N – alkanes in molluscs of Shatt Al-Arab river

Abstract

This study comprises monitoring of the n-alkanes in the Shatt Al-Arab river by using the seven molluscs species as bioindicators. These species are: snails Lymnaea auricularia, Theodoxus jordani, Physa acuta, Melanopsis nodosa, and Melanoides tuberculata and bivalves Corbicula fluminea and Corbicula fluminalis. The species of molluscs are collected from different locations of the 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 3500 adult of individuals of uniform sizes. The hydrocarbons from these species were extracted and analyzed both by spectroflurometer (total hydrocarbons) and high resolution capillary gas chromatography (n-alkanes). The concentrations of total hydrocarbons in mollusc’s species of the Shatt Al-Arab river ranged from 1.93 μg/g dry weight in T. jordani to 26.56 μg/g dry weight in C. fluminea. The range of carbon chain length of n-alkanes in these individuals was ranging from C13 - C32. The bimodal distribution with two maxima around C17 and C27 suggested two different sources of hydrocarbons both biogenic and anthropogenic. The dominance of the odd carbon numbers n-alkanes (C15, C17, C25 and C29) in the mollusc’s species indicated biogenic origin of hydrocarbons .The pristane values were more than those of phytane. Pristane and phytane in the mollusc’s species suggest biogenic origin. CPI values are more than one indicating a biogenic origin of hydrocarbons in these species. Squalane is also present in some these species intimately related to anthropogenic sources of hydrocarbons. The presence of Unresolved Complex Mixture (UCM) reflects the anthropogenic sources. The lower fat contents were found in T. jordani (0.33 mg/g) and the higher were in C. fluminea (0.98 mg/g). A significant relationship is found between the fat contents and hydrocarbons concentrations in the tissues of molluscs species (r = 0.8 - 0.9).

Determining the sources and distribution of polycyclic aromatic hydrocarbons in the soil of different oil fields at Basrah governorate, Iraq

“…The pollution that results from all activities at all phases of oil and gas production, from exploration activities to refining, is the most pervasive and hazardous effect of the oil and gas industry's activities. Over 800 different chemicals are produced during drilling, production, refining (which is the most polluting process), and transportation wastes, gas emissions, solid waste, and aerosols, with oil and petroleum products predominating among these [6]. The lowest recorded concentration of PAHs in this investigation was 0.16 ng/g dry weight of benzo(a)anthracene at station 7 -WQ1, and the highest recorded concentration of PAHs was 680 ng/g of benzo(g,h,i)perylene, which appeared at station 10 -North Rumail.…”

Study the regional and seasonal variation of polychlorinated biphenyl in sediments of the Eastern AL-Hammar Marshes, Iraq

“…Due to the limited solubility of PCBs in water, which results in a high adsorption coefficient in sediments and a high enrichment factor in aquatic species, the channels of direct waste dumping, nonpoint resource runoff, and home and industrial wastewater are all sources of PCBs in the river environment (Raghad et al, 2020). It has been hypothesized that PCBs associate with particulate matter in aquatic environments and then accumulate in underlying sediments (Qu et al,2022;Farid et al, 2016).…”

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

“…Petroleum hydrocarbons are considered as important pollutants in marine and estuarine environments, and therefore their biological effects need to be established at each level of biological organization (El-Nemr et al, 2004). Molluscs are one of the species used in monitoring programs as sentinels of marine pollution and their tissues are an important hydrocarbon storage site (Farid et al, 2010). It is reported that the molluscs are ideal monitoring species as they are dominate members of coastal and estuarine communities, accumulate different toxicants in their tissues, are responsive to many environment pollutants, and have a wide geographical distribution (Farid et al, 2008).…”

“…This molluscs occur frequently in the areas receiving acute and chronic oil exposures and are often considered as an important part of food web in the stream. Farid et al (2008 and2010) used the above species of molluscs in the monitoring of biogenic and anthropogenic hydrocarbons in Shatt Al-Arab river.…”