Direct Laser-Induced Breakdown Spectroscopy Analysis of Estuarine Suspended Particulate Matter Collected on Filters

Area of Science:

• Environmental Science
• Analytical Chemistry
• Geochemistry

Background:

• Estuaries are critical interfaces for land-sea material transport, with suspended particulate matter (SPM) acting as a primary vector for metals and nutrients.
• Effective monitoring of estuarine environments requires rapid and versatile analytical techniques for characterizing SPM composition.
• Laser-Induced Breakdown Spectroscopy (LIBS) presents a non-destructive, multi-elemental analysis method suitable for direct SPM measurement on filters.

Purpose of the Study:

• To assess the spatio-temporal variability of major and trace elements in SPM from the Pacoti River estuary, Brazil.
• To evaluate the effectiveness of Laser-Induced Breakdown Spectroscopy (LIBS) for analyzing estuarine SPM.
• To investigate the relationship between elemental distribution in SPM and estuarine environmental factors like salinity and tidal dynamics.

Main Methods:

• Application of Laser-Induced Breakdown Spectroscopy (LIBS) for the direct, multi-elemental analysis of SPM collected on filters.
• Spatio-temporal sampling of SPM along the Pacoti River estuary during both rainy and dry seasons.
• Analysis of major elements (Si, Fe, Al, Ti, Na, K, Ca, Mg) and trace elements (Li, Rb).

Main Results:

• Elemental patterns in SPM were strongly influenced by the salinity gradient and tidal dynamics of the estuary.
• Most analyzed elements (Si, Fe, Al, Ti, Na, Li, K, Rb) showed inverse correlations with salinity, indicating dilution or different sources.
• Calcium (Ca) and Magnesium (Mg) exhibited positive correlations with salinity, suggesting a link to marine water influence.

Conclusions:

• Laser-Induced Breakdown Spectroscopy (LIBS) is a highly effective tool for rapid, high-throughput characterization of SPM in estuarine systems.
• The study demonstrates LIBS's capability for environmental monitoring and understanding complex biogeochemical processes in estuaries.
• Elemental distribution in SPM provides valuable insights into the interplay between freshwater discharge, tidal influences, and material transport.