Colloid & Nanoparticle Transport

Colloids—particularly when shaped irregularly or when present at the nanoscale—exhibit complex transport and retention patterns in the unsaturated zone. Experiments comparing barrel-shaped versus spherical colloids demonstrated that geometry and flow rates can significantly influence attachment in pores and secondary energy minima. Additionally, research in aquaculture ponds highlighted how small colloids and nanoparticles (<450 nm) can carry considerable nutrient loads, such as phosphorus, underscoring their role in environmental contamination and harmful algal blooms.

(References: Transport of barrel and spherical shaped colloids in unsaturated porous media; Long-term missing role of small colloids and nanoparticles on the loading and speciation of phosphorus in catfish aquaculture ponds in west Alabama; Does Water Content or Flow Rate Control Colloid Transport in Unsaturated Porous Media?)

Thermal and Hydraulic Properties of Clayey Soils

Clayey soils shrink significantly upon drying, modifying pore space, water retention, and hydraulic conductivity. Recent work integrated simultaneous measurements of soil volume, heat-pulse parameters, and evaporation rates, revealing that neglecting soil volume change can lead to large errors in modeling hydraulic and thermal properties. These findings highlight how accurate characterization of shrink-swell cycles is critical for designing water management strategies and predicting heat and solute transport in clay-dominated landscapes.

(Reference: Effects of drying-induced shrinkage on thermal and hydraulic properties of clayey soils)