Experimental and Micro-CT study on the Oil Distribution in laboratory grown Sea Ice

Abstract

Increasing activities in Arctic waters bare a risk of oil spills under ice-covered conditions and afford sound understanding of the interplay between sea ice and oil. Towards better knowledge, this study focuses on X-ray- micro computed-tomography (μ-CT) investigations of a laboratory oil- in ice experiment. The 3-dimensional distribution of oil in the porous space of 11- 13 cm columnar ice grown in a laboratory was investigated. Two different oil content measurement methods are discussed. (i) The first method quantifies the oil volume fraction based on μ -CT-scan investigations, allowing spatial oil distribution analysis in the porous space of sea ice. Oil inclusions were mapped manually over the acquired CT-scans with a resolution of 18 μm and 25 μm, respectively. Results give higher oil contents for smaller resolutions. Oil migration of 4 cm was observed. (ii) The second method quantifies the present oil concentration with fluorescent measurements. CT- scans give in comparison to fluorescent measurements a root mean square error of 1.27 % (18 μm) 0.76 % (25 μm), respectively. Bulk salinity determined from melted samples is compared with salinity estimated from μ –CT data.