Tania Mascarenhas Tavares

Urban air pollution in Brazil: acetaldehyde and other carbonyls

We have measured ambient levels of carbonyls in three major urban areas of Brazil: Sao Paulo, Rio de Janeiro and Salvador. The most abundant carbonyls were acetaldehyde (up to 63 μg m−3, or 35 ppb) followed by formaldehyde (up to 42 μg m−3, or 34 ppb), and acetone (up to 20 ppb). Levels of 10 other aliphatic and aromatic carbonyls were in the range 0–5 ppb. Total carbonyl concentrations were in the range 11–75 ppb. Indoor levels were also measured at several locations in Salvador. High levels of acetaldehyde, 430 μg m−3 or 240 ppb, were measured in a highway tunnel. Using carbonyl/CO concentration ratios, mobile source emissions of carbonyls are estimated for the Sao Paulo area. Ambient levels of acetaldehyde and acetaldehyde/formaldehyde concentration ratios in Brazil are compared to those for other urban areas, and are briefly discussed in relation with the large scale use of ethanol as a vehicle fuel.

Atmospheric volatile organic compounds (VOC) at a remote tropical forest site in central Amazonia

According to recent assessments, tropical woodlands contribute about half of all global natural non-methane volatile organic compound (VOC) emissions. Large uncertainties exist especially about fluxes of compounds other than isoprene and monoterpenes. During the Large-Scale Biosphere/Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment 1998 (LBA-CLAIRE-98) campaign, we measured the atmospheric mixing ratios of different species of VOC at a ground station at Balbina, Amazonia. The station was located 100 km north of Manaus, SE of the Balbina reservoir, with 200-1000 km of pristine forest in the prevailing wind directions. Sampling methods included DNPH-coated cartridges for carbonyls and cartridges filled with graphitic carbons of different surface characteristics for other VOCs. The most prominent VOC species present in air were formaldehyde and isoprene, each up to several ppb. Concentrations of methylvinyl ketone as well as methacroleine, both oxidation products of isoprene, were relatively low, indicating a very low oxidation capacity in the lower atmospheric boundary layer, which is in agreement with a daily ozone maximum of <20 ppb. Total monoterpene concentration was below 1 ppb. We detected only very low amounts of VOC species, such as benzene, deriving exclusively from anthropogenic sources.

Exchange of short‐chain monocarboxylic acids by vegetation at a remote tropical forest site in Amazonia

[1] As part of the project LBA-EUSTACH (European Studies on Trace gases and Atmospheric Chemistry as a contribution to the Large-Scale Biosphere-Atmosphere experiment in Amazonia), the exchange of formic acid and acetic acid between vegetation and the atmosphere was investigated in the wet-to-dry season transition and the dry-to-wet season transition periods in 1999 in Rondonia, Brazil. Direct exchange measurements on the branch level mainly exhibited uptake of formic acid and acetic acid for all plant species in both seasons, although diel, seasonal, and interspecies variations were observed. Even though other physiological and physico-chemical parameters may have contributed, the uptake of organic acids was found to be primarily a function of the ambient atmospheric mixing ratios. The linear dependence suggests a bidirectional exchange behavior of the plants and calculated deposition velocities (0.17-0.23 cm s -1 ), compensation point mixing ratios (0.16-0.30 ppb), and potential emission rates under purified air conditions (0.013-0.031 nmol m -2 s -1 ) are discussed. Vertical profile measurements in and above the primary forest canopy further strengthened the assumption that the forest is rather a sink than a source for organic acids. The generally lower mixing ratios observed within the canopy were indicative of an uptake by vegetation and/or the soil surface. Continuous measurements of the ambient atmospheric mixing ratios at the canopy top revealed strong diel variations in both seasons and a marked seasonality with higher mixing ratios during the dry season, both being mirrored in the variation of observed uptake rates of the plants. High atmospheric concentrations during the dry season were attributed to biomass burning. During the wet season, when biomass burning activity was low, indirect emission by the vegetation, i.e., photochemical oxidation of primarily emitted biogenic reactive hydrocarbons, was assumed to dominantly contribute to the atmospheric burden of the organic acids. The high degree of correlation between atmospheric formic acid and acetic acid indicated that similar atmospheric processes were affecting their mixing ratios.

Chumbo no sangue de crianças e passivo ambiental de uma fundição de chumbo no Brasil

OBJETIVO: Determinar os niveis de chumbo no sangue de criancas que moravam proximo a uma fundicao de chumbo desativada na Cidade de Santo Amaro da Purificacao, Estado da Bahia, em setembro de 1998; e identificar fatores associados a variacao destes niveis. METODOS: Estudo de corte transversal com criancas de 1 a 4 anos de idade que residiam a menos de 1 km da fundicao. Maes ou responsaveis por 47 criancas responderam questionarios sobre transtornos do habito alimentar (comer barro, terra, reboco ou outros materiais) e outros aspectos epidemiologicos relevantes. A concentracao de chumbo no sangue foi determinada por espectrofotometria de absorcao atomica. RESULTADOS: O nivel medio de chumbo foi de 17,1 ± 7,3 mig/dL. Os niveis de chumbo no sangue foram cerca de 5 mig/dL mais elevados em criancas que tinham transtorno do habito alimentar, independentemente da idade, presenca de escoria visivel no peridomicilio, situacao de emprego do pai, historia familiar de intoxicacao pelo chumbo e desnutricao. CONCLUSOES: O passivo ambiental da fundicao de chumbo, desativada em 1993, permanece como um fator de risco relevante para elevar os niveis desse metal no sangue de criancas, particularmente aquelas que apresentam transtornos do habito alimentar.

EXCHANGE OF SHORT-CHAIN ALDEHYDES BETWEEN AMAZONIAN VEGETATION AND THE ATMOSPHERE

As a part of the LBA-EUSTACH (EUropean Studies on Trace Gases and Atmospheric CHemistry as a contribution of the Large-scale Biosphere-Atmosphere ex- periment in Amazonia) project, the exchanges of formaldehyde (HCHO) and acetaldehyde (CH3CHO) between Amazonian vegetation and the atmosphere were investigated by branch enclosures and compared with gradient measurements during the wet-to-dry transition and dry-to-wet-transition periods at a remote forest site in Brazil, 1999. Branch enclosure measurements of several tree species showed emission as well as deposition of short-chain aldehydes, but fluxes were clearly dominated by deposition during both seasons. This bidirectional exchange was found to depend mainly on the actual ambient concentrations of these compounds and to exhibit a compensation point below 0.6 ppb of the compound in air with deposition velocities between 0.16 and 0.21 cm/s during the wet-to-dry season. During the dry-to-wet season, the deposition velocities and the compensation point in- creased. Under the clean air conditions of the wet-to-dry season, the major pathway for the aldehyde uptake was via leaf stomata. For HCHO, a mesophyll resistance of the same order of magnitude as the stomatal resistance contributed to the total leaf surface resistance, whereas the mesophyll resistance for CH3CHO was small, allowing a rapid uptake. This finding indicates a major contribution of metabolic consumption processes in addition to physical and chemical processes to the overall resistance. During the dry-to-wet period, when ambient air concentrations substantially increased, we found indications for an ad- ditional deposition to the leaf cuticle. Vertical gradient measurements of ambient air con- centrations in and above the canopy closely agreed with the branch enclosure studies and confirmed that the forest acts rather as a sink than as a direct source for HCHO and CH3CHO. Diel courses of ambient air concentrations and ratios of HCHO and CH3CHO above the canopy suggest photochemical oxidation of biogenically or pyrogenically emitted precursor compounds as the major sources for short-chain aldehydes in the tropical atmosphere.

Repeated surveillance of lead poisoning among children

In 1980, a survey of lead poisoning was carried out among 592 children aged 1 to 9 years living within 900 m of a lead smelter in Santo Amaro, Brazil. From 1980 to 1985, the lead smelter carried out a number of major improvements aimed at reducing environmental pollution. In January, 1985, a second survey was carried out among a sample of 250 children living in this same geographical area. The geometric mean of zinc protoporphyrin (ZPP) concentration in whole blood was 1.17 (standard deviation = 1.5) mumol l-1. Blood lead concentrations (PbB) determined in a subsample of 53 children had an arithmetic mean and standard deviation of 1.77 +/- 1.00 mumol l-1, with 22 children showing PbB greater than or equal to 1.68 mumol l-1. Twenty-nine (11.6%) of the 250 children lived in houses where the lead content of the soil was greater than 10,000 ppm, and they presented higher ZPP levels than the rest of the population. Children with the habit of pica for soil had elevated ZPP levels. Comparing the results from the 1980 and 1985 surveys, slight improvements in ZPP and PbB levels were observed. However, new cases of lead poisoning are still occurring in the area. The soil is highly contaminated by lead and represents a long-lasting risk factor for child intoxication.

Methodology for the determination of gaseous hydrogen peroxide in ambient air

ZusammenfassungEin Verfahren zur Bestimmung von gasförmigem Wasserstoffperoxid in Umgebungsluft wird beschrieben. Die vorgeschlagene Verwendung eines Kryo-Sammlers (−45 °C) stellt insofern eine Verbesserung gegenüber der bisher üblichen Waschflaschen-Probenahme dar, als damit die bei Absorption in flüssiger Phase beobachteten Artefakte — Bildung und auch Zersetzung von Wasserstoffperoxid — deutlich vermindert werden. Feldmessungen, die zwischen Oktober 1984 und Juli 1985 auf dem Gelände der Universität Dortmund durchgeführt wurden, ergaben mittlere H2O2-Gasphasenkonzentrationen um 30 pptv. Darüber hinaus werden die Ergebnisse erster Versuche mit beschichteten Diffusionsabscheidern als Sammler für gasförmiges Wasserstoffperoxid vorgestellt.SummaryA method for the determination of gaseous hydrogen peroxide in ambient air is described. The cryogenic sampling technique (−45 ° C) employed represents an improvement compared with the impinger technique by diminishing artifacts which are bound to liquid phase production and decomposition, respectively. Results are given of H2O2 measurements from October 1984 to July 1985 in Dortmund (FRG), with mean concentrations of about 30 ppt (v/v). Preliminary results obtained with a coated denuder as a sampling device are also presented.

Cadmium concentrations in blood of children living near a lead smelter in Bahia, Brazil.

A prevalence study of cadmium absorption was carried out among 396 children aged 1 to 9 years living at less than 900 m from a primary lead smelter in Santo Amaro City, northeast Brazil. Geometric mean and geometric standard deviation of cadmium concentrations in blood (CdB) were 0.087 and 2.5 mumole/liter, respectively, ranging from 0.004 to 0.511 units. Ninety-six per cent of these children presented CdB higher than 0.0089 mumole/liter (or 1.0 microgram/liter) which is usually taken as a reference level. Higher CdB levels were significantly associated with shorter distance from childs home to smelter chimney, residence time in the area greater than 7 months, racial groups Light and Medium, and heavy infection by hookworm. The variation in CdB levels was not associated with childs age, nutritional status, iron status, family per capita income, blood lead level, being a child of a lead worker, the habit of pica, and contamination of childs peridomiciliar environment by smelter dross.

Lead and Cadmium Concentrations in the Hair of Fishermen from the Subae River Basin, Brazil

Previous studies have shown heavy pollution by lead and cadmium in the Subae River basin, State of Bahia, Brazil, caused by a lead smelter. Concentrations of these metals were determined in scalp hair of fishermen from three riverside towns and from a reference town. Increased levels for both metals were associated with increasing proximity to the smelter. Mean concentrations of lead and cadmium were higher among fishermen with straight hair than among those with curly hair. The effects of hair washing, hair type, and color and age on metal concentrations in fishermens hair were studied.

Multiple causes of anaemia amongst children living near a lead smelter in Brazil

A prevalence study of anaemia was carried out amongst children, aged one to nine years, living near a lead smelter in Santo Amaro City, Northeast Brazil. It was found that the variation in haemoglobin levels was significantly associated with malnutrition and with the interaction between malnutrition and iron deficiency, but not with lead poisoning, iron deficiency, or hookworm infection, having allowed for the effects of age, area of residence, family per capita income and race. The effect of the interaction between malnutrition and iron deficiency on haemoglobin levels was most prominent amongst children aged one year and amongst those living in the most deprived area. The lack of demonstrable interaction between lead poisoning and iron deficiency in the causation of anaemia amongst these children is discussed.