Composition of metals in suspended particulate matter of Alfonso basin, southern Gulf of California

Suspended particulate matter residues collected by 0.4μm pore size filters were analyzed for 9 trace metals (Mp) and phosphorus (Pp) from seawater samples taken from depths ranging from 0-300 m. The samples were obtained from a marginal basin located in southwestern Gulf of California. Four different sampling trips occurred during the year to coincide with periods of known contrasting hydrographic conditions. The depth-integrated concentration values followed the sequence Fe>Pp>Zn>Cu>Ni>Mo>Cd>Pb>V>Co. Temporal and vertical distribution of the largest concentrations of Mp and Mp/Pp trace metals with their concentrations normalized to phosphorus were consistent with enrichment processes in March and May. These were respectively associated with intense mixing and a submesoscale cyclonic eddy. The highest abundances of autotrophic picoplankton and nanoplankton, diatoms and dinoflagellates and chlorophyll a concentrations were also noted at this time. Wind speed was the only environmental variable that correlated positively (Spearman, p<0.05) with the temporal distribution of most of the Mp trace metals (except Cd, Co and V) in the euphotic zone, which was attributed to increases in the eolic contribution, sediment resuspension and horizontal transport towards the basin. The biological significance of Fe, Cu, Ni, Mo and V is discussed within the document based on the detected significant correlations with phytoplankton-assessed components. Our observations suggest a link between environmental forcing, the entrainment of metals and phytoplankton response as a reservoir of these metals in the euphotic zone, and as a possible source of replenishment for remineralization in the deeper layer. Future research should corroborate the assumptions about the origin and dynamics of dissolved and particulate fractions of metals and influence the biological activity and biogeochemistry of these elements in the basin.