The sustainability of irrigated agriculture in India is threatened by waterlogging, soil salinity, and alkalinity. To reverse declining agricultural productivity, a combination of surface and subsurface drainage, supplemented by improved irrigation management, has been identi®ed as the most appropriate strategy. But subsurface drainage for salinity control is costly. Therefore, its bene®ts in t...

Aerobic heterotrophs were isolated from subsurface soil samples obtained from the U.S. Department of Energy's (DOE) Field Research Center (FRC) located at Oak Ridge, Tenn. The FRC represents a unique, extreme environment consisting of highly acidic soils with co-occurring heavy metals, radionuclides, and high nitrate concentrations. Four hundred isolates obtained from contaminated soil were ass...

The soil mantle in Namaqualand is immature in terms of weathering. Despite or even because of this, the diversity and spatial variability of soil physical and chemical properties is exceptionally high and could be fundamental in governing biodiversity and ecosystem function. In arid landscapes, the way the soil sheds, admits, stores, diverts and transmits water is crucially important. Namaquala...

Saturated fine-grained soils can undergo large settlements over a long period of time. Therefore, the estimation of both the total settlement and the rate of change of cohesive soils under field loading is essential for geotechnical engineering design and analysis. The total settlement can be determined from deformation moduli such as the tangent constrained modulus, M, while the time rate of s...

A long-term in situ subsurface instrument for monitoring radioactive contaminant plumes, as an alternative to soil analysis, is described. A portable, laser-based reader optically stimulates luminescence from sensors, each containing an Al2O3:C dosemeter. The sensors, designed for placement at various subsurface locations around a waste site, are allowed to accumulate dose for a predetermined t...

(1) Airflow is induced in the subsurface by applying a pressure gradient through vertical or horizontal wells or horizontal trenches. In SVE, this is usually accomplished by withdrawal, rather than injection, of air. The SVE gas flow increases rates of contaminant mass transfer to air in the unsaturated zone by evaporation of NAPL, volatilization of contaminants dissolved in pore water, and des...

The boundary that separates the earth from the atmosphere is a crucial zone of study for meteorology and hydrology. Here, solar energy is partitioned into sensible heat which drives atmospheric circulation, latent heat needed for evaporation from the soil and transpiration of vegetation, and soil heat which warms the subsurface. Precipitation is partitioned into interception that evaporates dir...

Abstract—A coplanar rectangular slot antenna operating in the very wide frequency band from 0.27 to 3.1GHz (bandwidth over 166%) has been designed for GPR applications. The antenna, which is supposed to be positioned on the soil surface, appears particularly compact (34 × 29 cm2) and exhibits a low cross-polarization in the E-plane. 3D FDTD simulations have allowed to make a detailed parametric...

The analysis of the denaturated gradient gel electrophoresis (DGGE) of the polymerase chain reaction (PCR) amplified 16S rDNA fingerprints demonstrated a high diversity of bacterial communities in the soils from the three study sites at the surface and subsurface soil layers. The undegraded site possessed maximum number of 16S rDNA fingerprints than the degraded and undegraded sites at both soi...

Abstract. Solute transport in the subsurface is often considered to be a nonequilibrium process. Nonequilibrium during transport of solutes in porous medium has been categorized as either transport-related or sorption-related. For steady state flow in a homogeneous soil and assuming a linear sorption process, we will consider advection-diffusion adsorption equations. In this paper, numerical me...