Some aspects of air pollution in Córdoba,Argentina

Córdoba, as well as many other Latin American cities, is facing problems concerning air pollution. The increase in the number of cars, the poor control on emissions and the little use of catalytic converters, produce a great amount of toxic gases and particulate. Many cities have started air quality measurement programs being the size of the network strongly dependent on the available funds. In 1995, Córdoba started a measurement campaign with two mobile stations. A major part of the city has been characterized, mostly the city center and the suburban zone. Lack of data at the prevailing wind direction is the major shortcoming, but this is mainly a political decision. In this work, we review the air quality measurements performed, and we attempt to explain the causes for the low ozone values found.     

Technical and economic evaluation of biogas capture and treatment for the Piedras Blancas landfill in Córdoba,Argentina

Landfill gas (LFG) management is one of the most important tasks for landfill operation and closure because of its impact in potential global warming. The aim of this work is to present a case history evaluating an LFG capture and treatment system for the present landfill facility in Córdoba, Argentina. The results may be relevant for many developing countries around the world where landfill gas is not being properly managed. The LFG generation is evaluated by modeling gas production applying the zero-order model, Landfill Gas Emissions Model (LandGEM; U.S. Environmental Protection Agency [EPA]), Scholl Canyon model, and triangular model. Variability in waste properties, weather, and landfill management conditions are analyzed in order to evaluate the feasibility of implementing different treatment systems. The results show the advantages of capturing and treating LFG in order to reduce the emissions of gases responsible for global warming and to determine the revenue rate needed for the project’s financial requirements. This particular project reduces by half the emission of equivalent tons of carbon dioxide (CO₂) compared with the situation where there is no gas treatment. In addition, the study highlights the need for a change in the electricity prices if it is to be economically feasible to implement the project in the current Argentinean electrical market.

Implications: Methane has 21 times more greenhouse gas potential than carbon dioxide. Because of that, it is of great importance to adequately manage biogas emissions from landfills. In addition, it is environmentally convenient to use this product as an alternative energy source, since it prevents methane emissions while preventing fossil fuel consumption, minimizing carbon dioxide emissions. Performed analysis indicated that biogas capturing and energy generation implies 3 times less equivalent carbon dioxide emissions; however, a change in the Argentinean electrical market fees are required to guarantee the financial feasibility of the project.     

Assessment of human health risk related to metals by the use of biomonitors in the province of Córdoba, Argentina

The evaluation of metal contents in the environment is of vital importance for the assessment of human exposure. Thus the species Usnea amblyoclada, Ramalina celastri and Tillandsia capillaris were tested as bioaccumulators of transition metals in the urban area of Córdoba city, Argentina. The level of metals on biomonitors was compared to that of total deposition samples. All three species discriminated zones within the urban area of Córdoba city with different pollution levels; they revealed high levels of Zn in the downtown area and confirmed high levels of some transition metals in an industrial area. The correlation analysis revealed that the lichen R. celastri had the highest correlation rates with total deposition samples, suggesting it is a valuable biomonitor of atmospheric pollution. A significant relationship was also observed between respiratory diseases in children and the contents of metal accumulated in R. celastri and T. capillaris, indicating their usefulness when assessing human exposure to metals.     

Biomonitoring of air pollutants from traffic and industries employing Ramalina ecklonii (Spreng.) Mey. and Flot. in Córdoba, Argentina

The lichen Ramalina ecklonii (Spreng.) Mey. and Flot. was transplanted to 29 biomonitoring sites in the southeastern area of Córdoba, Argentina and tested for chlorophyll a, phaeophytin a, conjugated dienes concentration, malondialdehyde, soluble protein content and sulfur accumulation. The biomonitoring sites were determined according to (i) vehicular traffic levels, and (ii) industrial density, i.e. number and type of industries (small and medium) close to each of the sites. Each of the two groups were then broken down into three categories which provided a basis for performance analysis and quantification of the chemical parameters in the biomonitor. A pollution index (P.I.) was calculated based on the ratio of phaeophytin a to chlorophyll a and ratio of sulfur, malonaldehyde and conjugated dienes in transplanted specimens to sulfur, malonaldehyde and conjugated dienes in the freshly picked specimens. Significant differences were observed in sulfur content and P.I. in lichen samples that had been transplanted to sites with different vehicular traffic levels. At the same time, significant differences in the phaeophytin a concentration, phaeophytin a/chlorophyll a ratio and P.I. were observed at sites characterized by different levels of industrial density (all with low-to-medium traffic).     

Antioxidant and biotransformation enzymes in Myriophyllum quitense as biomarkers of heavy metal exposure and eutrophication in Suquía River basin (Córdoba, Argentina)

We report the evaluation of changes in water quality, increasing pollution level, of a section of Suquía River basin (Córdoba, Argentina) by using Myriophyllum quitense as bioindicator in addition to the measurement of chemical parameters, combined with chemometrics (ANOVA, Cluster and Discriminant Analysis). Myriophyllum quitense was collected upstream from Córdoba city at an unpolluted site of Suquía River basin. After collection plants were transplanted to different sites with different pollution levels. Subsequent to transplantation plants were weekly collected from the original site as well as from transplantation stations. Water quality was evaluated throughout the transplantation experiment, while the use of this macrophyte as bioindicator was verified through the activation of its antioxidant defenses and biotransformation system. Myriophyllum quitense reacts to the pollution stress increasing the activity of glutathione-S-transferases (CDNB and Fluorodifen), glutathione reductase (GR) and peroxidase (POD). Elevated enzyme activities agreed to different pollution levels, especially inorganic nitrogen loads combined with elevated lead and aluminum concentrations, all of them originated by anthropogenic activities, thus presenting Myriophyllum quitense as a good biomonitor for assessment of water quality in this polluted aquatic ecosystem.     

Deposition and regional distribution of HCHs and p,p′-DDX in the western and southern Tibetan Plateau: records from a lake sediment core and the surface soils

Tibetan Plateau is the world’s highest plateau, which provides a unique location for the investigation of global fractionation of organochlorine pesticides (OCPs). In this study, deposition and regional distribution of HCHs and p,p′-DDX in the western and southern Tibetan Plateau were investigated by the records from a sediment core of Lake Zige Tangco and 24 surface soils. Concentration of ΣHCHs in the surface soils of the western Tibetan Plateau was much higher than that of the southern part. Maximum fluxes of α-, β-, and δ-HCH in the sediment core were 9.0, 222, and 21 pg cm^?2 year^?1, respectively, which appeared in the mid-1960s. Significant correlations were observed between concentrations of α- and β-HCH in both the surface soils and the sediment core. Concentrations of both α- and β-HCH increased with the inverse of the average annual temperature of these sites. γ-HCH became the dominant isomer of HCHs after the late 1970s, and reached the maximum flux of 160 pg cm^?2 year^?1 in the early 1990s. There were no significant correlations between concentrations of γ-HCH and the other isomers in both the surface soils and the sediment core. The results suggested that there was input of Lindane at scattered sites in this area. In contrast to ΣHCHs, concentration of Σp,p′-DDX in the surface soils of the southern part was much higher than that of the western part. Maximum flux of Σp,p′-DDX was 44 pg cm^?2 year^?1, which appeared in the mid-1960s. Local emission of p,p′-DDT was found at scattered sites. This study provides novel data and knowledge for the OCPs in the western and southern Tibetan Plateau, which will help understand the global fractionation of OCPs in remote alpine regions.     

Effect of ethylenediamine-N,N′-disuccinic acid on Fenton and photo-Fenton processes using goethite as an iron source: optimization of parameters for bisphenol A degradation

The main disadvantage of using iron mineral in Fenton-like reactions is that the decomposition rate of organic contaminants is slower than in classic Fenton reaction using ferrous ions at acidic pH. In order to overcome these drawbacks of the Fenton process, chelating agents have been used in the investigation of Fenton heterogeneous reaction with some Fe-bearing minerals. In this work, the effect of new iron complexing agent, ethylenediamine-N,N'-disuccinic acid (EDDS), on heterogeneous Fenton and photo-Fenton system using goethite as an iron source was tested at circumneutral pH. Batch experiments including adsorption of EDDS and bisphenol A (BPA) on goethite, H₂O₂ decomposition, dissolved iron measurement, and BPA degradation were conducted. The effects of pH, H₂O₂ concentration, EDDS concentration, and goethite dose were studied, and the production of hydroxyl radical (^?OH) was detected. The addition of EDDS inhibited the heterogeneous Fenton degradation of BPA but also the formation of ^?OH. The presence of EDDS decreases the reactivity of goethite toward H₂O₂ because EDDS adsorbs strongly onto the goethite surface and alters catalytic sites. However, the addition of EDDS can improve the heterogeneous photo-Fenton degradation of BPA through the propagation into homogeneous reaction and formation of photochemically efficient Fe-EDDS complex. The overall effect of EDDS is dependent on the H₂O₂ and EDDS concentrations and pH value. The high performance observed at pH 6.2 could be explained by the ability of O ₂ ^?? to generate Fe(II) species from Fe(III) reduction. Low concentrations of H₂O₂ (0.1 mM) and EDDS (0.1 mM) were required as optimal conditions for complete BPA removal. These findings regarding the capability of EDDS/goethite system to promote heterogeneous photo-Fenton oxidation have important practical implications for water treatment technologies.