An intermediate-scale flow cell experiment was conducted to study the removal of a DNAPL mixture from a layered porous medium through soil vapor extraction (SVE) with moist and dry air. A dual-energy gamma radiation system was used at various times to non-intrusively determine fluid saturations. The mixture, which contained the volatile organic carbon tetrachloride, mimics the DNAPL disposed at...

The Holocene Rajang River delta plain, which covers an area of 6500 km, has developed in a tropical, ever-wet climatic setting. Peat deposits, up to 15 m thick, occur in this delta plain. The tributary system to the delta is about 50,000 km in area. Elevations exceed 2000 m in the drainage basin and hill slopes are steep. Rainfall in the region exceeds 370 cm/year, with highest rainfall levels ...

BACKGROUND The objectives of these laboratory experiments were: (1) to assess bromoxynil sorption, mineralization, bound residue formation and extractable residue persistence in a Dundee silt loam collected from 0-2 cm and 2-10 cm depths under continuous conventional tillage and no-tillage; (2) to assess the effects of autoclaving on bromoxynil mineralization and bound residue formation; (3) to...

One of soil microbiology's most intriguing puzzles is how so many different bacterial species can coexist in small volumes of soil when competition theory predicts that less competitive species should decline and eventually disappear. We provide evidence supporting the theory that low pore connectivity caused by low water potential (and therefore low water content) increases the diversity of a ...

Dust samples collected annually for 5 years from 55 sites in southern Nevada and California provide the first regional source of information on modem rates of dust deposition, grain size, and mineralogical and chemical composition relative to climate and to type and lithology of dust source. The average silt and clay flux (rate of deposition) in southern Nevada and southeastern California range...

Significantly more occlusion bodies (OB) of DuPont viral construct HzSNPV-LqhIT2, expressing a scorpion toxin, were transported by artificial rainfall to cotton plants from sandy soil (70:15:15 sand-silt-clay) than from silt (15:70:15) and significantly more from silt than from clay (15:15:70). The amounts transported by 5 versus 50 mm of precipitation were the same, and transport was zero when...