Fig. 5.

Average CI value for seven PP specimens larger than 5 mm (labeled from 1 cd to 8 cd) sieved off the sediment samples. Each column provides the average CI from three measurements performed in different spots of the specimen to account for the local variability of the oxidation degree. The capital letters (A–D) are indicative of four groups of specimens characterized by statistically dissimilar oxidation degree; two-letter label indicates specimens with features shared by either one of two groups from which they do not show statistically meaningful differences