Comments:1) “Fine-grain” refers to sediment grain size <63 μm.2) July 2017 refers to samples collected before Hurricane Maria and January 2018 refers to samples collected after Hurricane Maria.3) Samples were measured at Lawrence Livermore National Laboratory. Ratios were normalized against standard 07KNSTD3110 with an assumed ratio of 2.85 x 10^12 (Nishiizumi et al., 2007).4) Measured ratios were corrected for backgrounds using the average of blanks and 1SD: 6.61 ± 0.70 x 10^-15 (average ± 1SD). See doi:10.1594/PANGAEA.918099.5) Percent difference equals (after-hurricane measurement – before-hurricane measurement)/((after-hurricane measurement + before-hurricane measurement)/2)*100.