Distribuição espaço-temporal de hidrocarbonetos de petróleo no estuário do Rio Vaza Barris-SE
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Notice bibliographique
Résumé
The Vaza Barris river estuarine system is located at 11o 08 ´S and 37o 10´ W, at sea level. It has a total area of 115 km2, with a ecosystem with great biological diversity and vegetation composition. Due its great importance in biological and vegetative diversity, it has been inserted in an Environmental Protection area, called EPA. The Vaza Barris river estuarine system has been suffering with human actions, such as recreation and leisure, traffic of maritime vessels, shrimp farming and real estate activities. The present work aims to understand the spatial and temporal distribution of geochemical biomarkers, the Aliphatic Hydrocarbons (AH) and Polycyclic Aromatic Hydrocarbons (PAH) on the superficial sediments of the Vaza Barris river. This work also intends to understand how sedimentary deposition has happened and the importance of this deposition. To conduct this study, samples were collected in two campaigns (Winter and Summer). During the winter, 13 sites were sampled with a triplicate in the station 13 (13a, 13b and 13c). In the summer campaign, it was repeated the 13 sites previous sampled and added two others, giving a total of 15 sites. For the extraction of hydrocarbons from the sediments, it was used Ultrasonic extraction, with dichloromethane as the extraction solvent. In the samples clean-up (alumina and silica), hexane was used for the AH (F1) Fraction elution and dichloromethane/n-hexane (1:1) for the elution of PAH fraction (F2). The analysis was carried out by Gas Chromatography/Mass Spectrometry (GC/MS). To understand the distribution of hydrocarbons, it as used several Diagnostic Index Ratios (DIR). The AH and its isoprenoid (Pristane and Phytane) had good recoveries, wit values between 50.74 and 108.95% and a mean recovery above 60% with relative standard deviation RSD of 18.8%. Their concentrations ranged from 0.19 up to 8.5 Êg.g-1 of dry sediment. The Carbon Preference Index (CPI) calculated for all points (except for VB2 and VB3 in winter) associated with reasons °alifaticos/n-C16 and BMM/AMM (ratio of Low Molecular Weight/High Molecular Weight) suggested biogenic contribution. Their values of RTA (Terrestrial to Aquatic Ratio) and predominance of odd chains and high concentrations of the n-C29 homologue indicated biogenic contribution with significant contribution of higher terrestrial plants. The recoveries of PAH ranged between 45.46 and 163.0% with a mean recovery above 100% and RSD of 28.31%. Their total concentrations ranged from 0.09 a 410.4 ng.g-1 of dry sediment, with levels above the TEL (NOAA) and PQT (Environment Canada). Its DIR indicated a mixture of contributions (petrogenico, pyrolytic and combustion of biomass), with a strong tendency of pyrolytic contribution. Its distribution shows a predominance of high molecular weight compounds, registering significant concentrations for Benzo(a)pyrene, Pyrene, followed by Benzo(b)fluoranthene and Benzo(a)anthracene, both considered mutagenic and carcinogenic. The predominance of pyrolytic contribution may be justified by the existing heavy boat traffic in the estuary.
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Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,001 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,001 |
| Communication savante | 0,000 | 0,001 |
| Science ouverte | 0,002 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,022 | 0,001 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle