Photochemical Conversion of NO to NO2 by Hydrocarbons in an Outdoor Chamber

Significant differences occur between results of chamber work conducted outdoors versus work conducted indoors under constant light intensity. Under outdoor conditions at constant [NO_X]_O, lower [HC]o resulted in lower [NO₂]_max and NO₂ dosage during the daylight hours. The percent reduction in [NO₂]_max was a function of the [HC]₀ reduction and the [NO_X]_O level. Under all experimental conditions the 10 hour N0₂ average to maximum N0₂ concentration ratio appeared to be constant at 0.73 during the daylight hours. A regression equation relating [NO_x]_max to [NO_X]_O, [HC]_O, and measures of solar radiation accounted for 92% of the variance in the data. Although there is unavoidable confoundment between [HC]₀ and solar radiation, the HC term in this regression equation can introduce ±20 % change in [N0₂]_max - This variation can be partially offset or enhanced by variations in solar radiation.     

How CO2 emissions respond to changes in government size and level of digitalization? Evidence from the BRICS countries

Environmental Science and Pollution Research - The role of government size and digitization in the process of environmental quality is a matter of considerable debate in the field of environmental...     

Numerical and experimental study on the SO2 pollution produced by Lerdo thermal power plant,Mexico

This paper presents a study on the pollution produced by a fossil fuel plant located in a complex rural environment in México. The study was carried out both experimentally and numerically; experimental measurements were obtained from a monitoring network around the plant. Numerical simulations were carried out employing EPA VALLEY Gaussian model. We are particular interested in annual average ground level concentration of SO₂, that is considered the main pollutant emitted by the plant. Comparison of numerical results with experimental data, suggest significant uncertainties involved in the use of traditional Gaussian models.     

Urinary hydroxyproline to creatinine ratio as a biological effect marker for exposure to NO2 and tobacco smoke

In order to study the relationship between NO₂ exposure and effects, we monitored personal NO₂ exposures and the hydroxyproline to creatinine ratio in urine of about 800 women in two communities near Tokyo. Monitoring was conducted during two seasons, winter and summer 1982. The hydroxyproline to creatinine ratio (HOP:C) was determined from urine samples collected in the early morning. Daily average personal NO₂ exposures (ENO₂) were measured by using a filter badge.In both seasons, HOP:C was found to have significant correlation with ENO₂ and active and passive smoking. In addition, subjects living near major roads had significantly higher HOP:C levels in the summer compared with those living far from them. We hypothesize that these higher HOP:C levels in the summer were due to higher air exchange rates resulting in infiltration of automobile exhaust into homes. ENO₂, however, did not correlate with either the distance of the subject's house from major roads or with the amount of smoking. Stepwise multiple regression analysis revealed that HOP:C could be predicted by personal NO₂ exposures and smoking variables with a high level of confidence.     

Oxidation of SO2 by NO2 and O3 on carbon: Implications to tropospheric chemistry

The oxidation of SO₂ to sulfate in air at 65%, relative humidity on carbon particles was investigated gravimetrically in the presence of NO₂ and O₃. Approximately 1 mg samples of carbon black were exposed to continuously flowing ppbv mixtures of SO₂, SO₂ + NO₂ and SO₂ + O₃ for prescribed periods of time before desorption into dry N₂. Wet chemical analysis of the particles followed desorption. NO₂ and O₃ were found to have little, if any, effect relative to air on sulfate yields at the concentrations studied.     

Evidence for bioaccumulation of PAHs within internal shoot tissues by a halophytic plant artificially exposed to petroleum-polluted sediments

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants of natural and anthropic origins. Despite their poor water solubility, they can be taken up and bioaccumulated by plants. This study was aimed at determining whether the PAHs present in sediments artificially polluted by heavy fuel oil are transferred to shoots of a coastal and edible plant, Salicornia fragilis Ball et Tutin. Bioaccumulation was quantified after a one-week exposure to sediments polluted with 0.2%, 2% and 20% fuel oil (w/w) and over a six-week monitoring at 0.2%. Quantification by GC-MS of PAH amounts in plants and sediments evidenced a bioaccumulation in the shoots by a soil-to-plant transfer through the root system. This bioaccumulation depended on the duration of exposure and on the substratum contamination. PAHs distributions in plants and sediments looked alike with a predominance of low- and medium-weight hydrocarbons. Moreover, high-weight PAHs were also detected in the upper part of plants.     

Ca(2+) -dependent plant response to Pb(2+) is regulated by LCT1

Tobacco plants transformed with TaLCT1 were cultured on Knop's medium with modified calcium concentrations (0.01-3 mM) in the presence of Pb(2+), and in soil contaminated by lead. A 4-5 microM Pb(2+) administered in the presence of 1 mM Ca(2+) inhibited the root growth of transgenic plants to much lesser degree than of control plants, whereas in the presence of 3mM Ca(2+) no differences were found between the studied lines. The reduction of Pb(2+) toxicity in the presence of 1 mM Ca(2+) was not accompanied by a change in the lead tissue concentration. However, when Ca(2+) level in the medium was lowered to 0.01 mM, several fold higher root/shoot Pb ratio in transgenic plants was observed, twofold increase in the total amount of metal accumulated, and lower concentration of Pb in the xylem sap. Results suggest the involvement of TaLCT1 in the regulation of Ca-dependent Pb-detoxification, and under conditions of low calcium in lead uptake and distribution.     

Monitoring H2S air pollution caused by the industrial exploitation of geothermal energy: The pitfall of using lichens as bioindicators

This study showed that NH₃ emitted from geothermal power plants affects the surrounding epiphytic lichen vegetation and diversity, confounding the interpretation of lichen diversity counts in terms of air pollution by H₂S. The presence of nitrophytic lichen species around geothermal installations, determined by NH₃, caused relatively high diversity values that were not related with the levels of air pollution by H₂S. It is recommended that in the presence of NH₃ emission, nitrophytic species are excluded from the calculation of lichen diversity values.     

Air pollution particulate matter as a potential carrier of SARS-CoV-2 to the nervous system and/or neurological symptom enhancer: arguments in favor

Environmental Science and Pollution Research - Entry receptor for SARS-CoV-2 is expressed in nasal epithelial cells, and nasal delivery pathway can be a key feature of transmission. Here, a...     

Influence of plant growth stage and season on the release of root phenolics by mulberry as related to development of phytoremediation technology

The phenolics released by red mulberry (Morus rubra L.) roots at different growth stages within a season were quantified and the makeup of phenols analyzed by reverse-phase high performance liquid chromatography (RP-HPLC). The data show that total phenols released into the soil solution increased continuously from an early vegetative stage to leaf senescence, indicating their accumulation in the rhizosphere. From the RP-HPLC analysis of the butanol-extractable phenolics at various growth stages, there appears to be a massive release of an assortment of less polar phenolics into the rhizosphere at the end of the season accompanying leaf senescence. The rhizosphere phenolics may create an environment suitable for the biodegradation of recalcitrant environmental pollutants, by selectively fostering the growth of some, while inhibiting the growth of other microbes.     

Evaluating threats to an endangered species by proxy: air pollution as threat to the blue swallow (<Emphasis Type="Italic">Hirundo atrocaerulea</Emphasis>) in South Africa

Background, aim, and scope  

The blue swallow (Hirundo atrocaerulea) is one of the most threatened bird species in southern Africa. Among terrestrial birds, its plumage is known to be the most water repellent, an adaptation to foraging on the wing in dense fog. Despite this unique adaptation, the nesting success of the blue swallow at the Blue Swallow Natural Heritage Site (BSNHS) is lower during years with high incidence of fog. As the phenomenon is not observed at other nesting sites, we hypothesized that this is due to changes in the air chemistry at the BSNHS. In the immediate proximity of the BSNHS, plantations of exotic trees (e.g., pines and eucalypts), rich in volatile organic compounds (VOCs), are dominant features. In addition, air pollution from the Johannesburg area is transported with the surface winds and mix with VOCs released from exotic trees. Together with the high humidity and high elevation, these conditions may result in the formation of sulphonates. Sulphonates are strong detergents, and the presence of these in the fog could lead to decreased water repellence of the plumage. This study was performed in order to determine the occurrence and distribution of sulphonates in the BSNHS and to compare these with sulphonates formed in other locations in South Africa. Because the blue swallow is endangered, pine needles were used as proxy to detect formation of sulphonates.