Browsing by Author "Brito, Pedro"
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- Accumulation, elimination and neuro-oxidative damage under lanthanum exposure in glass eels (Anguilla anguilla)Publication . Figueiredo, Cátia; F. Grilo, Tiago; Lopes, Clara; Brito, Pedro; Diniz, Mário S.; Caetano, Miguel; Rosa, Rui; Raimundo, JoanaRare earth elements (REEs) comprise elements from lanthanum to lutetium that together with yttrium and scandium are emergent contaminants of critical importance for numerous groundbreaking environmental technologies. Transfer to aquatic ecosystems is expected to increase, however, little information is known about their potential impacts in marine biota. Considering the endangered conservation status of the European eel (Anguilla anguilla) and the vulnerability of early fish life stages to contaminants, we exposed glass eels, through water, to an environmentally relevant concentration (120 ng.L-1) of lanthanum (La) for 7 days (plus 7 days of depuration). The aim was to study the accumulation and elimination of La in eel's body and subsequent quantification of acetylcholinesterase (AchE), lipid peroxidation and antioxidant enzymatic machinery. Accumulation peaked after 72 h-exposure to La, decreasing afterwards, even in continuous exposure. Accumulation was higher in the viscera, followed by the skinless body and ultimately in the head, possibly as a protective mechanism to cope with La neurotoxicity. A significant increase in AChE activity was observed in La-exposed glass eels, suggesting that La3+ may inhibit the binding of acetylcholine. A depression in lipid peroxidation was registered under La exposure, possibly indicating that La3+ may play physiological activities and functions as a free radical scavenger. Catalase activity was significantly inhibited in La-exposed glass eels after 72 h, indicating that the availability of La may induce physiological impairment. The quantification of Glutathione S-Transferase activity revealed no differences between control and La-exposed organisms. Further investigation is needed towards understanding the biological effects of REEs.
- Impactos da elevação do nível médio do mar em ambientes costeiros : o caso do estuário do SadoPublication . Brito, Pedro; Andrade, César Augusto Canelhas Freire de, 1955-; Terrinha, Pedro, 1959-Reconstitui-se a evolução recente do estuário do Sado e plataforma continental contígua baseada em mapas históricos, sonar de varrimento lateral e sísmica de alta resolução. O estuário do Sado é separado do oceano pela península de Tróia, tem um prisma de maré de 2,1x108m3 e uma área submersa de ~200km2, cujo ~¼ corresponde ao seu domínio externo dominado pelo delta de vazante submarino e ~¾ ao domínio interno. Entre 1968 e 1995/2002, tanto a área estuarina, como os volumes do prisma de maré e do espaço de acomodação sofreram reduções totais de 6%, 7% e 8%, respectivamente. O domínio interno teve taxas de sedimentação positivas, com um decréscimo acentuado a partir de 1979. No estuário externo verificou-se acumulação para o período de 1968-1979, invertendo-se para o período 1979-1995/2002, em que a erosão focalizada no lobo frontal do delta passa a ser dominante, com perda de 150x106m3 de sedimentos (14%) entre 2002-1930, resultante da redução do prisma de maré. Identificaram-se 3 superfícies sísmicas principais S1-S3, individualizando 4 unidades US1-US4. US1 corresponde ao actual delta do estuário, cuja idade máxima estimada é 7,5kanos. US2 é uma unidade transgressiva, cuja base se associa ao ravinamento da transgressão Holocénica. US3 tem uma idade estimada de 60-25kanos e é interpretada como correspondendo a barreiras costeiras progradantes que ocorrem dos 26m aos 85m de profundidade e são entalhadas por duas plataformas costeiras, definindo uma faixa do fundo do mar marcada por quebras de declive, fundos rochosos e/ou uma fina película de US2. US4 é heterogénea, incluindo sedimentos do Plio-Plistocénico ao Miocénico. A evolução da plataforma desde os 60kanos é reconstituída com base na relação estabelecida entre curvas de variação do NMM publicadas e estruturas interpretadas como paleo-linhas de costa marcadas por quebras de declive aos 35-45m (~60- 50kanos e ~13kanos), 65-75m (~55-25kanos), 80m (~35-25kanos e ~11kanos) e 95- 100m (~16kanos).
- Impacts of phytoplankton blooms on trace metal recycling and bioavailability during dredging events in the Sado estuary (Portugal)Publication . Cabrita, Maria Teresa; Brito, Pedro; Caçador, Isabel; Duarte, BernardoThis work evaluates the impact of phytoplankton blooms on metal availability driven by dredging, in an area of the Sado estuary (Portugal), subject to ongoing dredging operations during the entire sampling period. In situ changes of chlorophyll a concentration, bioavailable trace metals (Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) in the water column, metal content in particulate matter, and particulate metal to bioavailable metal ratios were investigated during pre-bloom, bloom and post-bloom conditions to evaluate the potential of the phytoplankton-mediated metal removal. Metals in particulate matter significantly enhanced concomitantly with the decline of metals (mostly Mn, Co, Cu, Zn, and Pb) in the water column during the bloom, in comparison with pre- and post-bloom periods. During the peak of the phytoplankton bloom, bioavailable Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb were reduced to 30, 99, 100, 87, 98, 72, 84 and 88% of their original levels (pre-bloom values). Copper and Pb, and to a lesser extent, Zn and Mn, were ranked as more particle reactive. Volume particulate matter concentrations of Mn, Ni, Cu and Pb much higher than the bioavailable concentrations, indicated that phytoplankton is likely to be a dominant sink of these metals during the bloom period. Thus, Mn, Ni, Cu and Pb are prone to be transferred and biomagnified into the marine food web. These results highlight phytoplankton blooms as important biological sinks of trace metals during dredging, which should be taken into consideration in planning and management of dredging, to minimise environmental impacts and protect estuarine and coastal ecosystems.
- Rare earth elements in the Tagus Estuary : sources, biogeochemistry and toxicityPublication . Brito, Pedro; Caçador, Maria Isabel Violante; Caetano, Miguel José MartinsSince its discovery in the late 18th century, REE demand has increased exponentially, leading to a worldwide value of 210,000 tonnes of REE-oxides extracted in 2019. Its use in a variety of applications, from industry to agriculture and medicine, led to an increase in its environmental levels. Salt marshes have acted as deposits of REE in the last decades, with concern rise all over the world about its effects on the aquatic environment. Although REE has long been used as micro-fertiliser, many studies have shown its toxic effect on biota. This thesis aimed to study the potential toxicological effect that continuous growth in the REE use and dispersion may represent to the Tagus estuary. The REE spatial distribution in estuarine superficial sediments allowed to confirm that concentrations are dependent on the sedimentary nature and were found mainly associated with the fine-grained material and located in flat mud areas and salt marshes. It also allowed identifying the main anthropogenic sources, located in the wastewater treatment plants outfalls and in an old inactive industrial area, located in the south bank, that continues to contribute to the REE dispersion into the estuary. The study of sediments interaction with the salt marsh flora revealed the important role that halophyte species Halimione portulacoides may play in the sediments REE mobility and bioavailability. Although these plants have shown to be feeble REE phytoremediation agents, its biological activity might be capable of altering sediments’ conditions and enhance REE mobility. The redox-sensitive Ce is one of the highest natural abundant REE and the most applied at industrial level. It is also capable of promoting reactive oxygen species (ROS) due to its chemical characteristics and this study revealed its ability to induce oxidative stress in the halophyte H. portulacoides when exposed to critical concentrations (1200 μg∙L-1). This work finally highlights the importance of monitoring REE environmental levels and developing more research studies on REE interactions and their effects on estuarine systems.
- Sources and distribution of yttrium and rare earth elements in surface sediments from Tagus estuary, PortugalPublication . Brito, Pedro; Prego, Ricardo; Mil-Homens, Mário; Caçador, Isabel; Caetano, MiguelThe distribution and sources of yttrium and rare-earth elements (YREE) in surface sediments were studied on 78 samples collected in the Tagus estuary (SW Portugal, SW Europe). Yttrium and total REE contents ranged from 2.4 to 32mg·kg-1 and 18 to 210mg·kg-1, respectively, and exhibited significant correlations with sediment grain-size, Al, Fe, Mg and Mn, suggesting a preferential association to fine-grained material (e.g. aluminosilicates but also Al hydroxides and Fe oxyhydroxides). The PAAS (Post-Archean Australian Shale) normalized patterns display three distinct YREE fractionation pattern groups along the Tagus estuary: a first group, characterized by medium to coarse-grained material, a depleted and almost flat PAAS-normalized pattern, with a positive anomaly of Eu, representing one of the lithogenic components; a second group, characterized mainly by fine-grained sediment, with higher shale-normalized ratios and an enrichment of LREE relative to HREE, associated with waste water treatment plant (WWTP) outfalls, located in the northern margin; and, a third group, of fine-grained material, marked by a significant enrichment of Y, a depletion of Ce and an enrichment of HREE over LREE, located near an inactive chemical-industrial complex (e.g. pyrite roast plant, chemical and phosphorous fertilizer industries), in the southern margin. The data allow the quantification of the YREE contents and its spatial distribution in the surface sediments of the Tagus estuary, identifying the main potential sources and confirming the use of rare earth elements as tracers of anthropogenic activities in highly hydrodynamic estuaries.
- Yttrium and rare earth elements fractionation in salt marsh halophyte plantsPublication . Brito, Pedro; Malvar, Margarida; Galinha, Catarina; Caçador, Isabel; Canário, João; Araújo, M. Fátima; Raimundo, JoanaSalt marshes act as natural deposits of different metals (e.g. heavy-metals), while halophyte plants are known to retain and accumulate them in the different tissues. Scarce data exists on accumulation, partition and fractionation of YREE in these plants. To study the relationship between halophyte plants and YREE, contents of these metals were determined by ICP-MS in sediment, and in the different plants organs, from Rosário's salt marsh, in Tagus estuary (SW Europe). Results show significant differences (p < 0.001) in YREE contents between sediments. In non-colonised sediment Y was lower (5.0-18 mg·kg-1) compared to the Sarcocornia fruticosa and Spartina maritima sediment cores (19-26 and 20-26 mg·kg-1, respectively). The same was observed for ΣREE, with lower values in non-colonised sediment (32-138 mg·kg-1), while colonised ones presented higher contents (146-174 and 151-190 mg·kg-1, for S. fruticosa and S. maritima, respectively). These significant differences (p < 0.05) are explained by the sediments' nature. Yttrium and ΣREE Al-normalised ratios in non-colonised sediment ranged from 1.5 to 2.3 and 11 to 13, respectively. The colonised sediments revealed significant higher ratios (particularly for ΣREE/Al ratios; p < 0.001), varying from Y/Al: 1.8-2.3 and ΣREE: 13-16 for S. fruticosa, and Y/Al: 1.4-2.3 and ΣREE: 12-18, for S. maritima. Results suggest that these plants may promote YREE enrichment in the sediments. No differences in fractionation patterns among sediments and in both species roots were found, but fractionation was different from those in the sediment, with similar middle-REE (MREE) enrichment and no light-REE (LREE) and heavy-REE (HREE) fractionation. No evidence of YREE transfer to aboveground organs was observed. Different fractionation patterns in stems and leaves were registered, with clear enrichment of LREE relative to HREE and an increase in the MREE enrichment. Therefore, these plants showed low ability to accumulate and translocate YREE but may promote its enrichment in the sediments.