Banca de DEFESA: PAULA CAROLINE FERREIRA RODRIGUES

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : PAULA CAROLINE FERREIRA RODRIGUES
DATE: 28/02/2023
TIME: 14:00
LOCAL: Prédio Prof. Mateus Rosas Ribeiro
TITLE:

Geochemistry of rare earth elements in areas with radionuclide anomalies and ultramafic lithology in the state of Pernambuco

KEY WORDS:

 Emerging contaminants. Brazilian semi-arid native plants. Lanthanides. Soil 41 mineralogy. Environmental monitoring. Natural radionuclides. Soil quality reference values.

PAGES: 140
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Química do Solo
SUMMARY:

Rare earth elements are a group of economic importance, being used in renewable resources, medicine and metallurgy. However, REEs can cause harm to human health and the environment. In the state of Pernambuco there are two areas of anomalous lithologies, an area in the Agreste of the state with the occurrence of natural radionuclides enriched with REEs constituting an area of environmental and social concern, related to human exposure. The other area with the occurrence of ultramafic lithology where REEs can be evaluated as pedogenetic tracers. Thus, the objective of this work was to evaluate how the mineralogy and geochemistry in areas with anomaly of radioactive elements and ultramafic rocks in the state of Pernambuco influence the natural grades, mobility and fractionation of REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Yb, Lu, Dy, Er, Ho, Tb, Tm, Y and Sc), U and Th in soil profiles in order to understand the dynamics of these elements. In the area of radiometric anomaly, four soil and rock profiles were opened after samples were collected, selected according to natural radioactivity with Th contents greater than 20 mg kg-1 and high REE contents. While in the ultramafic rock anomaly area, soil samples from three profiles were opened and collected. The following analyzes were carried out: (I) petrography and chemical composition of the rock; IV) mineralogical analysis of the soil; II) chemical and physical analysis of the soil; III) total, environmentally available, and bioaccessibility of REEs, U and Th. The radiometric anomaly area was enriched in REEs (213.95-1340.95 mg kg-1), uranium (0.93-8.08 mg kg-1) and thorium (48.03-194.58 mg kg-1) in the soil profiles. The metagranitic rocks presented 148.25-460.15 mg kg-1 of REEs, 2.83 – 4.25 mg kg-1 of uranium, 25.20 - 73.33 mg kg-1 of thorium. The ΣETRLs/ΣETRPs, Lan/Ybn, Gdn/Ybn, Lan/Smn, δEu and δCe relationships are similar between source materials and derived profiles confirming the geochemical signature of metagranitic rocks. These high ratios indicate the enrichment of ETRLs, associated with low rate of weathering in soils of semi-arid climate and the kaolinite mineralogy of these soils. Although the area has high levels of REEs, U and Th, the bioaccessible and bioavailable levels are low. The native plants developed in this area showed high ETRs and Th levels, however they did not show symptoms of visible toxicity. The average contents of ΣETRs in the ultramafic soil profiles were 79.13 mg kg-1. The parent materials showed 34.25 mg kg-1 of ΣETRs in serpentinite and 56.45 mg kg-1 in pyroxenite. The ΣETRLs/ΣETRPs, Lan/Ybn, Gdn/Ybn, Lan/Smn relationships are similar between serpentinite and pyroxenite and the derived soil profiles, respectively, confirming the geochemical signature.

COMMITTEE MEMBERS:
Interna - CAROLINE MIRANDA BIONDI
Interno - JEAN CHEYSON BARROS DOS SANTOS
Interno - ***.385.794-** - YURI JACQUES AGRA BEZERRA DA SILVA - UFPI
Externo à Instituição - RONNY SOBREIRA BARBOSA - UFPI
Externa à Instituição - PAULA RENATA MUNIZ ARAUJO - UFRPE