Fertilização interna de fósforo a partir de inundação de sedimento exposto em reservatório do semiárido tropical: experimento em microescala
Surface waters are highly vulnerable to nutrient inputs, mainly phosphorus (P) and nitrogen (N) from external or internal sources (sediment). The excessive enrichment of nutrients, a phenomenon known as eutrophication, is currently the major problem when it comes to aquatic ecosystems, the main c...
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| Formato: | bachelorThesis |
| Idioma: | pt_BR |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/48777 |
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| Resumo: | Surface waters are highly vulnerable to nutrient inputs, mainly phosphorus (P)
and nitrogen (N) from external or internal sources (sediment). The excessive
enrichment of nutrients, a phenomenon known as eutrophication, is currently the major
problem when it comes to aquatic ecosystems, the main consequence being the
increase in primary productivity. The phosphorus in the sediment associated with the
environmental conditions of the medium can promote the release or retention of the
more mobile, more bioavailable forms, into the water column. Considering this
problem, this study aims to evaluate the potential for phosphorus release from dry
sediment, after a re-inundation event in a spring of the semi-arid tropical region. The
study was carried out taking samples collected in July 2016 and April 2022, with the
dried sediment from the Dourado reservoir, in Currais Novos/ RN, on a bench scale
(microcosm). The concentration of soluble reactive phosphorus (SRP) extracted from
the sediment with deionized water ranged from 122.8 µg.l-1 to 366.1 µg.l-1, in 2016;
and 22.86 µg.l-1 to 61.19 µg.l-1, in 2022; for the different stirring times (0.25h; 0.5h;
1h; 2h; 3h; 4h; 14h; 24h). Between the time range of 0.25h to 4h there was little
change in value of SRP concentration, when compared to the range of 4h to 24h. The
alteration of SRP values, by drying the sediment, in surface waters, may be related to
the different characteristics of the sediment, such as: the presence of the mineral iron,
its crystallinity; these may disfavor the accumulation of phosphorus in the sediment;
and biogeochemical processes that favor the release of P. The concentration of SRP in
the year 2016 was higher when compared to that of the second sampling (2022); but
despite the value of P in 2022 being lower than in 2016, it can still be considered high,
since the phytoplankton limitation value is 3µg.l-1 of phosphate; demonstrating that
the reservoir is in potential release of phosphorus, which may be bioavailable and,
consequently, collaborating to the intensification of eutrophication. |
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