The Middle East is located in a semiarid and arid region and is faced with an intense water shortage crisis. Therefore, studying the hydrochemical characteristics of precipitation as a main part of the water cycle has great importance in this region. The hydrochemical analyses showed that the quality of precipitation was mainly affected by dust particles originating from terrestrial environments, while marine and anthropogenic sources had a minor role. The statistical studies showed that the dissolution of evaporative and carbonate minerals mainly controlled the hydrochemistry of precipitation. Precipitation had an acidic nature in some stations and a nonacidic nature in others. Ca2+ was the major acid-neutralizing cation in the Middle East precipitation. Various machine learning methods were also used to simulate the TDS values in precipitation. The accuracy of the developed models was validated, showing that the model developed by the Gboost method was more accurate than those developed by other machine learning techniques due to its higher R2 values. To conclude, the hydrochemistry of precipitation showed significant variations across the Middle East. The dissolution of particles with terrestrial origins dominantly controlled the hydrochemistry of precipitation, while marine and anthropogenic sources had minor roles

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