Proper handling of frozen nutrient samples is essential for high quality data

Melissa T Miller and Susan M Becker, Scripps Institution of Oceanography, La Jolla, CA, United States
The increased focus on biogeochemical sensors to collect data autonomously doesn’t supersede the need for high quality bottle data. Years worth of collected unattended sensor data relies on a one-time calibration value. Ideally, seawater samples are analyzed for nutrient concentrations including nitrate, nitrite, phosphate, silicate, and ammonia within hours of being collected. However, many instrument deployments take place on research cruises with little or no opportunity to analyze samples onboard. Nutrient samples can be contaminated by improper handling and storage techniques. Experiments were conducted to determine if the length of time a sample is frozen affects the analytical value of thawed nutrient samples. A range of concentrations and variety of seawater types were included. This study will guide standard practices for researchers who require high quality nutrient data for current and emerging sensor technologies.