Sediments as a potential tool for assessment of sewage pollution in Barigüi River, Brazil

Sediments constitute a pollutant trap and have proven to be an efficient tool to identify environmental impacts. Sediments are considered a very important means to assess the level of contamination of water bodies because of their ability to accumulate metals and organic. The anthropogenic inputs of sewage, with or without prior treatment, in aquatic environments, affect the geochemical composition of sediment. In addition, the sediment adsorbs hydrophobic compounds found in feces, such as the fecal sterols. The granulometric and geochemical composition of the sediment of Barigüi River-Brazil was investigated. The results show that silt and clay dominate the granulometric composition of the sediments. The geochemical composition of sediments showed high concentrations of phosphorus and nitrogen. The Redfield ratios confirm the inputs of phosphorus and nitrogen. The TOC/N ratio was used to identify the source of pollution. N/TP ratios were found between 1.0 and 3.5. Clearly, an input of phosphorus, sewage is the most acceptable source, following the historic profile of the Barigüi River. High concentration of nitrogen phosphorus labels the area to be polluted by sewage. To confirm the sewage pollution, adsorbed fecal sterols in sediments were investigated. The concentration of total sterols was found between 0.86 and 304.58 μg g^???1. Two distinguished scenario was found, one severely polluted and another slightly polluted. The highest concentrations of total fecal sterols were associated with sediment whose geochemical composition showed higher levels of TOC, as well as higher proportions of silt and clay. Also, epicoprostanol, a coprostanol isomer, was used as an indicator of the level of treatment or age of the fecal matter because it is formed during the treatment of wastewater and sludge digestion. If the treatment of sludge takes a long time, epicoprostanol can form from cholesterol, and relative proportions of those compounds may be used as an indicator of the presence of untreated sewage in the sediments. The epicoprostanol was found in the range between 0.02 and 9.71 μg g^???1; concentration of up to 0.015 μg g^???1 represents situations where there is strong contamination by sewage. All sites investigated showed a concentration of epicoprostanol higher than the value adopted as threshold. The lower concentration of epicoprostanol found for all sites is consistent with the high concentration found for coprostanol, and this is typical for untreated sewage.     

Predicting bioaccumulation of PAHs in the trophic chain in the estuary region of Paranagua, Brazil

The presence of polycyclic aromatic hydrocarbon (PAH) compounds in sediment and water samples collected in the estuary area of Paranagua, southern Brazil, was investigated. There is a lot of port activity in the region. Recreational fishing is widespread; thus, there is concern about possible contamination by PAHs. The 16 priority PAHs were investigated, and only eight were found. The total concentration of PAHs ranged from 40.8 to 406.8 ng/g. High molecular weight were the most abundant, while PAHs with a low molecular weight were absent. There are suspicions that the main source of PAHs is combustion, but some uncertainties exist, and there may even be the presence of PAHs resulting from accidental spills of crude oil. Although the sediments contain PAHs, the amount is below the maximum concentrations allowed by the Brazilian environmental legislation, as well as the maximum levels at which adverse effects are observed. From the analytical results, a probable bioaccumulation was assessed in the local trophic chain using a mathematical model (Arnot and Gobas, Environ Toxicol Chem 23(10):2343?C2355, 2004). The model showed that there is a possibility of biomagnification along the food chain selected. Three fishes with high local consumption were selected, and the concentration of some PAHs could be found in those fishes.     

Assessment of bioaccumulation of biphenyls in the trophic chain of a coastal area of Parana, Brazil

The presence of biphenyl was investigated in sediments and water in Paranagua Bay. Chemicals compounds like biphenyl can cause several effects on the ecosystems such as bioaccumulation. Biphenyl and similar compounds are subject to bioaccumulation, which in turn may harm the local ecosystem. The bioaccumulation in the local trophic chain was evaluated using a mathematical model based on toxicokinetic properties of the compound in the organisms. The results showed that even in water, the concentration of biphenyl was high, 0.82 ng/L. Also, in the fishes, the concentrations calculated by the model were higher than the maximum than the maximum allowed for human consumption.     

Assessment of the natural attenuation of chlorinated ethenes in an anaerobic contaminated aquifer in the Bitterfeld/Wolfen area using stable isotope techniques, microcosm studies and molecular biomarkers

The in situ degradation of chlorinated ethenes was assessed in an anaerobic aquifer using stable isotope fractionation approaches, microcosm studies and taxon specific detection of specific dehalogenating groups of bacteria. The aquifer in the Bitterfeld/Wolfen region in Germany contained all chlorinated ethenes, benzene and toluene as contaminants. The concentrations and isotope composition of the chlorinated ethenes indicated biodegradation of the contaminants. Microcosm studies confirmed the presence of in situ microbial communities capable of the complete dechlorination of tetrachloroethene. Taxon specific investigation of the microbial communities indicated the presence of various potential dechlorinating organisms including Dehalococcoides, Desulfuromonas, Desulfitobacterium and Dehalobacter. The integrated approach, using metabolite spectra, molecular marker analysis and isotope studies, provided several lines of evidence for natural attenuation of the chlorinated ethenes.     

Effects of habitat fragmentation and degradation on flocks of African ant-following birds.

Tropical rain forests are rapidly cleared, fragmented, and degraded in sub-Saharan Africa; however, little is known about the response of species and even of key ecological groups to these processes. One of the most intriguing (but often neglected) ecological phenomena in African rain forests is the interaction between swarm-raiding army ants and ant-following birds. Similar to their well-known Neotropical representatives, ant-following birds in Africa track the massive swarm raids of army ants and feed on arthropods flushed by the ants. In this study we analyzed the effect of habitat fragmentation and degradation of a mid-altitude Congo-Guinean rain forest in western Kenya on the structure of ant-following bird flocks. Significant numbers of swarm raids were located in all forest fragments and in both undegraded and degraded forest. Fifty-six different species of birds followed army ant raids, forming bird flocks of one to 15 species. We quantitatively differentiated the bird community into five species of specialized ant-followers and 51 species of opportunistic ant-followers. Species richness and size of bird flocks decreased with decreasing size of forest fragments and was higher in undegraded than in degraded habitat. This was caused by the decrease of the species richness and number of specialized ant-followers at swarms, while the group of opportunistic ant-followers was affected little by habitat fragmentation and degradation. The composition of bird flocks was more variable in small fragments and degraded forest, compared to undegraded habitat in large fragments. The effect of habitat fragmentation on flock structure was best explained by the strong decline of the abundance of specialized ant-followers in small forest fragments. To conserve the association of army ants and ant-following birds in its natural state, vast areas of unfragmented and undegraded tropical rain forest are necessary.     

Distribution of polycyclic aromatic hydrocarbons in marine sediments and their potential toxic effects

The presence of polycyclic aromatic hydrocarbons (PAHs) in samples of marine sediments from Paranagua Bay on the southern coast of Brazil was investigated. Paranagua Bay is the location of a major port, one of the busiest in Brazil. The region has a great potential for tourism and port-related industries and activities. Due to its characteristics as a venue for tourism, two major campaigns were planned: one 3 months before the summer (between December and February) and a second after the vacation season. Total concentration of PAHs in sediments ranged from 26.33 to 406.76 ng/g (in both campaigns). The highest values were found in sediments with higher organic carbon content. We found no substantial differences between the two campaigns, and the values are quite similar. Ternary diagrams show that points P5 and P6 were considered polluted, while others were classified as non-polluted. Molecular ratios indicate that the main sources of PAHs are petrogenic and the burning of fossil fuels. Sediment toxicity was assessed by the presence of PAHs in terms of benzo(a)pyrene (BaP) concentration. The toxicity of PAHs mixtures can be characterized more accurately by developing and establishing toxic equivalency factors (TEFs) for PAHs. Considering TEFs, the BaP_eq concentrations vary between 0.264 and 5.922 ng/g (considering both campaigns). Thus, two points are above the maximum level recommended (3 ng/g) by the Netherlands sediment quality guidelines. In fact, sites P5 and P6 apparently are exposed to a greater number of pollution sources, thus reflecting the higher concentration of PAHs compounds in sediments.     

Experimental measurements and numerical simulations of the transport and retention of nanocrystal CdSe/ZnS quantum dots in saturated porous media: effects of pH,organic ligand,and natural organic matter

Environmental Science and Pollution Research - The risks of environmental exposures of quantum dot (QD) nanoparticles are increasing, but these risks are difficult to assess because fundamental...     

Copper and lead ion removal from wastewater using fava d’anta fodder (Dimorphandra gardneriana Tulasne)

Environmental Geochemistry and Health - The contamination of bodies of water by potentially hazardous elements has in recent decades become an environmental problem that poses serious risks to...