Water Res. Vol. 19. No. 4. pp. 457-462. 1985 0043-135485 53.0~)- 0.00 Printed in Great Britain. All rights reserved Copyright ~S 1985 Pergamon Press Ltd TRACE METALS IN SHATT AL-ARAB RIVER, IRAQ JAMAL K. ABAYCHI and ALt A. Z. DOUABUL* Marine Science Centre, The University of Basrah, Basrah. The Republic of Iraq ( Receit'ed January 1984) AMtract--The distribution of 10 trace metals Cd. Co, Cr, Cu, Fe. Mn, Ni, Pb. V and Zn have been determined along the northern section of the Shatt al-Arab River, Iraq. Analyses were carried out, employing a flameless AAS instrument. The mean concentrations of the dissolved species were as follows (expressed in /xg I-~): 0.25 Cd. 0.9 Cu, 716 Fe, 1.3 Mn, 0.3 Pb, 0.2 V and 1.8 Zn. Mean concentrations of Cd. Co, Cr, Cu, Fe, Mn, Ni, Pb. V and Zn in the particulate matter were 55.2.6.0, 188, 77, 31 472. 173t. 3807, 93, 207 and 77/z g g- t respectively. In the exchangeable fraction of the sediment were 0.15, 5.5, t 1.1, 11.9, 1625, 482, 42, 30.5, 25.7 and 6#g g - t whereas in the residual were 0.025, 11.5, 96.1, 22, 5176, 258. 613, 3.9, 162 and 56.8 ~g g-~ respectively. Thus, the exchangeable trace metals represent the following mean percentage of the total; 750/0Cd, 33°0 Co, 103/Cr, 34% Cu, 24% Fe, 63°0 Mn, 7% Ni, 74°./0Pb, 14°o V and 23°o Zn. The concentration of Ni and V were relatively high, this was attributed to the petroleum-rich deposits of the region. The concentrations observed for other metals were lower or equal to those reported for control sites except for Pb which was slightly higher. The data obtained were subjected to simple linear regression analysis and expressed in the form of correlation coefficients. It was found that the inter-elemental relationships are rather complex. Key words--Shatt al-Arab River, Arabian Gulf, trace metals, water, sediment, particulate matter, atomic absorption spectrophotometry, baseline levels INTRODUCTION There are always traces of metal ions in water, particulates and sediments from fiverine areas, but the "background" levels are poorly documented in the literatures (Frenet, 1981). What can be considered as a normal metal-content in such environments has not been clearly defined, since it varies from one place to another according to the geological nature of the catchment area. No study has been undertaken, however, addressing the distribution of trace metals in the Shatt aI-Arab River, which is of a major concern. This fiver is the prime fresh-water body in the rather arid surroundings of southern Iraq, con- sequently its waters are utilized for several purposes (e.g. drinking, irrigation etc.). Moreover several spe- cies of commercial fish are present in it. Agricultural and industrial developments along the Shatt al-Arab River's banks have been proceeding rapidly during the last decade, hence, the magnitude of pollution may increase year by year. Rivers are known to contribute substantially to the total input of trace metals to the sea (Windom, 1981). Shatt al-Arab drainage is thought to be a possible source of pollutants to the Arabian Gulf, thus effecting Kuwait coastal waters (Anderlini et al., 1982). The aim of the present study was to provide information on the distribution of ten trace metals in the Shatt aI-Arab River. These data may be of use to other researchers who require a baseline for com- pafison of trace metal distributions. *To whom correspondence should be addressed. STUDY AREA The Shatt aI-Arab River originates from the confluence of the two major rivers of lraq (Tigris and Euphrates) at Qurna. Karun giver, the only tributary of the Shatt al-Arab River, joins its eastern bank south of Basrah City (Fig. 1). The length of the Shatt al-Arab River from Qurna, i.e. its place of origin, to its mouth in the Arabian Gulf, extends about 175 km. Its width 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 maximum of 12.5 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 waters are characterized as being well mixed with limited vertical stratifications of temperature (Saad and Kell, 1975) and chlorinities (Huq et a1.,1978). It has been estimated that the Shatt al-Arab River annually discharges into the Arabian Gulf approx. 5 x 109m 3 of fresh water (Hartmann et al,, 1971). EXPERIMENTS Water and sediment samples were collected during April 1983 from 6 sites to provide representative coverage of the northern section of the Shatt al-Arab River (Fig. l). Water samples (10 l.) were collected in acid-washed polyethylene bottles held just below the surface. These samples have been suction filtered as soon as possible (within an average of 6 h, maximum < 12 h) through prewashed, preweighed 0.45 ,urn Millipore membrane filters (Klinkhammer and Bender, 1981). Materials passing through the filters were considered as "dissolved" while those retained as "particulate". The dissolved trace ions were concentrated using chelex 100 resin following a procedure described by Riley and Taylor (1968). 457