SEASONAL-VARIATIONS OF DISSOLVED NORMAL-ALKANES IN THE WATER MARSHES OF IRAQ

The distribution and seasonal variations of n-alkanes in the dissolved water of the marshes have been determined by gas-chromatography. Temperature variations, including evaporation, bacterial degradation and adsorption as well as photochemical oxidation, are postulated to produce pronounced seasonal variations of n-alkanes in the water. Higher concentrations of n-alkanes were observed in the winter than in the summer. The n-alkanes showed a regular distribution pattern of the odd and even carbon number compounds between C13 to C34 with additional characteristics associated with biological phenomena; abundance of C17, C19 of algal origin and C25, C27, C29 of terrestrial plant inputs was evident. Pristane and phytane were the most common of the isoprenoids in the water samples, suggesting biological origin, while the presence of Unresolved Complex Mixture (UCM) reflects the anthropogenic (urban and petroleum related) inputs.