Distribution and seasonal variations of n-alkanes in some species of molluscs from Shatt Al-Arab river

Abstract

The seasonal variations of n-alkanes compounds in molluscs of Shatt Al-Arab river have been studied. The species of molluscs were the snails, Lymnaea auricularia, Theodoxus jordani, Physa acuta, Melanopsis nodosa, Melanoides tuberculata while the bivalves were Corbicula fluminea and Corbicula fluminalis. The molluscs were collected from different locations of Shatt Al-Arab river (along the region extended from Abu-Al-Khasib to Garmat-Ali) during 2004 and 2005. Each species consisted of at least 350 adults of uniform size of individuals. The n-alkanes compounds from species of molluscs were extracted and analyzed by high resolution capillary gas chromatography. The total concentrations of n–alkanes in the molluscs varied from 1.50 μg/g dry weight in the T. jordani to 8.78 μg/g dry weight in the C. fluminea during summer and from 2.26 μg/g dry weight to 12.37 μg/g dry weight during autumn. While ranged from 3.15 μg/g dry weight to 12.44 μg/g dry weight and from 1.78 μg/g dry weight to 5.31 μg/g dry weight during winter and spring. The study confirmed lower concentrations of n-alkanes compounds in the molluscs of Shatt Al-Arab river during summer and spring while higher concentrations were recorded during winter and autumn. This is due to several factors which could act to produce such seasonal variations.

Study the Concentration of PAHS in Al-Rumayth River Water-Iraq

“…The high concentrations of Acenaphthene and acenaphthylene in water of river during winter was due to a number of factors, including low temperatures, which results in less evaporation of these compound [25]. In addition, by decreasing the temperature and using an inverse ratio, less effective microbes can breakdown hydrocarbons [26]. The lowest mean value of dissolved anthracene was 14.9 ppm at St.3 during June , while the highest mean value 48.9 ppm at St.2 during November (fig.…”

Sources and apportionment of aliphatic hydrocarbons in freshwater fish species from Shatt Al-Arab River, Iraq

“…Other factors that affected the levels of n-alkanes in fish tissues could be the differences in species, age, sex, route and duration of contact, and exposure to other xenobiotics (Johnson-Restrep et al, 2008;Al-Ali et al, 2016). The aliphatic hydrocarbons were most likely added to the fish species tissues directly from solution or suspended particles or via the digestion processes of contaminated phytoplankton, zooplankton, crustacean, and higher plant and eventually accumulated in the tissues of the species (Al-Saad et al, 2011;Wang et al, 2019).…”

“…The major sources aliphatic hydrocarbons in the aquatic environment of the Shatt Al-Arab river and Iraqi wetlands are from oil refinery effluents during loading operations (Bedair and Al-Saad, 1992); where about 48 tones of oil are shipped annually across the river for domestic usage (DouAbul and Al-Saad, 1985). Significant levels of petroleum hydrocarbon have been recently reported in the water column and sediments of aquatic systems of Iraq including Shatt Al-Arab and coastal zone (Rushdi et al, 2006a(Rushdi et al, , 2017(Rushdi et al, , 2018Al-Saad et al, 2011;Douabul et al 2012;Kadhim et al, 2019). Other potential sources include coastal higher plants, freshwater phytoplankton, and biogeochemical alteration of sedimentary organic matter (Rushdi et al 2006a(Rushdi et al ,b,2018.…”