Behavior of rare earth elements in an aquifer perturbed by CO2 injection: Environmental implications

Claudio Inguaggiato, Paolo Censi, Claudio Inguaggiato, Jean Rillard, Philippe Gombert, Olivier Pourret, Pierpaolo Zuddas, Pierre Toulhoat, Lorenzo Brusca, Pierpaolo Zuddas

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Three cubic-meters of CO2-saturated water was injected into a subsurface fractured aquifer in a post-mined area, using a push-pull test protocol. Groundwater samples were collected before and after CO2-injection to quantify geochemical changes. CO2-injection initially reduced the pH of water from 7.3 to 5.7, led to the enrichment of major ions (Ca 2, Mg 2, and alkalinity), and dissolved trace metals (including Fe, Mn, As, and Zn) in the groundwa- ter. Rare earth elements (REE) and yttrium concentrations were also measured in these samples before and after CO 2perturbation, to evaluate their behavior. An enrichment of total Y plus REE (REY) occurred. REY fractionation was observed with higher heavy REE (HREE) enrichment compared to light REE (LREE), and significant variations in La/Yb and Y/Ho ratios were observed following CO 2perturbation. Enrichment by a factor of three was observed for Y, Lu, and Tm, and by nearly one order of magnitude for Dy and Yb. A geochemical model was used to evaluate the amount of REE aqueous ions complexed throughout the experiment. Modeling of the results showed that speciation of dissolved REE with carbonate, along with desorption from iron oxyhydroxide surface were the main factors controlling REE behavior. This study increases an understanding of dissolved REE behavior in the environment, and the potential use for applying iron oxides for REE recovery from mine drainages. Furthermore, the description of REE fractionation patterns may assist in surveying CO 2geological storage sites, surveying underground waste disposal sites, and for understanding the formation of ore deposits and fluid inclusions in geological formations.
Original languageEnglish
Pages (from-to)978-990
Number of pages13
JournalScience of the Total Environment
Publication statusPublished - 2019

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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