Short residence time and fast transport of fine detritus in the Judean Desert: Clues from ⁷Be in settled dust

The cosmogenic isotope ⁷Be (t_1/2 = 53.3d) was measured in sediments collected from dust traps deployed in the Judean Desert which is part of the Dead Sea drainage basin. The results show that (a) the ⁷Be dry deposition flux in the Dead Sea region is 2.0 0.6 × 10⁴ atoms cm^-2 y^-1 during summer and winter and 5.3 0.7 × 10⁴ atoms cm^-2 y^-1 during fall; (b) the residence time of dust in the Dead Sea drainage basin is less than one year; (c) the recycled component of the cosmogenic isotope ¹⁰Be (t_1/2 = 1.39 10⁶y) in Judean desert dust is potentially small; and (d) the ⁷Be inventory (atoms cm^-2) in dust settled in the drainage basin did not reach steady state between consecutive rare events of desert winter floods suggesting a short transport rate of fine detritus material from the marginal terraces into the Dead Sea. Provided ¹⁰Be behaves similarly (as implied by the common geochemistry and cosmogenic origin of ⁷Be and ¹⁰Be), we suggest ¹⁰Be in Lake Lisan (Pleistocene Dead Sea) detrital sediments as a potential proxy for paleo-flood frequency and dust transport.