UFPR revealed the presence of aromatic hydrocarbons (HPA) in samples collected in the Paranaguá Bay. An unprecedented study carried out by researchers at the Center for Marine Studies at the Federal University of Paraná.
Hydrocarbons are substances that come from petroleum, from burning fossil fuels or from burning vegetation, they can be carcinogenic and mutagenic in large concentrations.
The warning concerning environmental pollution is part of the doctoral thesis defended by Marina Reback Garcia, whose professor is Cesar de Castro Martins. Different classes of hydrocarbons have been found in mangroves and may have a natural origin as well as pollutants from the environment.
“This is the initial study in the region, and it involves an extensive spatial scale since we were able to carry out these analyzes both in the region that is more subject to human activities, as in the bays of Paranaguá and Antonina, but we also collected and analyzed sediments from more isolated mangroves, in the region of Laranjeiras bay, Pinheiros and Guaraqueçaba”, explains the professor.
Although the study identified PAHs, it also indicated that the levels of these substances present in the mangroves of Paraná are lower than in other Brazilian bays. The fact, however, does not reduce the risks for a region that is considered a natural nursery for countless marine species and is an important carbon-capturing ecosystem, contributing to minimize global warming.
According to Marina, the accumulation of these compounds is worrying due to the fishing of crabs and oysters, which indicates that they can affect animals at the base of the food chain of this ecosystem. “These compounds, mainly from the burning of oil and its derivatives, used in navigation or even coming from sewage may be accumulating in these places, which will then be used for fishing. So this is the main alert that can be given”, he summarizes.
In addition to polycyclic aromatic hydrocarbons, the investigation covered other compounds formed by the combination of hydrogen and carbon. Paraffin, gasoline and mothballs are some of the most popular names associated with hydrocarbons and used in everyday life.
The UFPR research also identified compounds that are very resistant to degradation, called oil biomarkers, which are like ‘skeletons’ of ancient life forms that form oil. “Studying these molecules in the mangroves helps us to identify the presence of oil in this ecosystem, even when other pollutants such as PAHs, suggest low human impact”, ponders the professor.
According to scientists, the impact of hydrocarbons associated with human activity in the mangroves of the Estuarino Complex can be considered low. Still, it is important to analyze the signs in the Antonina and Paranaguá Bays and around the Ilha do Mel, regions in which urban occupations occur and port activities.
On the other hand, the North-South axis, in the Laranjeiras and Pinheiros bays, presented low evidence of compounds related to human activity. “Such conditions must be considered when planning new projects in the region”, warn the researchers.
UFPR Professor César also points out another relevant result
With the characterization and analysis of the hydrocarbons present in the mangroves of these regions, it will be possible to have a more precise notion, in the long run, of the evolution of the contamination state of these same points. In case of an environmental accident, for example, these data obtained in the research would be a kind of ground zero for the Paranaguá Estuarine System.
Sample collection by UFPR was carried out at about 40 points distributed in the main bays of the Paranaguá Estuarino Complex: Antonina, Paranaguá, Laranjeiras, Guaraqueçaba and Pinheiros.
The researchers removed the mud from the surface of the mangroves to about two centimetres deep, an indication that they had been deposited more recently. Then, they were taken to the laboratory and extracted with organic solvents so that the team, using gas chromatography and mass spectrometry techniques, could identify and quantify these substances.
The analyzes were intentionally carried out in more preserved regions and others more subject to human activities. “Low hydrocarbon concentrations show the region’s preservation status. However, at some points closer to where there is more intense human activity, the concentrations of PAHs and biomarkers are slightly higher. These are places that demand more attention and monitoring”, emphasizes the professor.