Fluxes of Cu, Pb and Mn to the north-eastern Irish Sea: The importance of sedimental and atmospheric inputs

The concentrations of dissolved and particulate Cu, Fe, Mn and Pb have been determined in four cores obtained from the north-eastern Irish Sea. The diffusional fluxes of Cu, Pb and Mn from the sediments have been estimated from the concentration gradients between the porewaters and the overlying seawater. The concentrations of Cu, Pb and Mn in marine aerosols and rainwater have been obtained from a long-term collection campaign and used to determine their atmosphere-coastal ocean fluxes. The results show that of the total inputs (from rivers, direct wastes, dumping, atmospheric deposition and sediment-water exchange), the atmospheric component constitutes about 6% of the total Cu input, whereas sediment-water fluxes contribute about 34%. For Pb the atmospheric input is 3% and the flux from the sediments is 29%. The amounts of Cu and Pb diffusing from the coastal sediments are similar to the sum of the quantities entering via the rivers and direct waste inputs from industrial and domestic sources. These estimates of metal fluxes have important consequences for the long-term environmental health of the Irish Sea.