This datset presents trace gas measurements and derived variables such as basal glacial meltwater (GMW) fractions and water mass ages from the RV POLARSTERN expedition PS124 in the southern Weddell Sea in austral summer 2021. The trace gases comprise the lighter noble gases, i.e., total helium (He) and the excess above solubility equilibrium ΔHe, the 3He/4He ratio reported as δ3He, total neon (Ne) and the excess ΔNe, and the deviation from the equilibrium He/Ne ratio Δ(He/Ne), as well as the transient anthropogenic trace gases chlorofluorocarbon (CFC-12) and sulphur hexafluoride (SF6) concentrations. From these noble gases (He and Ne) we derived glacial meltwater fractions. From the transient tracers we computed SF6-concentration ages, CFC-12/SF6 ratio ages and TTD (Transit Time Distribution) mean ages.