Paul M. Barlow Brian L. Howes Leslie A. DeSimone 1996 Physical, chemical, and microbial processes controlled transport of a nitrogen-rich ground-water plume through a glacial aquifer. Lithologic heterogeneity and vertical head gradients influenced plume movement and geometry. Nitrate was the predominant nitrogen form and oxygen was depleted in the ground-water plume. However, denitrification transformed only 2 percent of plume nitrogen because of limited organic-carbon availability. Aerobic respiration, nitrification and cation exchange (unsaturated zone) and ammonium sorption (saturated zone) had larger effects. application/pdf 10.3133/wsp2456 en U.S. G.P.O. ; For sale by the U.S. Geological Survey, Information Services, A nitrogen-rich septage-effluent plume in a glacial aquifer, Cape Cod, Massachusetts, February 1990 through December 1992 reports