Landfilling, as a system to discard municipal waste, is still widely used in the tropics, often without appropriate protection against pollution of its surroundings. Leachate generation from landfills, and its chemical composition, varies widely and is significantly influenced by landfill geometry, the type and age of waste, seasonal precipitation, moisture and temperature. In the tropics, clim...

The uncontrolled release of the industrial solvent methylene chloride, also known as dichloromethane (DCM), has resulted in widespread groundwater contamination in the United States. Here we investigate the role of groundwater bacterial communities in the natural attenuation of DCM at an undisclosed manufacturing site in New Jersey. This study investigates the bacterial community structure of g...

Many anti-tumor drugs function by intercalating into DNA. The xanthine alkaloid caffeine can also intercalate into DNA as well as form π-π molecular complexes with other planar alkaloids and anti-tumor drugs. The presence of caffeine could interfere with the intercalating anti-tumor drug by forming π-π molecular complexes with the drug, thereby blocking the planar aromatic drugs from intercalat...

This paper describes one of the first well-documented field examples of natural attenuation of trichloroethylene (TCE) in groundwater in a fractured shale bedrock. The study was carried out adjacent to a former waste burial site in Waste Area Grouping 5 (WAG5) on the Oak Ridge Reservation, Oak Ridge, TN. A contaminant plume containing TCE and its daughter products were detected downgradient fro...

We review theoretical models to show that contrast reduction at a specific wavelength in the horizontal direction depends directly on the beam attenuation coefficient at that wavelength. If a black target is used, the inherent contrast is always negative unity, so that the visibility of a black target in the horizontal direction depends on a single parameter only. That is not the case for any o...

W ater scarcity has become a harsh reality in many parts of the world. In the past, water needs were often met by building large dams and importing water over long distances. This approach is proving increasingly infeasible because social and environmental costs are too high (1). As the increased need for dependable water resources mirrors the growth in population, many communities are turning ...

Abiotic degradative pathways are often overlooked when evaluating natural attenuation at chlorinated solvent sites. Yet, at many sites, significant degradation of parent compounds such as 1,1,1-TCA, PCE and TCE is observed without the corresponding accumulation of daughter products, a sure indication of abiotic reactions. The problems in integrating abiotic processes into MNA are how to prove t...

• Review the existing literature on diver visibility. • Carry out experimental determinations of the sighting range of a black disk using DaviesColley’s method together with spectral absorption and attenuation measurements in a wide range of natural optical environments. • Determine the proper wavelength or wavelength combination for the limiting beam attenuation for the horizontal black target...