Banca de DEFESA: FERNANDA MONICELLI CÂMARA BRITO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FERNANDA MONICELLI CÂMARA BRITO
DATE: 23/01/2024
TIME: 13:30
LOCAL: https://meet.google.com/jfr-jhuy-jcy e auditório do CTEC
TITLE:

Effects of the geoengineering technique on the control of eutrophication in planktonic organisms

KEY WORDS:

cyanobacteria; phytoplankton, Floc & Sink; Floc & Lock; mitigation. 

PAGES: 150
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUBÁREA: Ecologia de Ecossistemas
SUMMARY:

There are several techniques to control eutrophication, physical and chemical techniques have been widely used, however there are few studies on the effects of these techniques in the semiarid region and on planktonic communities. The Floc & Sink and Floc & Lock are geoengineering techniques that aim to manipulate the biogeochemical phosphorus (P) cycle, removing particulate P (algal biomass) by sedimentation (Floc & Sink), and dissolved P from water by adsorption and capping. of the sediment (Floc & Lock). The technique uses a combination of coagulant and clays (natural or modified) for sedimentation and/or adsorption. Therefore, the main goal of this thesis is to analyze the responses of the planktonic community to the geoengineering technique to control eutrophication and its efficiency in spring waters in the tropical semi-arid region. The first chapter aimed to carry out a scientometric analysis of the literature to observe the effect of chemical and physical techniques for controlling eutrophication on planktonic organisms in eutrophic environments, evaluating bibliometric production and determining knowledge gaps. The results showed that the most studied techniques were: Floc & Sink, algaecides, Floc & Lock, aeration, dredging and ultrasound, and that there has been more interest in them over the years. The effects of the technique on other phytoplankton groups, in addition to cyanobacteria and zooplankton, are little addressed, being one of the gaps found. Furthermore, studies that observe the effects over time, showing the succession of the planktonic community and in mesocosms are in the minority. Overall, all chemical techniques removed the biomass or biovolume of cyanobacteria. Unlike physical techniques that had conflicting results, with inconclusive results. The few studies following the application of the technique show positive effects on phytoplankton diversity after Floc & Sink and an increase in richness after Floc & Lock and aeration. All techniques negatively affected zooplankton, decreasing the biomass, survival or abundance of these organisms. Chapter two aimed to analyze the effects on biomass and phytoplankton composition, when applying the Floc & Sink (F&S) mitigation technique, in eutrophicated waters from reservoirs in the tropical semi-arid region. On an experimental scale, a chemical coagulant (Polyaluminum Chloride-PAC) and natural materials (Planossol and limestone beige or white) were used as ballasts for sedimentation and we applied a functional approach, Morphology-Based Functional Groups (MBFG), based on morphological characteristics of phytoplankton (Kruk et al., 2010), to evaluate which adaptive mechanisms are more resistant to sedimentation. The technique was capable of sedimenting algal biomass with the addition of coagulant plus ballast (PAC+Planosso; PAC+Beige Limestone and PAC+White Limestone). The effects of the technique on phytoplankton biomass and composition varied according to the sedimentation resistance mechanism. MBFG IV, without specialized characteristics, sedimented only with the use of coagulant. The presence of mucilaginous sheath and aerotopes (Microcystis aeruginosa, MBFG VII) prevented its sedimentation in all treatments. Neither MBFG V (flagellates) nor MBFG VI (small diatoms) exhibited sedimentation. Furthermore, filamentous cyanobacteria (MBFG VIII) demonstrated greater resistance to sedimentation. The use of natural ballast materials provides an economical alternative for removing algal biomass. The third chapter aims to test the efficiency of the Floc & Lock technique in controlling internal fertilization and removing algal biomass from a eutrophic environment in the semi-arid region. We hypothesized that the technique would be able to immobilize the phosphorus present in the sediment, reducing the release of phosphorus and thus limiting phytoplankton growth. The study was conducted on an experimental scale in PVC tubes containing water and sediment, incubated for 47 days. The treatments were: addition of PAC, addition of Phoslock® (PHOS), PAC + PHOS and PAC+PHOS+Beige Limestone (CB), in addition to the control, without the addition of any treatment. Our results showed that the Floc & Lock technique managed to reduce the release of phosphorus into the sediment and limit phytoplankton growth, confirming the study hypothesis. Although all treatments were efficient in capping the sediment and removing algal biomass, the combination of PAC+PHOS was the one that achieved the lowest phosphorus release rates. However, the PAC+ PHOS+CB and PHOS only treatments also obtained good results in removing algal biomass and capping the sediment, showing more economical application alternatives. 

COMMITTEE MEMBERS:
Presidente - 1764855 - VANESSA BECKER
Interna - 2412921 - JULIANA DEO DIAS
Externa ao Programa - 3216945 - HÉRIKA CAVALCANTE DANTAS DA SILVA - UFRNExterno à Instituição - JOSÉ NEUCIANO PINHEIRO DE OLIVEIRA - IFCE
Externa à Instituição - MARCELA APARECIDA CAMPOS NEVES MIRANDA - INPE
Externa à Instituição - MARIANA RODRIGUES AMARAL DA COSTA