Trace Element Scavenging and Variable Particle Flux: A Time-Series Investigation

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Study will be made of trace element scavenging mechanisms and particle dynamics through measurements of temporal variations in dissolved, suspended particulate and sinking particulate elemental distributions during a two year time-series study in the northeast Pacific. A recently-developed in situ pump will be used for collection of contamination-free size-fractionated samples of suspended matter throughout the water column. Five occupations of a deep-water station in the California Current will sample three seasons of varying productivity. This sampling will be coupled with simultaneous sediment trap and dissolved element measurements to examine the effect of changing productivity and vertical mass flux on the overall distribution of trace elements in a productive eastern boundary water column. Samples of all three pools will be analyzed for Al, Fe, Ca, Si, Mn, Pb, Zn, Cu, Ni, Cd, Ba, I, U, and 232Th. This research will address the shortage of fundamental information on the distribution of particulate trace elements which currently limits formulation of realistic scavenging models. The chemical differences in the behavior of elements will be used as probes of the scavenging process, as illustrated by our previous measurements of a subset of these elements in samples from Bermuda, the Northeast Atlantic, and the Northeast Pacific. In addition, elemental composition of particulate matter will be used as a tracer of mass exchange among particulate pools.