An approach for determining air pollution monitoring sites

EC Directive 2008/50/CE on ambient air quality and cleaner air for Europe specifies the obligations of Member States regarding fixed measurements of atmospheric pollutants in areas where maximum concentration levels exceed the lower assessment threshold. However, indications as to the siting of atmospheric monitoring stations are less precise and sometimes confusing. Campaigns to measure benzene and other volatile organic compounds in Murcia in 2007 and 2008 revealed that the areas where measurements coincided with the mean concentration for the whole city were always practically the same. Consequently, we propose a method for siting atmospheric monitoring stations in cities for which emission sources remain steady throughout the year, as is the case for cities in most southern European countries, where the most important emission source is traffic. The method is particularly useful for towns in which only one fixed measuring point is compulsory and should help local authorities in making correct decisions in this context.     

Validation of a hydride generation atomic absorption spectrometry methodology for determination of mercury in fish designed for application in the Brazilian national residue control plan

In the present study, a method for the determination of mercury (Hg) in fish was validated according to ISO/IEC 17025, INMETRO (Brazil), and more recent European recommendations (Commission Decision 2007/333/EC and 2002/657/EC) for implementation in the Brazilian Residue Control Plan (NRCP) in routine applications. The parameters evaluated in the validation were investigated in detail. The results obtained for limit of detection and quantification were respectively, 2.36 and 7.88 μg kg^?1 of Hg. While the recovery varies between 90–96%. The coefficient of variation was of 4.06–8.94% for the repeatability. Furthermore, a comparison using an external proficiency testing scheme was realized. The results of method validated for the determination of the mercury in fish by Hydride generation atomic absorption spectrometry were considered suitable for implementation in routine analysis.     

Potential application of 2-(6-ethylamino-3-ethylimino-2,7-dimethyl-3H-xanthen-9-yl) benzoic acid phenyl thiourea for mercury determination

Heavy metal contamination of the environment is a public health problem and research to develop new tools for monitoring the environmental impact of these elements is necessary. This study describes the preparation of a rhodamine-based probe 1 and its potential applications for detecting mercuric ion [Hg(II)] in samples from a nutrition media containing Salvinia auriculata. It was observed that an excess of probe 1 led to quenching in the fluorescence/absorption response, which was evidenced by a decrease in the signal when the stoichiometry differed from 1:1. Consequently, this probe is not suitable for quantitative analysis of Hg(II). Also, probe 1 reacts with methylmercury (MeHg) with different stoichiometry than that observed for Hg(II). These results indicate the potential application of probe 1 for qualitative detection of Hg(II) and MeHg in environmental samples.     

Health impact assessment of air pollutants during the COVID-19 pandemic in a Brazilian metropolis

Environmental Science and Pollution Research - Studies around the world have revealed reduced levels of atmospheric particulate matter in periods of greatest human mobility restriction to contain...     

Impacts of climatic change and low frequency variability in reference series on daily maximum and minimum temperature in southern South America

Understanding the climate and its variability, in particular with regard to their socioeconomic impact, requires specific measurements of precipitation and temperature and their circulations. This becomes more important in applications to diverse systems. In order to improve knowledge about temporal changes and trends in temperature, we analyzed series of maximum and minimum daily surface temperatures at eight reference stations in southeastern South America during variable periods, with the longest periods of around 100 years. To study the evolution of the temperature series and to reduce the number of parameters, a nonhierarchical cluster analysis was performed. The algorithm assigns each day to one of four groups: warm, wet, cold and dry. Low frequency variations were found in these groups and their association with circulation structure, circulation patterns and precipitation. We concluded that the set of wet days is one of the main factors driving secular variations of maximum and minimum temperature and variations in precipitation. We also inferred that after 1920 till 1930, a low frequency oscillation is observed in the form of linear trends (increase of warm days and decrease of cold days).     

Pollutant Transport During a Regional O3 Episode in the Mid-Atlantic States

ABSTRACT

Ozone (O₃) concentrations in the Baltimore-Washington (B-W) metropolitan area frequently exceed the National Ambient Air Quality Standard (NAAQS) in the summer months. The most extreme O₃ events occur in multi-day high O₃ episodes.¹ These events can be regional in scale, with O₃ concentrations exceeding the NAAQS at numerous locations along the eastern U.S. seaboard, and are typically associated with slow-moving or stagnant high pressure systems.^2-5 In the B-W region, the most extreme events typically occur with surface high pressure overhead or just west of the region and an upper air high-pressure area (ridge) to the west or northwest.¹ Besides providing conditions conducive to local O₃ production (subsidence and strong low-level inversions, weak horizontal winds, little cloud cover), this weather pattern may also result in transport of O₃ and its precursors from heavily industrialized areas west and north of the B-W region. In this paper, observations and back trajectories made during the severe regional O₃ event of July 12-15, 1995, are used to confirm the hypothesis that significant regional-scale transport of O₃ and its precursors occur during extreme O₃ events of the standard type in the B-W area.     

Avoiding over-implementation of agri-environmental schemes for steppe bird conservation: A species-focused proposal based on expert criteria

This study presents an assessment, resulting from consultation with experts in steppe-bird conservation (scientists, officers and conservationists) using the Delphi method, of a broad range of agri-environmental measures (AEMs) which have been applied in agricultural areas in Spain, with particular reference to four threatened steppe bird species. The measures which experts have valued most highly relate to the maintenance of fallow land, the prohibition of agrochemicals and the suspension of certain agricultural practices when the species are nesting. Other AEMs which have frequently been mentioned as beneficial for steppe birds, including the maintenance of straw-mulched fallows and the abandonment of farmland, were rejected by the experts. The assessment showed a high degree of consensus between experts, although differences between the four studied species were detected. Delphi assessment indicated that different birds need different AEMs. In addition, expert evaluation showed that different AEMs can cause the same effect on the target species, which could generate an over-implementation of measures. Finally, we evaluated the financial implementation of the AEMs selected by the Delphi using a Special Protection Area for birds (SPA) in the Madrid region as a case study. All the hypothetical scenarios used yielded assumable costs, oscillating between 1 and 2 times the current AEMs expenditure. In conclusion, in extensive agrarian systems with already high conservation merits, the implementation of AEMS could be improved using species-specific assessments, thus avoiding over-implementation and improving the fit between costs and benefits for conservation.     

The effects of plant distribution and frugivore density on the scale and shape of dispersal kernels

For many plant species, seed dispersal is one of the most important spatial demographic processes. We used a diffusion approximation and a spatially explicit simulation model to explore the mechanisms generating seed dispersal kernels for plants dispersed by frugivores. The simulation model combined simple movement and foraging rules with seed gut passage time, plant distribution, and fruit production. A simulation experiment using plant spatial aggregation and frugivore density as factors showed that seed dispersal scale was largely determined by the degree of plant aggregation, whereas kernel shape was mostly dominated by frugivore density. Kernel shapes ranged from fat tailed to thin tailed, but most shapes were between an exponential and that of the solution of a diffusion equation. The proportion of dispersal kernels with fat tails was highest for landscapes with clumped plant distributions and increased with increasing number of dispersers. The diffusion model provides a basis for models including more behavioral details but can also be used to approximate dispersal kernels once a diffusion rate is estimated from animal movement data. Our results suggest that important characteristics of dispersal kernels will depend on the spatial pattern of plant distribution and on disperser density when frugivores mediate seed dispersal.     

First fossil evidence of an “interglacial refugium” in the Pyrenean region

A refugium is generally understood as an area where temperate species survive cold periods, such as the Iberian, Italian, or Balkan Peninsulas in Europe. Strictly speaking, this definition refers to what is known as a glacial refugium. However, there are various types of lesser-known refugia such as the interglacial refugium, which denotes a mountainous region at low latitudes, such as the Pyrenees, where species adapted to the cold survive during interstadial periods. The small-vertebrate association from the sequence of Cova Colomera, which is located on the southern face of the Pyrenees and contains the final cold spell of the Late Pleistocene and the beginnings of the temperate period in which we currently find ourselves (the Holocene), could constitute the first fossil evidence of such an interglacial refugium, thus providing new paleoecological data on the phenomenon.     

Atrazine leaching through surface and subsurface of a tropical Oxisol

The fate of (14)C atrazine was investigated using microcosms and an undisturbed Red-Yellow Latossol (Oxisol) under simulated rainfall conditions of 200 mm water month(-1). Experiments were carried out using microcosm cores, the first with an uncovered surface soil; the second set with uncovered subsurface soil; the third with subsurface soil covered with 3 cm of cow manure and the last with subsurface soil covered with 5 cm of grass straw. Average values for the amount of atrazine leached after 60 days were as follows: surface soil 1.6%; subsurface 47.3%; subsurface plus manure 17.3% and subsurface plus straw 24.8%. In the surface soil, 53% of the (14)C atrazine remained within the upper 1 cm, while in the subsurface microcosms the atrazine was more evenly distributed. The authors report that surface soil was retained atrazine and its metabolites for 60 days. The addition of a straw or manure covering to exposed subsoil helped to retard atrazine leaching.