engleski

Application of image-based granulometry to siliceous and calcareous estuarine and marine sediment

Grain size analysis has been studied for decades as a descriptor of transport and depositional processes. For this paper we present the possibility of using image-based granulometry to characterize granulometric composition of loose sediments, as an alternative to classical techniques, such as sieving and coulter counter analysis. Conventional sediment analysis of siliceous and calcareous sediments was carried out and compared to image-based anaysis of sediments obtained along the Öre estuary (Northern Sweden) and the Adriatic Sea (Croatia and Italy). These grains have different textural characteristics, composition, roundness and specific surface area. Granulometric parameters are calculated using both a graphical method and the mathematical method of moments. For proposed new method, grains were imaged using a microscope and on these digital data, mathematical granulometry was applied. Image-based granulometric moment descriptors were compared with sieve+coulter counter derived moments. Direct scale sediment moment descriptors were compared to adapted granulometric moments obtained for the entire sample. The results of granulometric-shape based sizing to mass-based sieving processes are encouraging. They show the potential of applying digital electronic imaging to granulometric analysis of sediments. This idea, which could be realized in the future, can make the analysis easier as one needs only to take photographs of sediments from its fractional ranges using a high resolution digital camera linked to an on-board computer to obtain the grain size distribution. In this way, sampling for granulometric analysis and sieving process combined with cumbersome coulter counter analysis of fraction < 32 ľm could be eliminated and a large area of loose sediment surface could be covered in a short time.

image-based granulometry; mathematical granulometry; siliceous sediments; calcareous sediments

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