Nutrient Dynamics in Bottom Sediment of a Reservoir in the Semi-Arid Region

Sedimentos e nutrientes aportados a um reservatório de pequeno porte no Semiárido tropical

“…Higher concentrations of exchangeable Al and TFe are seen at acidic pH, demonstrated by the negative correlations of r = -0.48 and r = -0.46 between the pH and each element respectively. According to Almeida et al (2017), under acidic conditions there is greater P ** Significant correlation at 0.01, * Significant correlation at 0.05 According to Santos et al (2016), the main phosphorus regulators at the interface between the deposited material and the water depth in the reservoir are the fine-sediment fraction, the organic matter, and the Fe and Al oxides/hydroxides. As such, the negative correlation of available P with TOC and TN (representative of organic matter), as well as with the fine sediment, TFe and Al, demonstrates the principal components of the sediment which retain the phosphorus fractions, thereby reducing detection of available P in the sediment.…”

“…This is due to natural conditions, such as shallow soils, long periods with no rain followed by intense rainfall, high rates of evaporation, and little natural soil cover that is intensified by human exploitation (MALVEIRA; ARAÚJO; GÜTNNER, 2012). Such characteristics favour the deposition of high levels of sediment and nutrients in the waterbody during periods of flooding; whereas during times of little rainfall, reductions in the volume of water in the reservoir accelerate the deposition of dissolved nutrients on the sediment (ALMEIDA et al, 2017;CAVA L CATNE et al, 2018). Monitoring silting in these reservoirs therefore becomes a fundamental tool for evaluating their useful life, and the quantitative and qualitative changes in the stored water, as well as understanding the impact on the reservoir of land use and occupation in the drainage basin on the reservoir (LOPES et al, 2014;MILLARES;MOÑINO, 2018).…”