Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Adsorption-desorption behavior of dissolved organic carbon by soil clay fractions of varying mineralogy
AU - Singh, Mandeep
AU - Sarkar, Binoy
AU - Biswas, Bhabananda
AU - Churchman, Jock
AU - Bolan, Nanthi S.
PY - 2016/10/15
Y1 - 2016/10/15
N2 - Soil clay minerals significantly influence the accumulation and stabilization of organic carbon (OC). However, the effect of interactions among phyllosilicate clay minerals, native OC and sesquioxides (Fe/Al oxides) on the adsorption-desorption of dissolved organic carbon (DOC) under different background electrolyte types and concentration is poorly understood. A set of batch adsorption-desorption experiments were conducted using pedogenic clays extracted from soils dominated by kaolinite-illite (Kaol-Ill), smectite (Smec) and allophane (Allo). The clay samples were sequentially treated to remove native OC and sesquioxides, and tested for adsorption-desorption of DOC under various solution conditions. All the experiments were conducted at pH 7 using water extractable fraction of OC from wheat residues. DOC adsorption increased with increasing background electrolyte concentration, and the presence of Ca2+ significantly enhanced the uptake in comparison to Na+ due to a possible cationic bridging effect. Under all electrolyte conditions, the maximum DOC adsorption capacity (Qmax) (mg g-1) of the soil clay fractions (SCF) maintained the order: Allo > Smec > Kaol-Ill. A similar order was also observed when the adsorption capacities were normalized to the specific surface area (SSA) of the SCFs (mg m-2). DOC adsorption showed a positive relationship with SSA, and sesquioxides and allophanic minerals provided the largest contributions to the SSA in the SCF. Removal of sesquioxides from the SCF resulted in a decrease in SSA and thus DOC adsorption, whereas removal of native OC increased the SSA and subsequent DOC adsorption. Because this study used pedogenic SCFs which represented soils formed in different environments instead of processed clays from geological deposits, it provided realistic information about the interaction of DOC with SCF in relation to their native OC and sesquioxide contents. It also revealed the importance of Ca2+ in enhancing the carbon adsorption capacities of these SCFs.
AB - Soil clay minerals significantly influence the accumulation and stabilization of organic carbon (OC). However, the effect of interactions among phyllosilicate clay minerals, native OC and sesquioxides (Fe/Al oxides) on the adsorption-desorption of dissolved organic carbon (DOC) under different background electrolyte types and concentration is poorly understood. A set of batch adsorption-desorption experiments were conducted using pedogenic clays extracted from soils dominated by kaolinite-illite (Kaol-Ill), smectite (Smec) and allophane (Allo). The clay samples were sequentially treated to remove native OC and sesquioxides, and tested for adsorption-desorption of DOC under various solution conditions. All the experiments were conducted at pH 7 using water extractable fraction of OC from wheat residues. DOC adsorption increased with increasing background electrolyte concentration, and the presence of Ca2+ significantly enhanced the uptake in comparison to Na+ due to a possible cationic bridging effect. Under all electrolyte conditions, the maximum DOC adsorption capacity (Qmax) (mg g-1) of the soil clay fractions (SCF) maintained the order: Allo > Smec > Kaol-Ill. A similar order was also observed when the adsorption capacities were normalized to the specific surface area (SSA) of the SCFs (mg m-2). DOC adsorption showed a positive relationship with SSA, and sesquioxides and allophanic minerals provided the largest contributions to the SSA in the SCF. Removal of sesquioxides from the SCF resulted in a decrease in SSA and thus DOC adsorption, whereas removal of native OC increased the SSA and subsequent DOC adsorption. Because this study used pedogenic SCFs which represented soils formed in different environments instead of processed clays from geological deposits, it provided realistic information about the interaction of DOC with SCF in relation to their native OC and sesquioxide contents. It also revealed the importance of Ca2+ in enhancing the carbon adsorption capacities of these SCFs.
KW - Adsorption-desorption
KW - Background electrolyte
KW - Organic carbon stabilization
KW - Sesquioxides
KW - Soil clay fractions
KW - Specific surface area
U2 - 10.1016/j.geoderma.2016.06.005
DO - 10.1016/j.geoderma.2016.06.005
M3 - Journal article
AN - SCOPUS:84974652866
VL - 280
SP - 47
EP - 56
JO - Geoderma
JF - Geoderma
SN - 0016-7061
ER -