Collaborative Research: SGER - Rapid Resolution of Particle Sampling Issues for GEOTRACES

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With funds from this Small Grant for Exploratory Research (SGER), researchers at the University of California at Berkeley and the Woods Hole Oceanographic Institution will participate in the first phase of the US-GEOTRACES Intercalibration study by providing deployment of the Multiple Unit Large Volume in-situ Filtration System (MULVFS) at sea in the Atlantic in the summer of 2008. Large sampling methodological biases (with one reported differences between bottles and pumps as large as a factor of 200, and multiple cases of factor of 3 or more differences) continue to confound the particulate sampling community. There is good evidence that MULVFS particulate matter samples are not subject to bias. Furthermore, such sampling biases far out weigh issues of analytical methodology issues that the currently funded IC particle work is almost exclusively designed to address.The central goal of this project is to eliminate PI/sampling approach dependency for the GEOTRACES Program particulate sampling and to reconcile the different sampling approaches to be used in the science phase of the Program. Work will support multi-investigator particulate matter intercalibration studies using MULVFS in both the environmentally easy locations such as BATS and in physically dynamic and biologically variable locations such as in the Gulf Stream. Comparison with other particle sampling methodologies in both challenging and non-challenging environments will lead to understanding and resolution of biases /differences that are both substantial, documented in published literature, and further documented in this proposal. Such an inter calibration has never been done before. A Further benefit is that MULVFS will greatly improve the efficiency of the June 2008 IC experiment by providing high resolution baseline profiles of trace metals and nuclides in the upper water column.Broader Impacts: This project will tackle the very real problems of method-dependent particle sampling and pre-analysis biases (large particle loss from some pumps, significant settling loss before filtration in bottles, poor sample preservation, etc.). The work is of relevance to all members of the oceanography community who engage in particle studies, and thus is of relevance to broad elements of the NSF Chemical and Biological Oceanography Programs.