title: Pyrogenic carbon in Australian soils.
abstract: Pyrogenic carbon (PyC), the combustion residues of fossil fuel and biomass, is a versatile soil fraction active in biogeochemical processes. In this study, the chemo-thermal oxidation method (CTO-375) was applied to investigate the content and distribution of PyC in 30 Australian agricultural, pastoral, bushland and parkland soil with various soil types. Soils were sampled incrementally to 50cm in 6 locations and at another 7 locations at 0-10cm. Results showed that PyC in Australian soils typically ranged from 0.27-5.62mg/g, with three Dermosol soils ranging within 2.58-5.62mg/g. Soil PyC contributed 2.0-11% (N=29) to the total organic carbon (TOC), with one Ferrosol as high as 26%. PyC was concentrated either in the top (0-10cm) or bottom (30-50cm) soil layers, with the highest PyC:TOC ratio in the bottom (30-50cm) soil horizon in all soils. Principal component analysis - multiple linear regression (PCA-MLR) suggested the silt-associated organic C factor accounted for 38.5% of the variation in PyC. Our findings suggest that PyC is an important fraction of the TOC (2.0-11%, N=18) and chemically recalcitrant organic C (ROC) obtained by chemical C fractionation method accounts for a significant proportion of soil TOC (47.3-84.9%, N=18). This is the first study comparing these two methods, and it indicates both CTO-375 and C speciation methods can determine a fraction of recalcitrant organic C. However, estimated chemically recalcitrant organic carbon pool (ROC) was approximately an order of magnitude greater than that of thermally stable organic carbon (PyC).
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
authors.forename: Fangjie
authors.initials: F
authors.lastname: Qi
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia. Electronic address: Ravi.Naidu@newcastle.edu.au.
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
authors.forename: Nanthi S
authors.initials: NS
authors.lastname: Bolan
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
authors.forename: Zhaomin
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
authors.forename: Yubo
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
authors.forename: Dane
authors.initials: D
authors.lastname: Lamb
authors.affiliation: Agroscope Reckenholz-Tänikon Research Station ART, Reckenholzstrasse 191, 8046 Zürich, Switzerland.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Bucheli
authors.affiliation: Southern Cross GeoScience, Southern Cross University, PO Box 157, Lismore 2480, NSW, Australia.
authors.forename: Girish
authors.initials: G
authors.lastname: Choppala
authors.affiliation: Global Centre for Environmental Research, ATC Building, Faculty of Science and Information Technology, The University of Newcastle, University Drive, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of Environment (CRC CARE), The University of Newcastle, PO Box 18, Callaghan, NSW 2308, Australia.
authors.forename: Luchun
authors.initials: L
authors.lastname: Duan
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom.
authors.forename: Kirk T
authors.initials: KT
authors.lastname: Semple
keywords: Content; Distribution; Pyrogenic carbon (PyC); Soil; Soil properties