Future Industries Institute (FII), University of South Australia, Mawson Lakes, SA, 5095, Australia.
Natural and Built Environments Research Centre, School of Natural and Built Environments, University of South Australia, Mawson Lakes, SA, 5095, Australia.
Environ Geochem Health. 2017 Dec;39(6):1335-1350. doi: 10.1007/s10653-017-9939-0. Epub 2017 Mar 28.
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 (R = 0.93, p < 0.05) between the Langmuir maximum DOC adsorption capacity (Q ) and SSA. The Q value also showed a moderately strong relationship (R = 0.55, p < 0.05) with zeta potential (at pH 7). Q was 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.
本研究调查了三种土壤粘粒分（SCF）（高岭石-伊利石、蒙脱石和无定形二氧化硅）的表面官能团、阳离子交换容量（CEC）、表面电荷、三氧化二硅和比表面积（SSA）对土壤中溶解有机碳（DOC）保留的影响。在去除天然碳和/或三氧化二硅前后，对 SCF 的物理化学性质进行了表征，并采用批量法进行了 DOC 吸附-解吸试验。去除天然有机碳（OC）/三氧化二硅的处理导致高岭石-伊利石的 CEC 值略有变化，但蒙脱石和无定形二氧化硅的 CEC 值变化显著。随着 pH 值的增加，所有样品的净负表面电荷增加，表明其可变电荷特性。去除天然 OC 导致土壤粘粒表面净正电荷略有增加，而去除三氧化二硅则增加了负电荷。SCF 表面官能团的变化导致 CEC 和 ζ 电位值的变化。Langmuir 最大 DOC 吸附容量（Q ）与 SSA 之间存在很强的关系（R = 0.93，p < 0.05）。Q 值与 ζ 电位（在 pH 7 时）也存在中度强关系（R = 0.55，p < 0.05）。Q 值与 CEC 和天然 OC 含量的相关性较差。因此，与 SSA 一起，SCF 的表面电荷和官能团在决定土壤中 DOC 的吸附亲和力和保留方面起着关键作用。
