This dataset presents in situ measurements of sea water chemical and physical parameters collected during the NABOS-2021 expedition aboard the R/V Akademik Tryoshnikov in the Nansen, Amundsen, and Makarov Basins of the Arctic Ocean (over the 125°E-170°W area) from September 15 to October 11, 2021.Conducted with the Sea-Bird Electronics Inc SBE911plus CTD system and a SBE32 Carousel Water Sampler, a total of 9025 seawater samples were collected at 103 oceanographic stations. Physical parameters include temperature, salinity, and depth. Chemical analyses encompass dissolved inorganic nutrients (nitrate, nitrite, phosphate, ammonium, silicate), oxygen, total alkalinity, and pH. Dissolved inorganic nutrients were analyzed using a segmented flow analyzer from Seal Analytical. Ammonium was measured manually (via the colorimetric method) using a spectrophotometer (Shimadzu UV-1800). Dissolved oxygen was determined by the standard Winkler titration method using a handheld titrator (BRAND). Both pH and total alkalinity were measured by potentiometric titration using an automatic titrator (Metrohm 916 TiTouch).This dataset is contributed by the NABOS project, a collaboration between the University of Alaska Fairbanks and the Arctic and Antarctic Research Institute, funded by the International Arctic Research Center (Fairbanks, USA).

The data is processed from raw measurements to quality checked parameters (the bad data was deleted).QF - quality flag:0 - good quality1 - unknown quality4 - questionable quality8 - bad quality