Loess is susceptible to loading effects such as significant changes in strength and volume variation caused by loading and wetting. In this study, considering the different connection states of pore water and gas in loess fabric, the gas phase closure case is incorporated into a unified form of the generalized effective stress framework, introducing a damage parameter considering the effects of closed pore gas. The loading effects of unsaturated loess under wide variations in saturation are described in a unified way, and the model performance is verified by corresponding stress and hydraulic path tests. The results indicated that the collapse response involves the initial void ratio of loess, and the coupled outwards motion of the loading-collapse (LC) yield surface under loading enhances its structural strength. Suction-enhanced yield stress requires a greater tensile stress to counteract its structural stability. The nucleation of bubbles at high saturation causes a decrease in yield stress. The loading effect exhibits a smaller collapse behavior when the influence of closed gas is considered, whereas the suction path does not cross the LC in the stress space under hydraulic action for the same parameters, which amplifies the influence of closed gas on loess deformation. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Spectral light-absorption properties measured with an Aethalometer (AE; Model AE33; Magee Scientific) are widely used in radiative forcing studies and source appointment in China. However, considerable uncertainty regarding the measured absorption coefficient (sigma(abs)) exists because of the multiple-scattering effects, loading effects, and differences in filter tape. This study evaluated sigma(abs) by comparing the values measured with an AE33 using Tape 8050, an AE33 using Tape 8060 (which differs from Tape 8050 in material), and a three-wavelength photoacoustic soot spectrometer (PASS-3) during two field campaigns in eastern China. The results indicated that the AE33-measured sigma(abs) using either tape exceeded the PASS3-measured value by approximately three times, mainly owing to the multiple-scattering effect. A wavelength-independent multiple-scattering compensation factor (2.90), which varies slightly (+/- 0.04) for eastern China, is recommended for these regions. When sigma(abs) was measured with the AE33 using Tape 8050, the value highly depended on the loading on the tape, which led to significant uncertainty and discontinuity in the absorption Angstrom exponent compared to using Tape 8060. A method was proposed to effectively correct the historical datasets of sigma(abs) and the absorption A ngstrom exponent by using the AE33 with Tape 8050. This work provides insight into the quality of measured absorption data when filter-based measurement technology is applied.