The effect of pH on phosphorus sorbed from sediments in a river with a natural pH gradient

TEMPORETTI PEDRO; BAFFICO GUSTAVO; NICHELA, DANIELA; BEAMUD GUADALUPE; PEDROZO FERNANDO

CHEMOSPHERE

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2019 p. 287 - 299

0045-6535

Phosphorus (P) is an essential nutrient for algal growth and its increase in water bodies produceseutrophication. On the other hand, sediments play an essential role in the processes of transformationand accumulation of P in aquatic systems. pH became a major factor to control the availability of P boundsediment not only for algal utilization and the consequent eutrophication of lakes but also for P pre-cipitation to sediment. Most studies focused on the effect of pH on P release from sediments wereperformed in laboratories where the pH gradient was simulated by adding hydrochloric acid solutions orsodium hydroxide. The aim of this paper is to evaluate the effect of pH on sediment P dynamics (release/uptake) in a river (River Agrio, Argentina) with a natural pH gradient (1.5e6.7) both in water and insediments. The results obtained showed that: all chemical species analyzed in water decreased accordingto pH-gradient increase; pH affects sediment P retention capacity, demonstrating that P retention ca-pacity is lower at high pH; P retention capacity is different dependent on the time of year: in fall, theaverage retention coefficient (R) was 41; in winter, the average R was 38; and in summer, the average Rwas 46. It was found that sediment P, in all the pH gradient, was controlled, mainly, by the oxyhydroxidesof Fe and Al and, to a lesser extent, by the Organic Matter and not by Ca as would be expected in higherpH sediments