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

The 7Be mean annual flux in the Dead Sea region is 3.94+/-0.84 104 atoms cm-2 y-1 The 7Be mean atmospheric residence time in the Dead Sea region is 220+/-45 days The 7Be inventories(atoms cm-2) increase with time and floods suppress steady state The cosmogenic isotope 7Be (t1/2 = 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 (t1/2 = 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.