Adsorption of phosphorus on sediments of the balearic islands (Spain) related to their composition

The adsorption of phosphorus onto sediment particles has a major role in coastal areas, where continental inputs may increase levels of phosphate in the water mass. This paper reports a study of the adsorption capacity of phosphorus in two coastal areas located in the Balearic Islands: one in Majorca (The Albufera of Alcudia), and the other in Minorca (The Albufera of Es Grau). The range of adsorption capacity was 35-121 mu mol Pg(-1) in Majorca, and 30-55 mu mol Pg(-1) in Minorca. Considering the slope of the Langmuir equation for low or moderate phosphorus concentrations as a measure of the efficiency of sediments in taking up phosphate, sediments from Minorca were more efficient than those from Majorca (21-36 ml g(-1) and 14-21 ml g(-1), respectively. A horizontal pattern of variation was observed in both areas, with the highest values near the sea and at the points with least marine influence. In Majorca, maximum adsorption capacities (C-max) were positively correlated with concentrations of iron and aluminium, and efficiencies of sorption were related to carbon. In Minorca, C-max and efficiencies were negatively correlated with iron and aluminium, and positively correlated with carbon and calcium. (C) 1996 Academic Press Limited