Marine Pollution Bulletin, Vol. 34, No. 9, pp. 706-711, 1997 Pergamon © 1997 Elsevier Science Ltd All rights reserved. Printed in Great Britain PII: S0025-326X(97)00018-0 0025-326X/97 $17.00 + 0.00 Particulate Metals Contamination in the Kishon River Estuary, Israel BARAK HERUT and NURIT KRESS Israel Oceanographic and Limnological Research, National Institute of Oceanography, P.O. Box 8030, Haifa 31080, Israel Suspended particulate matter (SPM) collected along the Estuaries act as a transition zone in which continental axis of the Kishon River, its estuary and Haifa Bay weathering material is trapped and through which some were analysed for trace metal concentrations together of the material is transported to the open sea. The with measurements of water density, pH and dissolved composition and variability of suspended particulate oxygen. The concentrations of particulate Cd, Zn and matter (SPM) in this river-ocean boundary are affected Cu generally increased from the upper Kishon system by many complex geochemical processes (precipitation (upstream from Tzipori-Kishon Junction) downstream and flocculation, desorption--adsorption, etc.) and by and decreased from the Kishon Harbour seaward, while physical processes (river flow, tidal energy, currents) particulate AI concentrations decreased downstream and and are, therefore, often difficult to interpret (Morris et towards the open sea. Enrichment of Cd, Zn and Cu al., 1978; Turner et al., 1991, 1994). was found at Hnifa Bay compared to the upper Kishon The Kishon River, which empties into Haifa Bay, is system. The axial profile of Mn concentrations regarded as the most polluted coastal river in Israel. The indicated reduction of Mn at the anoxie and low pH river runs through the largest industrial area in the zone of the lower river system and precipitation of Mn- country and is subjected to considerable inputs of oxides at the estuary in response to the increase in pH organic and trace metal contaminants from oil and dissolved oxygen concentrations. Although Fe refineries, petrochemical and fertilizer plants, a sewage concentrations showed similar behavior to that of AI, treatment plant, intensive agriculture in the recharge the higher Fe/A1 ratios at the estuary are probably due area and other sources. Trace metal contamination in to precipitation of Fe-oxides onto pre-existing particles, the sediments at the lower Kishon River system was first This spatial non-conservative behavior of metals is observed in 1972 by Kronfeld and Navrot (1974, 1975) presumably due to the: 1. mixing between polluted and later by Krumgalz et al. (1990), Cohen et al. (1993) river-borne particles and material of drainage basin and and Herut et al. (1993a). Studies conducted in Haifa coastal origin; 2. changes of the distribution coefficient Bay since the 1980s indicated that the Kishon Estuary is of metals between the particulate and solution phases the major source contributing trace metal contamina- (Kd) with variations of salinity, pH and SPM tion to the sediments of the southernmost part of the concentrations; and 3. physical settling and currents. Bay (Hornung et al., 1984, 1989; Herut et al., 1993a,b, Short-term, tidal cycle measurements undertaken at the 1986). However, it has been suggested that the lower lower Kishon system (Julius Simon Bridge) indicated a reach of the Kishon River and its harbours act as a trap high contribution of resuspended sediments to the SPM for polluted material, except during heavy flood events amounts due to the high tidal energy. It is hypothesized (Krumgalz et al., 1990; Cohen et al., 1993). Although that the latter is the main mechanism by which SPM, SPM is a major carrier through which toxic metals are which settles in the estuary, is transported landward transported to the open sea, no related observations creating a turbidity maximum zone between the Julius have been performed in the Kishon system. In this study Simon and Histadrut bridges, i.e. about 3 km upstream we examine the variability of trace metals in SPM along from the estuary. It is proposed that the upper estuary the axis of the Kishon River, its estuary and Haifa Bay zone acts as a purging system through which a low flux in relation to physical and chemical processes in this of SPM, enriched by organic and trace metal content, is system. transported seaward and from which a high flux of SPM is returned landward due to tidal stress. © 1997 Study Site Elsevier Science Ltd The Kishon River is one of the largest rivers in Israel, draining an area of approximately 1100 km 2 (Fig. 1). Its Keywords: trace metals; suspended particulate matter; discharge basin includes the north-eastern flank of the estuaries; Mediterranean; contamination; Kishon River Carmel Mountains via the Yizrael Valley to the Upper (Israel). Galilee in the north. The river system can be divided 706