Banca de DEFESA: GABRIELA DA ROCHA SALDANHA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GABRIELA DA ROCHA SALDANHA
DATE: 31/08/2022
TIME: 09:00
LOCAL: Online
TITLE:

Geochemical Fractionation of Cu, Pb and Cr in Soils of the Serrana Region – RJ: Reference Values for Bioavailability and Assessment of Contamination in Areas Cultivated with Leaf Vegetables.

KEY WORDS:

Mountain Mountain Agriculture, Pollution Index, Bioavailability of Metals.

PAGES: 94
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Química do Solo
SUMMARY:

The intensive mode of agricultural production in the Serrana Region - RJ is characterized by the massive use of agrochemicals (soluble mineral fertilizers and pesticides), organic residues from animal protein production and also by inadequate soil management, with mechanized preparation and in favor of the slope. This type of exploration has provided severe environmental impacts such as: soil loss by erosion; contamination of soil and surface and subsurface waters, and compromising the quality of the vegetables produced. In view of the above, the present work had the following objectives: to propose the Bioavailability Reference Values (VRB) for Cu, Pb and Cr, for the soils of the Serrana Region of Rio de Janeiro; to evaluate the contamination of the soil by Cu, Pb and Cr, through the joint use of the pollution indexes (IP) and bioavailability (IB), in areas of production of leafy vegetables and evaluation of the risk to human health caused by the consumption of vegetables of leaf contaminated by these three metals. To determine the VRBs, soil samples were collected at 62 points, in areas with or without human activity, forest and pasture, at depths of 0-20 cm and 20-40 cm. To assess Cu, Pb and Cr contamination of areas cultivated with leafy vegetables (parsley, lettuce and common cabbage), surface samples were collected at 205 points, at a depth of 0-20 cm. In these areas, leaf samples of vegetables were also collected. The determination of the pseudototal contents of these three metals was performed following the EPA 3051 methodology. However, the geochemical fractionation was performed by the modified BCR method. For leaf samples, the EPA 3050B methodology was used. In the areas of production of leafy vegetables, the IPs and IBs were determined. The extracts obtained were analyzed in an Inductively Coupled Plasma Emission Spectrometry (ICP-OES) (Chapter 1) and Atomic Absorption (Chapter 2) device. It was verified that the areas of forest and extensive pasture did not present significant differences in the pseudototal contents and in the different chemical forms of Cu, Pb and Cr, indicating that both could be used to establish the reference values of quality and bioavailability. Through cluster analysis, soil samples with low anthropic activity were subdivided into 3 homogeneous groups. In this work, the 75th percentile (P75) of each group was chosen to establish the VRBs. The Cu VRBs for groups G1, G2 and G3 were: 0.40; 0.33, and 0.16 mg.kg-1, respectively. For Pb, they were: 1.05; 0.30 and 0.90 mg.kg-1 and for Cr, 0.09; 0.00 and 0.15 mg.kg-1, respectively. The bioavailable contents of Cu, Pb and Cr were mainly influenced by pH and Mn oxides and hydroxides, as indicated by Principal Component Analysis (PCA). It was also found by the ACPs that the higher bioavailable levels would be associated with the lower areas of the relief. The vegetable growing areas were subdivided into 2 groups by cluster analysis. Using the VRQs and VRBs for the Serrana region, the Pollution Index (IP) and Bioavailability (IB) values were determined. In G1, the Cu IP presented moderate risk of contamination, Pb low risk and Cu no risk. However, the Pb and Cr BIs showed severe contamination. However, for G2, the PIs of all the elements studied showed no contamination, however, the IBs of Pb and Cr indicated moderate and severe risk of transfer to the food chain. The absorption of Cu, Pb and Cr by lettuce, parsley and common cabbage plants is related to their bioavailable contents. As observed throughout the work, Pb represented a greater risk of entry into the trophic chain, due to its greater lability. Regarding the leafy vegetables produced in the region, even having the IBs of Cr, in both groups, indicating severe risk, only Pb presented average levels in hardwoods above the maximum limit established by the Brazilian regulatory agency. However, the risks associated with the consumption of vegetables produced in the study region did not exceed the considerable tolerable limits, due to the low consumption of such hardwoods.

BANKING MEMBERS:
Presidente - 387263 - NELSON MOURA BRASIL DO AMARAL SOBRINHO
Externa à Instituição - ANA CAROLINA CALLEGARIO PEREIRA - UNIFOA
Externo à Instituição - FARLEY ALEXANDRE DA FONSECA BREDA