Seawater dissolved chromium concentration, redox speciation, and stable isotope composition in the North Pacific Ocean

Dissolved seawater chromium concentrations, redox speciation, and stable isotope composition were measured on samples collected in the North Pacific Ocean. Samples were collected over diel cycles (2 for stations 1-5, 1 for station 6) on board the RV Kilo Moana cruise KM1713 from Seward Alaska to Honolulu Hawai’i. Sampling stations spanned the subarctic North Pacific (stations 1 & 2), the dynamic subarctic-subtropical convergence zone (stations 3 and 4) and the subtropical North Pacific (stations 5 and 6). Chromium was enriched from filtered samples by Mg(OH)2 co-precipitation and analyzed by MC-ICP-MS using either isotope dilution (Cr redox speciation) or double spike methodology.