Search for: All records

Abstract Plastic liners are sometimes used with soil samplers in order to collect and store intact soil cores. Gaps at the soil–wall interface caused by the flexibility of plastic liners can result in wall flow, preventing accurate fluid flux density measurements. A subsampling method was developed to overcome problems with wall flow from soil samples collected with plastic liners in order to measure air permeability (k_a) and saturated hydraulic conductivity (K_sat) on the intact cores. Subsamples were obtained after first immobilizing the soil within plastic liners by injecting expanding foam into the gaps between the soil and the liners. Once the soil was fixed in place, the soil samples were cut to the desired length, and sharpened metal rings were inserted into the original soil sample with a vise. With the metal ring at the desired depth, the subsample was removed from the original soil sample by cutting the liner and removing excess soil from the ends of the rings. Initial attempts to measurek_aandK_saton samples within the original liners led to unrealistically high values because significant wall flow occurred. However, after implementing the improved subsampling approach, the measuredk_aandK_satof the subsamples were within the range of expected values based on the literature. The subsampling method effectively eliminated wall flow on soil originally collected in plastic liners and is relatively easy to implement without the need for specialized tools. 

Abstract The vadose zone—the variably saturated, near‐surface environment that is critical for ecosystem services such as food and water provisioning, climate regulation, and infrastructure support—faces increasing pressures from both anthropogenic and natural factors, including changing climatic conditions. A more comprehensive understanding of vadose zone processes and interactions is imperative to effectively address these challenges and safeguard water and soil resources. This review outlines selected key issues, knowledge gaps, and research opportunities across six thematic sections. Each section presents a problem statement, a summary of recent innovations, and a compilation of emerging challenges and study opportunities. The selected topics include scaling and modeling of vadose zone properties and processes, soil moisture monitoring initiatives, surface energy balance, interplay between preferential water flow paths and biogeochemical processes, interactions between fires and vadose zone dynamics, and emerging contaminants and their fate in the vadose zone. This overview is intended to serve as a compendium of vadose zone science that encompasses both insights gained from prior research and anticipated needs for the coming years.