High-Resolution Characterization of the Size Exclusion Effect on the Transport of Low-Concentration Mixed-Size...

Area of Science:

• Environmental Science
• Geochemistry
• Colloid Science

Background:

• Colloid transport in groundwater is crucial for understanding pollutant dispersion.
• The size exclusion effect (SEE) significantly influences colloid behavior.
• Accurate measurement of low-concentration and mixed-size colloids is technically challenging.

Purpose of the Study:

• To develop and validate a DNA labeling technique for enhanced detection and size differentiation of colloids.
• To quantify the size exclusion effect (SEE) in porous media using column-scale experiments.
• To establish a quantitative relationship between colloid size and the SEE parameter (γ).

Main Methods:

• Encapsulating DNA fragments within model colloids of various sizes (0.1–5.0 μm).
• Conducting column-scale experiments with single-size and multi-size colloids.
• Analyzing colloid breakthrough curves to quantify the inaccessible water saturation (γ).

Main Results:

• DNA labeling enabled sensitive detection of colloids at concentrations ≤10 mg L⁻¹.
• Precise differentiation between various colloid sizes was achieved.
• A power-law relationship was identified between colloid diameter and the SEE parameter (γ), showing SEE intensifies with larger colloids.

Conclusions:

• DNA labeling offers a powerful tool for high-resolution characterization of colloid transport in porous media.
• The study provides quantitative insights into the size exclusion effect, crucial for environmental pollutant fate modeling.
• Findings advance the understanding of colloid behavior in groundwater systems and their environmental implications.