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.     

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.     

Exposure to particulate matter in traffic: A comparison of cyclists and car passengers

Emerging evidence suggests that short episodes of high exposure to air pollution occur while commuting. These events can result in potentially adverse health effects. We present a quantification of the exposure of car passengers and cyclists to particulate matter (PM). We have simultaneously measured concentrations (PNC, PM2.5 and PM10) and ventilatory parameters (minute ventilation (VE), breathing frequency and tidal volume) in three Belgian locations (Brussels, Louvain-la-Neuve and Mol) for 55 persons (38 male and 17 female). Subjects were first driven by car and then cycled along identical routes in a pairwise design. Concentrations and lung deposition of PNC and PM mass were compared between biking trips and car trips.Mean bicycle/car ratios for PNC and PM are close to 1 and rarely significant. The size and magnitude of the differences in concentrations depend on the location which confirms similar inconsistencies reported in literature. On the other hand, the results from this study demonstrate that bicycle/car differences for inhaled quantities and lung deposited dose are large and consistent across locations. These differences are caused by increased VE in cyclists which significantly increases their exposure to traffic exhaust. The VE while riding a bicycle is 4.3 times higher compared to car passengers. This aspect has been ignored or severely underestimated in previous studies. Integrated health risk evaluations of transport modes or cycling policies should therefore use exposure estimates rather than concentrations.     

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.     

Association between Levels of Fine Particulate and Emergency Visits for Pneumonia and other Respiratory Illnesses among Children in Santiago,Chile

ABSTRACT

Recent evidence has implicated the fine fraction of particulate as the major contributor to the increase in mortality and morbidity related to particulate ambient levels. We therefore evaluated the impact of daily variation of ambient PM_2.5 and other pollutants on the number of daily respiratory-related emergency visits (REVs) to a large pediatric hospital of Santiago, Chile. The study was conducted from February 1995 to August 1996. Four monitoring stations from the network of Santiago provided air pollution data. The PM2.5 24-hr average ranged from 10 to 111 μg/m³ during September to April (warm months) and from 10 to 156 μg/m³ during May to August (cold months). Other contaminants (ozone (O₃), nitrogen dioxide (NO₂), and sulfur dioxide (SO₂)) were, in general, low during the study period. The increase in REVs was significantly related to PM₁₀ and PM_2.5 ambient levels, with the relationship between PM_2.5 levels and the number of REVs the stronger. During the cold months, an increase of 45 ìg/m³ in the PM_2.5 24-hr average was related to a 2.7% increase in the number of REVs (95% CI, 1.1–4.4%) with a two-day lag, and to an increase of 6.7% (95% CI, 1.7–12.0%) in the number of visits for pneumonia with a three-day lag. SO₂ and NO₂ were also related to REVs. We conclude that urban air pollutant mixture, particularly fine particulates, adversely affect the respiratory health of children residing in Santiago.     

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.     

Uptake of Cd(II) and Pb(II) by microalgae in presence of colloidal organic matter from wastewater treatment plant effluents

The present study addresses the key issue of linking the chemical speciation to the uptake of priority pollutants Cd(II) and Pb(II) in the wastewater treatment plant effluents, with emphasis on the role of the colloidal organic matter (EfOM). Binding of Cd(II) and Pb(II) by EfOM was examined by an ion exchange technique and flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry in parallel to bioassays with green microalga Chlorella kesslerii in ultrafiltrate (<1 kDa) and colloidal isolates (1 kDa to 0.45 μm). The uptake of Cd by C. kesslerii was consistent with the speciation analysis and measured free metal ion concentrations, while Pb uptake was much greater than that expected from the speciation measurement. Better understanding of the differences in the effects of the EfOM on Cd(II) and Pb(II) uptake required to take into account the size dependence of metal binding by EfOM.