Urban Air Pollution in Latin America and the Caribbean

Urban air pollution has become an increasing problem in Latin America and the Caribbean. One reason is the rapid expansion in the size of the urban population. This phenomenon is associated with an increase in the number of vehicles and in energy utilization which, in addition to industrial processes often concentrated in the cities, are the primary sources of air pollution in Latin American cities. The air quality standards established in such countries are frequently exceeded although control programs have been implemented. The urban areas more affected by anthropogenic pollutant emissions are Sao Paulo, Brazil; Santiago, Chile; and Mexico City. In Latin America, the population of cities with high priority air pollution problems include approximately 81 million people or 26.5 percent of the total urban population of Latin America, corresponding to 30 million children (< 15 years), 47 million adults (15-59 years) and 4 million elderly people (≧60 years) who are exposed to air pollutant levels that exceed World Health Organization (WHO) guidelines for adequate health protection.     

Evaluation of an urban NMHC emission inventory by measurements and impact on CTM results

This paper presents an evaluation of the consistency of an urban state-of-the-art hydrocarbon (HC) emission inventory. The evaluation was conducted through the comparison of this inventory with hourly HC measurements during two summer months in the centre of Marseille, on the Mediterranean French coast. Factors of under or overestimation could be calculated for each compound on the basis of a systematic HC to HC ratio analysis. These results, associated with a deep analysis of the speciation profiles, show that most of the common and highly concentrated hydrocarbons (such as butanes) are too much predominant in the emission speciation, while the heavy and less common species (branched alkanes, substituted aromatics) are under-represented in the inventory. The urban diffuse sources appear here as one critical point of the inventories. The disagreements were shown to have a strong incidence on the representation of the air mass reactivity. In a last step, the identified uncertainties in emissions were implemented in an air-quality model for sensitivity studies. It was shown that the observed biases in the inventory could affect the regional ozone production, with a probable impact on ozone peaks of 2–10 ppbv over the area.     

Characterization of endocrine disruptors from a complex matrix using estrogen receptor affinity columns and high performance liquid chromatography–high resolution mass spectrometry

Complex mixtures of contaminants with potential adverse effects on human health and wildlife are found in the environment and in the food chain. These mixtures include numerous anthropogenic compounds of various origins and structures, which may behave as endocrine disruptors. Mixture’s complexity is further enhanced by biotic and abiotic transformations. It is therefore necessary to develop new strategies allowing the identification of the structure of known, as well as unknown, nuclear receptor (NR) ligands present in complex matrices. We explored the possibility to use NR-based affinity columns to characterize the presence of bioactive molecules in environmental complex mixtures. Estrogen receptor α (ERα)-based affinity columns were used to trap and purify estrogenic substances present in surface sediment samples collected in a French river under mixed anthropogenic pressure. We combined biological, biochemical and analytical approaches to characterize the structure of ligands retained on columns and demonstrate the presence of known active molecules such as bisphenol A and octylphenol, but also of unexpected ERα ligands (n-butylparaben, hydroxyl-methyl-benzofuranone). High resolution mass spectrometry results demonstrate that ERα affinity columns can be used for the isolation, purification and identification of known as well as unknown estrogenic contaminants present in complex matrices.     

Effect of oxic/anoxic switches on bacterial communities and PAH biodegradation in an oil-contaminated sludge

Purpose  

We studied the effect of alternations of aeration on both the autochthonous bacterial communities from an oily sludge to the endogenous polycyclic aromatic hydrocarbons (PAH) biodegradation compared to a permanent oxic condition.     

Changes in soil organic matter chemical properties after organic amendments

Organic inputs are used to improve soil physical and chemical properties, but the corresponding changes in soil organic matter (SOM) chemical properties are not well known. In this study, we compared some characteristics of the SOM of a soil receiving either no organic inputs, or two different amendments during 15 years (straw or conifer compost). Quantities of organic carbon and C/N values were determined on particle size fractions after physical soil fractionation to localize changes due to amendments. Contents in reactive functional groups, acid-base properties and copper binding affinities were determined by titration experiments for the soluble fraction of SOM: the fulvic acid fraction (FA). Data of FA extracted from the bulk soil were compared to data of FA extracted from the <20 microm size fraction with the help of either a discrete or a continuous model (fit of data with FITEQL or NICA, respectively). Copper binding characteristics of FA extracted from the <20 microm size fraction did not change significantly after organic inputs, while those of FA extracted from the bulk organic-amended soils were found different from the ones with no amendment. Minor effects observed in the finer soil fractions were ascribed to their low turn-over of organic carbon and/or to a greater homogeneity in the nature of the organic carbon entering these fractions. Our results show major chemical changes in coarser soil organic fractions after organic amendments.     

Process-based modeling of species' distributions: what limits temperate tree species' range boundaries?

Niche-based models are widely used to understand what environmental factors determine species' distributions, but they do not provide a clear framework to study the processes involved in defining species' ranges. Here we used a process-based model to identify these processes and to assess the potential distribution of 17 North American boreal/temperate tree species. Using input of only climate and soil properties, the model reproduced the 17 species' distributions accurately. Our results allowed us to identify the climatic factors as well as the biological processes involved in limiting species' ranges. The model showed that climatic constraints limit species' distributions mainly through their impact on phenological processes, and secondarily through their impact on drought and frost mortality. The northern limit of species' ranges appears to be caused mainly by the inability to undergo full fruit ripening and/or flowering, while the southern limit is caused by the inability to flower or by frost injury to flowers. These findings about the ecological processes shaping tree species' distribution represent a crucial step toward obtaining a more complete picture of the potential impact of climate on species' ranges.     

Geochemical and solute transport modelling for CO2 storage, what to expect from it?

Geochemistry plays an important role when assessing the impact of CO₂ storage. Due to the potential corrosive character of CO₂, it might affect the chemical and physical properties of the wells, the reservoir and its surroundings and increase the environmental and financial risk of CO₂ storage projects in deep geological structures. An overview of geochemical and solute transport modelling for CO₂ storage purposes is given, its data requirements and gaps are highlighted, and its progress over the last 10 years is discussed. Four different application domains are identified: long-term integrity modelling, injectivity modelling, well integrity modelling and experimental modelling and their current state of the art is discussed. One of the major gaps remaining is the lack of basic thermodynamical and kinetic data at relevant temperature and pressure conditions for each of these four application domains. Real challenges are the coupled solute transport and geomechanical modelling, the modelling of impurities in the CO₂ stream and pore-scale modelling applications.     

Tributyltin and triphenyltin uptake by lettuce

This paper provides quantitative information on the transfer of TBT (tributyltin) and TPhT (triphenyltin) from sludged soil to cultivated lettuce. The effect of their initial concentrations in the soil (varying from 20 to 50 microg(Sn)kg(-1) for each triorganotin), sludge amount (between 1% and 9%), and cultivation duration (32-54 days) was evaluated by means of experimental designs. The impact of the cultivation temperature at 13 degrees C and 19 degrees C on organotin fate in the soil/plant system was also considered. The final concentration of a given organotin in the plant roots was found to depend directly on its initial concentration in the soil. A total of (85+/-15)% of initial TBT in the soil was still present at the end of the experiments, regardless of the cultivation duration. Consequently, TBT appeared to be taken up by lettuce continually. A total of (75+/-5)% of TPhT was found to be degraded in the soil at 54 days. So, this compound could have been taken up by the plant at the beginning of the cultivation. Sludge amount seemed to have a negative effect on TPhT concentration in a plant at 32 days. This could be due to the quantitative TPhT sorption onto the sludge, observed just after spiking. Organotin plant uptake appeared to be more important at 19 degrees C than at 13 degrees C. TBT and TPhT were mainly accumulated in the roots, and up to 2% and 10% of TPhT and TBT, respectively, were translocated to the shoots. Despite TPhT degradation, products in large amounts were present in the soil and were not significantly taken up by the plant. They possibly remained immobilized on solid phases of the sludged soil.     

Antagonistic effect of natural habitat conversion on community adjustment to climate warming in nonbreeding waterbirds

Although the impacts of climate and land-use changes on biodiversity have been widely documented, their joint effects remain poorly understood. We evaluated how nonbreeding waterbird communities adjust to climate warming along a gradient of land-use change. Using midwinter waterbird counts (132 species) at 164 major nonbreeding sites in 22 Mediterranean countries, we assessed the changes in species composition from 1991 to 2010, relative to thermal niche position and breadth, in response to regional and local winter temperature anomalies and conversion of natural habitats. We observed a low-level, nonsignificant community adjustment to the temperature increase where natural habitat conversion occurred. At the sites affected by natural habitat conversion, the relative increase of warm-dwelling species in response to climate warming was 6 times lower and the relative species decline was 3 times higher than in the sites without natural habitat conversion. We found no evidence of community adjustment to climate warming when natural habitat conversion was >5% over 15 years. This strong negative effect suggests an antagonistic interaction between climate warming and habitat change. These results underline the importance of habitat conservation in community adjustment to climate warming.     

Assessment of short and long-term effects of imidacloprid on the burrowing behaviour of two earthworm species (Aporrectodea caliginosa and Lumbricus terrestris) by using 2D and 3D post-exposure techniques

Adverse effects of agrochemicals on earthworms’ burrowing behaviour can have crucial impacts on the entire ecosystem. In the present study, we have therefore assessed short- and long-term effects on burrowing behaviour in the earthworm species Aporrectodea caliginosa and Lumbricus terrestris after exposure to a range of imidacloprid concentrations (0.2-4 mg kg⁻¹ dry weight (DW)) for different exposure times (1, 7, 14 d). 2D-terraria were used for the examination of post-exposure short-term effects (24-96 h), while post-exposure long-term effects were assessed by means of X-ray burrow reconstruction in three dimensional soil cores (6 weeks). For the latter each core was incubated with two specimens of L. terrestris and four of A. calignosa. Short-term effects on the burrowing behaviour (2D) of A. caliginosa were already detected at the lowest test concentration (0.2 mg kg⁻¹ DW), whereas such effects in L. terrestris were not observed until exposure to concentrations 10 times higher (2 mg kg⁻¹ DW). For both species tested in the 2D-terraria, “total burrow length after 24 h” and “maximal burrow depth after 24 h” were the most sensitive endpoints. 3D reconstructions of the burrow systems made by both earthworm species in the repacked soil cores revealed a significant linear decrease in burrow volume with increasing imidacloprid concentration.Since many of the observed effects occurred at imidacloprid concentrations relevant to natural conditions and since reduced activities of earthworms in soils can have crucial impacts on the ecosystem level, our results are of environmental concern.