Presence and distribution of N - alkanes in the waters of some areas of the Shatt Al-Arab River, southern Iraq

The study dealt with (4) stations distributed along the Shatt Al-Arab, namely Al-Mashab, Al-Ashar, Abu Al-Khasib and Al-Faw. Samples were collected monthly over a whole year, starting from January 2012 until December of the same year to estimate and diagnose the n - alkanes in them using Gas Chromatography (GC) . The highest recorded concentrations were (154.92 , 167.34 , 104.56 , 191.00 ) µg/l in the stations ( Al - Mshab , Al - Ashar , Abu Al - Khasib and Al - Faw ) respectively during the month of December . The lowest recorded concentrations were (4.79, 5.46, 3.34, 5.00) µg/l in the same stations, respectively. In terms of seasonal changes, the results showed that the highest rate of normal alkanes was recorded during the winter months and the lowest during the summer months. As for the results of the evidence of the Carbon Preference Index (CPI )and the ratio of Pr/Ph compounds (Pristan / Phytan) it was more than one in some months and less than one in other months, which indicates the common sources of hydrocarbons in the water.