Origem e acúmulo de compostos policíclicos aromáticos em sedimentos da Baía de Todos os Santos.

Abstract

The vertical distribution of pollutants in marine sediments preserves and acts as a reservoir of quantitative data on anthropogenic emissions that have occurred. Polycyclic aromatic compounds (PAC) include conventional polycyclic aromatic hydrocarbons (HPA), in addition to their nitrated (NHPA), oxygenated (OHPA) and heterocyclic polycyclic aromatic sulfur (PASH) derivatives, considered unconventional are ubiquitous in the environment, many of them have toxic, mutagenic and carcinogenic properties. Studies of unconventional PAC in sediments in Todos os Santos Bay (TSB) are scarce, although several of them have shown greater toxicity than their HPA precursors. In addition, there is no complete study on the temporal distribution of anthropogenic impacts from PACs sedimentary records in the TSB. The TSB is of significant interest due to its socioeconomic and cultural importance to Brazil. This thesis evaluates the occurrence and possible origins of PAH, NPAH, OPAH and PASH in a temporal historical context in four sediment cores from the northern region of the Baía de Todos os Santos (Brazil). This work aimed to evaluate the vertical distribution of anthropogenic impacts through the concentration of PAH, NPAH, OPAH and PASH and their possible origins in a temporal historical context in four sediment cores collected in the north, northeast and west regions of the BTS. In total, 51 compounds were extracted using a microscale solid-liquid extraction procedure and the determination of these compounds was performed using gas chromatography-mass spectrometry (GC-MS). The method was validated and applied to cores collected near the mouth of the Paraguaçu River, the Port of TEMADRE, the Port of Aratu and the RLAM refinery. From the results, it was possible to verify quantitative changes of the chemical groups analyzed in the cores over time and to relate them to the anthropic activities developed in the region. The highest total concentration of PAH and PASH were for the core collected near to Port of Aratu, in turn, NHPA were higher in the core collected at mouth of the Paraguaçu River and OHPA were more abundant in the core collected of RLAM refinery area. The age estimation of the cores was calculated through the sedimentation rate of other cores collected nearby. In general, it was possible to observe an increase in the PAH concentrations and its derivatives over the years at four cores, being significant in the mid-20th century. This period in accordance with the growth TBS’s industrialization, urbanization and population increase promoted by the discovery and petroleum exploration. Temporal variations were observed for low molecular weight PAH (petrogenic sources) and high molecular weight PAH (petrogenic sources), mainly for the Aratu Port core, because was evident a change from petrogenic PAH in older sediments to a greater abundance of pyrogenic PAH in modern samples. The results of this work provide an insight into the historical inputs of PAH, NPAH, OPAH and PASH at cores impacted by different anthropic sources. The profiles of these pollutan have generally followed the historical development of BTS. Differences in the PAH concentrations and compositions, together with the presence of their derivatives NHPA, OHPA and PASH in the four sediment cores, indicated the different input intensities from anthropogenic sources. On the end of the 20th century and the beginning of the 21st century despite of decrease trend for PAH concentrations on Aratu Port and the refinery's cores, PASH concentrations showed maximum values in that time period.