title: Influence of physico-chemical properties of soil clay fractions on the retention of dissolved organic carbon.
abstract: This study investigated the effects of surface functional groups, cation exchange capacity (CEC), surface charge, sesquioxides and specific surface area (SSA) of three soil clay fractions (SCFs) (kaolinite-illite, smectite and allophane) on the retention of dissolved organic carbon (DOC) in soils. Physico-chemical properties of the SCFs before and after removing native carbon and/or sesquioxides were characterised, and the DOC adsorption-desorption tests were conducted by a batch method. Native organic carbon (OC)/sesquioxide removal treatments led to a small change in the CEC values of kaolinite-illite, but significant changes in those of smectite and allophane. The net negative surface charge increased in all samples with an increase in pH indicating their variable charge characteristics. The removal of native OC resulted in a slight increase in the net positive charge on soil clay surfaces, while sesquioxide removal increased the negative charge. Changes in the functional groups on the SCF surfaces contributed to the changes in CEC and zeta potential values. There was a strong relationship (R2= 0.93, p < 0.05) between the Langmuir maximum DOC adsorption capacity (Qmax) and SSA. The Qmaxvalue also showed a moderately strong relationship (R2= 0.55, p < 0.05) with zeta potential (at pH 7). Qmaxwas only poorly correlated with CEC and native OC content. Therefore, along with SSA, the surface charge and functional groups of SCFs played the key role in determining the adsorption affinity and hence retention of DOC in soils.
authors.affiliation: Future Industries Institute (FII), University of South Australia, Mawson Lakes, SA, 5095, Australia.
authors.forename: Mandeep
authors.initials: M
authors.lastname: Singh
authors.affiliation: Future Industries Institute (FII), University of South Australia, Mawson Lakes, SA, 5095, Australia. binoy.sarkar@unisa.edu.au.
authors.forename: Binoy
authors.identifier: http://orcid.org/0000-0002-4196-1225
authors.initials: B
authors.lastname: Sarkar
authors.affiliation: Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA, 5095, Australia.
authors.forename: Sabir
authors.initials: S
authors.lastname: Hussain
authors.affiliation: Department of Biological Environment, Korea Biochar Research Centre, Kangwon National University, Chuncheon, 200701, Republic of Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: Global Centre for Environmental Remediation, University of Newcastle, Callaghan, NSW, 2308, Australia.|Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, ACT Building, University of Newcastle, Callaghan, NSW, 2308, Australia.
authors.forename: Nanthi S
authors.initials: NS
authors.lastname: Bolan
authors.affiliation: School of Agriculture, Food and Wine, University of Adelaide, Urrbrae, SA, 5064, Australia. jock.churchman@adelaide.edu.au.
authors.forename: Gordon Jock
authors.initials: GJ
authors.lastname: Churchman
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D057965:Carbon Sequestration; D002412:Cations / Q000737:chemistry; D000077215:Clay; D006863:Hydrogen-Ion Concentration; D009930:Organic Chemicals / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D012987:Soil / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D000538:Aluminum Silicates; D002412:Cations; D009930:Organic Chemicals; D010087:Oxides; D012987:Soil; D002244:Carbon; D000077215:Clay
keywords: Adsorption–desorption; Physico-chemical properties; Sesquioxides; Soil carbon sequestration; Soil clay fractions