Identification and Quantification of Trace Metal Speciation in Sediments Using Hyperspectral Imaging

Area of Science:

• Environmental Science
• Analytical Chemistry
• Spectroscopy

Background:

• Sediment contamination by trace elements (TE) poses significant environmental risks.
• TE speciation dictates their mobility, bioavailability, and toxicity, making its characterization crucial.
• Current analytical methods for TE speciation are often complex and costly.

Purpose of the Study:

• To explore the potential of visible and near-infrared hyperspectral imaging (HSI) for estimating TE speciation in sediments.
• To assess the capability of HSI to identify and quantify different chemical species of TEs based on spectral properties.
• To evaluate HSI as a rapid and accurate alternative or complement to conventional analytical techniques.

Main Methods:

• Preparation of standard ranges of sixteen chemical species of six TEs (As, Cd, Cu, Ni, Pb, Zn).
• Use of three model sediment matrices: clay, silt, and organic matter.
• Application of visible and near-infrared hyperspectral imaging (HSI) to analyze spectral properties.

Main Results:

• Specific spectral absorptions were identified for each TE species.
• Nine TE species were successfully quantified using HSI.
• Detection limits were approximately 1 g/kg in the visible range and 10 g/kg in the short-wave infrared range.

Conclusions:

• HSI is a promising non-destructive spectroscopic method for characterizing TE speciation in sediments.
• This approach allows for a more accurate and rapid assessment of environmental risk.
• HSI can complement conventional analytical methods for TE analysis in complex matrices.