laboratory data, which relate the liquefaction resistance of firoozkooh sand and non-plastic silt mixtures to shear wave velocity are presented and compared to liquefaction criteria derived from seismic field measurements by andrus and stokoe [1]. in the work described herein, cyclic triaxial and resonant column tests were conducted on specimens of clean sand and sand-silt mixtures with silt co...

Continuous flow experiments were conducted using sand-packed columns to investigate the relative significance of bacterial growth, metal precipitation, and anaerobic gas formation on biologically induced clogging of soils. Natural leachate from a local municipal landfill, amended with acetic acid, was fed to two sand-packed columns operated in upflow mode. Degradation of the influent acetic aci...

The use of stormwater for managed aquifer recharge (MAR) has become one the most important ways to deal with water shortages and corresponding environmental geological problems, especially in north China. Fe (III) clogging porous media is a common significant problem that influences effect infiltration rate. This paper focuses on migration characteristics mechanisms iron hydroxides sand columns...

The addition of charcoal (or biochar) to soil has significant carbon sequestration and agronomic potential, making it important to determine how this potentially large anthropogenic carbon influx will alter ecosystem functions. We used column experiments to quantify how hydrologic and nutrient-retention characteristics of three soil materials differed with biochar amendment. We compared three h...

To assess the effect of organic matter on the transport of Cryptosporidium parvum oocysts in a geochemically heterogeneous saturated porous medium, we measured the breakthrough and collision efficiencies of oocysts as a function of dissolved organic matter concentration in a flow-through column containing ferric oxyhydroxide-coated sand. We characterized the surface properties of the oocysts an...

Concentrated animal feeding operations typically store livestock waste in clay-lined ponds. Although these ponds are regulated to include a liner with a small hydraulic conductivity to limit leaching, previous studies have traced surface and groundwater contamination from such regulated animal waste ponds. This research examined the transport of 17β-estradiol (E2) and its primary metabolite, es...

During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius) excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed...

The role of biochar as a soil amendment on the transport of acetamiprid, a widely used neonicotinoid pesticide, is little known. We conducted saturated column experiments to examine cotransport of acetamiprid and silica nanoparticles (NPs) in pure and biochar-amended sands. Retention of acetamiprid was minor in the pure sand, whereas application of biochar in the sand significantly increased re...

The aim of this research was to investigate the long-term hydraulic conductivity changes in sand-bed columns exposed to 2,4,6-trichlorophenol (TCP). Continuous flow laboratory studies were conducted using sand-bed columns (15 cm i.d.; 200 cm length) at 20+/-1 degrees C during 365 d. The influence of (i) initial loads of 2,4,6-TCP (15, 30, 45 and 60 mg kg(-1) of 2,4,6-TCP), and (ii) recirculatin...

AIMS To develop an anti-microbial filter media using an attached quaternary ammonium compound (QAC) and evaluate its performance under conditions relevant to household drinking water treatment in developing countries. METHODS AND RESULTS Silica sand was coated with dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride via covalent silane chemistry. Filter columns packed with coated...