Several studies have evaluated human risks due mercury (Hg) exposure through fish consumption. However, relatively few studies have explored effects of environmental Hg concentrations in biota, especially tropical fish species. The aim of this work was to assess in situ hematological, biochemical and genotoxic effects in tropical fish due to environmental exposure to mercury in estuarine ecosystems. A total of 282 fishes were collected from September 2003 to October 2005 in two estuarine areas: Ribeira Bay (reference area - 22° 55’ to 23° 02’ S and 44° 18’ to 44° 26’ W) and Guanabara Bay (highly impacted area by human activities - 22° 40’ to 23° 00’ S and 43° 00’ to 43° 20’ E). Total mercury levels in fish from Guanabara were twice higher than in Ribeira bay for the catfish species Genidens genidens (Ariidae), with significant differences among areas after standardization using length intervals (exposure time indicator). The species Haemulon steindachneri (Haemulidae) showed the highest mercury concentration, reflecting its position in trophic chain. Among effect biomarkers, only haematocrit, global leucometry and micronucleus assays seemed to reflect the differences on mercury exposure among areas, what may support their use for evaluations of fish exposure to mercury compounds. However, it’s necessary both laboratory experiments to establish cause-effect relationship and a continuous in situ study to obtain more information, involving more trophic levels, searching for sensible species to mercury exposure.
The degradation of 3-chlorobenzoic acid in polluted waters and synthetic effluents by a previously isolated indigenous strain of Pseudomonas putida was studied. Batch biodegradation assays were performed using a 2 L microfermentor at 28 °C with agitation. To simulate polluted water, 100 mg.L–1 of 3-chlorobenzoic acid were added to surface river water. Continuous-flow assays were performed in an aerobic up-flow fixed-bed reactor constructed from PVC employing hollow PVC cylinders as support material. Synthetic wastewater was prepared by dissolving 3-chlorobenzoic acid in non-sterile groundwater. Biodegradation was evaluated by spectrophotometry, chloride release, gas chromatography and microbial growth. In batch experiments the indigenous strain of Pseudomonas putida degrades 100 mg.L–1 of 3-chlorobenzoic acid in 28 hours with a removal efficiency of 92.2 and 87.2%, expressed as compound and chemical oxygen demand removal, respectively. In the continuous-flow reactor the removal of an average influent concentration of 98.6 mg.L–1 reached 91.7% of compound and 88.9% of COD removal. The process efficiency remained approximately constant despite changes in the influent flow, compound concentration and temperature. The absence of metabolites was determined by gas chromatography performed at the end of the batch process and at the effluent of the continuous reactor. The ability of the isolated indigenous strain to degrade 3-chlorobenzoic acid in both batch and continuous reactors represents a promising feature to improve the treatment of effluents.
The composition of the phytoplankton and parameters of the water quality were studied in a tropical reservoir during cyanobacterial bloom episode. Samples were collected at two sites during October 2004. The phytoplankton community consisted of 69 taxa, distributed into 9 classes. Most taxa belonged to Cyanobacteria (17), Chlorophyceae (21), Bacillariophyceae (8), Conjugatophyceae (7), Dinophyceae (1), Chrysophyceae (4), Euglenophyceae (9), Cryptophyceae (1) and Xanthophyceae (1). Anabaena circinalis Rabenhorst ex Bornet et Flahault e Anabaena spiroides Klebahn were the dominant species. Statistical analyses revealed significant spatial variation (p < 0.05) between sampling points only for N compounds and chlorophyll a. Most limnological variables analyzed showed no significant temporal variation (p > 0.05). Cyanobacteria bloom was concomitant with the following environmental conditions, warm water temperatures (19 to 22 oC), periods of water column stability and high concentrations of N (724.9 μg.L-1) and P (90.9 μg.L-1) in the reservoir and NH4 as being the predominant nitrogen compounds. It is speculated that those conditions could play a role in the dominance of cyanobacteria.
With the purpose of evaluating the consumed fish quality, total mercury concentration were analyzed in muscle samples from two tropical freshwater fish (Hypostomus affinis Steindachner,1877 and Hypostomus c.f. luetkini, Barlenger,1887) from the Muriaé River, Itaperuna Municipality, in the North of Rio de Janeiro State. A secondary objective of the present study was to compare mercury concentration in these two species during dry and wet seasons. In order to achieve these goals, five organisms from each species were monthly collected between August 2005 and January 2006. H. affinis always presented lower total mercury average concentration when compared with H. c.f. luetkini with exception of August 2005 when an opposite trend was observed. The highest mercury concentrations were observed in October for both species (H. affinis 33.4 ng.g–1 in wet weight and H. c.f. luetkini 39.5 ng.g–1 in wet weight) during the beginning of dry season. There was a clear trend of higher Hg concentrations during the dry season when compared to the wet season probably related with the dilution effect caused by the increasing water discharges during the wet season. All analyzed samples presented total mercury concentrations lower than the maximum permitted concentration for human consumption established by ANVISA and WHO (500 ng.g–1 in wet weight), therefore no risk for human consumption was observed.
The Negro River is the most important hydrological system of Patagonia, Argentina, drains a watershed of 140,000 km2. Its main economic activities are agriculture and industry, representing potential sources of organochlorine compounds (OCCs): organochlorine pesticides (OCPs) and PCBs, respectively. These pollutants are persistent, ubiquitous and hydrophobics and are accumulated in the lipid fraction of biota. Fish are excellent biomonitors of pollution because incorporate COCs from water and through diet, and represent different trophic levels. The aims of the present study were to investigate OCCs levels in wild common carp, Cyprinus carpio (Cyprynidae) focusing on: a) the distribution pattern of OCPs and PCBs in gills, gonads, liver, muscle, and stomach content, b) the potential of common carp as indicator of aquatic OCCs pollution, and c) the evaluation of residues in gills and stomach content to discuss different input pathways of OCCs. HCHs, Chlordanes, DDTs, Endosulfan, Heptachlors, Drines and PCBs were quantified by GC-ECD. The distribution of OCCs (ng.g–1 lipid) was gills> gonads> liver> muscle> stomach content. Endosulfan accounted for 64% of OCCs in gills while, DDTs, PCBs and Chlordanes predominated in the stomach content suggesting the incorporation of more hydrophilic pollutants from the water column and those most persistent and hydrophobic from the diet.
