Resumo

SEGOVIA-ZAVALA, JA et al. Vertical distribution of dissolved iron, copper, and cadmium in Ballenas Channel, Gulf of California. Cienc. mar [online]. 2011, vol.37, n.4a, pp.457-469. ISSN 0185-3880.

Dissolved iron, copper, and cadmium data are reported for the upper 450 m of the water column in Ballenas Channel, Gulf of California. Two water masses were identified: Gulf of California Water and Subtropical Subsurface Water. The 34.95 isohaline moved upward from 400 to 250 m depth, suggesting deep-water upwelling. Similarly, at surface level (50-60 m), the 26 and 27 °C isotherms and 35.45 and 35.65 isohalines moved up to the surface. Sea surface temperature imagery showed that Ballenas Channel surface water was relatively cooler (1.5-2.0 °C) than the water of the Midriff region during the study period. The vertical distribution of iron and copper showed mixed profiles (scavenging and nutrient types) with high concentrations at the surface (Fe = 3.58 and Cu = 3.29 nM), which immediately decrease with depth (Fe = 0.88 and Cu = 1.16 nM, scavenging type) and subsequently increase towards the bottom (Fe = 1.90 and Cu = 1.69 nM, nutrient type). Cadmium showed a nutrient-type vertical profile with low surface concentrations (0.75 nM) that increase with depth (1.12 nM). The dissolved concentrations of these three metals are higher in relation to highly productive areas in the Gulf of California and California Current. Preliminary estimates suggest that dissolved iron (76%) and copper (70%) are mostly generated by vertical advection and the rest by surface advection and atmospheric contributions, whereas 80% of cadmium enrichment is the result of vertical advection and the rest seems to be removed from surface water by photosynthesis.

Palavras-chave : metals; iron; copper; cadmium; Gulf of California.

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