Heavy metals in coastal sediments of the Baja California (Mexico)-California (USA) border zone

Abstract

Metal pollution and distribution in marine surface (0-5 cm) sediments of the Baja California border region were characterized during 1989. The total organic carbon, clay, silt and sand contents in the sediments and their correlation with the metals examined were also analysed. The results show higher concentrations (µg g–1 dry weight) of Al (7493), Mn (78.8) Cr (24.2) Zn (16.5) Cu (6.2) Cd (0.29) and Ag (0.30) in sediments of the 60-m isobath, with a gradient in their concentrations toward the shoreline. Analyses of simple correlation, principal components and similarity indicate that this behaviour is explained by the association of the elements with grain size and with silicoaluminate and organic matter contents. The possible influence of pollution and productivity phenomena as other processes that may control the distribution and origin of the metals in the study area, particularly Cd and Ag, is also noted. The results obtained show a decrease in Zn (15%), Cu (16%) Ag (20%) and Cd (22%) with respect to the values measured in coastal sediments of San Diego, California, in 1979.

Keywords

• metals
• sediment
• Baja California-California