Volume 14/Number 12/December 1983 Barnola, J. M., Raynaud, D., Neftel, A. & Oeschger, H. (1983). Comparison of CO2 measurements by two laboratories on air from bubbles in polar ice. Nature, Lond. 303, 410--413. Bjorkstrom, A. (1983). Modelling the oceanic CO 2 uptake and future CO 2 levels. In Carbon Dioxide: Current Views and Developments in Energy/Climate Research (W. Bach, A. J. Crane, A. Berger and A. Longhetto, eds), pp. 57-92. D. Reidel, Dordrecht. Broecker, W. S., Peng, T.-H. & Engh, R. (1980). Modelling the carbon system. Radiocarbon, 22, 565-598. Callendar, G. S. (1958). On the amount of carbon dioxide in the atmos- phere. Tellus, 10, 243-248. Clark, W. C., Cook, K. H., Marland, G., Weinberg, A. M., Rotty, R. M., Bell, P. R., Allison, L. J. & Cooper, C. L. (1982). The carbon dioxide question: perspectives for 1982. In Carbon Dioxide Review: 1982 (W. C. Clark, ed.), pp. 3--44. Oxford University Press, London. Fraser, P. J., Pearman, G. I. & Hyson, P. (1983). 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Incidence of Urban Sewage Disposal in the Salt-ponds Areas of the South of the Bay of Cadiz D. SALES,* A. GOMEZ~ and D. CANTERO* *Department of Chemical Engineering, Faculty of Sciences, University of Cadiz, Spain t Department of Chemical Physics, Faculty of Sciences, University of Cadiz, Spain The highest pollution indices in the marsh and tide4ands situated to the south of the Bay of Cadiz have been evalua- ted. At the present, the salt industry of this area is being transformed into mariculture installations. This study con- sisted of the systematic evaluation of different parameters at 26 sampling stations during the period 1976-1981. The results suggest that extensive zones are too seriously affected to make use of them as marine piscifactories. This report shows the results obtained in various studies undertaken in the years 1977 to 1981 at the Faculty of Sciences, University of Cadiz, Spain. The purpose was to determine general levels of contamination affecting the area of saline and marshland which surrounds the Sancti Petri channel and the various secondary channels which flow from it, given the present tendency to transform the salt industry into marine piscifactories. 447