Seasonal Variation of Copper, Nickel and Lead in Western Brittany Coastal Waters (France)

Abstract

Seasonal variation of copper, nickel and lead were studied in the Douarnenez Bay and the Iroise Sea during April 1983-February 1984 period. Our results compare favourably with those found in neighbouring coastal areas (1·5 nmol 1-1 <Cu <8·0 nmol l-1; 1·4 nmol l-1 <Ni <6·8 nmol l-1; and 0·07 nmol l-1 <Pb < 2·70 nmol l-1).Analyses of metal-salinity and metal-nutrient (nitrate and silicon) relationships, according to different hydrological patterns, show clearly that both the concentration and distribution of Cu, Ni and Pb are significantly influenced by seasonal changes. The main factors which control the cycle of the metal are: (a) the mixing of fresh and saline water, (b) the phytoplankton development and (c) the establishment of the frontal structures.