The Barigui River watershed is located in the metropolitan region of Curitiba, southern Brazil, passing through several neighboring counties. In recent years, due to growth and disorderly occupation along the river, in addition to lack of sanitation, the Basin suffered a very large inflow of untreated domestic sewage. Current programs to monitor the watershed use traditional physical-chemical parameters and generally the analysis is performed only with water samples. This study analyzes the presence of fecal sterols in sediment samples. Sediment samples were collected from six points along the river and the stanols were extracted, purified and analyzed by GC-MS. Eight compounds were analyzed, among sterols and ketones. The presence of coprostanol was also identified. Coprostanol is a stanol containing a large amount in human feces. It is found near sources of pollution and can be associated with contamination by domestic sewage. The results showed high concentrations of coprostanol, ranging from 0.25 to 196 μg g − 1. The ratio of coprostanol and epicoprostanol, was below 0.20 at most stations, indicating that the sewage discharged into the river does not undergo prior treatment. Contamination by untreated sewage was also confirmed by ratios of isomeric forms of sterols and ketones 5β/(5β + 5α).
In this work we studied the phenol sorption from contaminated water onto modified clay mineral vermiculite and bentonite by insertion of hexadecyltrimethylammonium in the interlayer of clays. The non modified clays showed negligible interaction with phenol. The experimental data were treated using the Freunlich equation which had a good fit. The removal percentages were higher than 35% for modified vermiculite and for modified bentonite, 30%. Vermiculite and bentonite were compared for the removal of phenol from an aqueous solution based on the maximum adsorption capacity of each adsorbent, and no significant difference was found. The adsorption mechanism for both is the same, according to the results. Although, there is a lack of studies using vermiculite for this purpose, it can be concluded that hydrophobic modified vermiculite is very effective for removing phenol from water. Hydrophobic modified bentonite also remove phenol, but in lower proportions.
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.
Sediment samples from the Barigui River in Curitiba, south of Brazil, were evaluated following granulometric composition, organic carbon content, nitrogen, phosphorus and metals such as zinc, lead, chrome, nickel and cadmium. The sediments shown high percentage of phosphorus and nitrogen. Also the elemental organic C:N:P exceed the Redfield ratios possible because the large amount of sewage input into river. The presence of metals is also high, however the metal cadmium has not been found. But the other metals are in greater concentrations and possibly the presence of these metals is given by industrial and domestic sewage.
BENZO(A)PIRENE BY COMPUTER MODELING.The objective of this work was to evaluate the environmental distribution of benzo(a)pirene, a polycyclic aromatic hydrocarbon, by the EQC model.The modeling of the contaminant distribution was accomplished by means of the fugacity model applied to a hypothetical scenario constituted by air, water, soil and sediment.The modeling and simulations revealed that the soil is the preferential compartment.We also discuss the implications of the results about fate and ecological risks associated with benzo(a)pirene.We concluded that the emissions of HPAs can not be ignored and bioaccumulation among others risks can be induced.
Sediment samples from the Barigui River in Curitiba, south of Brazil, were evaluated following granulometric composition, organic carbon content, nitrogen, phosphorus and metals such as zinc, lead, chrome, nickel and cadmium. The sediments shown high percentage of phosphorus and nitrogen. Also the elemental organic C:N:P exceed the Redfield ratios possible because the large amount of sewage input into river. The presence of metals is also high, however the metal cadmium has not been found. But the other metals are in greater concentrations and possibly the presence of these metals is given by industrial and domestic sewage.
The objective of this work was to evaluate the environmental distribution of benzo(a)pirene, a polycyclic aromatic hydrocarbon, by the EQC model. The modeling of the contaminant distribution was accomplished by means of the fugacity model applied to a hypothetical scenario constituted by air, water, soil and sediment. The modeling and simulations revealed that the soil is the preferential compartment. We also discuss the implications of the results about fate and ecological risks associated with benzo(a)pirene. We concluded that the emissions of HPAs can not be ignored and bioaccumulation among others risks can be induced.
The objective of this work was to evaluate the environmental distribution of benzo(a)pirene, a polycyclic aromatic hydrocarbon, by the EQC model. The modeling of the contaminant distribution was accomplished by means of the fugacity model applied to a hypothetical scenario constituted by air, water, soil and sediment. The modeling and simulations revealed that the soil is the preferential compartment. We also discuss the implications of the results about fate and ecological risks associated with benzo(a)pirene. We concluded that the emissions of HPAs can not be ignored and bioaccumulation among others risks can be induced.
