Application of image analysis technique for measurement of sand grains in sediments

This paper provides a methodological protocol for measuring diameter and other properties of mineral sand grains using an image analysis technique. The aeolian sand influx (ASI) from coastal bogs has been used to reconstruct changes in the past storminess. However, concentrations of sand grains in peat deposits, from which the ASI is calculated, tend to be low, and sieving and laser diffractometry cannot be applied. Manual counting of sands under microscope is time-consuming and less efficient because of possible human errors. This paper describes a protocol for an image analysis method used in our recent paper (Vandel et al. 2019) that overcomes those issues in sand grain measurements. After preliminary sample preparations, including loss-on-ignition and chemical pretreatments, this study uses ImageJ - a semi-automated image processing program - to analyze images captured under microscope. With proper sample size selection, pre-treatment, image capturing and image analysis settings in ImageJ described in this paper, the approach proved to be:•objective and efficient for analysing grain-size distribution even with low concentrations of sands in samples,•increasing reliability of the measurement and providing reproducible results by avoiding manual measuring processes, and•non-destructive and enabling further analyses on mineral composition and other properties of sand grains.