Polycyclic aromatic hydrocarbons in surface water of rivers in Sergipe State, Brazil: A comprehensive analysis of sources, spatial and temporal variation, and ecotoxicological risk.

This study conducted in Sergipe State, Brazil, aimed to investigate the presence of polycyclic aromatic hydrocarbons (PAHs) in the surface water of five rivers, determining their sources, spatial and temporal variations, and ecotoxicological risks. Correlation and principal component analyses were utilized to identify the relationship between PAH concentrations and water sample properties. Results indicated higher PAH concentrations during the rainy season, attributed to increased run-off and sediment resuspension. The composition of PAHs suggested a main petroleum source with organic material combustion in minor scale. Ecological risk assessment revealed potential risks to the ecosystem, emphasizing the need for continuous monitoring of PAHs pollution. This study highlights the importance of understanding and mitigating PAHs contamination in rivers to protect aquatic ecosystems.

Pendimethalin biodegradation by soil strains of Burkholderia sp. and Methylobacterium radiotolerans.

Pendimethalin herbicide is widely used and persists in the environment as a contaminant causing negative impacts, including for human health. Microorganisms have the capacity to remove many contaminants from the environment. Thus, the aim of this work was to evaluate the efficiency of soil bacterial species prospected by molecular modelling of cytochrome P450 in to degrade pendimethalin. Strains of Burkholderia sp. and Methylobacterium radiotolerans were cultivated in a mineral saline medium enriched with 281 mg/L pendimethalin (MSPEN) and another containing glucose 1.0 g/L as extra carbon source (MSPENGLI). Both strains were able to degrade pendimethalin under the two conditions experienced. Burkholderia sp. F7G4PR33-4 was more efficient in degrading 65% of the herbicide in MSPEN medium, with 49.3% in MSPENGLI; while Methylobacterium radiotolerans A6A1PR46-4 degraded 55.4% in MSPEN and 29.8% in MSPENGLI mediums. These findings contribute to the expansion of knowledge on the competence of isolates of these two bacterial genera in degrading herbicidal xenobiotics and biotechnological potential for pendimethalin degradation and bioremediation.

Assessment of polycyclic aromatic hydrocarbons in three environmental components from a tropical estuary in Northeast Brazil.

The evaluation of occurrence, risk quotient (RQ), bioaccumulation factor (BAF), and sources of PAH was conducted in Sergipe-Poxim estuarine system. PAH distribution that ranged from 7.1 to 30.9 ng L-1 (surface water, SW), 5.4 to 19.5 ng g-1 (sediment, S), and 4.3 to 18.1 ng g-1 (oyster, O), characterized the environment with low contamination; 2-3 (SW), 5-6 (S), and 4 (O) PAH rings accounted for 54.5%, 68.7%, and 87.7%, respectively, along with naphthalene (SW), dibenzo(a,h)anthracene (S), and pyrene (O) as the prevailing compounds. PCA suggested the predominance of particular groups related to SW (LMW-PAH), S (HMW-PAH), and O (pyrene and fluoranthene). Furthermore, one sample of O presented a high PAH bioavailability as shown through the BAF, with emphasis on pyrene (BAF = 26.8). The RQ showed a low to moderate range in SW and S; hence, in-depth information about the possible toxic effect in organisms of this region is required.

Sterol biomarkers and fecal coliforms in a tropical estuary: Seasonal distribution and sources.

The Sergipe River estuary has been subjected to a range of anthropogenic activities including food, plastic, textile, ceramic and metallurgical production plants along with domestic sewage inputs, all of which are of environmental concern. In this study, the levels of fecal coliforms (FC) in surface water samples and sterols in superficial sediment samples collected from the Sergipe River estuary were determined. Based on the FC concentrations, 58% of the water samples were considered Water Potentially Unusable (WPU) according to the United States Environmental Protection Agency (USEPA). Concentrations of coprostanol ranged from 13 to 1072 ng g-1, indicating a significant input of sewage at some points in the estuary. Principal Component Analysis (PCA) showed that there is no clear correlation between the coprostanol and coliform data, which may be due to the high resistance to degradation of coprostanol in sediments and to recent inputs of sewage at the water sample collection points.

Polycyclic aromatic hydrocarbons (PAH) in superficial water from a tropical estuarine system: Distribution, seasonal variations, sources and ecological risk assessment.

This study aimed to evaluate the PAH distribution, sources, seasonal variations and ecological risk assessment in superficial water from the Japaratuba River, Brazil. PAH concentrations ranged from 4 to 119ngL-1. It was observed that the PAH total concentrations and profiles showed significant differences when comparing the dry season (summer) with the rainy season (winter). Furthermore, most of the PAH originated from pyrogenic sources in the winter, whereas a mixture of sources was observed in the summer. PAH concentration levels found in this study were considered lower than those obtained in other estuarine systems. Ecological risk assessment was determined for individual PAH, based on the risk quotient (RQ) to evaluate the risk of aquatic biota's exposure to PAH. Results suggested that the Japaratuba River has achieved a moderate degree of ecological risk for high molecular weight, showing the importance of identifying these carcinogenic and mutagenic compounds in aquatic systems.

Concentration, distribution and source apportionment of polycyclic aromatic hydrocarbons (PAH) in Poxim River sediments, Brazil.

The individual concentrations, total amount and sources of 16 priority polycyclic aromatic hydrocarbons (PAH) in sediments collected along of the Poxim River, Aracaju, Brazil, were for the first time determined. The ΣPAH ranged between 2.2±1.5ngg-1 and 28.4±6.9ngg-1, with a mean value of 14.4±9.3ngg-1. The Pearson correlation test and Principal component analysis (PCA) were used to assess the correlation between the PAH, organic matter and grain size; and to differentiate the sampling stations. Diagnostic ratios presented predominance of pyrogenic sources. Therefore, the PAH quantified showed the influence of anthropogenic activities near of the Poxim River.

Distribution and sources of sterol biomarkers in sediments collected from a tropical estuary in Northeast Brazil.

The Piauí-Real estuary is located along the southern coast of Sergipe state, Northeast Brazil. This estuary has great economic importance due to its physical, biological, and socioeconomic diversity, but it is subject to anthropogenic stress since the resident population in the town bordered by the estuarine system has grown in recent years. Thus, the possibility of sewage contamination originating from the approximately 450,000 inhabitants living within its drainage basin was investigated in this study. Sediment samples were collected from 15 sampling stations along the estuarine system and extracted, followed by gas chromatography-mass spectrometry (GC-MS) analysis. Six sterols were quantified, indicating natural and anthropogenic sources. Coprostanol concentrations higher than 100 ng g-1 were observed in 47 % of the stations analyzed, indicating sewage contamination, which was confirmed by the diagnostic ratios calculated. Based on the Pearson correlation test, a significant correlation between coprostanol concentrations and total organic carbon content (TOC) was observed, indicating that sterols record the history of sewage inputs in this area. These results indicate that control of the organic inputs into the estuarine system is required. Graphical abstract Sterol markers were determined and sources assessed in surface sediments from Piauí-Real estuarine system.

Evaluation of anthropogenic contamination using sterol markers in a tropical estuarine system of northeast Brazil.

The São Francisco River estuarine system, located in the Northeast coast of Brazil, has great economic, tourist and social importance. Its waters are used for activities such as agriculture, aquaculture, navigation and fishery, which supplies the surrounding communities. In this study, sterols markers were determined in twenty-eight sediment samples from São Francisco River estuary by gas chromatography - mass spectrometry (GC-MS). Sterol analysis was useful to distinguish between anthropogenic and biogenic organic matter (OM) sources in the studied area. Six sterols were quantified, suggesting different sources. Concentrations of fecal sterol (coprostanol) were lower than 500ngg(-1), suggesting no indicative of severe sewage contamination.However, two stations showed concentrations around 100ngg(-1) and the values for the coprostanol/(coprostanol+cholestanol) and coprostanol/cholesterol ratios indicates sewage contamination. The results in this study may be considered as baseline concentrations to be used as future reference for monitoring programs to prevent anthropogenic impacts.

Seasonal distribution of aliphatic hydrocarbons in the Vaza Barris Estuarine System, Sergipe, Brazil.

The seasonal assessment of anthropogenic activities in the Vaza Barris estuarine river system, located in the Sergipe state, northeastern Brazil, was performed using the aliphatic hydrocarbon distribution. The aliphatic hydrocarbon and isoprenoid (Pristane and Phytane) concentrations ranged between 0.19 µg g(-1) and 8.5 µg g(-1) of dry weight. Data were analyzed using Kruskal-Wallis test, with significance level set at p<0.05, and no seasonality distribution change was observed. The Carbon Preference Index (CPI), associated with n-alkanes/n-C16, Low Molecular Weight/High Molecular Weight ratio (LMW/HMW) and Terrigenous to Aquatic Ratio (TAR) suggested biogenic input of aliphatic hydrocarbons for most samples, with significant contribution of higher plants.

Assessment of anthropogenic contamination with sterol markers in surface sediments of a tropical estuary (Itajaí-Açu, Brazil).

The Itajaí-Açu estuarine region is one of the most important estuarine systems of south Brazil, due to the location of the Itajaí Harbor, which is the major route of international trading of the state and the largest national fishing pole landing. In addition, industries as well as urban and tourism activities are potential sources of pollution in this area. In the present study, sediment samples from 12 stations along the estuarine system were collected and extracted followed by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis. Eight sterols were identified and quantified, indicating natural and anthropogenic sources. Coprostanol concentrations ranged from <4 up to 8930 ng g(-1) of dry weight sediment with higher values being observed in the area next to the Itajaí Harbor and under influence of Itajaí-Mirim River flow, which receives wastewater from several cities. Concentrations and selected sterol ratios were useful tools used to distinguish anthropogenic and biogenic organic matter (OM) sources in the studied area, where coprostanol concentrations higher than 500 ng g(-1) were observed in 42% of the stations analyzed, indicating strong sewage contamination. Factor analysis with principal component analysis (FA/PCA) has distinguished two different groups of samples, with high and low total sterol concentrations. FA/PCA results revealed that the stations located in the estuary were separated by PC1 because they are clearly contaminated by sewage, also pointed by coprostanol/(coprostanol+cholestanol) and coprostanol/cholesterol ratios and by the higher concentrations of fecal sterols.

Distribution and sources of aliphatic hydrocarbons in surface sediments of Sergipe River estuarine system.

The assessment of aliphatic hydrocarbons was performed in the Sergipe River estuarine system, northeastern Brazil. Aliphatic hydrocarbons concentration ranged from 9.9 ug g⁻¹ up to 30.8 ug g⁻¹ of dry sediment. The carbon preference index (CPI, based on nC24 to nC34 range), indicated predominance of petrogenic input in two of the sites analyzed (P4 and P5). The unresolved complex mixture (UCM) was found to be present in seven of the nine sites sampled (except for P4 and P5). Overall, the results of this work suggest that there is a mix of organic matter sources to the sediment. Although the coast of Sergipe has an intense off shore petroleum exploration and the Sergipe River crosses the entire city of Aracaju, the capital city of Sergipe, non-significant anthropogenic fingerprint was assessed.

Radiocarbon dating of individual lignin phenols: a new approach for establishing chronology of late quaternary lake sediments.

The reliability of chronology is a prerequisite for meaningful paleoclimate reconstructions from sedimentary archives. The conventional approach of radiocarbon dating bulk organic carbon in lake sediments is often hampered by the old carbon effect, i.e., the assimilation of ancient dissolved inorganic carbon (DIC) derived from carbonate bedrocks or other sources. Therefore, radiocarbon dating is ideally performed on organic compounds derived from land plants that use atmospheric CO(2) and rapidly delivered to sediments. We demonstrate that lignin phenols isolated from lake sediments using reversed phase high performance liquid chromatography (HPLC) can serve as effective (14)C dating materials for establishing chronology during the late Quaternary. We developed a procedure to purify lignin phenols, building upon a published method. By isolating lignin from standard wood reference substances, we show that our method yields pure lignin phenols and consistent ages as the consensus ages and that our procedure does not introduce radiocarbon contamination. We further demonstrate that lignin phenol ages are compatible with varve counted and macrofossil dated sediment horizons in Steel Lake and Fayetteville Green Lake. Applying the new method to lake sediment cores from Lake Qinghai demonstrates that lignin phenol ages in Lake Qinghai are consistently younger than bulk total organic carbon (TOC) ages which are contaminated by old carbon effect. We also show that the age offset between lignin and bulk organic carbon differs at different Lake Qinghai sedimentary horizons, suggesting a variable hard water effect at different times and that a uniform age correction throughout the core is inappropriate.

Molecular asymmetry in extraterrestrial chemistry: Insights from a pristine meteorite.

The nonracemic amino acids of meteorites provide the only natural example of molecular asymmetry measured so far outside the biosphere. Because extant life depends on chiral homogeneity for the structure and function of biopolymers, the study of these meteoritic compounds may offer insights into the establishment of prebiotic attributes in chemical evolution as well as the origin of terrestrial homochirality. However, all efforts to understand the origin, distribution, and scope of these amino acids' enantiomeric excesses (ee) have been frustrated by the ready exposure of meteorites to terrestrial contaminants and the ubiquitous homochirality of such contamination. We have analyzed the soluble organic composition of a carbonaceous meteorite from Antarctica that was collected and stored under controlled conditions, largely escaped terrestrial contamination and offers an exceptionally pristine sample of prebiotic material. Analyses of the meteorite diastereomeric amino acids alloisoleucine and isoleucine allowed us to show that their likely precursor molecules, the aldehydes, also carried a sizable molecular asymmetry of up to 14% in the asteroidal parent body. Aldehydes are widespread and abundant interstellar molecules; that they came to be present, survived, and evolved in the solar system carrying ee gives support to the idea that biomolecular traits such as chiral asymmetry could have been seeded in abiotic chemistry ahead of life.