Soil contamination enters aquatic ecosystems affecting sediment quality. The region studied is the Taquari River, Brazil, close to a site contaminated by wood preservatives, with a runoff route into the river. The first stage of the remediation process (In this article, the terms intervention and remediation have been used with slightly different meanings. We consider intervention to be the first phase of the remediation process, which aims to remove active sources) was an intervention to remove the main active sources. The Salmonella/microsome assay and polycyclic aromatic hydrocarbons (PAHs) were used to assess sediment quality in organic extracts during different intervention phases. The strains used were TA98, TA97a, and TA100 with and without S9mix (±S9). The results indicated the presence of pro-mutagens at site Ta010 (closest to the contaminated site) in all samplings, and the highest result occurred before intervention for TA100 + S9 (1,672 ± 215.9 rev/g). These values decreased during (83 ± 23.6 rev/g) and after this process (403 ± 105.9 rev/g), although the PAHs concentrations increased. Samples from this site presented PAHs with a carcinogenic potential during the assessed periods. After intervention, Ta006 (4 km downstream from Ta010) showed the most significant mutagenesis for TA100 + S9 (764 ± 230.2 rev/g) and, although the total PAHs values were lower, the species considered carcinogenic had higher concentrations. Mutagenesis predicted values of PAHs confirmed that carcinogenic species were predominantly detected by TA100, and the other PAHs by TA97a strains. Marked contaminant release to the river was observed, mainly in Ta010 at different periods. Mutagenicity and PAHs values in an internal stream, upstream from Ta010, showed a dispersion route of these agents. Thus, contamination in Ta010 and possible contribution to Ta006, after intervention, provides a warning regarding environmental quality in the region. Environ. Mol. Mutagen. 59:625-638, 2018. © 2018 Wiley Periodicals, Inc.
The region studied on the Taquari River, is close to a site with soil contaminated by wood preservatives, where a route of contaminants into the river was identified. This site was submitted to the first stage of the intervention process excavating the soil to remove the main active sources. To assess sediment quality the PAHs concentrations were analyzed: before, during and after the process. The PAHs concentration was compared to the guide values adopted by CONAMA resolution 344/04, aiming to protect aquatic life. Four points on Taquari River were tested, upper (TA032), in front (TA010) and lower (TA006, TA004) the contaminated site. Besides these, the Stream that is considered a source of contamination for TA010 was evaluated in the last step. The results indicated values between ISQG (Interim Sediment Quality Guidelines and PEL (Probable Effect Level) observed for eight PAHs. The PAHs values, probably carcinogenic to humans, were between ISQG and PEL in different samplings at TA010, more expressives during and after intervention. These values were also found at TA006 and TA004 during the same periods. The persistent contamination of the critical point TA010, even after intervention, is a warning regarding the environmental quality and aquatic life of this region.
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