| Summary: | ABSTRACT
This study examined the organic constituents aquatically leached from leaf components of two tree species (wandoo eucalyptus and pinus radiate). In particular this study aimed to assess the stable isotope composition behaviour of dissolved organic carbon (DOC) from the residue leaves after leaching over five months. The changes in the stable carbon and nitrogen isotope compositions of the leached leaves materials were investigated using an elemental analyzer-isotope ratio mass spectrometry (EA-irMS). The stable isotope compositions were found to vary according to microbially-mediatedalteration and decomposition. The average 813Ccontent of the raw plant elements
was consistent with the 813C values of te"estrial plants. using a C3 photosynthetic pathway. The isotope
compositions of leached materials of wandoo eucalyptus fresh leaf were continually depleted in 813Cover the leaching period of three months. These variations co"elated well with its DOC profile. Changes in 813Cvalues may also relate to the differential leaching of the macromolecularprecursors of the original material. Lignin, for example,
has a typically low 813Cand probably contributed to the decrease of 813Cin residue of the plant materials.
Keywords: isotope composition,leached materials, C3 plant
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