Continental Shelf Research 23 (2003) 1929–1944 Water and sediment quality assessment of the Axios River and its coastal environment A.P. Karageorgis a, *, N.P. Nikolaidis b , H. Karamanos c , N. Skoulikidis a a National Centre for Marine Research (NCMR), Institute of Oceanography, P.O. Box 712, Mavro Lithari, 19013 Anavyssos, Greece b Department of Environmental Engineering, Technical University of Crete, Polytechnioupolis, 73100 Chania, Greece c Institute of Geology and Mineral Exploration, 70 Messogeion Str., 11527 Athens, Greece Received 17 January 2002; accepted 30 June 2003 Abstract The Axios River (Axios R.) receives substantial loads of nutrients, heavy metals and other compounds, resulting from anthropogenic activities within its catchment. Long-term trends in nutrients were assessed. Dissolved and particulate fluxes of nutrients and selected metals to the Thermaikos Gulf were calculated and finally, data evaluation with water and sediment quality criteria was performed. Dissolved nutrient concentrations exhibited intra-annual variations related to the agricultural practices of the drainage area with elevated autumn–winter NO 3 concentrations (related to fertilizers applied early spring) and high levels of total phosphorous in the summer attributed to point source pollution. Long-term inter-annual variability showed a 2.5-fold increase in nitrate concentration, coupled with a 3-fold decrease in water discharge. Elevated concentrations of dissolved Pb and As have been observed in the Axios R., and freshwater quality criteria for Pb were exceeded. Stream sediments exhibited high contents for Zn, Cr, Pb, and As, mainly originating in tailings and industrial effluents. On the other hand, a considerable portion of the heavy metals is derived from the weathering of ultra-mafic ophiolite complexes. Similar patterns were observed in the Thermaikos Gulf sediment chemistry; the geochemical signatures of the Axios and Aliakmon Rivers (Aliakmon R.), in respect to their contribution in heavy metals, were identified, as well as the impact of the Thessaloniki city. Quality criteria for both river and marine sediments were violated for As and Cr. Overall, the water and sediment quality of the Axios R. and the Thermaikos Gulf have been impacted by anthropogenic activities in the hinterland. The coastal waters and sediments do not appear to pose any threat to human health and aquatic life, however, the need for regular monitoring is highly recommended. r 2003 Elsevier Ltd. All rights reserved. Keywords: Nutrients; Heavy metals; Sediments; Quality criteria; Axios River; Aegean Sea; Greece; FYROM 1. Introduction Increased loads of nutrients, heavy metals, and other compounds (e.g., pesticides, fertilizers) have resulted from changes in land use and anthropo- genic development of the basins. Assessment of the environmental impacts and development of a ARTICLE IN PRESS *Corresponding author. Fax: +30-2910-76323. E-mail addresses: ak@ncmr.gr (A.P. Karageorgis), nnikolai@mred.tuc.gr (N.P. Nikolaidis), hkaramanos@thes. igme.gr (H. Karamanos), nskoul@ncmr.gr (N. Skoulikidis). 0278-4343/$-see front matter r 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.csr.2003.06.009