Dataset: Monthly cross-shore transects of biogeochemical properties in La Jolla, CA

General study design:
In this study, seawater samples were collected between 0-40m on a monthly transect extending from the coastline to ~2km offshore in La Jolla, CA. Seawater samples were collected for analysis of dissolved carbonate chemistry parameters and inorganic nutrient concentrations. The study was designed to characterize the biogeochemical near-shore spatiotemporal variability in the Southern California Bight, and in particular, the influence of seasonal upwelling.

Methods description:
Seawater was collected with a 5 L Niskin bottle between the surface and bottom in 10 m intervals at four stations between the end of the SIO pier and ~2 km offshore. Transect stations were separated by ~400 m. Seawater carbonate chemistry samples were collected into 250 ml Pyrex Corning glass bottle and immediately poised with 100 μL HgCL₂ following standard protocols (Dickson et al., 2007). Inorganic nutrient samples were filtered through a 0.45 μm polycarbonate filter into 30 mL Falcon tubes and immediate placed on ice and kept frozen until analysis. Temperature, salinity, and dissolved oxygen were measured in the residual seawater in the Niskin bottle following seawater collection using a YSI multiprobe.

Analytical Methods:
Seawater samples were analyzed for DIC and TA at the Scripps Coastal and Open Ocean Biogeochemistry lab. DIC analyses were conducted with an automated infrared inorganic carbon analyzer (AIRICA, Marianda) and TA with an open-cell potentiometric acid titration system developed at Scripps Institution of Oceanography (SIO) by A. Dickson (Dickson et al. 2007).

Inorganic nutrient samples were analyzed for dissolved NO3, PO4, H4SIO4, NO2, and NH3 at the Ocean Data Facilities (ODF) at the Scripps Institution of Oceanography either spectrophotometrically or fluorometrically via an analytical continuous-flow autoanalyzer. For details see: https://scripps.ucsd.edu/ships/shipboard-technical-support/odf/documentation/nutrient-analysis.

Quality Control:
Samples for seawater carbon chemistry analysis were collected and analyzed following standard protocol (Dickson et al., 2007). The handheld YSI multiprobe was calibrated prior to each survey with and accuracy of ±0.2°C for temperature and 1% for salinity. The accuracy and precision for DIC and TA samples were 0.45 ± 1.57 and 0.93 ± 1.40, respectively and were evaluated using CRMs provided by the laboratory of A. Dickson at SIO. CRMs were analyzed every 5 samples for DIC and every 10 for TA.