Discoloration and fungal growth on three fiber cement formulations exposed in urban,rural and coastal zones

Three formulations of fiber cement were evaluated for fungal colonization and color change after five years of exposure in aging stations located in urban (São Paulo), rural (Pirassununga) and coastal (Rio Grande) zones in Brazil. The lowest color change and fungal colonization were registered in Rio Grande, which has a temperate climate, as opposed to São Paulo and Pirassununga, which are tropical. The highest fungal colonization was recorded in São Paulo, one of the most air polluted cities in Brazil. Pirassununga samples had an intermediate fungal colonization, in spite of showing the highest color change with visible dark spots on the surfaces. These spots were identified as cyanobacteria, which significantly contributed to the darkening of the specimens. The fiber cement formulation, varying in proportion of organic fibers such as poly (vinyl alcohol) and cellulose, was less significant for fungal bioreceptivity than the characteristics of the exposure site. The most frequent fungal genus found in the tropical climate, in both urban and rural zones, and the main one responsible for the higher records in São Paulo, was Scytalidium sp. which was registered for the first time on this building material in Brazil.     

Situating Fortaleza: Urban space and uneven development in northeastern Brazil

The academic literature on Brazilian cities focuses overwhelmingly upon the metropolises of Rio de Janeiro and São Paulo. While fruitful in its own right, this research confronts scholars of Latin American cities elsewhere with two ongoing limitations: (1) Despite estimates that nearly one quarter of Brazil’s urban population inhabits the conurbation of Rio and São Paulo, at least 75% of urban space in Brazil, an area populated by roughly 120 million people, is consistently overlooked; and (2) the findings from these two megacities are often (and unfairly) extrapolated across other urban contexts in Brazil, perpetuating lingering misgivings about the overall ‘nature’ of Brazilian cities.In this paper, I consider the Northeast of Brazil, drawing upon my own research from the favela (slum) community of Pirambu, located in the city of Fortaleza, to help understand urban development outside of the Rio/São Paulo corridor. By considering historical circumstances, geographic specificity, theoretical implications, and the course of Brazilian development, I highlight informal urban growth in an oft-overlooked region of Latin America while, at the same time, revealing many of the geographic attributes that give Rio and São Paulo their truly exceptional character. My goal in this work is not to refute the work of others, but rather to underscore the importance of geographic context to socio-spatial processes of urban development.     

The Rio/São Paulo Extended Metropolitan Region: A quest for global integration

This paper explores whether the Rio/São Paulo Extended Metropolitan Region, an area with 36 million and accounting for one-third of Brazil's GNP, can successfully integrate into the global economy. Analysis of private investment projects in different sub-regions over the period 1995–2002 suggests that most of the investments are in high-tech or average technology rather than in low technology projects. Decentralization into the Paraiba Valley appears to be taking place rapidly. However, in the region as a whole, severe imbalances between the Rio and the São Paulo remain, and these are an obstacle to the region's attempt to climb up the global urban hierarchy rankings.     

Lead in saliva from lead-exposed and unexposed children

Introduction

Whole blood is used for diagnosis of lead exposure. A non-invasive method to obtain samples for the biomonitoring of lead contamination has become a necessity. This study 1) compares the lead content in whole saliva samples (Pb-saliva) of children from a city with no reported lead contamination (Ribeirão Preto, São Paulo State, Brazil) and children of a region notoriously contaminated with lead (Bauru, São Paulo State, Brazil), and 2) correlates Pb-saliva with the lead content in the enamel microbiopsy samples (Pb-enamel) in the case of these two populations.

Methods

From a population of our previous study that had included 247 children (4- to 6-year-old) from Ribeirão Preto, and 26 children from Bauru, Pb-saliva was analyzed in 125 children from Ribeirão Preto and 19 children from Bauru by inductively coupled plasma mass spectrometry (ICPMS). To correlate Pb-saliva with Pb-enamel, we used Pb-enamel data obtained in our previous study. The Mann-Whitney test was employed to compare the Pb-saliva data of the two cities. Pb-saliva and Pb-enamel values were then Log₁₀ transformed to normalize data, and Pb-saliva and Pb-enamel were correlated using Pearson's correlation coefficient.

Results

Median Pb-saliva from the Ribeirão Preto population (1.64 μg/L) and the Bauru population (5.85 μg/L) were statistically different (p < 0.0001). Pearson's correlation coefficient for Log₁₀ Pb-saliva versus Log₁₀ Pb-enamel was 0.15 (p = 0.08) for Ribeirão Preto and 0.38 (p = 0.11) for Bauru.

Conclusions

A clear relationship between Pb-saliva and environmental contamination by lead is shown. Further studies on Pb-saliva should be undertaken to elucidate the usefulness of saliva as a biomarker of lead exposure, particularly in children.     

Ozone precursors for the São Paulo Metropolitan Area

Ozone represents the main atmospheric pollutant in the São Paulo Metropolitan Area (SPMA). In this region, its concentration exceeds the national air quality standards for several days out of the year. Ozone is a secondary pollutant and is a product of VOCs, NO_x, and sunlight. Thus, it is very difficult to elaborate efficient strategies for its reduction. Computational simulations may provide an interesting alternative to evaluate the many factors that affect ozone formation. In this study, the trajectory model OZIPR was used together with the SAPRC chemical mechanism to determine the incremental reactivity scale for VOCs in the SPMA. VOC input data were obtained from two campaigns that were performed in the studied area in 2006. Values for CO, NO_x, and meteorological parameters were obtained by automatic monitors. Five base-cases were created to verify the variation in maximum ozone concentration and thus determine the ozone formation potential of each VOC. NO_x and VOC emissions were independently and simultaneously reduced by 5, 10, 20, and 30% to verify variations in ozone formation. With the simulator output data, ozone isopleths charts were generated for the city of São Paulo. Analysis of the obtained results shows that the most frequent compounds found among the ten main ozone precursors in São Paulo, using the reactivity scales created from the five base-cases, were: formaldehyde, acetaldehyde, propene, isoprene, cis-2-butene, and trans-2-butene, with formaldehyde being always the main ozone precursor compound. The simulations also show that an efficient strategy to decrease ozone concentrations in the SPMA would be to reduce total VOC emissions. The same strategy is not possible for NO_x, as the reduction of these pollutants would increase ozone concentrations.     

Seasonal variation, sources and gas/particle partitioning of polycyclic aromatic hydrocarbons in Guangzhou, China

Air samples were collected weekly at an urban site and a suburban site in Guangzhou City, China, from April 2005 to March 2006, to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the ambient air and study their seasonal variations, gas/particle partitioning, origins and sources. The concentrations of ∑ 16-PAHs (particle + gas) were 129.9 ± 73.1 ng m⁻³ at the urban site and 120.4 ± 48.5 ng m⁻³ at the suburban site, respectively. It was found that there was no significant difference in PAH concentrations between the urban and suburban sites. Seasonal variations of PAH concentrations at the two sampling sites were similar, with higher levels in the winter that gradually decreased to the lowest levels in the summer. The average concentrations of ∑ 16-PAHs in the winter samples were approximately three times higher than those of the summer samples because in the summer local emissions dominated, and in the winter the contribution from outside sources or transported PAHs is increased. The plot of logK_p versus logP_L⁰ for the data sets of summer and winter season samples had significantly different slopes at both sampling sites. The slopes for the winter samples were steeper than those for the summer samples. It was also observed that gas/particle partitioning of PAHs showed different characteristics depending on air parcel trajectories. Steeper slopes were obtained for an air parcel that traveled across the continent to the sampling site from the northern or northeastern sector, whereas shallower slopes were obtained for air masses that traveled across the sea from the southern or eastern sector. Diagnostic ratio analytical results imply that the origins of PAHs were mainly from petroleum combustion and coal/biomass burning. The anthracene/phenanthrene and benzo[a]anthracene/chrysene ratios in the winter were significantly lower than those in the summer, which indicate that there might be long-range transported PAH input to Guangzhou in the winter.     

Extractable organic matter in PM10 from LiWan district of Guangzhou City,PR China

PM10 (particulate matter with aerodynamic diameter <10 microm) samples were collected at LiWan District of Guangzhou, PR China during April and July 2001 using a high volume air sampler to determine the distributions of homologous compounds and biomarkers. Polycyclic aromatic hydrocarbons (PAHs) including non-alkylated PAHs, methyl-alkylated PAHs, and some PAHs containing S/O atoms and n-alkanes were measured using gas chromatography/mass spectrometry analysis. The sigma(n)-alkane and sigmaPAHs ranged from 26.4 to 719.2 ng/m3 and 7.4 to 159.4 ng/m3, respectively. A seasonal fluctuation was clearly evident with higher concentrations occurring during the colder months (April). In addition, some compositional differences are observed for the organic compounds in samples collected from different heights above ground level. Higher sites had a significant contribution from vascular plant wax. The presence of petroleum products with no carbon number preference, pristane, phytane and a significant unresolved complex mixture (UCM) with unresolved to resolved components ratio (U/R) of 6.2-13.2 confirm the petroleum component. The relative distribution of n-alkanes and the values of molecular diagnostic ratio, such as carbon preference index (CPI) values ranging from 1.0 to 1.4 (for the whole range of n-alkanes), indicated the importance of petroleum and diesel residues and gasoline emissions, as well as the minor contribution of n-alkanes emitted directly from epicuticular waxes. Indeed, the percent contribution of leaf 'wax' n-alkanes (5.2-19.4%) indicated a low contribution of biogenic sources. The fossil fuel biomarkers, hopanes and steranes were observed in the PM10 samples, which indicate a petroleum origin. The distribution pattern of PAHs was characteristic of anthropogenic emissions. Coupling carbon number maximum (Cmax), CPI, U/R values, molecular marker and molecular diagnostic ratios for alkanes and PAHs revealed a classification of natural biogenic and anthropogenic components of atmospheric aerosols. These analyses support the conclusion that vehicular emission was the major source of organic compounds during the study period, while the contribution of epicuticular waxes emitted by terrestrial plants was minor.     

Modeling study of the aspect ratio influence on urban canopy energy fluxes with a modified wall-canyon energy budget scheme

The influence of the aspect ratio (building height/street canyon width) and the mean building height of cities on local energy fluxes and temperatures is studied by means of an Urban Canopy Model (UCM) coupled with a one-dimensional second-order turbulence closure model. The UCM presented is similar to the Town Energy Balance (TEB) model in most of its features but differs in a few important aspects. In particular, the street canyon walls are treated separately which leads to a different budget of radiation within the street canyon walls. The UCM has been calibrated using observations of incoming global and diffuse solar radiation, incoming long-wave radiation and air temperature at a site in São Paulo, Brazil. Sensitivity studies with various aspect ratios have been performed to assess their impact on urban temperatures and energy fluxes at the top of the canopy layer. In these simulations, it is assumed that the anthropogenic heat flux and latent heat fluxes are negligible. Results show that the simulated net radiation and sensible heat fluxes at the top of the canopy decrease and the stored heat increases as the aspect ratio increases. The simulated air temperature follows the behavior of the sensible heat flux.     

Emissions of soot,PAHs, ultrafine particles,NOx, and other health relevant compounds from stressed burning of candles in indoor air

Burning candles release a variety of pollutants to indoor air, some of which are of concern for human health. We studied emissions of particles and gases from the stressed burning of five types of pillar candles with different wax and wick compositions. The stressed burning was introduced by controlled fluctuating air velocities in a 21.6 m³ laboratory chamber. The aerosol physicochemical properties were measured both in well-mixed chamber air and directly above the candle flame with online and offline techniques. All candles showed different emission profiles over time with high repeatability among replicates. The particle mass emissions from stressed burning for all candle types were dominated by soot (black carbon; BC). The wax and wick composition strongly influenced emissions of BC, PM_2.5, and particle-phase polycyclic aromatic hydrocarbons (PAHs), and to lower degree ultrafine particles, inorganic and organic carbon fraction of PM, but did not influence NO_x, formaldehyde, and gas-phase PAHs. Measurements directly above the flame showed empirical evidence of short-lived strong emission peaks of soot particles. The results show the importance of including the entire burn time of candles in exposure assessments, as their emissions can vary strongly over time. Preventing stressed burning of candles can reduce exposure to pollutants in indoor air.     

Effects of genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 on urinary 1-hydroxypyrene levels in sugarcane workers

Sugarcane workers in Brazil are exposed to various genotoxic compounds, including polycyclic aromatic hydrocarbons (PAHs), derived from an incomplete combustion process of burnt sugarcane fields. The effects of the occupational exposure to sugarcane fields burning were measured in urine samples of sugarcane workers from the northwest of the State of S?o Paulo when exposed (harvesting) and when non-exposed (non-harvesting). The urinary levels of 1-hydroxypyrene (1-OHP) and the influence of the genetic polymorphisms CYP1A1, GSTM1, GSTT1 and GSTP1 were evaluated. Our results showed that the 1-OHP levels were significantly higher (P<0.0000) in the exposed sugarcane workers (0.318 mumol mol(-1) creatinine) than in the non-exposed workers (0.035 mumol mol(-1) creatinine). In an unvaried analysis, no influence regarding the polymorphisms was observed. However, multivariate regression analysis showed that the CYP1A1()4 polymorphism in the exposed group, and age and the GSTP1 polymorphism in the non-exposed group significantly influenced urinary 1-OHP excretion levels (P<0.10). The same group of sugarcane workers was significantly more exposed to PAHs during the harvesting period than during the non-harvesting period.     

An evaluation method for school building design at the preliminary phase with optimisation of aspects of environmental comfort for the school system of the State São Paulo in Brazil

This study presents a method for evaluating and optimising environmental comfort parameters of school buildings during the preliminary stages of design. In order to test the method, 39 existing public school building designs in the State of São Paulo, Brazil, had their plans analysed and characterised in relation to their influence on environmental comfort. Four aspects of comfort were considered: thermal, acoustic, natural lighting and functionality. Since the evaluation method is based on preliminary design information only, parameters that otherwise would be analysed quantitatively had to be assessed by interviews with specialists using a qualitative five-point semantic scale. For each aspect of comfort, possible design solutions were rated from 0 to 1, according to the fuzzy set theory. The final mean grades for each comfort stated the building's average performance. Although conflicts between different comfort parameters are apparent, results show that multi-criteria optimisation can be applied as a design tool during the creative process. Maximisation of various aspects of comfort simultaneously was shown to be impossible, but compromise solutions could be found.     

Characterization, identification of ambient air and road dust polycyclic aromatic hydrocarbons in central Taiwan, Taichung

The concentrations of ambient air polycyclic aromatic hydrocarbons (PAHs) were measured simultaneously in an industrial area (Taichung Industrial Park, TIP) and suburban area (Tunghai University, THU) in central Taiwan, Taichung. A total of samples were collected simultaneously at the two sites between August 2002 and March 2003. Particle-bound PAHs (p-PAHs) were collected on quartz filters and gas-phase PAHs (g-PAHs) on glass cartridges using polyurethane foam sampler, respectively. Both types of samples were extracted with dichloromethane/n-hexane mixture (50/50, v/v) for 24 h, then the extracts were subjected to gas chromatography/mass spectrometric analysis. Moreover, the roadside dust particle PAHs composition were also collected and analyzed at TIP, THU and traffic road sampling sites. The five main road lines in Taichung City were selected as traffic road sampling sites. Correlation studies between PAHs concentrations and meteorological parameters were revealed that temperature has greater effects (P>0.6) than other meteorological parameters such as wind speed, relative humidity and atmospheric pressure on g-PAHs and p-PAHs. PAHs sources were resolved by using principal component analysis and diagnostic ratios. The major sources of PAHs were combustion, traffic vehicle exhaust (diesel and gasoline engine), incinerator and industrial stationary sources at both sampling sites in central Taiwan.     

Suspended particulate variations and mass size distributions of incense burning at Tzu Yun Yen temple in Taiwan,Taichung

Concentrations of eight trace elements (As, Cd, Cu, Hg, Ni, Pb, Se and Zn), lindane and six groups of organic contaminants (total-chlordane, total-PCB, total-DDT, Dieldrin and Aldrin, total-butyltins, total-PAHs) at the 11 NOAA mussel watch project (MWP) sites located in North and South Carolina have been compared with the national US MWP data. Three sites from North and South Carolina had concentrations of PAHs in the upper 15th percentile on a national scale. One site had high concentrations of butyltins, and two sites had high Se concentrations. All sites from Beaufort, North Carolina, south had high As concentrations. Decreasing temporal trends were found for As, Cd, total-chlordane, DDT, PCB, and PAHs at some sites.     

Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin

An analysis of geomorphic system's response to change in human and natural drivers in some areas within the Río de la Plata basin is presented. The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers. Study areas of different size, socio-economic and geomorphic conditions have been selected: the Río de la Plata estuary and three sub-basins within its watershed. Sediment cores were extracted and dated (²¹⁰Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface. Data on river discharge were also gathered. Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the São Paulo metropolitan area. Rates in the estuary are somewhere in between. It appears that there is an intensification of denudation/sedimentation processes within the basin.Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes. It appears that a marked increase in denudation, of a “technological” nature, is taking place in this basin and leading to an acceleration of sediment supply. This is coherent with similar increases observed in other regions.     

Composition of particulate and dissolved organic matter in a disturbed watershed of southeast Brazil (Piracicaba River basin)

The elemental and isotopic composition of particulate and dissolved organic matter was investigated in the Piracicaba River basin, S?o Paulo State, Brazil. Comparison of riverine organic matter from the Piracicaba River basin, a region where rivers and streams receive urban sewage and industrial effluents, with data reported for the pristine Amazon system revealed significant differences associated with anthropogenic impacts. One important difference was N enrichment in the particulate organic material of the Piracicaba basin rivers, due to (a) urban and industrial effluents, and (b) enhanced phytoplankton growth, which results from the combination of nutrient enrichment and damming of sections of the rivers. Radiocarbon concentrations were overall more depleted (older 14C age) in the Piracicaba basin rivers than in the Amazon, which may reflect the importance of soil erosion in the former. Analyses of stable and radioactive carbon isotopes and lignin-derived compounds indicated that coarse particulate organic material is composed of a mixture of soil particles and degraded organic matter from C3 and C4 vascular plants. Fine particulate organic material was composed mainly of soil particles and phytoplankton cell remains, the latter especially during low water. Ultrafiltered dissolved organic matter was the most degraded fraction according to its lignin oxidation products, and showed the greatest influence of C4 plant sources.     

Size distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in aerosol particle samples from the atmospheric environment of Delhi, India

Ambient aerosol particles were collected using a five-stage impactor at six different sites in Delhi. The impactor segregates the TSPM into five different sizes (viz. > 10.9, 10.9-5.4, 5.4-1.6, 1.6-0.7, and < 0.7 μm). Samples collected were chemically analyzed for all the five size ranges, for the estimation of 16 different PAHs. The particle size distribution of PAHs was observed to be unimodal in nature with the highest peak towards the smallest size aerosol particle (< 0.7 μm). The five size ranges were categorized into two broad categories viz. coarse (> 10.9 + 10.9 to 5.4 + 5.4 to 1.6 μm) and fine (1.6 to 0.7 + < 0.7 μm). It was observed that the dominant PAHs found were pyrene, benzo(a)pyrene, benzo(ghi)perylene and benzo(b)fluoranthene for both the coarse and fine fractions. Source apportionment of polycyclic aromatic hydrocarbons (PAHs) has been carried out using principal component analysis method (PCA) in both coarse and fine size modes. The major sources identified in this study, responsible for the elevated concentration of PAHs in Delhi, are vehicular emission and coal combustion. Some contribution from biomass burning was also observed.     

Polycyclic aromatic hydrocarbons, nickel and vanadium in air particulate matter in Bahrain during the burning of oil fields in Kuwait.

Inhalable air particulate matter (APM) was collected in Bahrain from July 31, 1991 to August 4, 1991, during the burning of the oil fields in Kuwait. The filters collected were black and the levels of APM ranged from 139 to 673 micrograms m-3 with an average value of 199 micrograms m-3. APM were analysed for their contents of PAHs, Ni and V. Analysis was carried out for 32 PAHs and total PAHs ranged from 3.1 to 9.1 ng m-3 and averaged 5.3 ng m-3. The highest individual PAH levels were benzo[ghi]perylene, benzo[b]fluoranthene, benzo[a]pyrene and indeno[1,2,3-cd]pyrene. The concentration of Ni and V ranged from 7 to 42 and 11 to 42 ng m-3, with an average value of 22 and 26 ng m-3, respectively. A strong correlation was found between Ni and V (r = 0.98, P less than 0.01). The results show that the smoke from burning oil wells in Kuwait has contributed to the concentrations of particulate matter, PAHs, Ni and V in APM in Bahrain.     

Atmospheric concentrations and air-soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in remote, rural village and urban areas of Beijing-Tianjin region, North China

Forty passive air samplers were deployed to study the occurrence of gas and particulate phase PAHs in remote, rural village and urban areas of Beijing-Tianjin region, North China for four seasons (spring, summer, fall and winter) from 2007 to 2008. The influence of emissions on the spatial distribution pattern of air PAH concentrations was addressed. In addition, the air-soil gas exchange of PAHs was studied using fugacity calculations. The median gaseous and particulate phase PAH concentrations were 222 ng/m³ and 114 ng/m³, respectively, with a median total PAH concentration of 349 ng/m³. Higher PAH concentrations were measured in winter than in other seasons. Air PAH concentrations measured at the rural villages and urban sites in the northern mountain region were significantly lower than those measured at sites in the southern plain during all seasons. However, there was no significant difference in PAH concentrations between the rural villages and urban sites in the northern and southern areas. This urban-rural PAH distribution pattern was related to the location of PAH emission sources and the population distribution. The location of PAH emission sources explained 56%-77% of the spatial variation in ambient air PAH concentrations. The annual median air-soil gas exchange flux of PAHs was 42.2 ng/m²/day from soil to air. Among the 15 PAHs measured, acenaphthylene (ACY) and acenaphthene (ACE) contributed to more than half of the total exchange flux. Furthermore, the air-soil gas exchange fluxes of PAHs at the urban sites were higher than those at the remote and rural sites. In summer, more gaseous PAHs volatilized from soil to air because of higher temperatures and increased rainfall. However, in winter, more gaseous PAHs deposited from air to soil due to higher PAH emissions and lower temperatures. The soil TOC concentration had no significant influence on the air-soil gas exchange of PAHs.     

Nitrogen dioxide and household fuel use in the Pakistan

More than half the world's population use biomass fuels as a household energy source and, hence, face significant exposure to a number of air pollutants. In Pakistan about 90% of rural households and 22% of urban households use biomass fuels. In order to assess the levels of NO₂ in the residential micro-environment, two sampling campaigns were carried out at different times of the year (summer and winter) at an urban and two rural sites during 2005 and 2007. Rural site I used biomass fuels while natural gas was utilized at rural site II and the urban site. In winter NO₂ concentrations at all three sites were higher in the kitchens than living rooms and outdoors. ANOVA showed that, although, there was a significant difference among NO₂ concentrations in the kitchens, living rooms and courtyards, at all the three sites, there was no significant different between kitchens using biomass fuels and natural gas. During the summer NO₂ levels fell sharply at both rural sites (from 256 μg/m³ and 242 μg/m³ to 51 μg/m³ and 81 μg/m³). However at the urban site the mean levels were slightly higher in summer (234 μg/m³) than in winter (218 μg/m³). The considerable seasonal variation at the rural sites was due to a shift of indoor kitchens to open outdoor kitchens at rural site I and more ventilation at rural site II during summer. There was no significant difference between kitchens using biomass (site I) or natural gas (site II), however the kitchens at rural site II and urban site showed a significant difference. Overall fuel selection showed no significant effect on NO₂ levels. However the NO₂ concentrations may pose a significant threat to the health of people, especially women and children.     

Effects of initial climatic conditions on growth and accumulation of fluoride and nitrogen in leaves of two tropical tree species exposed to industrial air pollution

Saplings of Tibouchina pulchra and Psidium guajava, cultivated under standardized soil conditions, were placed in two sites at Cubat?o (state of S?o Paulo, southeast Brazil) to study the effects of air pollution on growth, biomass allocation and foliar nitrogen and fluoride concentrations. Thirty-six potted plants were maintained over two periods of one year (Jul/00 to Jun/01; Dec/00 to Nov/01) at each of two experimental sites with distinct levels of air pollution: Pil?es River Valley (PV) with vegetation virtually unaffected by air pollution; and Mogi River Valley (MV) severely affected by pollutants released mainly by chemical, fertilizer, iron and steel industries. For both species, saplings growing at MV showed alterations of growth and biomass allocation, as well as increased leaf concentrations of nitrogen and fluoride. Comparing both experimental periods, the one starting in winter (the driest season in Southeastern Brazil) seemed to affect the saplings more severely, the differences of the measured parameters between MV and PV being higher than in the second period. Multivariate analysis revealed two groups of data: one representing the MV and the other the PV saplings. For both species, saplings growing at MV showed differences in chemical composition, growth and biomass allocation, compared with the PV saplings. The results suggested that seasonal conditions of the first months of sapling exposure (summer or winter) modulate the intensity of responses to pollution stress.