| » Home » HOT » Analytical Methods & Results | |||||
Analytical Method
Particle flux was measured at a standard reference depth of 150 m using multiple cylindrical particle interceptor traps deployed on a free-floating array for approximately 60 h during each cruise. Sediment trap design and collection methods are described in Winn et al. (1991). Samples were analyzed for particulate C, N, P & Si. Typically six traps are analyzed for PC and PN, three for PP, and another three traps for PSi.
Results
Particulate carbon (PC), nitrogen (PN), phosphorus (PP) and silica (PSi) fluxes at 150 m are presented in Figure 56 for the 1988-2007 time period. All four fluxes show large month-to-month and interannual variations. The magnitudes of PC and PN fluxes vary by about a factor of five, while PP and PSi fluxes varies by about a factor of 20. These particle flux measurements are consistent in magnitude with those measured in the central North Pacific Ocean during the VERTEX program (Martin et al. 1987, Knauer et al. 1990). However, the HOT data set reveals interannual changes not documented by earlier studies. Of particular note is the change from a more variable, high-flux time period (1988-1991) to a low-flux low-variability regime (1992-1996). There is a suggestion in the 1997-2007 data that particle fluxes may have increased in magnitude and variability. | |||||