| Summary: | VERTIGO project Niskin bottle sample data from KM0414 and RR_K2 cruises including measurements of pressure, temperature, salinity, dissolved oxygen and fluorescence. See Processing Methodology for VERTIGO documents for further information. The main goal of VERTIGO is the investigation of the mechanisms that control the efficiency of particle transport through the mesopelagic portion of the water column. Question: What controls the efficiency of particle transport between the surface and deep ocean? More specifically, what is the fate of sinking particles leaving the upper ocean and what factors influence remineralization length scales for different sinking particle classes? VERTIGO researchers have set out to test two basic hypotheses regarding remineralization control, namely: 1. particle source characteristics are the dominant control on the efficiency of particle transport; and/or that 2. mid-water processing, either by zooplankton or bacteria, controls transport efficiency. To test their hypotheses, they will conduct process studies in the field focused on particle flux and composition changes in the upper 500-1000m of the ocean. The basic approach is to examine changes in particle composition and flux with depth within a given source region using a combination of approaches, many of which are new to the field. These include neutrally buoyant sediment traps, particle pumps, settling columns and respiration chambers, along with the development of new biological and geochemical tools for an integrated biogeochemical assessment of the biological pump. Three week process study cruises have been planned at two sites - the Hawaii Ocean Time-series site (HOT) and a new moored time-series site in the subarctic NW Pacific (Japanese site K2; 47°N 160°E) - where there are strong contrasts in rates of production, export, particle composition and expected remineralization length scales. Evidence for variability in the flux vs. depth relationship of sinking particles is not in dispute but the controls on particle ...
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