Maria do Carmo Freitas

Recent advances in the k0-standardization of neutron activation analysis: Extensions, applications, prospects

This paper reports on the contribution made by some cooperating laboratories to the further development of the k0-method. As to the extensions and improvements, emphasis is put on the availability of an Al−0.1% Au reference material for the k0-standardization of NAA, on the counting of large-diameter samples, on the use of a low-energy photon detector, and on the introduction of the Westcott formalism for the handling of “non-1/v” (n, γ) reactions. A survey is given of a large variety of scientific and industrial applications, including the analysis of biological, geological and geochronological samples, various kinds of reference materials, high-purity products and ceramics, and a number of environmental pollution indicators. As shown, the advantage of the k0-standardization will be fully exploited with an increasing level of automation in NAA laboratories. Eventually, new measurements and evaluations of k0-factors and related nuclear data are given in an Appendix.

Outdoor/indoor air quality in primary schools in Lisbon: a preliminary study

Simultaneous measurements of outdoor and indoor pollution were performed at three schools in Lisbon. Volatile organic compounds (VOCs), formaldehyde and NO2 were passively monitored over a two-week period. Bacterial and fungal colony-forming units and comfort parameters were also monitored at classrooms and playgrounds. The highest indoor levels of CO2 (2666 μg/m3), NO2 (40.3 μg/m3), VOCs (10.3 μg/m3), formaldehyde (1.03 μg/m3) and bioaerosols (1634 CFU/m3), and some indoor/outdoor ratios greater than unity, suggest that indoor sources and building conditions might have negative effects on air indoors. Increasing ventilation rates and use of low-emission materials would contribute towards improving indoor air quality.

Quality assurance in elemental analysis of airborne particles

Abstract Instrumental neutron activation analysis (INAA) and particle induced X-ray emission (PIXE) are commonly used to yield multielemental data in atmospheric studies. In this work the quality assurance of the analytical data is discussed based on two studies. The first is a precision study, involving sampling and analysis of air particulate matter in the size ranges of the aerodynamic diameter (AD)

Quality assessment on airborne particulate matter of k0-INAA

The analysis of airborne particulate matter (APM) by k0-NAA was assessed using: (1) BCR reference material (RM) simulated air-filters, (2) synthetic air-filters prepared by spiking blank filters with standard solutions, and (3) real APM filters. k0-INAA is a suitable technique for the analysis of APM, delivering accurate and precise results. However, the quality assessment of APM analysis appears to be a difficult task.

Indoor Air Quality in Primary Schools

The indoor air quality (IAQ) in classrooms is expected to play a key role in the assessment of the effects of the children’s personal exposure to air pollution since they spend on average 7–11 h per weekday at school. A statistical treatment was conducted over a database of indoor air parameters and the primary schools where these parameters were sampled (urban area of Lisbon, Portugal). The aim of this study was to assess the associations between indoor air parameters with the schools’ building characteristics, through the use of statistical methods. Several associations were found and allow pointing out from this study several recommendations to improve the classrooms IAQ. For example, some factors such as ventilation, cleanings and chalk use instead whiteboard pens, can reduce or increase specific contaminants inside the classrooms.

Interference from uranium fission products in the determination of rare earths, zirconium and ruthenium by instrumental neutron activation analysis in rocks and minerals

A numerical procedure is given to correct for the interference of U in the determination of the light rare earths, Zr, and Ru. The corresponding interference factors were calculated and their values compared with experimental results. The agreement is favourable in most cases.

Air quality control monitoring at an urban and industrialized area

Air particulate matter analysis has been performed since 1999, within a contract for air quality monitoring of an urban waste incinerator. Air collection was made with Gent samplers, which collect size-fractionated aerosol samples in three sampling sites. Samples were analyzed by instrumental neutron activation analysis (INAA) and proton induced X-ray emission (PIXE). In this study some INAA results are discussed. PM10 mass concentrations are compared with the limit values for human health protection regulated by the European Council Directive 1999/30/CE. Weekend day and weekday samples are compared concerning As, Co, Fe, K, La, Na, Sb, Sc, Se and Zn mean concentrations collected at Bobadela for 1999. Enrichment factors are also presented. Enrichments were found for As, Sb, Se and Zn for both fractions in the three sampling sites. In order to quantify the evolution for the 1999-2001 period, basic statistics was performed for the enriched elements.

Comparison of continental Portugal and Azores Islands aerosol during a Sahara dust storm

Airborne particulate matter plays an important role in the Earths energy balance. One of the main reasons is that the real size of a significant number of the particles, mainly those of anthropogenic origin, is similar to the wavelength of visible light. Knowledge of the composition of such particles, as well as their dynamics and trajectories in the atmosphere is therefore very important. In the period from 23 February to 22 March 2000, a movement of airborne particulate matter going over Europe and towards Azores was identified based on satellite observation. This work presents a preliminary study based on PIXE and nuclear micro-probe analysis of samples collected during that period both in Portugal mainland and in Terceira Island in the Azores. Time-shifted correlation of sample composition and individual particle composition are presented and discussed. Results point to the possibility of inferring long-range transport of aerosol particles from the samples multi-element analysis, and to the existence of fractions of the North Atlantic aerosol identical at both Portugal mainland and Terceira Island.

Lichens as biomonitors at indoor environments of primary schools

A biomonitoring study, using transplanted lichens Flavoparmelia caperata, was conducted to assess the indoor air quality in primary schools in urban (Lisbon) and rural (Ponte de Sor) Portuguese sites. The lichens exposure period occurred between April and June 2010 and two types of environments of the primary schools were studied: classrooms and outdoor/courtyard. Afterwards, the lichen samples were processed and analyzed by instrumental neutron activation analysis (INAA) to assess a total of 20 chemical elements. Accumulated elements in the exposed lichens were assessed and enrichment factors (EF) were determined. Indoor and outdoor biomonitoring results were compared to evaluate how biomonitors (as lichens) react at indoor environments and to assess the type of pollutants that are prevalent in those environments.

Air pollution and emergency admissions for cardiorespiratory diseases in Lisbon (Portugal)

Daily records of hospital admissions due to cardiorespiratory diseases and levels of PM10, SO2, CO, NO, NO2, and O3 were collected from 1999-2004 to evaluate the relationship between air pollution and morbidity in Lisbon. Generalised additive Poisson regression models were adopted, controlling for temperature, humidity, and both short and long-term seasonality. Significant positive associations, lagged by 1 or 2 days, were found between markers of traffic-related pollution (CO and NO2) and cardiocirculatory diseases in all age groups. Increased childhood emergency admissions for respiratory illness were significantly correlated with the 1-day lagged SO2 levels coming from industrial activities.