DISTRIBUTION, SOURCES, AND SEASONAL VARIATIONS OF HYDROCARBONS IN SHAT AL-ARAB RIVER WATER

JOURNAL OF INTERNATIONAL ACADEMIC RESEARCH FOR MULTIDISCIPLINARY

Impact Factor 1.393, ISSN: 2320-5083, Volume 2, Issue 2, March 2014

DISTRIBUTION, SOURCES, AND SEASONAL VARIATIONS OF

HYDROCARBONS IN SHAT AL-ARAB RIVER WATER

WISAM ABDUL AMEER FARID*

ABDUL–MUTTALIB ABDULLAH AL-EED**

LUAAY ABDUL WAHED SHIHAB***

HAMID TALIB AL-SAAD****

*College of Health and Medical Technology in Basrah, Foundation of Technical Education, Iraq **College of Nursing, University of Basrah, Iraq

***College of Nursing, University of Basrah, Iraq

****Dept. of Marine Environmental Chemistry, Marine Science Center, University of Basrah, Iraq

ABSTRACT: 

The distribution and seasonal variations of hydrocarbons in the Shatt Al-Arab River water column were determined. Total hydrocarbons concentrations were found to vary between 16.77 μg l-1 to 42.6 μg l-1. N-alkanes carbon chain length ranged from C12 to C32 with total concentrations varied from 6.50 μg l-1 to 14.23 μg l-1. The bimodal distribution pattern of n-alkanes with two maxima around C19 to C32 suggested two different sources of hydrocarbons in Shatt Al-Arab River both biogenic and anthropogenic. Polycyclic aromatic hydrocarbons (PAH) appeared divisible into two groups, the low molecular weight (naphthalene, biphenyl, phenanthrene, acenaphthene, and anthracene) and the larger molecular weight (fluoranthene, pyrene, chrysene, benzo (a) pyrene and perylene) with total concentrations varied from 7.19 ng l-1 to 22.47 ng l-1. Their sources derived from different origins. The results indicated that there were distinct seasonal variations of hydrocarbons in Shatt Al-Arab River. The compounds tend to be highest in winter (averaged 31.46 μg l-1) and lowest in summer (averaged 25.63 μg l-1).

KEYWORDS: Shatt Al-Arab River, Total Hydrocarbons, Biogenic Hydrocarbons, N-Alkanes, Pahs, Hydrocarbons Pollution

INTRODUCTION

The Shatt Al-Arab River is the most important river and the only source of freshwater in the arid surroundings of southern Iraq. It is the prime freshwater source and pours about 5x109 m3 nutrient rich water into the Arabian Gulf each year (DouAbul and Al-Saad, 1985). The Shatt Al-Arab River has an area of million km2. Extensive areas are occupied by mangroves and aquatic grasses which are thought to be the major supporters of aquatic food web via detritus. The aquatic fauna and flora of the river are unique assemblages of subtropical and temperate representatives creating an exceedingly diverse and delicately balanced ecosystem.

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JOURNAL OF INTERNATIONAL ACADEMIC RESEARCH FOR MULTIDISCIPLINARY

Impact Factor 1.393, ISSN: 2320-5083, Volume 2, Issue 2, March 2014

The Shatt Al-Arab River region is with a large catchment area utilized for agriculture, grazing, and urban (Farid, 2007).

Development pressures to make Shatt Al-Arab River are mounting as the river provides easy access to small tankers. Many heavy industries are already located along the Shatt Al-Arab River shore, an oil refinery, electrical power stations, a paper mill, a fertilizers factory, a petrochemical complex, and iron and steel mills. The oil industries have established tanker unloading facilities. As yet, no large oil spills have occurred. Thus, even though the Shatt Al-Arab River is relatively unspoiled, it suffers constant threat of oil pollution from tanker activities as well as chronic inputs from sources such as boating, refinery and other industrial outfalls, and domestic sewage.

The Shatt Al-Arab River environmental studies were taken to gain knowledge of the physical, chemical, and biological systems in Shatt Al-Arab River and to identify man's impact on the ecosystem with a goal of water management policies. The hydrocarbons study described in this paper is part of these programmes.

To predict the impact of petroleum hydrocarbons pollution in Shatt Al-Arab River, an ecosystem approach was followed. It was necessary firstly to study hydrocarbons inputs into the river and then to establish the means by which the ecosystem dissipated these compounds. Hydrocarbons enter the aquatic environment either by loss and discharge of petroleum products or by the decomposition of organisms containing biogenic hydrocarbons. These compounds are readily transported in the form of dissolved and particulate adsorbed organic matter within the water column. The hydrocarbons contribution from the two sources (i.e. biogenic and anthropogenic) can be determined by chemical isolation of hydrocarbons constituents and their separation into components on a gas chromatography. Biogenic hydrocarbons are usually much different in chemical composition than petroleum. By comparing sample chromatograms with those from known sources one can compute the contribution of each in a sample (Wang and Fingas, 2003). Other techniques such as fluorescence provide information on types of hydrocarbons and are also useful in distinguishing petroleum sources.

The objectives of the present study are to determine the regional distributions of hydrocarbons, both in solution or dispersed through the Shatt Al-Arab River water column, in an attempt to identify major sources and estimate the seasonal variations of hydrocarbons to study the main ecological factors acting upon the weathering of hydrocarbons in Shatt Al-Arab River water.

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JOURNAL OF INTERNATIONAL ACADEMIC RESEARCH FOR MULTIDISCIPLINARY

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MATERIALS AND METHODS

The Shatt Al-Arab River originates from the confluence of the two major rivers of Iraq (Tigris and Euphrates) at Qurna. Karun River, the only tributary of the Shatt Al-Arab River, joins its eastern bank south of Basrah City (Figure 1). The length of the Shatt Al-Arab River from Qurna i.e. its place of origin, to its mouth in Arabian Gulf, extends about 175 km. It's with varies at different points, ranging from 0.4 km at Basrah City to 1.5 km at its mouth. The water depth increases in general towards the Gulf with a maximum of 12.2 m. The water level is, however, affected by the high and low tides of the Arabian Gulf where the average tidal range is about 1.7 m. Shatt Al-Arab water characterized as being well mixed with limited vertical stratification of temperature and chlorinities. The water of Shatt Al-Arab mouth may be traced as far as 5 km into the Arabian Gulf. The discharge of this river reaches the waters of Kuwait Bay during the flood season.

Five sampling locations were selected along the Shatt Al-Arab River to represent different locations of north section of the River. The sampling programme was carried out during winter and summer seasons. Areas included in the present study and their positions are shown on the map. Replicate water samples were collected using water collector device at low tide from each location during 2012. After collecting water samples, the determination of hydrocarbons concentrations was carried out without delay.

Figure 1. Map of Shatt Al-Arab River showing the position of stationsHydrocarbons were extracted from water followed the procedure described by Grimalt and Olive (1993) and Tuteja et al. (2011) with some modification. The extracts were divided into two portions. The first portion was used to determine total petroleum hydrocarbons using a Shimadzu RF-540 spectroflurometer. The extract volume was reduced using a rotary

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