Nitrous oxide (N 2 O) emissions result from the nitrification and denitrification processes, the latter strongly affected by soil organic carbon (C) derived from plant residues. This study addressed two questions: (1) does plant residue C become less available to denitrifiers after a period of aerobic incubation, and (2) do plant residues with smaller particle sizes provide C for higher rates of N 2 O production due to a faster decomposition rate? Nitrous oxide fluxes from soil amended with alfalfa or corn residues, or glucose were measured in the laboratory using a gas flow-through chamber system. Soil amended with these C substrates was also subjected to a 5-d aerobic preincubation treatment. The significance of particle size on C availability was studied by comparing N 2 O released from soil amended with ground 878 SHELP, BEAUCHAMP, AND THURTELL (particle size <1 mm) and large pieces (5-cm lengths) of alfalfa residues. A 5-d aerobic preincubation of soil amended with plant residues resulted in reduced N 2 O production during a subsequent anaerobic period. Results suggested that, due to consumption of the most available substrate, remaining C in plant residues is less available to denitrifiers after a period of aerobic incubation. Higher N 2 O losses were found with large alfalfa particles than with ground alfalfa.

Mineral resources are often discovered in remote or mountainous areas where long-term hydrological records are either absent or limited. Satellite-based remote sensing techniques can provide indirect observations of phenomena of interest, such as rainfall depth, snow cover, evapotranspiration, and changes in groundwater levels. Quality and applicability of the data are limited by the spatial, spectral, and temporal resolution of images. Other limitations may arise from the algorithms used to interpret the data. Examples are provided on how new remote sensing has been used at sites owned by Barrick Gold Corporation. It should be stressed that, for the foreseeable future, remote sensing data can supplement, not replace, more traditional sources of information.