Water samples were collected in September 2013 during the "Lena Delta 2013" hydrological survey expedition on board RV Dalnie Zelentsy (Gonçalves-Araujo et al., 2015, doi:10.3389/fmars.2015.00108). A well pump was lowered to the desired depth and the sample was pumped through a hose into a cubitainer on deck.Water samples were immediately passed over Mn-coated acrylic fiber and analyzed on board for the short-lived radium isotopes with RaDeCC (Moore and Arnold, 1996. Measurement of 223Ra and 224Ra in coastal waters using a delayed coincidence counter. J. Geophys. Res. 101, 1321-1329, doi:10.1029/95JC03139). The analysis of supported activities in these samples was performed later in the Alfred-Wegener Institute (AWI) home laboratory in Bremerhaven. Ra was leached from the fiber with hot 6M HCl, coprecipitated as BaSO4, and counted with gamma spectroscopy for 226Ra and 228Ra (Moore, W.S., 1984. Radium isotope measurements using germanium detectors. Nuclear Instruments and Methods in Physics Research 223, 407-411).

Activities of excess 224Ra, 226Ra and 228Ra in water samples collected in September 2013 during the "Lena Delta 2013" hydrological survey expedition on board RV Dalnie Zelentsy (Gonçalves-Araujo et al., 2015, doi:10.3389/fmars.2015.00108).

Supplement to: Charkin, Alexander N; Rutgers van der Loeff, Michiel M; Shakhova, Natalia E; Gustafsson, Örjan; Dudarev, Oleg V; Cherepnev, Maxim S; Salyuk, Anatoly; Koshurnikov, Andrey V; Spivak, Eduard A; Gunar, Alexey Y; Ruban, Alexey S; Semiletov, Igor P (2017): Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea. The Cryosphere, 11(5), 2305-2327