Landfill and composting are the most important treatment methods for municipal solid waste containing a significant proportion of organic matter. With time the landfill leachate undergoes changes through humification and mineralisation. The influence of landfill age on temporal changes in leachate composition when exposed to different environmental conditions is discussed. The study is based on 3 years monitoring of leachate from a landfill site in Adelaide, Australia and the investigation uses size exclusion chromatography and an excitation emission matrix approach combined with parallel factor analysis. This study showed that the matured leachate contained a broad range of low molecular weight organics with less aromaticity. Fluorescent analysis showed less-matured leachate contained more bio-polymer components. Leachate exposed to ponds showed microbial activity but the biopolymer percentage decreased with increased duration of exposure. The parallel factor analysis revealed four major components (C1-C4) at excitation/emissions of C1: 240/440 nm and 205/440 nm, C2: 225/490 nm and 225/420 nm, C3: 215/390 nm and 215/445 nm, and C4: 250/465 nm. These four components represented humic and fulvic acid-like organics of different molecular compositions. The results demonstrated that environmental variation had a direct effect on the mineralisation and humification of organic matter. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.