Turbulent mass transfer near gas-liquid interfaces in water and shear-thinning dilute polymer solution

•Turbulence enhances gas-liquid mass transfer in water and dilute polymer solution.•Conditional analysis of coupled optical methods help analyse turbulent mass fluxes.•Surface renewal is frequent, injection events are efficient.•Polymer enhances injection mass transfer outside the viscous sub-layer.•Conventional boundary layer gradient models fail at describing mass transfer.