Impregnation of peat soils using polyethylene glycol 4000 for the preparation of thin sections

Abstract

A method was developed to impregnate peat soils for the preparation of thin sections. Peat soil samples used consisted of wet tropical peat collected from Indonesia. To allow miscible impregnation without prior water replacement from the sample, polyethylene glycol 4000 was used as the impregnant because this material is soluble in water in all proportions. The impregnation procedure consisted of consecutive heat-immersion of the samples at 60 to 70°C in polyethylene glycol 4000 solutions with increasing concentrations. Consecutive impregnation for 2, 3, 4, and 5 d in 25, 50, 75, and 100% polyethylene glycol 4000 solutions, respectively, was found to be suitable for impregnating and hardening the samples. The heating temperature during the period of impregnation should be properly kept so as to avoid too fast vaporization, bubbling, or even boiling, while maintaining polyethylene glycol 4000 always under solution conditions. Immersed conditions should be maintained in order to avoid air trapping. After the impregnation was completed, the samples should be cooled slowly to allow homogeneous solidification of polyethylene glycol 4000. For the preparation of thin sections, a sliding microtome was used to obtain slices as thick as 20-30 µm after coating with a cellulose adhesive. The proposed method was found to be convenient for, and applicable to the preparation of high quality thin sections of peat soils. © 2001, Taylor & Francis Group, LLC.