SOURCE CONTROL ON THE DISTRIBUTION OF PARTICULATE TRACE-METALS IN THE NORTH-SEA ATMOSPHERE

Baseline data are presented on the concentrations of particulate atmospheric trace metals over open sea regions of the southern North Sea. It is shown that there is a south --> north decreasing gradient in the emission of trace metals from the land masses surrounding the North Sea which imposes a control on the concentrations of the metals in the air masses which cross the source regions. However, air masses from a variety of sources can be transported to almost any region of the open southern North Sea. As a result, it is the origin of the air masses themselves, and not the location at which they are sampled, which constrains particulate trace metal concentrations in the North Sea atmosphere. Over long periods, a south --> north decreasing gradient in particulate trace metal concentrations over the North Sea will therefore only be found if the prevailing winds to a specific location are dominantly from a similar source off the surrounding land masses. It is important, therefore, to take long term air mass flow trends into account when attempts are made to model the input of particulate trace metals to the surface of the North Sea.