masterThesis
Poluentes em sedimento depositado em rodovia: implicações sobre um manancial de abastecimento em Natal/RN
Fecha
2018-06-20Registro en:
SANTOS, Paula Rafahela Silva dos. Poluentes em sedimento depositado em rodovia: implicações sobre um manancial de abastecimento em Natal/RN. 2018. 96f. Dissertação (Mestrado em Engenharia Sanitária) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2018.
Autor
Santos, Paula Rafahela Silva dos
Resumen
Road-deposited sediment (RDS) can represent a source harmful to human health and the
aquatic environment, since it is associated with a wide range of pollutants of organic and
inorganic origin. The study of these pollutants associated to the vehicular traffic allows to
identify the different types of pollutants and the generating sources. The aim of this
research was to evaluate the metals and organic compounds n-alkanes and polycyclic
aromatic hydrocarbons (PAHs), since they are pollutants derived from vehicular emissions,
exhaust particles, lubricating oil residues, tires, brakes, bodywork, asphalt waste and wear
of the paving. The Pitimbu River, located in the metropolitan region of Natal-RN, Brazil,
has its river channel intercepted by three high traffic highways. At the points of interception
with the river, the surface runoff associated with the precipitation transfers the RDS to the
river environment, causing the pollution of this river and may render water improper for
human consumption, since the Pitimbu River is used for this purpose. The objective of this
research was to evaluate the presence of the Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn metals,
the organic compounds n-alkane and the Aromatic Polycyclic Hydrocarbons (PAHs)
considered as priority in samples of RDS collected in areas of discharge from the Pitimbu
river channel. Samples of RDS, containment boxes and sediment from the riverbed were
collected in August and December 2017. The analysis of the metals was performed by
Flame Atomic Absorption Spectrometry (FAAS), n-Alkane compounds by Gas
Chromatography – Flame Ionization Detector (CG-FID) and the PAHs by Gas
Chromatography / Mass Spectrometry (GC-MS). In addition, a possible correlation of
these pollutants between RDS environmental matrices and fluvial bed sediment was
investigated. The metal concentrations observed for RDS were as follows (in mg kg-1
):
copper <LQ at 108.40; cadmium <LQ at 4.84; lead <LQ at 76.91; chromium <LQ at 33.71;
manganese <LQ at 86.28; zinc <LQ at 149.80; iron from 7225 to 23810. For nickel the
concentration was lower than the limit of quantification in all samples. PCA analysis and
Pearson's correlation showed a good correlation between Cu, Mn, Fe, Pb, Cr and Zn
metals, indicating that the contribution of these compounds probably comes from the same
sources. The total sum of the n-alkanes (n-C8 to n-C39) ranged from 6.04 to 42.88 mg kg1
. The carbon preference index (CPI) showed that all samples received contributions from
n-alkanes originating from petrogenic and biogenic sources. The sum of PAHs ranged
from 0.221 to 2.789 mg kg-1
. Among the eleven sampling points evaluated for the organic
compounds, four samples of RDS and a sample of the fluvial bed sediment presented
values of PAHs above the guideline value established by CONAMA Resolution 454/12. In addition, the presence of PAHs considered carcinogenic in most samples was observed.
Considering the diagnostic indices used, it was observed that the contribution of PAHs
occurred both by pyrolytic and petrogenic source contributions. It was observed that the
contribution of anthropic (vehicular) origin presented a potential contamination of the fluvial
environment.