Evaluación de la calidad de sedimentos marinos acidificados por fugas en almacenamiento de co2biodisponibilidad de metales y toxicidad en microalgas

  1. Romanó de Orte, Manoela
Supervised by:
  1. Tomás Angel del Valls Casillas Director
  2. Aguasanta Miguel Sarmiento Co-director

Defence university: Universidad de Cádiz

Fecha de defensa: 10 December 2013

  1. Alejo Carballeira Ocaña Chair
  2. Inmaculada Vallejo Fernández de la Reguera Secretary
  3. Sandra Sofia Ferreira Da Silva Caeiro Committee member
  1. Química Física

Type: Thesis

Teseo: 354209 DIALNET


Carbon dioxide capture and storage (CCS) in submarine geological formations has been proposed as a mitigation measure for the prevention of global warming. However, leakage of CO2 to overlying sediments may occur over time, leading to various effects on ecosystems. Laboratory-scale experiments were performed, involving direct release of carbon dioxide into sediment, inside non-pressurized chambers, in order to provide data on the possible effects of CO2 leakage from geological storage sites on the fate of several metals. Marine sediments from three sites with different levels of contamination were sampled and submitted to acidification by means of CO2 injection. The experiment lasted 10 days and sediment samples were collected on the beginning and end of the experiment for metal analysis. The results revealed that mobility of metals from sediment to pore water and seawater depends on the site, metal and length of time exposed. Mobilization of the metals Al, Fe, Zn, Co, Pb and Cu increases with acidification, and this response generally increases with time of exposure to CO2 injection. The geochemical model applied suggests that acidification also influences the speciation of metals, transforming metals and metalloids, like As, into species much more toxic to biota. Furthermore, sediments elutriate were prepared to perform toxicity tests with the microalgae Phaeodactylum tricornutum. The results showed that sediment acidification enhanced the release of metals to elutriates. Iron and zinc were the metals most influenced by this process and their concentration increased greatly with pH decreases. Diatom growth was inhibited by both processes: acidification and the presence of metals. Data obtained is this study is useful to calculate the potential risk of CCS activities to the marine environment.