Exploring the interactions and binding sites between Cd and functional groups in soil using two-dimensional...

Area of Science:

• Environmental Science
• Soil Science
• Spectroscopy

Background:

• Understanding heavy metal interactions in soils is crucial for environmental fate prediction.
• Soil contamination by heavy metals poses risks to ecosystems and human health.

Purpose of the Study:

• To develop a novel strategy combining 2D COS and synchrotron-based spectromicroscopies for identifying heavy metal binding sites in soils.
• To investigate the impact of long-term fertilization treatments on cadmium (Cd) binding and bioavailability in soil.

Main Methods:

• Two-dimensional correlation spectroscopy (2D COS) was employed to analyze changes in soil functional groups.
• Synchrotron radiation-based spectromicroscopies, including micro X-ray fluorescence and FTIR, were used for micro-scale elemental and chemical mapping.
• Electron probe micro-analyzer mapping was utilized for detailed spatial analysis.

Main Results:

• Long-term organic fertilization significantly increased soil Cd accumulation (over 3 times) but reduced Cd concentration in wheat grain (p<0.05).
• 2D COS analysis indicated that fertilization treatments altered soil functional groups controlling Cd binding, reducing its bioavailability.
• Micro-scale analysis revealed heterogeneous distributions of Cd, minerals, and organic functional groups, with Cd distribution correlating more closely with minerals than organic groups.

Conclusions:

• The combined 2D COS and synchrotron-based spectromicroscopy strategy is effective for elucidating heavy metal interactions with soil components.
• Organic fertilization can reduce heavy metal bioavailability in soils despite increased accumulation, offering insights for soil remediation and management.
• Mineral components play a significant role in the spatial distribution and binding of heavy metals like cadmium in soil colloids.