title: Phosphorus seasonal sorption-desorption kinetics in suspended sediment in response to land use and management in the Guaporé catchment, Southern Brazil.
abstract: Phosphate sorption-desorption parameters like maximum phosphorus (P) adsorption capacity (Pmax), equilibrium phosphorus concentration (EPC), water desorbable P (α), potentially bioavailable P (β), and mobility index (α/β ratio) were determined in order to understand the sediment source-sink nature in Guaporé catchment in southern Brazil during summer and winter 2013 and 2014. The result showed a significant (p = 0.05) variation across sediment site or seasons and revealed the most sorption-desorption parameters (Pmax, α, β) with the increments following the order urban sediments > intensive agriculture under CT > intensive agriculture under NT > low agriculture sub-catchments (sub1 and sub2) > native forest. In the main river points, these parameters decreased along the river (P1 to P5). The results were more obvious in winter than the summer season. In contrast, the low values of λ and α/β ratio in the sediment from native forest and relatively less polluted catchment (sub1) during summer season show the quick P desorption when compared to specific Fe and Al oxides bound to stable P in intensive agriculture sediments. These findings clearly indicated that agricultural practices, sediment characteristics, and hydrological factors have a major impact on seasonal sediment P bioavailability and mobility. The urban untreated discharges may be a single major P source and, if it is not wisely managed, proves a major threat to water quality. These results have serious implications for the river ecosystem and will be of great importance to improve the environmental and economic performance of agricultural practices aiming to reduce soil-based P legacy to surface waters.
authors: Department of Soil Science, Universidade Federal de Santa Maria (UFSM), 1000 Roraima Avenue, Santa Maria, Rio Grande do Sul, 97105-900, Brazil. mohsinses@gmail.com.|Department of Soil and Environmental Sciences, The University of Poonch Rawalakot, Azad Jammu and Kashmir, 12350, Pakistan. mohsinses@gmail.com.
authors: Mohsin
authors: M
authors: Zafar
authors: Department of Agricultural Sciences, Universidade Regional Integrada do Alto Uruguai e das Missões, Erechim, Rio Grande do Sul, Brazil.
authors: Tales
authors: T
authors: Tiecher
authors: Department of Soil Science, Universidade Federal de Santa Maria (UFSM), 1000 Roraima Avenue, Santa Maria, Rio Grande do Sul, 97105-900, Brazil.
authors: José Augusto Monteiro
authors: JA
authors: de Castro Lima
authors: Department of Soil Science, Universidade Federal de Santa Maria (UFSM), 1000 Roraima Avenue, Santa Maria, Rio Grande do Sul, 97105-900, Brazil.
authors: Gilmar Luiz
authors: GL
authors: Schaefer
authors: Department of Physics, Universidade Federal de Santa Maria (UFSM), 1000 Roraima Avenue, Santa Maria, Rio Grande do Sul, 97105-900, Brazil.
authors: Maria Alice
authors: MA
authors: Santanna
authors: Department of Soil Science, Universidade Federal de Santa Maria (UFSM), 1000 Roraima Avenue, Santa Maria, Rio Grande do Sul, 97105-900, Brazil.
authors: Danilo Rheinheimer
authors: DR
authors: Dos Santos
mesh_terms: D000327:Adsorption; D000383:Agriculture; D001938:Brazil; D017753:Ecosystem; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D010758:Phosphorus / Q000032:analysis*; D045483:Rivers; D012621:Seasons; D012987:Soil; D060753:Water Quality
chemical_list: D012987:Soil; D010758:Phosphorus
keywords: Anthropic activity; Catchment characteristics; Seasonal P release; Sediment phosphorus; Sorption-desorption