Banca de DEFESA: ALAN KELLNON NOBREGA DE CARVALHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALAN KELLNON NOBREGA DE CARVALHO
DATE: 28/09/2021
TIME: 08:30
LOCAL: Google Meet
TITLE:

Hydrochemical aspects of surface and groundwater in Carnaúba do Dantas/RN and risks associated with human use and irrigation

 

KEY WORDS:

Hydrochemical Diagrams, Water Quality for Irrigation, Sodium Absorption Ratio, Anthropogenic Contamination, Risk Assessment

PAGES: 147
BIG AREA: Outra
AREA: Ciências Ambientais
SUMMARY:

Surface and groundwater resources are an important source of water in the Brazilian semiarid region, where irregular rainfall and water-rock interaction produce saline water, which is generally seen in Carnaúba dos Dantas/RN. The water-rock interaction and climatological conditions impose hydrochemical characteristics on surface and groundwater, which can eventually cause problems for agricultural production, such as soil degradation by processes such as salinization and sodification. Anthropogenic contributions can also lead to the possibility of exposing the population that consumes these waters to health risks. To close hydrochemical data gaps in the municipality, 4 samples of surface water and 7 groundwater were collected at the beginning of the rainy season in February 2020. The pH, electrical conductivity, temperature and total dissolved solids were measured in situ. The results of the chemical analyzes were interpreted from the construction of hydrochemical diagrams, Spearman correlation matrix and mathematical equations. To perform the hydrochemical evaluation, analytical tools such as the Revelle Index, Piper and Stiff diagrams, Gibbs and mixing diagrams were applied, in addition to the calculation of the chlor-alkaline index. In order to investigate possible limitations to the use of water analyzed in irrigation, indices suitable for this purpose were used, such as magnesium ratio, sodium percentage, Kelley ratio, permeability index, potential salinity and sodium absorption ratio. The risk assessment included the calculation of risk ratios for exposure to nitrogenous compounds and heavy metals present in the samples. The surface samples showed the lowest amounts of total dissolved solids, while the underground samples showed the highest ionic concentrations, including concentrations of nitrogen compounds and heavy metals. The Revelle index indicates greater influence of salinization in samples collected in terrains dominated by mica schists and less where quartzites and surface waters predominate. The Piper diagram shows waters that vary between Ca2+-Mg2+-HCO3-, Na+-Cl- and Ca2+-Mg2+-Cl-, while the Stiff diagram shows clusters where two tubular well samples (LAJ1 and XIQ1) relate to each other surface water and the influence of NE-SW and EW deformations on groundwater recharge. The contribution of silicate dissolution is indicated in the mixing diagram, while the Gibbs diagram shows the potential anthropogenic input in RAJ1 and CDD1 groundwater samples by the influence of chlorides, this contribution corroborated by the positive correlations of chlorides with SO42-, NH3 and NO2-. The Chloro-Alkaline Index indicates the relationship of underground samples in terrains dominated by mica schists with ion exchange, while reverse ion exchange is predominant in surface waters. The Chloro-Alkaline Index indicates the relationship of groundwater samples in terrains dominated by mica schists with ion exchange, while reverse ion exchange is predominant in surface waters. The results of the tests carried out in the laboratory and the analysis of the Sodium Absorption Ratio graph indicate that the most suitable waters for irrigation are surface waters, while samples related to mica schists present a high risk of salinization and a low to medium risk for sodification. For magnesium risk, underground samples ERM1, GAR1 and CDD1 are unsuitable for irrigation, and the permeability index shows results consistent with sodium percentage, potential salinity and Kelley ratio. The samples show positive correlations for nitrogen compounds and metals such as Cd and Pb, characterizing an anthropic contribution to the CDD1 sample. The differentiation between surface and groundwater is evidenced in the hydrochemical diagrams. Except for samples LAJ1 and XIQ1, groundwater presents greater risks of sodification and salinization. Nitrogen compounds pose a risk due to exposure in samples CDD1 and RAJ1, while Pb poses risks in samples CDD1 and RAJ1.

BANKING MEMBERS:
Externo à Instituição - ELIS REGINA COSTA DE MORAIS - UFERSA
Interno - 707.819.324-59 - JULIO ALEJANDRO NAVONI - UFRN
Presidente - 1298966 - RAQUEL FRANCO DE SOUZA