Raman spectroscopic study of inorganic salts present in atmospheric particulate matter: their origin and implications

The aim of this doctoral thesis is to investigate aspects concerning the atmospheric origin of some inorganic salts of known atmospheric occurrence. In this context, based on laboratory experiments, the atmospheric formation of certain inorganic salts is proposed in view of the common presence of certain ions in the atmosphere and their interaction with atmospheric water. The condensation-evaporation cycles have a strong influence on the composition of the particles and the modifications taking place during the transport (aging). The evaporation of solution droplets containing specific ions results in the crystallization of mixed salts (e.g., bloedite, darapskite, koktaite, etc.) confirming the preponderant role of water in the modification of the atmospheric particles. Moreover, certain alkaline minerals can react with (NH4)2SO4 in contact with humid air, showing that water is a key factor to trigger chemical reactions in solid particles. Raman spectroscopy is the main analytical tool used in this work, therefore, the bands observed in the Raman spectra of all pure salts considered in this investigation have been properly assigned. The Raman-specific features of some salts were discussed from the point of view of their crystal structure. General aspects of the significance of atmospheric particulate matter to human health, the atmospheric chemistry and climate are outlined

Degradation of an Antibiotic from the Fluoroquinolone Group with a New Graphitic Carbon Nitride Photocatalyst

Ofloxacin (OFL), a fluoroquinolone, is an antibiotic found in hospital wastewater, groundwater, and other water bodies. Its occurrence in water results in several environmental problems, such as the emergence of antibiotic-resistant bacteria. This research is focused on determining the viability of removing and mineralizing OFL by photocatalysis under visible radiation with a graphitic carbon nitride photocatalyst (GCNP) synthesized from the pyrolysis of urea and calcium oxalate at 600°C. The photocatalyst was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the point of zero charge (PZC) of the photocatalyst was determined, and the adsorption isotherms were obtained. The photocatalytic activity of this new material was tested with a synthetic aqueous solution of OFL (20 mg/L) exposed to visible radiation. Three pH values (5, 7, and 10) and three doses of H2O2 (41.7, 83.3, and 333.2 mg/L) were considered. The achieved mineralization was evaluated through the decrease in the content of total organic carbon (TOC). The highest degradation of OFL was 23.9% after 40 min, with an initial concentration of H2O2 of 83.3 mg/L and a pH value of 10. It was confirmed that the reaction follows a kinetics of pseudo-first order.Ofloxacin (OFL), a fluoroquinolone, is an antibiotic found in hospital wastewater, groundwater, and other water bodies. Its occurrence in water results in several environmental problems, such as the emergence of antibiotic-resistant bacteria. This research is focused on determining the viability of removing and mineralizing OFL by photocatalysis under visible radiation with a graphitic carbon nitride photocatalyst (GCNP) synthesized from the pyrolysis of urea and calcium oxalate at 600°C. The photocatalyst was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the point of zero charge (PZC) of the photocatalyst was determined, and the adsorption isotherms were obtained. The photocatalytic activity of this new material was tested with a synthetic aqueous solution of OFL (20 mg/L) exposed to visible radiation. Three pH values (5, 7, and 10) and three doses of H2O2 (41.7, 83.3, and 333.2 mg/L) were considered. The achieved mineralization was evaluated through the decrease in the content of total organic carbon (TOC). The highest degradation of OFL was 23.9% after 40 min, with an initial concentration of H2O2 of 83.3 mg/L and a pH value of 10. It was confirmed that the reaction follows a kinetics of pseudo-first order

Exploratory Monitoring of the Quality and Authenticity of Commercial Honey in Ecuador

Honey is one of the oldest sweetening foods and has economic importance, making this product attractive to adulteration with cheap sugars. This can cause a critical problem in the honey industry and a possible health risk. The present work has the aim of evaluating the authenticity of honey commercialized in two different provinces of Ecuador (Pichincha and Loja) by performing physicochemical and spectroscopic analyses. For this study 25 samples were collected from different places and markets and characterized by water, sucrose, reducing sugars and electric conductivity measurement. Also, their Raman and Infrared (IR) spectra were recorded and analysed using a Principal Component Analysis (PCA) in order to verify the quality of the honeys. In addition, a screening of several pesticides was performed in order to verify possible chemical threats to human health and honey bees. It was found that 8 samples have a deviation from the Standard established parameters. Two of them have a high difference in the content of sucrose and reducing sugars, which are located deviated from all the other samples in the PCA of the applied vibrational spectroscopy (IR/Raman), shaping two clear clusters. The results show that Raman and IR spectroscopy is appropriate techniques for the quality control of honey and correlates well with the physicochemical analyses.Centro de Química Inorgánic

Handheld Raman Spectroscopy for the Distinction of Essential Oils Used in the Cosmetics Industry

Essential oils are highly appreciated by the cosmetics industry because they have antimicrobial and antioxidant properties, among others. Since essential oils are natural products, their inclusion in cosmetic formulations is a common practice. Currently, low-quality and/or adulterated essential oils can be found on the market; therefore, analytical methods for control are required. Raman spectroscopy is a versatile technique that can be used for quality control tasks; the portability of modern devices expand the analytical possibilities also to in situ measurements. Fifteen essential oils of interest for the cosmetics industry were measured using a handheld Raman spectrometer, and the assignment of the main bands observed in their average spectra was proposed. In most cases, it is possible to distinguish the essential oils by a simple visual inspection of their characteristic Raman bands. However, for essential oils extracted from closely-related vegetable species and containing the same main component in a very high proportion, the visual inspection of the spectra may be not enough, and the application of chemometric methods is suggested. Characteristic Raman bands for each essential oil can be used to both identify the essential oils and detect adulterations

Allelopathic properties of Calliandra haematocephala Hassk. extracts and fractions as an alternative for weed management in quinoa and rice crops

In this study, aqueous extracts of Calliandra haematocephala Hassk. leaves and inflorescences were tested on seeds of quinoa (Chenopodium album L.) and rice (Oryza sativa L.), and on some of the most noxious-associated weeds, Chenopodium album L. and Holcus lanatus L. in quinoa, and Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona L., Eclipta prostrata L. and Rottboellia cochinchinensis (Lou.) W.D. Clayton in rice. The objectives were to identify extract concentrations at which 50 and 90% of germination (GR[50,90]) and radicle elongation (RR[50,90]) were inhibited, to fractionate inflorescence extracts for facilitating identifying the chemical group causing allelopathic effects, and to evaluate the fraction showing the stronger weed suppression effects and the least crop damage. Increasing extract concentration rates (0, 6.25, 12.5, 25, 50 and 100% crude extract) were applied to seeds of target crops and weeds. Flower extracts at rates 0.52 caused the RR[50] on rice and all its target weeds. Fractions were quantitatively and qualitatively analysed to detect phytochemical groups, using specific chemical reagents and thin-layer chromatography (TLC). The fraction F3 from aqueous flower extract showed a high content of flavonoids, assumed as the potential allelochemical substance. Total flavonoid content in F3 was quantified as 2.7 mg of quercetin per g F3, i.e., 12.8 mg of quercetin per g of inflorescence material. Additionally, field equivalent extract rates obtained from the harvested fresh inflorescence biomass could be determined. These rates ranged between 90 and 143 mL l−1 of F3 aqueous fraction, while for ethanol F3 were 131 mL l−1. Our results are encouraging for finding sustainable and ecologically friendly alternatives for weed management in crops of high nutritional value, contributing also to counteract the growing problem of herbicide resistance.publishedVersio

Allelopathic properties of Calliandra haematocephala Hassk. extracts and fractions as an alternative for weed management in quinoa and rice crops

In this study, aqueous extracts of Calliandra haematocephala Hassk. leaves and inflorescences were tested on seeds of quinoa (Chenopodium album L.) and rice (Oryza sativa L.), and on some of the most noxious-associated weeds, Chenopodium album L. and Holcus lanatus L. in quinoa, and Echinochloa crus-galli (L.) P. Beauv., Echinochloa colona L., Eclipta prostrata L. and Rottboellia cochinchinensis (Lou.) W.D. Clayton in rice. The objectives were to identify extract concentrations at which 50 and 90% of germination (GR[50,90]) and radicle elongation (RR[50,90]) were inhibited, to fractionate inflorescence extracts for facilitating identifying the chemical group causing allelopathic effects, and to evaluate the fraction showing the stronger weed suppression effects and the least crop damage. Increasing extract concentration rates (0, 6.25, 12.5, 25, 50 and 100% crude extract) were applied to seeds of target crops and weeds. Flower extracts at rates 0.52 caused the RR[50] on rice and all its target weeds. Fractions were quantitatively and qualitatively analysed to detect phytochemical groups, using specific chemical reagents and thin-layer chromatography (TLC). The fraction F3 from aqueous flower extract showed a high content of flavonoids, assumed as the potential allelochemical substance. Total flavonoid content in F3 was quantified as 2.7 mg of quercetin per g F3, i.e., 12.8 mg of quercetin per g of inflorescence material. Additionally, field equivalent extract rates obtained from the harvested fresh inflorescence biomass could be determined. These rates ranged between 90 and 143 mL l−1 of F3 aqueous fraction, while for ethanol F3 were 131 mL l−1. Our results are encouraging for finding sustainable and ecologically friendly alternatives for weed management in crops of high nutritional value, contributing also to counteract the growing problem of herbicide resistance.Open Access funding provided by Norwegian Institute of Bioeconomy Research. We deeply thank the Ecuadorian Agency for Quality Assurance in Agriculture, AGROCALIDAD, for providing the laboratory facilities, equipment and materials for the bioassays, fractioning and phytochemical screening. Also, thanks to Andrés Rivera for carrying out some of the bioassays and laboratory assessments. No external funding supported this work.Peer reviewe

Environmental Impact Assessment of Remediation Strategy in an Oil Spill in the Ecuadorian Amazon Region

Past petroleum-extraction activities in Ecuador have contaminated its Amazon region. To assess the environmental impact attributed to remediation activities regarding the cleanup of these oil spills, two scenarios were studied according to Life Cycle Analysis methodology: (1) No-action, which means to leave the contamination in place without any further action and (2) Environmental remediation, where the environmental-load attributed to the remediation of the representative oil spill was studied. Results indicated that the no-action scenario presented a higher environmental impact for 12 out of the 16 environmental categories evaluated (climate change, ozone depletion, human toxicity non-cancer effects, particulate matter, ionizing radiation human health, ionizing radiation ecosystem, photochemical ozone formation, acidification, terrestrial eutrophication, marine eutrophication, freshwater ecotoxicity, mineral, fossil and renewable resource depletion). Moreover, the no-action scenario presented a global weighted score of contamination of 5.45 points, while the remediation scenario got a score of 3.3 points, which means that the remediation decreased by 39% of the global environmental impact due to the remediation activity applied, showing the positive influence of environmental remediation to mitigate the effects attributed to the presence of pollution sources associated to the petroleum industry in the Ecuadorian Amazon region

Environmental Impact Assessment of Remediation Strategy in an Oil Spill in the Ecuadorian Amazon Region

Past petroleum-extraction activities in Ecuador have contaminated its Amazon region. To assess the environmental impact attributed to remediation activities regarding the cleanup of these oil spills, two scenarios were studied according to Life Cycle Analysis methodology: (1) No-action, which means to leave the contamination in place without any further action and (2) Environmental remediation, where the environmental-load attributed to the remediation of the representative oil spill was studied. Results indicated that the no-action scenario presented a higher environmental impact for 12 out of the 16 environmental categories evaluated (climate change, ozone depletion, human toxicity non-cancer effects, particulate matter, ionizing radiation human health, ionizing radiation ecosystem, photochemical ozone formation, acidification, terrestrial eutrophication, marine eutrophication, freshwater ecotoxicity, mineral, fossil and renewable resource depletion). Moreover, the no-action scenario presented a global weighted score of contamination of 5.45 points, while the remediation scenario got a score of 3.3 points, which means that the remediation decreased by 39% of the global environmental impact due to the remediation activity applied, showing the positive influence of environmental remediation to mitigate the effects attributed to the presence of pollution sources associated to the petroleum industry in the Ecuadorian Amazon region

Pre-Hispanic Periods and Diet Analysis of the Inhabitants of the Quito Plateau (Ecuador): A Review

In all of the different historical periods during its development, the pre-Hispanic inhabitants of the Quito plateau and its valleys used the flora and fauna for food and the development of their society. The objective of this study is to review the chronological periods that correspond to the territory of the current city of Quito, as well as the possible diet, and the toxic substances to which the inhabitants could be exposed. The main archeological sites in the territory of Quito are as follows: (1) 11000–1500 BC (Preceramic): El Inga-Rancho Bajo; (2) 1500–500 BC (Formative): Rancho Bajo-Cotocollao-Tajamar; (3) 500 BC–500 AD (Regional Development): Jardín del Este; (4) 500–1500 AD (Integration): La Florida–Rumipamba-Chillogallo-Chilibulu and; (5) 1500–1534 AD (Inca period): Quito, which is today’s historic center and urban area. The probable main vegetable foods that were consumed were corn, potato, quinoa, beans, chili, and oca, while the main meat foods were rabbit, guinea pig, deer, guanta, and llama. The possible toxic substances to which the inhabitants could be exposed by consuming contaminated foods were glycoalkaloids (α-solanine and α-chaconine), tropane alkaloids, and heavy metals. The analysis of biomolecules in archeological remains is feasible, and some physicochemical analytical techniques are capable of using small samples. Moreover, the possible application of spectroscopic methods, supported by quantum chemistry, in order to predict the occurrence of molecules in the past cannot be ruled out

Degradation of Meropenem by Heterogeneous Photocatalysis Using TiO2/Fiberglass Substrates

Meropenem (MER), a carbapenem, is considered a last-resort antibiotic. Its presence in water bodies, together with other antibiotics, has brought about environmental problems related to the destruction of natural microorganisms and the development of antibiotic-resistant bacteria. Herein, the degradation of MER by heterogeneous photocatalysis using TiO2 immobilized on fiberglass substrates is reported. Morphological characterization of the substrates was performed by Scanning Electron Microscopy (SEM). Three pH values (4.0, 5.7, and 7.9) were tested for the treatment of MER solutions (100 mg/L). The best rate constants and MER removals were obtained at pH 4.0 (0.032 min−1; 83.79%) and 5.7 (0.032 min−1; 83.48%). Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) removals of 25.80% and 29.60% were achieved for the treatment at a pH value of 5.7. The reuse and regeneration of the plates were also tested. The activity of the substrates was maintained until the fourth cycle of reuse, nonetheless, a decrease in MER removal was observed for the 5th cycle. After the fourth cycle of reuse, the activity of the substrates was recovered by a regeneration procedure involving a wash stage of the substrates with a 1% H2O2 solution in an ultrasonic bath