Secondary and managed plantation forests comprise a rapidly increasing portion of the humid tropical forest biome, a region that, in turn, is a major source of nitrous oxide (N2O) emissions to the atmosphere. Previous work has demonstrated reduced N2O emissions in regenerating secondary stands compared to mature forests, yet the importance of species composition in regulating N2O production in ...

Tailings are mine wastes in the form of slurries stacked in mine sites abandoned after the exhaustion of ores. There are approximately 5000 abandoned mine sites in Korea, and tailings have become a serious environmental problem. Long-term environmental exposure of tailings can cause release of acidic and high concentrations of sulfate- and metal-contaminated water (acid mine drainage, AMD). Org...

Physical protection of soil carbon (C) is one of the important components of C storage. However, its exact mechanisms are still not sufficiently lucid. The goal of this study was to explore the influence of soil structure, that is, soil pore spatial arrangements, with and without presence of plant residue on (i) decomposition of added plant residue, (ii) CO2 emission from soil, and (iii) struct...

The generation and release of meltwater during the spring snowmelt season can be delayed because of spring storm episodes with snow accumulation and/or sustained subfreezing temperatures. The delayed release of snowmelt often extends beyond the particular storm event because of changes to the internal state of energy in the snowpack that prevents transmission of meltwater. Following a storm, tw...

mixed clayey soils occur as mixtures of sand (or gravel) and clay in widely varying proportions. their engineering behavior has not been comprehensively studied yet. an experimental program, comprising monotonic, cyclic, and post-cyclic triaxial tests was undertaken on compacted clay-granular material mixtures, having different proportions of clay and sand or gravel. this paper presents the res...

Characterization of the intragranular water regime within subsurface sediments: Pore volume, surface area, and mass transfer limitations" (2011). [1] Although ''intragranular'' pore space within grain aggregates, grain fractures, and mineral surface coatings may contain a relatively small fraction of the total porosity within a porous medium, it often contains a significant fraction of the reac...

Experimental measurements of the thermal expansion coefficient (alpha), permeability (k), and diffusivity (D) of water and 1 M solutions of NaCl and CaCl(2) are interpreted with the aid of molecular dynamics (MD) simulations of water in a 3 nm gap between glass plates. MD shows that there is a layer approximately 6 A thick near the glass surface that has alpha approximately 2.3 times higher and...

We present a discrete element model for simulating, at the grain scale, gas migration in brine-saturated deformable media. We rigorously account for the presence of two fluids in the pore space by incorporating forces on grains due to pore fluid pressures, and surface tension between fluids. This model, which couples multiphase fluid flow with sediment mechanics, permits investigating the upwar...

Measurement of soil saturated hydraulic conductivity, Ks, is normally affected by flow patterns such as macro pore; however, most current techniques do  not differentiate flow types, causing major problems in describing water and chemical flows within the soil matrix. This study compares eight models for scaling Ks and predicted matrix and macro pore Ks, using a database composed of 50 datasets...