Modern Meteoric 36Cl Deposition in the Atacama Desert, Chile

Abstract

AbstractModern atmospheric deposition along a west‐east transect in the Atacama Desert, Chile, was collected to constrain the meteoric 36Cl/Cl ratio and 36Cl deposition flux. The 36Cl deposition flux had a threefold change, from 3.62(±0.18) to 11.6(±0.2) atoms m−2 s−1, going from the coast to the high Andes. The 36Cl deposition was mainly as dry deposition, and the magnitude and differences between sites were attributed to stratosphere‐troposphere transport and chloride deficits by acid displacement, respectively. The meteoric 36Cl/Cl ratios varied greatly from 31.5(±1.1) × 10−15 to 247(±10) × 10−15, which was attributed to local inputs of oceanic chloride near the coast or chloride minerals entrained from nearby salt playas. This study presented refined estimates of the 36Cl deposition flux and meteoric 36Cl/Cl ratio in a desert region in southern tropical zone. The data set will provide a baseline for using natural 36Cl abundances to date salt accumulation in the Atacama.