5 research outputs found
Variability in fluvial suspended and streambed sediment phosphorus fractions among small agricultural streams
Agriculture is a major source of sediment and particulate phosphorus (P) inputs to freshwaters. Distinguishing between P fractions in sediment can aid in understanding its eutrophication risk. Although streams and rivers are important parts of the P cycle in agricultural catchments, streambed sediment and especially fluvial suspended sediment (FSS) and its P fractions are less studied. To address this knowledge gap, seasonal variations in FSS P fractions and their relation to water quality and streambed sediment were examined in three Swedish agricultural headwater catchments over 2 yr. Sequential fractionation was used to characterize P fractions in both streambed sediment and FSS. All catchments had similar annual P losses (0.4-0.8 kg ha(-1)), suspended solids (124-183 mg L-1), and FSS total P concentrations (1.15-1.19 mg g(-1)). However, distribution of P fractions and the dominant P fractions in FSS differed among catchments (p < .05), which was most likely dependent on differences in catchment geology, clay content, external P sources, and flow conditions. The most prominent seasonal pattern in all catchments was found for iron-bound P, with high concentrations during low summer flows and low concentrations during winter high flows. Streambed sediment P fractions were in the same concentration ranges as in FSS, and the distribution of the fractions differed between catchments. This study highlights the need to quantify P fractions, not just total P in FSS, to obtain a more complete understanding of the eutrophication risk posed by agricultural sediment losses
Evaluating the effectiveness of the phosphorus sorption index for estimating maximum phosphorus sorption capacity
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Resumen basado en el de la publicaciónDespués de un período de debate curricular -que pasó abajo con una gran indiferencia tanto por parte de la mayoría del profesorado como de los estamentos universitarios- se publicó provisionalmente, entre los de las otras áreas, los nuevos currículos correspondientes a las áreas de conocimiento del medio para la primaria y de ciencias sociales, geografía e historia para la secundaria obligatoria. Una vez leídos y analizados, se comentan que el resultado general es confuso y decepcionante.Universitat de Barcelona. Biblioteca del Campus de Mundet ; Passeig de la Vall d'Hebron 171; 08035 Barcelona; Tel. +34934021035; Fax +34934021034ES