Concentrations of chemicals in the North Sea arising from discharges from chemical tankers

A sampling survey in the North Sea has measured the concentrations of certain chemicals which are discharged into the sea from chemical tankers as a result of tank cleaning operations. The results obtained show that the concentrations of these chemicals are very low and many times less than their 96-h LC₅₀ values. The measured concentrations are of a similar order of magnitude as those calculated from a procedure based on estimated inputs and the turn-over time of the North Sea. It is concluded that because the implementation of Annex II of MARPOL 73/78 should further reduce the amount of chemicals discharged into the sea it does not appear to be necessary for the North Sea to be declared a Special Area for the purposes of Annex II.