Page 8 - Assessment

8 D. Melaku Canu et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx

Fig. 6. Hazard index along the Sicilian coastline (area in which the particles are more likely to strand) computed for the four seasons, for different slick-times and from all six
release areas (R1–R6). The qualitative index describes relative differences among areas and seasons.

The % of oil particles stranded on beaches is higher in winter Particles released from area R3 are characterized by relatively
and autumn than in spring and summer (Table 1). This is because, low stranding %s in all seasons, except during summer, when
as depicted in Fig. 4, during winter and autumn, the particles approximately 39% of particles are found onshore. This can be
released from the first source (R1) are intercepted by the southern- explained by the intensity of the southern branch of the MAW near
most branch of the northern MAW surface current and transported R3 during this season, which flows towards Pantelleria Island,
towards the western and northern Sicilian coasts and towards where the released particles tend to strand. The summer hazard
Pantelleria island to the south. During spring and summer, due index distribution computed for Pantelleria Island confirms this
to the reduction of the MAW surface flow intensity and the east- interpretation (see Fig. 6).
ward displacement of its southern branch, the number of particles Particles released from sources R4, R5, and R6 strand along the
stranded onshore is significantly lower. southern Sicilian coast, with maximum stranding due to cumula-
Spills at source R1 primarily cause stranding near the small tive effects in autumn followed by spring.
archipelagos along the eastern Sicilian coastline (the Egadi archipe- The hazard index of oil slicks at the coast was computed for
lagos), while spills at R2 strand at Pantelleria Island. each season and at 4 time intervals after a spill (24 h, 1 day,
The seasonal variability of the stranding % appears to be posi- 3 days, 10 days), considering each release source separately
tively correlated with the frequency and intensity of Sirocco wind (HI TRI ) and also considering the cumulative impact of all release
events. points (HI T,i ). HI TRI index maps can be produced for each season,

Please cite this article in press as: Melaku Canu, D., et al. Assessment of oil slick hazard and risk at vulnerable coastal sites. Mar. Pollut. Bull. (2015), http://
dx.doi.org/10.1016/j.marpolbul.2015.03.006