The presence of emerging compounds was investigated in surface water samples from Iguassu River watershed in the metropolitan region of Curitiba (Brazil). Emerging compounds are substances present in domestic and industrial sewage. Generally, the emerging compounds are present in the environment due to the indiscriminate release of untreated domestic and industrial sewage. Even treated sewage may contain emerging compounds due to the difficulty in removing them. In this work, the presence of caffeine, musk xylene (a fragrance), and bisphenol-A was investigated in surface water samples. Also, traditional parameters used in water quality monitoring were determined, such as biochemical oxygen demand (BOD), nitrate, and fecal coliforms. The emerging compounds were extracted in solid phase and analyzed by high performance liquid chromatography. Caffeine is eliminated in the urine (approximately 0.5% to 10% of the consumption), and the only source is domestic sewage. Bisphenol is widely used in food packs, while musk xylene is found in personal care products, easily eliminated in sewage. The caffeine concentration was between 1.74±0.54 and 123.45±0.81 μg/L. Musk xylene and bisphenol-A had their concentrations between 0.04±0.07 and 0.56±0.12 and between 0.62± 0.15 and 12.61±0.21 μg/L, respectively. Positive correlations were found between caffeine and traditional monitoring parameters (BOD and fecal coliforms). Higher values of emerging compounds were determined at points considered extremely polluted. The positive correlations confirm the origin of emerging compounds and show that chemical markers are good parameters for monitoring pollution when the use of traditional parameters makes the diagnosis doubtful.
The evaluation of potential environmental impacts from polycyclic aromatic hydrocarbon is a subject that requires investigation, especially related to emission sources from highway roads with high traffic. In this paper, the distribution of polycyclic aromatic hydrocarbons was investigated in the surface sediments from a subtropical lake, located in the south of Brazil and away from urban areas. The results showed that all sediments presented such compounds in significant concentration, ranging from 9.50 to 29.88 lg/g. The highest total concentration was found in those sites close to the highway (bridges) and the deepest area of the lake. Moreover, a high concentration of polycyclic aromatic hydrocarbons of high molecular weight, such as benzo(a)anthracene and dibenzo(a,h)anthracene was found. It was laso found that high concentrations might be related to asphalt and coal tar pavement used in the highway construction close to the lake. In addition, the potential capacity of sediment toxicity was compared with values of the interim sediment quality guidelines values. The results indicate that most of the sediment presents concentrations of hydrocarbons above these limits. Only fluoranthene and chrysene were found in concentrations below the guideline values. The concentrations of most of the polycyclic hydrocarbons are higher than the quality guidelines. However, the main concern is associated with the presence of benzo(a)anthracene whose concentration is 416 times higher than the limit establisehed by guidelines. The same observation can be done to traces of benzo(a)-pyrene and dibenz(a,h)anthracene, with concentration values of 13 and 1,993 times higher.
The adsorption capacity of vermiculite, a natural clay, for removing dibenzothiphene (DBTP) from water solutions was investigated. DBTP is an organic compound with sulfur, commonly found in fossil fuels and coal. This compound can also be found in the environment due accidental spills of oil and derivatives. Due to its structure and physicalchemical properties it is considered a persistent compound. Vermiculite (VT) was used as an adsorbent in its natural form, impregnated with copper ions (Cu-VT), and hydrophobically modified (HDTMA-VT) by replacement sodium cations by hexadecyltrimethyl ammonium ion. The results showed that DBTP was adsorbed in considerable amounts by HDTMA-VT; however, the Cu-VT adsorbed DBTP in some proportions of HDTMA-VT. Because of the presence of sulfur atoms in the structure of the molecule, π complexation can be observed. The adsorption isotherms were treated by the Freundlich equation. The values of K f are similar to Cu-VT and HDTMA-VT, showing that the adsorption may be either through hydrophobic interactions or interactions through the formation of π complex. Meanwhile, the results with the VT (natural form) showed a much smaller value of K f . It is believed, compared with the literature, and because of the chemical composition of the vermiculite, that the adsorption mechanism is also conducted by π complexation, considering the absence of organic carbon content.
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