Prog. Oceanog. Vol. 30, pp. 335-351, 1992. 0079 - 6611/92 $15.00 Printed in Great Britain. All rights reserved. © 1992 Pergamon Press Ltd Anthropogenic inputs of several heavy metals to nearshore basins off Los Angeles CHIH-AN HUH l, BRUCE P. FINNEY 2 and JANET K. STULL 3 ICoUege of Oceanography, Oregon State University, Corvallis, Oregon 97331, USA 2Institute of Marine Science, University of Alaska, Fairbanks, Alaska 99775, USA 3Los Angeles County Sanitation Districts, PO Box 4998, Whittier, California 90607, USA Abstract - Budgets of anthropogenically-derived Cr, Zn and Pb in the Santa Monica-San Pedro Basin and the Palos Verdes Shelf are estimated from profdes of these metals in a large number of sediment cores. Comparisons of inventories in the deep basin with combined emissions from the responsible sewage outfalls indicate that no more than 7% of the Cr, 2% of the Zn and 5% of the Pb derived from the sewage source are buried in the nearshore basin. A similar comparison of metal accumulation on the Palos Verdes Shelf with discharges from the nearby JWPCP outfall indicates that 12% of the Zn and 20% of the Cr and Pb are deposited locally. The annual percentages of sewage- derived Pb retained should be significantly lower, because surface runoffand atmospheric fallout are also important input pathways for anthropogenic Pb. Offshore variations in sediment metal composition suggest that Cr is most strongly attached to sewage particles while Zn and Pb are more labile. We conclude that the majority o f anthropogenic metals are exported offshore beyond the inner basin. CONTENTS 1. Introduction 336 2. Sampling and Analytical Methods 339 2.1 Sediment coring 330 2.2 Chemical analysis 339 2.3 Sediment chronology 340 3. Results 341 3.1 Metal profiles 34 l 3.2 Metal inventories and spatial variation 341 3.2.1 Santa Monica-San Pedro Basin 341 3.2.2 Palos Verdes Shelf 344 3.2.3 Santa Cruz Basin 347 3.3 Mobility of metals during their transport 347 4. Summary and Discussion 349 5. Acknowledgements 350 6. References 350 335