Occurrence of mercury in polychaete species (Annelida) and their associated sediments from an important Southern Atlantic Ocean Bay.

In the present study, the Hg levels in freshly collected polychaete species and their associated sediments were evaluated from Todos os Santos Bay, Northeastern Brazil. Additionally, it was also measured the Hg distribution along the annelids' body parts (anterior region, abdomen, and posterior region). Total Hg concentration was as follows: 13.6-144 µg kg-1 (Scolelepis chilensis, deposit feeder), 8.2-122 µg kg-1 (Laeonereis acuta, deposit feeder), 95-612 µg kg-1 (Armandia agilis, deposit feeder); 96.6-206 µg kg-1 (Lumbrineris sp., carnivorous), 75.3-112 µg kg-1 (Goniada echinulate, carnivorous), and 115-198 µg kg-1 (Branchiomma sp., suspension feeder). In turn, Hg levels in sediments ranged from 2.77 ± 0.24 to 6.38 ± 0.15 µg kg-1. Hg concentrations found in polychaete soft tissues were higher than those found in the sediments. Specific habits, feeding behavior, trophic level, and stressful environmental conditions are the main factors affecting the Hg levels in the species studied. The bioaccumulation factor (BAF), contamination factor (CF), and ecological risk assessment (Er) were calculated. The BAF values were higher than 1 for all studied species, indicating Hg bioaccumulation in the annelids, but the low levels of CF e Er showed those Hg levels present low to no significant ecological risk for the biota and benthonic organisms living in the sediments. Finally, no statistically significant difference was observed for Hg concentration levels along the polychaete body parts.

Occurrence, sources, and risk assessment of unconventional polycyclic aromatic compounds in marine sediments from sandy beach intertidal zones.

This study investigated the concentrations of polycyclic aromatic compounds (PACs), including parent polyaromatic hydrocarbons (PAHs) and their nitrated and oxygenated derivatives, in 48 sediment samples from the intertidal region of sandy beaches in Baía de Todos os Santos (BTS), Salvador, State of Bahia, Brazil. The total PAH (∑PAH) concentration, total nitro-PAH (∑nitro-PAH) concentration, and total oxy-PAH (∑oxy-PAH) concentration ranged from 2.11 µg g-1 dry weight (dw) to 28.0 µg g-1 dw, 2.58 µg g-1 dw to 30.2 µg g-1 dw, and 0.34 µg g-1 dw to 3.65 µg g-1 dw, respectively. Elevated concentrations of parent PAHs and nitro-PAHs were found in samples from two sites in BTS, which were also characterized by high percentages of fine-medium sand and low organic matter contents. Potent mutagenic 3-nitrobenzanthrone (3-NBA) was found in 86% of the samples at concentrations ranging from 0.200 µg g-1 dw to 0.690 µg g-1 dw. Furthermore, calculations of the benzo[a]pyrene toxicity equivalency (BaPTEQ) indicated that three carcinogenic high-molecular-weight PAHs accounted for 98.7% of the total maximum PAH concentration. Finally, we assessed the possible environmental risks posed to benthic species living in the sediments of BTS. The results showed that the risk quotient for PAHs (RQPAHs) was ≥1. In turn, the summed RQ for all PACs (∑RQmixture) ranged from 1 to 30, but did not exceed the maximum allowable threshold; thus, the risks posed to benthic species were moderate for all sediment samples.

Occurrence of 3-nitrobenzanthrone and other powerful mutagenic polycyclic aromatic compounds in living organisms: polychaetes.

In this work we report the occurrence of powerful mutagenic 3-nitrobenzanthrone (3-NBA), in addition to 18 polycyclic aromatic hydrocarbons (PAHs), 6 oxygenated PAHs and 27 nitrated PAHs in polychaete worms. Benzanthrone (BA), another important mutagenic polycyclic aromatic compound (PAC) also was detected in the samples. Polychaete annelids have great ecological relevance, being widely distributed in different environmental conditions, from intertidal zones up to seven thousand feet deep areas. They are abundantly found in both contaminated and uncontaminated areas and, therefore, used as indicators of the pollution status of a given area. As we know, so far, most of these PACs has not been previously reported in living organisms before. The 3-NBA concentrations determined in this study were within 0.11-5.18 µg g-1. Other relevant PACs such as PAHs, quinones and nitro-PAHs were found in maximum concentrations at 0.013 µg g-1 (coronene) to 11.1 µg g-1 (benzo[k]fluoranthene), 0.823 µg g-1 (9,10-phenenthrenequinone) to 12.1 µg g-1 (1,4-benzoquinone) and 0.434 (1-nitronaphthalene) µg g-1 to 19.2 µg g-1 (6-nitrobenzo[a]pyrene), respectively. Principal component analysis (PCA), ternary correlations and diagnostic ratios were employed in order to propose probable sources for PACs. Although statistical analysis preliminarily has indicated both pyrogenic and petrogenic contributions, petrogenic sources were predominant reflecting the impacts of petroleum exploration and intensive traffic of boats in the study area.