Maria Ascensão Trancoso

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.

Natural heavy metal and metalloid concentrations in sediments of the Minho River estuary (Portugal): baseline values for environmental studies.

Forty-nine surface sediment samples from the Minho estuary sector between Tui and Caminha were analyzed for grain-size contents, Al, As, Cr, Cu, Hg, Li, Pb, Sn, and Zn concentrations. Selected heavy metal (Cu, Cr, Hg, and Zn) and metalloid (As and Sn) distributions were normalized against Al and Li with the main goal of compensating for natural grain-size variability and to separate natural from anthropogenic contributions, by using a combination of normalization techniques (definition of regional geochemical baselines (RGB) and determination of enrichment factors (EF)). Lead did not reveal a significant relationship with Al and Li. Aluminum explained more variance than Li for As, Cu, Hg, and Zn. Assuming the general non-impacted metal character of the Minho River estuary sediments, RGBs are defined for differentiating between natural and anthropogenic contributions. Based on RGB defined for each heavy metal/metalloid, the degree of enrichment is estimated through the determination of EF. Despite the relatively low total heavy metal and metalloid concentrations, the defined RGB identifies a set of samples characterized by presenting As, Cu, Cr, Hg, and Zn enrichments relatively to expected natural levels. Mercury is the element showing the highest level of enrichment relative to the baseline values being spread through all the study area. Tin present enrichments relatively to Al and or Li always lower than 1.5 suggesting natural contributions.

Temporal evolution of lead isotope ratios in sediments of the Central Portuguese Margin: a fingerprint of human activities.

Stable Pb isotope ratios ((206)Pb/(207)Pb, (208)Pb/(206)Pb), (210)Pb, Pb, Al, Ca, Fe, Mn and Si concentrations were measured in 7 sediment cores from the west coast of the Iberian Peninsula to assess the Pb contamination throughout the last 200 years. Independently of their locations, all cores are characterized by increasing Pb/Al rends not related to grain-size changes. Conversely, decreasing trends of (206)Pb/(207)Pb were found towards the present. This tendency suggest a change in Pb sources reflecting an increased proportion derived from anthropogenic activities. The highest anthropogenic Pb inventories for sediments younger than 1950s were found in the two shallowest cores of Cascais and Lisboa submarine canyons, reflecting the proximity of the Tagus estuary. Lead isotope signatures also help demonstrate that sediments contaminated with Pb are not constrained to estuarine-coastal areas and upper parts of submarine canyons, but are also to transferred to a lesser extent to deeper parts of the Portuguese Margin.

Validation of an environmental friendly segmented flow method for the determination of phenol index in waters as alternative to the conventional one

Phenolic compounds are a sort of common pollutants in water. Phenol index becomes an expedite indicator for the evaluation of the contamination level of water samples, in spite of the knowledge of the individual phenol and its derivatives are also important. In this work, an environmental friendly method for the determination of phenols, using a segmented flow system based on the conventional methods reactions without the liquid-liquid extraction step, was validated. Three linear dynamic ranges using C(6)H(5)OH: 1-10 microg l(-1), 10-200 microg l(-1) and 0.2-2.5 mg l(-1), with a coefficient of variation lower than 2%, were obtained. Several methods performance parameters were determined: limits of detection, limits of quantification, precision through duplicate analysis and trueness using the reference materials purchased from LGC Promochem, RTC no. QCI-043-2 Lot:P1. Measurement uncertainty was evaluated using an interlaboratory approach based on proficiency testing data. Relative combined uncertainty for phenols in water samples, u(c)(rel)(gamma(sample)), of 0.054 were obtained, in according to those imposed by the Portuguese Legislation: target u(c)(rel)(gamma(sample))=0.58 for 1 microg l(-1) of phenol (surface waters) and target u(c)(rel)(gamma(sample))=0.06 for 500 microg l(-1) of phenol (wastewaters). A high efficiency reduction and elimination of reagents and wastes, reduction of analysis time and exposition of the analyst were also obtained.

Behaviour and fate of metals in urban wastewater treatment plants: a review

AbstractThe concerns on metals in urban wastewater treatment plants (WWTPs) are mainly related to its contents in discharges to environment, namely in the final effluent and in the sludge produced. In the near future, more restrictive limits will be imposed to final effluents, due to the recent guidelines of the European Water Framework Directive (EUWFD). Concerning the sludge, at least seven metals (Cd, Cr, Cu, Hg, Ni, Pb and Zn) have been regulated in different countries, four of which were classified by EUWFD as priority substances and two of which were also classified as hazardous substances. Although WWTPs are not designed to remove metals, the study of metals behaviour in these systems is a crucial issue to develop predictive models that can help more effectively the regulation of pre-treatment requirements and contribute to optimize the systems to get more acceptable metal concentrations in its discharges. Relevant data have been published in the literature in recent decades concerning the occurrence/fate/behaviour of metals in WWTPs. However, the information is dispersed and not standardized in terms of parameters for comparing results. This work provides a critical review on this issue through a careful systematization, in tables and graphs, of the results reported in the literature, which allows its comparison and so its analysis, in order to conclude about the state of the art in this field. A summary of the main consensus, divergences and constraints found, as well as some recommendations, is presented as conclusions, aiming to contribute to a more concerted action of future research.

Procedure validation and laboratory performance monitoring for the measurement of moisture, ash and volatile matter mass fractions in solid biofuels

AbstractParticipation in interlaboratory comparisons is a requirement of the accreditation bodies for granting laboratory accreditation by EN ISO/IEC 17025:2005 as external quality control. Proficiency testing (PT) is used to demonstrate the individual performance of a laboratory for a specific test or measurement. Monitoring PT performance over time shows the continuing performance and allows the identification of potential problems related to random and systematic errors. In this study, it is shown that the procedures applied to measure mass fractions of moisture, ash and volatile matter in solid fuels fulfill the conditions stated in the European standards EN 14774-3, EN 14775 and EN 15148:2009 regarding target uncertainty, repeatability and reproducibility. Repeatability was assessed from sample duplicate analysis and combined standard uncertainty. Limits of detection and quantification were also estimated although no target values are stated. The obtained values fulfill the requirements for specifications and classes of solid biofuels. Laboratory performance over the time from 2011 to 2013 regarding such measurements was evaluated with 18 materials provided by WEPAL within the BIMEP program. Apart from monitoring the individual z-scores, their sequence was checked with summarizing parameters including the ‘rescaled sum z-scores’, RSZ, the ‘sum squared z-scores’, SSZ, and J-scores. For none of the analytes, the parameters indicated a trend over time and therefore it was not necessary to trigger any investigation or correcting procedure.