Dataset: Time series of phytoplankton cells released from silicate sands column experiment in Pensacola Beach, FL Keys in Jun and Jul 2025

The columns used for this experiment had a length of 10 cm and a diameter of 1 cm. The sands used were silicate sands with the grain size diameter ranges 1) 125 to 250 um and 2) 250-500 um. Prior to the experiments, the sands were cleaned through repeated washing in NaCl solution (salinity 35). For testing particle separation within these sands, seawater with a natural phytoplankton community dominated by green algae (5-10 um cell diameter) and cyanobacteria (1-5 nm cell diameter) were pumped through the sand. Computer-controlled syringe pumps pushed the seawater with the algae through the columns at a pore front velocity of 20 cm per hour. The eluent of the 2 columns were collected in a rotating sampler at 15 minute intervals. A total of 36 fractions was collected for each of the sand column for a flushing period of 9 h. The resulting samples were analyzed in a Cytoflex flow cytometer with gating adjusted to capture the green algae and cyanobacteria. Data collected include the area under the forward scatter peak, which provides information on cell size side scatter data, which are related to cell granularity. Calibration of the instrument used calibration beads with particle size ranging from 0.29 to 16.8 um. Explanations regarding flow cytometer analysis of phytoplankton samples as performed here are presented in Trask et al. (1982), best practices in Gallot et al. (2025), and details on the more recent instrumentation in Ugawa et al. (2024).