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Effects of Rare Earth Elements on aquatic organisms under a changing environment
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Resumo(s)
O aumento da disponibilidade de elementos terras raras (REE) e as alterações climáticas constituem um desafio ambiental com consequências pouco conhecidas; daí, o objetivo desta tese de doutoramento consistiu em investigar a sua bioacumulação, eliminação e interação através da avaliação de estratégias bioquímicas de diversos grupos taxonómicos (esponjas, peixes, bivalves e algas). Os resultados mostram que espécies bioindicadoras costeiras e de alto mar acumulam REE, refletindo mudanças sazonais e concentrações ambientalmente disponíveis. Embora descritos como análogos, o Lantânio (La) e Gadolínio (Gd) comportam-se de forma diferente, e sua biodisponibilidade muda com a salinidade da água. Anguila anguila exposta a 120 ng L-1 La acumulou durante 3 dias e posteriormente a acumulação diminuiu em meio continuamente exposto. Exposta a 1,5 μg L-1 La e aquecimento global, a acumulação aumentou e a eliminação diminui. Ruditapes philippinarum exposta a 0,3 e 0,9 μg L-1 La acumulou de forma dependente da dose. Spisula solida exposta a 15 μg L-1 La, ou 10 μg L-1 de Gd e a alterações climáticas acumulou em 24h e uma eliminação de 7 dias foi insuficiente, apesar do aquecimento global aumentá-la. A resposta bioquímica desencadeada foi insuficiente. A acumulação de La e Gd em Ulva rigida ocorreu em 24h e a exposição em alterações climáticas exigiu uma resposta ao stress oxidativo superior. Os resultados enfatizam um potencial ecotoxicológico de REE aumentado num mundo em mudança. As respostas dos organismos foram específicas por espécie, por elemento e por dose, sugerindo que compreender a acumulação de REE e as respostas ecotoxicológicas num futuro próximo é excecionalmente complexo. Apesar disso, a acumulação de REE e os efeitos tóxicos podem ser exacerbados pelas mudanças climáticas, impondo consequências nocivas às espécies. No geral, os dados desta tese de doutoramento podem ser basilares para o processo de tomada de decisões políticas ao legislar para estas problemáticas emergentes.
Anthropogenically increased rare earth elements (REE) availability and climate change constitute a major environmental challenge. Their combined effects are poorly understood; hence, the main objective of this Ph.D. dissertation was to undertake their bioaccumulation, elimination, and interaction through assessing biochemical strategies of several taxonomic groups (sponges, fish, bivalves and algae). The findings show that coastal and deep-sea biomonitoring species can accumulate REE, mimicking environmentally available and seasonal changes in REE concentrations. Although described as chemically coherent, Lanthanum (La) and Gadolinium (Gd) behave differently, and their bioavailability changes with water salinity. Lanthanum accumulation in Anguilla anguilla exposed to 120 ng L-1 peaked after 3 days and decreased even in a continuously exposed medium. When exposed to 1.5 μg L-1 La and warming, the accumulation was exacerbated, and the elimination was less effective. Ruditapes philippinarum exposed to 0.3 and 0.9 μg L-1 La accumulated after two days, in a dose dependent manner. Spisula solida exposed to 15 μg L-1 La, or 10 μg L-1 of Gd and climate change accumulated after one day and a 7-day elimination phase was insufficient, however warming enhanced it. La and Gd triggered an insufficient biochemical response. La and Gd accumulation in the green macroalgae Ulva rigida occurred in 24h and REE exposure in a near future scenario triggered an overproduction of reactive oxygen species that requested a superior antioxidant response. The results emphasize enhanced REE toxicological potential in a changing world. Organisms’ responses were species-specific, element-specific, and dose-specific, suggesting that understanding REE accumulation and toxic responses in the near-future is exceptionally intricate. Nonetheless, REE accumulation and toxic effects may be exacerbated by climate change, imposing deleterious consequences to species. Overall, data deriving from this novel Ph.D. dissertation will be pivotal for the decision-making process of policy makers when legislating for these emergent problematics and timely environmental policies.
Anthropogenically increased rare earth elements (REE) availability and climate change constitute a major environmental challenge. Their combined effects are poorly understood; hence, the main objective of this Ph.D. dissertation was to undertake their bioaccumulation, elimination, and interaction through assessing biochemical strategies of several taxonomic groups (sponges, fish, bivalves and algae). The findings show that coastal and deep-sea biomonitoring species can accumulate REE, mimicking environmentally available and seasonal changes in REE concentrations. Although described as chemically coherent, Lanthanum (La) and Gadolinium (Gd) behave differently, and their bioavailability changes with water salinity. Lanthanum accumulation in Anguilla anguilla exposed to 120 ng L-1 peaked after 3 days and decreased even in a continuously exposed medium. When exposed to 1.5 μg L-1 La and warming, the accumulation was exacerbated, and the elimination was less effective. Ruditapes philippinarum exposed to 0.3 and 0.9 μg L-1 La accumulated after two days, in a dose dependent manner. Spisula solida exposed to 15 μg L-1 La, or 10 μg L-1 of Gd and climate change accumulated after one day and a 7-day elimination phase was insufficient, however warming enhanced it. La and Gd triggered an insufficient biochemical response. La and Gd accumulation in the green macroalgae Ulva rigida occurred in 24h and REE exposure in a near future scenario triggered an overproduction of reactive oxygen species that requested a superior antioxidant response. The results emphasize enhanced REE toxicological potential in a changing world. Organisms’ responses were species-specific, element-specific, and dose-specific, suggesting that understanding REE accumulation and toxic responses in the near-future is exceptionally intricate. Nonetheless, REE accumulation and toxic effects may be exacerbated by climate change, imposing deleterious consequences to species. Overall, data deriving from this novel Ph.D. dissertation will be pivotal for the decision-making process of policy makers when legislating for these emergent problematics and timely environmental policies.
Descrição
Palavras-chave
terras raras alterações climáticas bioacumulação ecotoxicologia respostas bioquímicas rare earth elements climate change bioaccumulation ecotoxicology biochemical defense mechanisms