Trace metal pollution in the Mediterranean Sea

In the Mediterranean Sea, the distribution of dissolved zinc, copper, lead and cadmium is primarily controlled by marine circulation, surface source dynamics and biological new production. We show that the present relatively high content of these metals in the surface layer is due to non-steady-state cycles as a result of source increases probably following increases in industrial, agricultural and urban activities around the Sea since 1960. Unlike the open ocean, for which the deep water response time to perturbations is of the order of 1000 years, the Mediterranean response to environmental disturbances is perceptible in two decades. Comparison of surface with deep concentrations permits an estimation of the growth of dissolvable anthropogenic discharges and a forecast of the biogeochemistry of this continental sea.