I presented a regional analysis of particulate Si/C_org ratios from US-JGOFS sediment traps and from work I've done on the central California margin (see also, Berelson, W., 2000, Water column remineralization of opal and organic carbon. AGU/Ocean Sciences, January 2000 meeting). There are many ways that the increase in Si/C_org (with depth and between regions) may be interpreted. One way calls for a significant difference in particle settling velocity as a function of particulate composition. My interpretation calls for significantly greater `net' particle settling velocities for carbonate dominated regions compared to opal dominated regions. This is detected between regions and within regions.

Opal falls slowly, carbonate falls quickly. Velocity is important!

Another analysis of US-JGOFS and E. Pacific margin data indicate that as export production increases, the fraction of exported carbon lost in the upper 1000 m also increases . The trend between the fraction of C_org remineralized in the upper 1000 m and export production noted in Berelson (2001; POC fluxes into the ocean interior: A comparison of 4 US-JGOFS regional studies. Oceanography, v. 14, 59-67) is repeated in POC rain vs. depth data from the margin.

The more C_org produced, the more it will be recycled at shallow depths.

This does not mean that there is no coherence between C_org produced and the amount falling at depth. There is a generally positive relationship that expresses the correlation between PP and C_org rain at 1000 or 3000 m (Berelson, 2001), the problem is that the slope of this relationship changes depending on region and season.