Hawaii Ocean Time-series (HOT)
in the School of Ocean and Earth Science and Technology at the University of Hawai'i at Manoa
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Particulate Biogenic Silica

Particle Filtration
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To assist in the interpretation of the data, it can be displayed using the Hawaii Ocean Time-series Data Organization & Graphical System (HOT-DOGS©).

Sampling Procedure

Samples for elemental analyses of Particulate biogenic silica (PSi) were collected into 4L polyethylene carboys; filtered through 47 mm polycarbonate filter holders; onto 47 mm polycarbonate, membrane filters; and placed into 50 ml polypropylene centrifuge tubes. Time course subsamples (1.5, 3, 4.5, 6.5 and 24 hours) were measured colorimetrically to distinguish Lithogenic-Si from Biogenic-Si (DeMaster, 1981). The average field variability between duplicate analyses during 2022 are presented in the Table below.


PSi
Cruise mean CV
(%) 		mean SD
(nmol/l) 		N
335 4.5 0.679 2
336 17.9 2.846 2
337 13.3 3.097 2
338 3.1 0.704 2
339 6.1 0.778 2
Mean 9.0 1.621 5

Results

Particulate biogenic silica (PSi) concetrations in the surface ocean over the last 26 years of the program are shown in Figure 68 and Figure 69. PSi typically ranges from < 5 to about 30 nmol kg-1 in the upper 100 m of the water column. During the summer months in 1998, 2000, 2005 and 2020, PSi increased dramatically in the upper 50 m of the water. This feature appears associated with a large bloom of diatomes, as evidenced from the sharp increases in fucoxanthin (Figure 48)