Geoquímica ambiental e estimativa de fontes de hidrocarbonetos alifáticos e isoprenóides (pristano e fitano) no litoral oeste do Ceará

Abstract

Coastal regions are areas that have environments that present more environmental actions, as they receive a large amount of organic matter residues, acting as environmental reservoirs for various organic contaminants. In this way, sediments become deposits of organic compounds that can compromise the health of the population and ecosystem risks. This work aims to evaluate the levels of aliphatic and isoprenoid hydrocarbons in the coastal zone of Praia do Ícaraí, Tabuba and Cumbuco, located in the city of Caucaia. Thus, investigating chemically their composition and differentiating them between natural and artificial sources. The organic tracers (aliphatic hydrocarbons) from descendants of 5 points of collection of superficial sediments were obtained by means of the ultrasound-assisted extraction methodology, in addition to an extract cleaning step. The levels of n-alkanes and isoprenoids were obtained by means of gas chromatography extracts using a flame ionization detector (GC-FID). The sum of the concentration of the C9-C34 series of n-alkanes ranged from 12.04-16.96 ng g-1. For evaluation of the origin of sedimentary organic matter in the coastal zone of the beaches of Ícaraí, Tabuba and Cumbuco, diagnostic reasons used as BMM / AMM, nC17 / Pr, nC18 / Fit and Pr / Fit, n-alkanes / n-C16. As lower values values of carbon preference index, relative indication of oil n-alkanes and anthropogenic activities. A qualitative analysis of the unresolved complex mixture , confirmed the presence of oil, found the small amounts of non-biogenic n-alkanes present in all of ours. Even so, it concludes that the transportation of aliphatic hydrocarbons thrown on the beach comes from sewers and the release of oil by the ships of the port of Pecém.