Abstract
Mangroves perform essential functions in biological cycles and are protected by law in Brazil. However, they are being degraded above their support limit, leading to a reduction in the areas around the world. The area investigated in the present study is a potentially unpolluted mangrove ecosystem in the south of Rio de Janeiro state, Brazil. The aim of this work was to investigate the presence of metals and polycyclic aromatic hydrocarbons (PAHs) in mangrove sediment and to correlate them with mutagenic and genotoxic activity. Four seasonal samplings undertaken between 2009 and 2010 at five sites were analyzed. Dichloromethane extracts were obtained under sonication and subjected to mutagenicity assays using Salmonella microsuspension. Metal (Cd, Cr, Cu, Ni and Pb) contents were determined by atomic absorption spectrometry, while the quantification of PAHs was performed by gas chromatography-mass spectrometry. Goniopsis cruentata hemocytes were used to assess potential genotoxic damage (Micronucleus assay). The absence of mutagenicity was observed for all samples using Salmonella typhimurium strains TA97, TA98, TA100 and TA102, in the absence and presence of an exogenous mammalian metabolizing system. Among the metals, Cd and Cu were detected in autumn at values exceeding the threshold effect level and below the probable effect level. Benzo[a] pyrene was detected at levels above the threshold at one site, where small effects could be observed in the biota. Significant differences in the micronucleated cells observed suggest DNA damage had been induced by the PAHs identified.
Highlights
The characterization of unpolluted or slightly impacted areas is necessary for monitoring the environment, preventing impacts and implementing solutions where the remediation of environmental accidents is required
Metal (Cd, Cr, Cu, Ni and Pb) contents were determined by atomic absorption spectrometry, while the quantification of polycyclic aromatic hydrocarbons (PAHs) was performed by gas chromatography-mass spectrometry
No mutagenic or cytotoxic responses were observed in any of the samples taken from any of the sites in any of the sampling campaigns, since the MI values were lower than 2. These results suggest that the toxic compounds could be interacting with carbonaceous matter in the sediment, reducing their mutagenicity [28] or their contents are lower than values for inducible DNA damage by addition, deletion or base pair substitution
Summary
The characterization of unpolluted or slightly impacted areas is necessary for monitoring the environment, preventing impacts and implementing solutions where the remediation of environmental accidents is required. In this context, mangrove areas are important as they provide a barrier against pollutants and perform unique ecological roles, representing direct economic value. Among the substances that may be pollutants (USEPA 2010), PAHs result mainly from the burning of fuels entering the aquatic environment mainly through atmospheric deposition, urban runoff, municipal effluents, industrial wastewater, and oil spill increasingly common. They have a low rate of degradation in the environment and are a widely used class of geochemical markers with known toxic and mutagenic potential, or carcinogenic properties [3]
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