Isotope and dissolved gas evidence for nitrogen attenuation in landfill leachate dispersing into a chalk aquifer

摘要

The authors present data for the chemical, stable isotope (C-13/C-12, N-15/N-14 and S-34/S-32), and dissolved gas (N-2, Ar, O-2 and CH4) composition of groundwaters sampled in and around a landfill site in Cambridgeshire, England. Decomposition of 3 x 10(6) m(3) of largely domestic waste, placed in unlined quarries, has given rise to the formation of an NH4-rich leachate dispersing as a plume into the surrounding Middle Chalk aquifer. In addition to identifying zones of methanogenesis and SO4 reduction, the data indicate processes of NH4 transformation by either assimilation or oxidation, and losses by formation of N-2. Depending on the mixing ratio between leachate and background water, it may be possible to account for all NH4 loss by combined nitrification + denitrification in a system where there are abrupt temporal and spatial changes in redox conditions. Crown Copyright (c) 2005 Published by Elsevier Ltd. All rights reserved.