Jonathan Sanderman , Jordahna Haig , Sourav Das , Colleen Partida , Christina Asanopoulos , Michael I. Bird
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引用次数: 0
Abstract
Soil pyrogenic carbon (PyC) is of considerable significance to the global carbon cycle as a carbon pool which is resistant to mineralization and thus offers opportunities to facilitate net carbon sequestration. Quantifying the size and dynamics of the soil PyC pool is hampered by the large number of techniques that yield a wide range of abundances even when applied to the same sample. We used hydrogen pyrolysis to quantify stable polycyclic aromatic carbon (SPAC) of pyrogenic origin (PyCSPAC) in a globally distributed set of coarse-textured soils, in which the percentage of particles finer than 53 µm ranged from 0.1 to 24.1 % (mean = 7.2 ± 5.8 % 1σ). PyCSPAC values ranged from 0 to 0.37 % (mean = 0.08 ± 0.06 %). We compared the PyCSPAC values with estimates derived from nuclear magnetic resonance spectroscopy (PyCNMR) and found a strong correlation between the two (r = 0.90). However, the PyCNMR estimates were ∼7 times higher than PyCSPAC values, attributed partly to NMR measuring a wider range of pyrogenic molecules but also likely due to the inclusion of aromatic ‘resistant’ soil carbon of non-pyrogenic origin. In contrast, there was little correspondence between either PyCSPAC or PyCNMR and abundances determined by dichromate oxidation (PyCOREC). Partial least squares modelling of the mid-infrared (MIR) spectra was able to predict both PyCSPAC and PyCNMR values with high confidence (r = 0.77 and 0.94 respectively). The study suggests that, with appropriate scaling factors, PyCSPAC and PyCNMR can be directly compared, and both can be predicted by MIR.
期刊介绍:
Geoderma - the global journal of soil science - welcomes authors, readers and soil research from all parts of the world, encourages worldwide soil studies, and embraces all aspects of soil science and its associated pedagogy. The journal particularly welcomes interdisciplinary work focusing on dynamic soil processes and functions across space and time.