Publications Published in Journal of Environmental Quality

1. Effects of Land Use on Soil Respiration: Conversion of Oak Woodlands to Vineyards. Carlisle, Eli A.; Steenwerth, Kerri L.; Smart, D. R..
   Journal of Environmental Quality: 2006
   Notes
   We examined constraints on soil CO2 respiration in natural oak woodlands, and adjacent vineyards that were converted approximately 30 yr ago from oak woodlands, in the Oakville Region of Napa Valley, California. All sites were located on the same soil type, a Bale (variant) gravelly loam (fine-loamy, mixed, superactive, thermic Cumulic Ultic Haploxeroll) and dominated by C3 vegetation. Seasonal soil CO2 efflux was greatest at the oak woodland sites, although during the summer drought the rates of soil CO2 efflux measured from oak sites were generally similar to those measured from the vineyards. Soil profile CO2 concentrations at the oak woodland sites were lower below 15 cm despite higher CO2 efflux rates. Soil gas diffusion coefficients for oak sites were larger than for vineyard sites, and this indicated that the apparent discrepancy in soil profile carbon dioxide concentration ([CO2]) may be caused by a diffusion limitation. Soil profile [CO2] and d13C values showed substantial temporal changes over the course of a year. Vineyard soil CO2 was more depleted in 13CO2 below 25 cm in the soil profile during the active growing season as indicated by more negative d13C ratios. This result indicated that different C sources were being oxidized in vineyard soils. Annual C losses were less from vineyard soils (7.02 6 0.58 Mg C ha21 yr21) as compared to oak soils (15.67 6 1.44 Mg C ha21 yr21), and both were comparable to losses reported in previous investigations.
   
   
   
2. Methane oxidation at low temperatures in soil exposed to landfill gas. Christophersen, M.; Linderod, L.; Jensen, P. E.; Kjeldsen, P..
   Journal of Environmental Quality: 2000
   Notes
   Soil exposed to elevated methane concentrations can develop a high capacity for methane oxidation. Methane oxidation at high and low methane concentrations is performed by different types of methanotrops and therefore oxidation rates found at low temperatures at the atmospheric methane content cannot be extrapolated to soils exposed to high methane concentrations. Four sandy soils with different organic matter content (1-9% w/w) from two landfills in Denmark were investigated in batch experiments in the laboratory to determine the response of methane oxidation at low temperatures and different soil moisture regimes, At 2 degreesC the methane oxidation rates were 0.005 to 0.17 mu mol g(-1) h(-1), and calculations showed that it was possible to oxidize all the produced methane at older landfills, even during the winter. Therefore, methane oxidation in top covers of landfills is an alternative to gas recovery at smaller and older landfills in northern Europe.
   
   
   
3. Temporal variations in greenhouse gas emissions at a midlatitude landfill. Bogner, J E; Spokas, K A; Burton, E A.
   Journal of Environmental Quality: 1999