The adsorbed water content is an attractive predictor for estimation of soil specific surface area (SSA) as its measurement is less laborious and more cost effective than standard laboratory techniques. We analysed the effects of total specific surface area (SSA_tot), external specific surface area (SSA_ex) and internal specific surface area (SSA_in) on water vapour sorption on 21 soil samples, and proposed models for estimating SSA_ex, SSA_tot and SSA_in from organic carbon content and the slope of soil water vapour sorption isotherm (SL_0.5) and water content (WC_0.5) at a water activity of 0.5. The results indicated that the variation of correlation coefficients between water content change at 0.05 water activity interval (WCC_0.05) and SSA_tot with water activity was mainly due to the differences in water vapour adsorption in interlayer spaces at different water activity levels. Furthermore, in the soil water content range from ~0.001 to ~0.03 g g⁻¹ (within the water activity range from ~0.45 to ~0.75), water vapour adsorption was related closely to SSA_ex. Cross-validation results on estimated SSA_ex, SSA_tot and SSA_in of the 21 samples produced root mean square error (RMSE) values less than 9.39 m² g⁻¹ and Nash-Sutcliffe model efficiency coefficients (E) greater than 0.93, suggesting that the proposed models provided reasonable estimates of SSA components. Thus, soil water vapour adsorption data can be applied to simultaneously estimate SSA_ex, SSA_tot and SSA_in. Variation of correlation between WCC_0.05 and SSA_tot with water activity depended on SSA_in. Soil water vapour sorption is related closely to SSA_ex at water activities from ~0.45 to ~0.75. The proposed models yield reasonable estimates of SSA_tot, SSA_ex and SSA_in. Adsorbed water content can be used as a predictor for SSA estimation.

中文翻译：

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从吸附的土壤含水量估算土壤比表面积

吸附水含量是估算土壤比表面积 (SSA) 的一个有吸引力的预测指标，因为它的测量比标准实验室技术更省力且更具成本效益。我们分析了总比表面积 (SSA _tot )、外比表面积 (SSA _ex ) 和内比表面积 (SSA _in ) 对 21 个土壤样品的水蒸气吸附的影响，并提出了估算 SSA _ex、SSA _{tot 的模型}和SSA_在从有机碳含量和土壤水蒸气吸附等温线（斜率SL _0.5）和水含量（WC _0.5) 的水分活度为 0.5。结果表明，0.05水分活度区间（WCC _0.05）的含水量变化与SSA _tot随水分活度变化的相关系数的变化主要是由于不同水分活度水平层间空间的水蒸气吸附量不同所致。此外，在~0.001 至~0.03 g g ^-1的土壤含水量范围内（在~0.45 至~0.75 的水分活度范围内），水蒸气吸附与 SSA _ex密切相关。21 个样本中估计的 SSA _ex、SSA _tot和 SSA _in的交叉验证结果产生小于 9.39 m ^{2 的}均方根误差 (RMSE) 值 g ^-1和 Nash-Sutcliffe 模型效率系数 (E) 大于 0.93，表明所提出的模型提供了对 SSA 组件的合理估计。因此，土壤水汽吸附数据可用于同时估计 SSA _ex、SSA _tot和 SSA _in。WCC之间的相关性的变化_0.05和SSA_地合计与水活性依赖于SSA_在。在~0.45 到~0.75 的水分活度下，土壤水蒸气吸附与 SSA _ex密切相关。所提出的模型产生了对 SSA _tot、 SSA _ex和 SSA _{in 的}合理估计。. 吸附水含量可用作 SSA 估计的预测因子。