Characterization and differentiation of dissolved organic matter in leachate derived from an old Japanese landfill site through Orbitrap mass spectrometry

Abstract

Elucidating the characteristics of dissolved organic matter (DOM) is crucial to assessing its impact on the bioavailability and mobility of pollutants in landfill leachate. This study reports a comprehensive 5-month investigation into the characteristics of DOM in leachate from an old Japanese landfill, collected at six different sampling points. The molecular composition, chemical properties, and structural characteristics of DOM were assessed using Orbitrap mass spectrometry and spectral analysis. The leachate DOM mainly consisted of CHO-containing molecules (58.5-88.9%), low-oxygen unsaturated phenolic compounds (40.5-54.0%), and aliphatic compounds (19.4-47.3%), with slight variation among sampling points. A significant portion of the nominal oxidation state of carbon was in the reduced zone (76.2-95.4%). The results underscore the distinct molecular composition of DOM in mature Japanese landfill leachate compared to young and mature leachates from other countries. Two of six sampling points, with notable differences in molecular characteristics, were compared and elucidated. The composition of landfill waste, rather than landfill age, was the main factor affecting the characteristics and differentiation of leachate DOM.