Elemental composition of equatorial Pacific diatoms exposed to additions of silicic acid and iron

摘要: Abstract The elemental content of diatoms determines in part their productivity and influence on biogeochemical cycles. We used a cell-specific technique, synchrotron based x-ray fluorescence microscopy (SXRF), to study for the first time how cellular Fe, Si, P S contents natural respond additions Fe Si eastern equatorial Pacific (EEP), major source CO2 atmosphere. then compare these measurements ratios silicic acid, nitrate phosphate drawdown experiments dissolved acid iron EEP. Addition (20 μM) resulted increases 25-50% cell volume silica two experiments, but there was no significant change either variable during third experiment. No other effects addition stoichiometry were observed. Cellular molar Fe:P Fe:S increased by 24- 14- 17- fold 48 hours after 2 nM declined 7-, 4- 6-fold higher than those Control 96 hours. (a proxy protein) both up 2-fold response addition, 50-80%. not affected Si:P Si:S due S. Our results suggest that supply affects at which are utilized blooming However, production biogenic per will be supply. Consequently, EEP availability is unlikely density vertical transport material affecting amount mineral ballast cells. relationship between may help dampen variability concentrations