Impact of a sea breeze event on air pollution at the Eastern Tunisian Coast

In this paper, air pollutants concentrations are analyzed during two sea breeze days (18 July 2004 and 17 September 2005) at the Mediterranean sea, just in front of Sousse (35° 48′ N, 10° 38′ E), Tunisia. During these two cases, we found that Sousse and its suburbs have been contaminated by a nearby coastal power plant emissions of pollutants. On 18 July 2004, onshore synoptic wind was uniform (up to 4 m/s) and roughly perpendicular to the coast and made breeze occurrence easier. The observed wind breeze is about 2 m/s. No return flow was recorded, due to the onshore synoptic wind. During this breeze event, wind direction changed by about 30° to be aligned with power plant and Sousse sites. In these conditions O 3 and SO 2 concentrations were multiplied by a factors 1.5 and 3 respectively. On 17 September 2005, a similar sea breeze wind (2–3 m/s) took place at the region but without significant synoptic wind. Pollutant concentrations are also comparable to those of 18 July 2004. A calm synoptic conditions case (13 July 2004) is also studied and compared with the previous cases.