Nitrate and nitrite data from a National Oceanography Centre (NOC) lab-on-chip (LOC) analyser at Knapp Mill (Hampshire Avon)

(1) National Oceanography Centre, Southampton; (2) University of Southampton School of Ocean and Earth Science; (3) University of Portsmouth School of Earth and Environmental Sciences

High resolution measurements of nutrients in rivers can provide unprecedented information about sources, fluxes and in-stream processing. NOC has developed a submersible lab-on-chip (LOC) nitrate analyser that can be operated without mains power for extended periods (e.g. three months of hourly measurements without intervention). As part of the Christchurch Harbour Macronutrients Project (NERC Macronutrient Cycles Programme), the LOC nitrate analyser was deployed at Knapp Mill, an Environment Agency gauging station on the Hampshire Avon, between 15th October 2014 and 15th October 2015. It collected hourly nitrate data (subject to some short gaps) for the entire year. The reagents an onboard 300 uM standard were replaced every three months on-site. Deployed alongside were a YSI EXO sonde (full year) and an ISCO water sampler (until 19th December 2014). Spot samples were also collected throughout the year. This is the first high-resolution (hourly) nitrate dataset from Knapp Mill, and also the first river dataset from a miniaturised LOC sensor.