Dataset: Water column data collected during Dataflow cruises in the lower York River Estuary, VA during and following two successive harmful algal blooms

High-resolution sampling via Dataflow was performed along the lower York River estuary during a Margalefidinium polykrikoides bloom in early August, an Alexandrium monilatum bloom in early September, and following disappearance of the bloom in mid-September for determinations of pCO2, salinity, temperature, pH, Chla, CDOM, turbidity, DO, and location (lat/long). Cruises were on 24ft Carolina skiffs. Concurrent with the DataFlow sampling, grab sampling was performed at 5 stations within bloom patches (as determined by levels of chlorophyll a), and at 5 stations outside of bloom patches for determinations of DIC, DOC, active Chla (extractable), nutrients (DIN, DON, DIP, DOC), TSS, and CDOM. Locations listed in the dataset were those recorded when grab samples were taken. Data shown are averages and standard errors per station.

High-resolution sampling was performed with a Dataflow system modified from Madden and Day (1992) and as described in Crosswell et al, (2017). The pCO2-DataFlow system is instrumented with a pCO2 analyzer, a multi-parameter datasonde (YSI 6600V2), Wet Labs CDOM sensor, Garmin global positioning system (GPS MAP 546S), and data acquisition system. The system continuously samples surface water (approximately every 30 m at an average speed of 20 knots) from a stern-mounted water intake located 0.5 m below the water surface with a pump, which delivers water in parallel to (1) a showerhead equilibrator and (2) a flow-through cell attached to the YSI which is configured to measure water temperature, salinity, chl-a fluorescence, DO, pH, and turbidity. pCO2 in the equilibration chamber is determined by recirculating a carrier gas at a flow of approximately 1.5 L min-1 through the equilibrator chamber and a nondispersive infrared absorbance detection analyzer (LI-COR, LI-840).

Instruments:
Laboratory analyzed CDOM and chl-a were used to calibrate in situ CDOM and chl-a measurements made during the DataFlow surveys, as described by Anderson et al. (2013). Water column analyses (NO3, NO2, NH4, PO4) were performed with a Lachat QuikChem 8000 automated ion analyzer (Lachat Instruments,Milwaukee, WI, USA); detection limits for NO3−,NH4+, and PO43− are 0.20, 0.36, and 0.16 μM, respectively. DIC was analyzed on an Apollo, model AS-C3 (Apollo SciTech, Newark DE); DOC on a Shimadzu TOC-VCSN combustion analyzer, and extracted chla on a Beckman Coulter DU800 Spectrophotometer.

Known problems/issues:
Missing pCO2 data for August 11 cruise because of instrument failure.