A total of 28 CTD (Conductivity/Temperature/Depth) stations were vertically profiled for benzene and toluene in the Southern Ocean. For the ease of visualisation and analysis, the CTD stations were classified by surface Chl a (Chlorophyll a) concentration; low Chl a 0-0.2 mg m -3 , medium Chl a 0.2-0.5 mg m -3 and high Chl a 0.5-1 mg m -3 .