Influence of Meteorological Variables and Forest Fires Events on Air Quality in an Urban Area (Córdoba, Argentina).

Extreme environmental events, such as forest fires, are a major emission source of aerosols into the atmosphere. Thus, to investigate the contribution of local forest fires to urban particulate matter, we selected several forest fire indicators, such as number of heat sources, fire events, and burnt area, and collected particles smaller than 2.5 µm (PM2.5) during a 2.5-year period in Cordoba City (Argentina). Temporal variation of PM2.5 concentration and composition was described considering fire and nonfire periods, and the influence of meteorological variables was estimated as well. On average, PM2.5 levels registered in Córdoba city during the study period were lower than values reported for other similar cities in Latin America, despite the fact that during wintertime an increase in PM2.5 levels was observed due to the occurrence of thermal inversions. Several fire events taking place in the nearby hills around the city during winter and spring 2013 suggest that biomass burning was a strong contribution to urban particles levels, which is consistent with the significant correlation between PM2.5 concentration and heat sources number. During fire periods, levels of Fe, Ca, and K, were significantly higher than in the nonfire periods, suggesting that these elements can be reliable forest fire markers.

Land use and air quality in urban environments: Human health risk assessment due to inhalation of airborne particles.

Particle matter (PM) and its associated compounds are a serious problem for urban air quality and a threat to human health. In the present study, we assessed the intraurban variation of PM, and characterized the human health risk associated to the inhalation of particles measured on PM filters, considering different land use areas in the urban area of Cordoba city (Argentina) and different age groups. To assess the intraurban variation of PM, a biomonitoring network of T. capillaris was established in 15 sampling sites with different land use and the bioaccumulation of Co, Cu, Fe, Mn, Ni, Pb and Zn was quantified. After that, particles were collected by instrumental monitors placed at the most representative sampling sites of each land use category and an inhalation risk was calculated. A remarkable intraurban difference in the heavy metals content measured in the biomonitors was observed, in relation with the sampling site land use. The higher content was detected at industrial areas as well as in sites with intense vehicular traffic. Mean PM10 levels exceeded the standard suggested by the U.S. EPA in all land use areas, except for the downtown. Hazard Index values were below EPA's safe limit in all land use areas and in the different age groups. In contrast, the carcinogenic risk analysis showed that all urban areas exceeded the acceptable limit (1 × 10-6), while the industrial sampling sites and the elder group presented a carcinogenic risk higher that the unacceptable limit. These findings validate the use of T. capillaris to assess intraurban air quality and also show there is an important intraurban variation in human health risk associated to different land use.

Accumulation of aluminium and physiological status of tree foliage in the vicinity of a large aluminium smelter.

A pollution gradient was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, and Populus hybridus and different needle ages of Pinus spec. were collected and concentrations of aluminium (Al) and sulphur (S) as well as physiological parameters (chlorophyll and lipid oxidation products) were analyzed. Al and S concentrations indicate a steep pollution gradient in the study showing a relationship with the physiological parameters in particular membrane lipid oxidation products. The present study confirms that aluminium smelting results in high Al and sulphur deposition in the study area, and therefore further studies should be carried out taking into account potentially adverse effects of these compounds on human and ecosystem health.

Integral assessment of pollution in the Suquía River (Córdoba, Argentina) as a contribution to lotic ecosystem restoration programs.

The Suquía River lower-middle basin (Córdoba, Argentina) is subject to a strong anthropic impact because it receives pollutants from different sources (industries, wastewaters, heavy traffic, agricultural land use, etc.) We have assessed the degree of watershed degradation of Suquía River lower-middle sections through the analysis of different ecosystem compartments (air, water, riparian soil, sediments and biota), in order to provide useful data to be considered in future river restoration programs. Four study sites were selected along the river (La Calera city, Córdoba city, Corazón de María village and Río Primero city) which were sampled during the low- and high-water flow periods. We analyzed: a) chemical and physical characteristics of water, sediments, and riparian soil; b) heavy metal content of water and sediments, and c) semi-volatile organic compounds in air. Besides, pollutant bioindicators such as fish assemblages, lichens (Usnea amblyoclada), vascular plants (Tradescantia pallida), and microorganisms (fecal coliform and Escherichia coli) were used to further assess the status of the river. All analyzed ecological compartments were affected by water pollution, particularly, fish assemblages, sediments and riparian soils by heavy metal and coliform bacteria. Moreover, we detected a possible contribution of sulfur and a high pollutant content in air that merit further research about other air-water exchanges. Accordingly, we strongly suggest that an action to restore or remediate the anthropic effect on the Suquía River be extended to all possible compartments along the river.

Nickel exposure enhances the susceptibility of lichens Usnea amblyoclada and Ramalina celastri to urban atmospheric pollutants.

In the present study, the effect of nickel incorporation on the chemical response of Ramalina celastri (Spreng.) Krog & Swinsc. and Usnea amblyoclada (Müll. Arg.) Zahlbr. exposed to urban atmospheric pollutants was assessed. Lichen thalli were treated with Ni solutions and then transplanted to two areas of the city of Córdoba with different levels of pollution. After exposure, the concentration of chlorophyll a, chlorophyll b, phaeophytin a, hydroperoxy conjugated dienes, malondialdehyde, sulphur content, electric conductivity of the immersion water, and nickel content were measured. Also, a Pollution Index was calculated for each lichen species. The exposure to Ni altered the physiological response to atmospheric pollutants in both lichen species, making them more sensitive to any damage caused by them. When the species were compared, it was observed that R. celastri accumulated more sulphur than U. amblyoclada.

Atmospheric quality and distribution of heavy metals in Argentina employing Tillandsia capillaris as a biomonitor.

The atmospheric quality and distribution of heavy metals were evaluated throughout a wide region of Argentina. In addition, the biomonitor performance of Tillandsia capillaris Ruiz & Pav. f. capillaris was studied in relation to the accumulation of heavy metals and to its physiologic response to air pollutants. A sampling area of 50,000 km2 was selected in the central region of the Argentine Republic. This area was subdivided into grids of 25 x 25 km. Pools of T. capillaris, where present, were collected at each intersection point. From each pool three sub-samples were analyzed independently. Furthermore, five replicates were collected at 20% of the points in order to analyze the variability within the site. The content of Co, Cu, Fe, Ni, Mn, Pb and Zn was determined by Atomic Absorption Spectrometry. Chemical-physiological parameters were also determined to detect symptoms of foliar damage. Chlorophylls, phaeophytins, hydroperoxy conjugated dienes, malondialdehyde and sulfur were quantified in T. capillaris. Some of these parameters were used to calculate a foliar damage index. Data sets were evaluated by one-way ANOVA, correlation analysis, principal component analysis and mapping. Geographical distribution patterns were obtained for the different metals reflecting the contribution of natural and anthropogenic emission sources. According to our results it can be inferred that Fe, Mn and Co probably originated in the soil. For Pb, the highest values were found in the mountainous area, which can be attributed to the presence of Pb in the granitic rocks. Ni showed mainly an anthropogenic origin, with higher values found in places next to industrial centers. For Zn the highest values were in areas of agricultural development. The same was observed for Cu, whose presence could be related to the employment of pesticides. The foliar damage index distribution map showed that the central and southeastern zones were the ones where the major damage in the bioindicator was found. The central zone coincides with the city of Córdoba whereas the southeastern area is strictly agricultural, so the high values found there could be related to the use of pesticides.

Comparison among air pollutants, meteorological conditions and some chemical parameters in the transplanted lichen Usnea amblyoclada.

The response of Usnea amblyoclada (Müll. Arg.) Zahlbr. to real concentrations of atmospheric pollutants measured by two automatic monitoring stations, was studied in Córdoba City, Argentina. The influence of different weather conditions on the biomonitor's response was also assessed. The concentration of chlorophyll a, chlorophyll b, hydroperoxy-conjugated dienes, and malondialdehyde were quantified in lichen thalli collected from a clean area and in transplanted thalli after 1 month of exposure in an urban area, from April to October, 1996. The dry weight/fresh weight, chlorophyll b/chlorophyll a and phaeophytin a/chlorophyll a ratios were also calculated. Data sets were evaluated by two-way analysis of variance and correlation analysis. It was observed that hydroperoxy-conjugated dienes, malondialdehyde, chlorophylls, and pigment degradation increase during winter-time, when higher levels of suspended particles, non-methane hydrocarbons, hydrogen sulfide and ozone were also measured. These findings would be connected mainly with meteorological conditions, as most pollutants did not exceed prescribed threshold levels.

Differences in responses to urban air pollutants by Ligustrum lucidum Ait. and Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd.

This study examined the chemical response of Ligustrum lucidum Ait. and Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd. when exposed to different sources of atmospheric pollutants. Dry weight/fresh weight ratio, specific leaf area (SLA), sulfur content, chlorophyll concentration, carotenoids, soluble proteins, malondialdehyde (MDA) and hydroperoxy conjugated dienes (HPCD) were determined for leaf samples taken from different sites in the city of Córdoba, Argentina. These sites were categorized in terms of their traffic levels and industrial levels. Both L. lucidum as well as L. lucidum f. tricolor accumulated sulfur in their leaves in sites with high traffic levels, the former being the most sensitive to this type of pollution. Ligustrum lucidum exhibited significantly low concentrations of soluble proteins, in sites with high industrial pollution levels. Ligustrum lucidum f. tricolor did not exhibit a significant response to industrial pollution.