In this article we combine NMRD experiments with MD simulations to study NMR relaxation time of NaCl and Na 2 SO 4 salt solutions confined within NaCl and Na 2 SO 4 salt crusts, respectively. Experimental measurements show a stronger dispersion of T 1 with the frequency ν for Na 2 SO 4 as compared to NaCl salt crusts. MD simulations of pure water within slit pores reveal some difference between NaCl and Na 2 SO 4 solid surfaces, such as a stronger polarization of water molecules next to the SO 2- 4 of the surface, which in turn lead to lower T 1 values in the case of Na 2 SO 4 pores compared to NaCl. MD simulation of salt solutions confined within slit pores, however, show a complex interplay between ion adsorption at the solid surface and the relaxation time T 1 . Ions, by adsorbing at the interface, induce a net surface charge while also creating a rough atomic landscape, which further reduce the measured values of T 1 . to the solid walls (Eq. 10 from the main text). Results have been obtained for pore size h ≈ 7 nm. Note that for cs > 0, the solid surface is not atomically flat due to adsorption, and therefore the first density layer of water may not be the best definition of the adsorbed layer. Simulations were performed for different values of the Lennard-Jones (LJ) cut-off ranging from r LJ = 0.9 to 1.5 nm using a bulk water system with a number N water molecules and temperature T = 293.15 K. Results show a significant impact of r LJ on the value of T 1 for r LJ < 1.2 nm, where we used N = 2000 (Table ). Simulations with different numbers of water molecules from N = 1000 to N = 3000 show no significant impact of N on T 1 , where we used r LJ = 1.4 nm (Table ). Finally, different values of maximal LINCS iterations N LINCS , the temperature coupling characteristic time t v-rescale , the timestep ts, as well as a different thermodynamic ensemble have been tested, without any significant influence on the value of T 1 (Table ). Each production run was divided into four equal parts of 0.5 ns each. From the four parts, four values of T 1 were extracted, allowing us to evaluate an average value of T 1 as well as a statistical error. For all simulations presented here, the statistical error on T 1 is bellow 1 %.