proposed method of using lowest concentrations aids in establishing accurate reference values for lichen elemental composition.