Relationship between the origin of precipitation in the Jordan Rift valley and their geochemical composition

Abstract

Rainwater was sampled during seven winters at eight sites along the Jordan Rift valley in Israel. The study area is divided into two regions: the northern part located between the Sea of Galilee and the Dead Sea and the southern part between the Dead Sea and the Dead Sea–Red Sea water divide line in the Arava valley. The Dead Sea region is considered as a desert, the northern part of the study area is semidesert whereas the southern region is considered as extreme desert. Good agreement was found between the chemical and isotopic composition of rainwater its sources and air mass trajectories. In the arid areas, the contribution of salts was mainly from local sources (of up to 500 Km in diameter). Significant chemical divergence was found between rainwater deriving from marine air masses characterized by NaCl enrichment and rainwater deriving from continental air masses which are mainly characterized by Ca‐carbonate enrichment. Six main marine and continental air mass trajectories were defined, i.e., northern, northwestern, western, southwestern, eastern and local. The northern air mass trajectories contribute more salts than the southwestern air mass trajectories which exhibit the lowest rainwater salinities. The western trajectory is exclusively marine originating from the Mediterranean, while the eastern trajectory is exclusively continental and originates in the Arabian Desert. Rainwater isotopes revealed three chemically differing systems. The western marine trajectories reflect chemical setting associated with East Mediterranean Meteoric Water Line system; the continental air masses are mainly associated with the Mean Meteoric Water Line system; and whenever the eastern component is significant, a Local Meteoric Water Line prevails.

Air parcel trajectory analysis of stable isotopes in water vapor in the eastern Mediterranean

“…First, it is a first step toward a quantitative interpretation of isotope measurements on short timescales in terms of their very complex transport and fractionation history. So far, this history was comprised qualitatively in such an interpretation by several studies [ Rindsberger et al , 1983; Gat et al , 2003; Anker et al , 2007; Strong et al , 2007]. However, an estimation of the effects of many different processes during water transport requires their quantification.…”

“…In order to improve our understanding of fractionation processes under atmospheric conditions, measurements on short timescales in the order of days to hours are needed, as mentioned above. Only few of these measurements are available, though the number has increased during the last years [ Gat et al , 2003; Lawrence et al , 2004; Anker et al , 2007; Strong et al , 2007; Tian et al , 2007; Barras and Simmonds , 2008]. Their physical interpretation is complicated, because a single isotope value reflects the integrated phase transition history of the respective water.…”

“…Their physical interpretation is complicated, because a single isotope value reflects the integrated phase transition history of the respective water. Several studies tried to deduce transport histories from meteorological considerations [ Tian et al , 2007] or with the help of trajectory calculations [ Rindsberger et al , 1983; Gat et al , 2003; Lawrence et al , 2004; Anker et al , 2007; Strong et al , 2007; Barras and Simmonds , 2008]. However, in all these studies relationships between isotope data and water history could only be given in qualitative terms.…”

Deuterium excess as a proxy for continental moisture recycling and plant transpiration

“…This Lagrangian tool is based on the diagnosis of changes in specific humidity along backward trajectories started at the location of measurement. Lagrangian techniques have been used in previous studies for the interpretation of stable water isotope measurements especially in precipitation (Rindsberger et al, 1983;Anker et al, 2007;Barras and Simmonds, 2008;Sodemann et al, 2008b) but also in water vapour (Gat et al, 2003;Lawrence et al, 2004;Strong et al, 2007;Pfahl and Wernli, 2008).…”

Subsistence and mobility strategies in the Epipalaeolithic: a stable isotope analysis of human and faunal remains at 'Uyun al-Hammam, northern Jordan

“…The d 18 O composition of rain water measured along the Rift Valley in Israel reveal three chemically differing systems with similarly differing meteoric d 18 O signatures (Anker et al, 2007). If similar isotopic trajectories existed during the Epipalaeolithic, groups moving south or west from 'Uyun al-Hammam would ingest water that was isotopically different than locally-ingested water.…”