No abstract

Uncontrolled urbanization growth contributes to the pollution of aquatic environments. Heavy metals released by domestic and industrial effluents can negatively affect aquatic organisms. This study aimed to evaluate the effect of environmental pollutants, such as metals, on fish DNA damage, in stretches of an urban stream. Specimens of the Neotropical fish, Astyanax lacustris , were exposed in situ for 96 h along the Antas stream, a Brazilian aquatic system deteriorated by anthropogenic factors. Water and sediment samples were collected simultaneously for physicochemical and heavy metal analyses. The comet assay was performed as a biomarker of genotoxicity. Fish located downstream had a higher frequency of DNA damage than in the reference site. We found concentrations of Cr and Ni above acceptable levels in sediment samples. Generally, Ba, Mn, Mg, Zn, Cr, and Ni were the elements most associated with genotoxic damage. Water and sediment of the Antas stream showed genotoxic potential in A. lacustris according to the urbanization gradient, demonstrating the importance to prevent the release of environmental pollutants, especially heavy metals in urban areas.

Microalgae biodiesel production depends on several factors to minimize the costs of the production process from both biomass and biodiesel. In some outdoor systems, the temperature can be higher than 35°C, which is lethal for several algae. Prospecting microalga from thermal environments seems to be a good option. Therefore, the objective of this work was to isolate a microalga (Acutodesmus obliquus (Turpin) Hegewald and Hanagata) from thermal water and evaluate its cultivation productivity in Bold Basal Medium (BBM) and in lower cost alternative media. One alternative medium contained only the main growth ingredients (DAF), the other included these same ingredients with the addition of wastewater from the purification of grease-based raw materials (DAF ? OGR). Microalga biodiesel productivity was also compared with the biodiesel yield of soybean, which is one of the main raw materials currently used for biodiesel production. The microalga was shown to provide biomass with similar productivity using the three different culture media in log phase. The microalga exhibited biodiesel productivity from 46 to 61 times higher than soybean; using 5.5-7.2% of the water and 1.6-2.2% of the land required for soybean cultivation to produce the same amount of biodiesel. The DAF ? OGR medium, which costs 29% of the cost of the BBM medium, proved to be an efficient alternative medium compared to other in biomass productivity. Levels of tri-unsaturated and polyunsaturated fatty acids from A. obliquus microalga were slightly higher than those standardized by EN14214, requiring that the biodiesel be mixed with antioxidants.

The use of natural antioxidants extracted from plants is an alternative to the application of synthetic antioxidants. In this study, we evaluated the oxidative stability of soybean oil after the addition of Curcuma longa L. leaf extracts compared to its oxidative stability with the synthetic antioxidant butylated hydroxytoluene (BHT Different concentrations (0.5%, 1.0%, and 1.5%) of ethanolic extract of Curcuma longa L. leaves were added to the oil, and the mixture was heated at 60 ±2 °C for 12 days. Several parameters of oxidative stability, including the peroxide index (PI), thiobarbituric acid reactive substances (TBARS), and conjugated dienes and trienes, were analyzed every three days. The results were promising, the oils to which the Curcuma longa L. leaf extract was added showed a reduction in all parameters, indicating oxidative deterioration under the influence of the concentration of the extract and the duration of treatment. The extract was less effective at low concentrations (0.5%), the parameters did not vary considerably. The PI was low in all treatments until the third day. The PI of the soybean oil treated with 1.5% extract was lower than that after treatment with the synthetic antioxidant and the blank treatment on days 6 to 12. The highest production of TBARS was observed in the blank treatment on days 6 to 12, and the lowest values of TBARS were recorded in the soybean oil treated with 1.5% extract. For the same concentration, the conjugated dienes varied from 2.05 to 8.6, and the trienes from 0.57 to 1.59.

The main contamination areas in Goiânia were exposed soil surfaces, and with the first rainfalls, 137Cs quickly reached the Meia-Ponte River, the main local waterway. Regular measurements of bottom sediment, surface water, and fish were begun 3 wk after the accident. In the first survey, 137Cs was detectable in sediments up to 12 km downstream from the accident area. Maximum 137Cs concentrations found in sediments of the Meia-Ponte River were 1.3 kBq kg-1 dry weight and 200 Bq kg-1 fresh weight for fish. Cesium-137 was always less than 10 Bq L-1 in surface waters plus suspended particulates, even in the most contaminated creeks. Because it was the beginning of the rainy season, downstream sediment transport was enhanced. This resulted in a decrease of 137Cs concentrations in sediments of the urban area by a factor of approximately 20, 5 wk after the accident. The main sedimentation area for suspended sediments in this portion of the river is the Rochedo Reservoir, which is 80 km downstream from the accident area. In a survey performed 10 mo after the accident, 137Cs concentrations in the reservoir were up to 14 Bq kg-1 for fish, 1 Bq kg-1 for aquatic plants, and 100 Bq kg-1 dry weight for bottom sediments.