Organic speciation of atmospheric particles in Alvão Natural Park (Portugal)

PM₁₀ continental rural background aerosols were collected during a summer field campaign (August–September 2006) at Lamas de Ôlo in the upper zone of the Alvão Natural Park, a mountain region of northern Portugal. In addition to the determination of the carbonaceous content by a thermal–optical method, the organic speciation of aerosols was performed by gas chromatography–mass spectrometry in an effort to evaluate photo-oxidation products of biogenic volatile organic compounds and other markers for source characterization. The detailed analysis revealed relatively high concentrations of polyols and short-chain dicarboxylic, tricarboxylic, hydroxycarboxylic, and oxocarboxylic acids, many of which are thought to be indicators of secondary aerosol formation, accounting for about 70% of global chromatographically resolved mass. Major photo-oxidation products of α- and β-pinene have been detected. The tracers for the photo-oxidation of isoprene comprise two diastereoisomeric 2-methyltetrols, C₅-alkene triols, and 2-methylglyceric acid, which have only recently been elucidated. In addition, the occurrence of levoglucosan and other biomass combustion tracers indicates that the site was affected by wildfires. This source contributed to more than 80% of the organic carbon mass during a period of strong forest fire influence.     

Risk of boron and heavy metal pollution from agro-industrial wastes applied for plant nutrition

In this study, the effects of various agro-industrial wastes were investigated when applied to soil alone or in combination with chemical fertilizers, regarding the risks of boron and heavy metal pollution of soils and plants. Nine combinations of production residues from various agro-industries, urban wastes, and mineral fertilizers were applied to potatoes in a field experiment. The content of available boron in the soil differed significantly (p < 0.05) among the applications. Generally, B values were found to be slightly higher when soapstock, prina, and blood were used alone or in combination. Although total Co, Cd, and Pb contents of soils showed no significant differences between the applications, Cr content differed significantly (p < 0.05). No pollution risk was observed in soil in respect to total Co, Cd, Pb, and Cr contents. The amount of boron and heavy metals in leaves showed no significant differences among the applications. Cobalt, Cd, and Pb in leaves were at normal levels whereas Cr was slightly above normal but well under the critical level. Boron was low in tubers and varied significantly between applications such as Co and Cd. The Co content of tubers was high, Cd and Cr contents were below average, and Pb content was between the given values. Some significant correlations were found between soil characteristics and the boron and heavy metal content of soil, leaves, and tubers.     

Modeling 4-Chlorophenol Removal from Aqueous Solutions by Granular Activated Carbon

Since phenols and phenolic compounds in many industrial wastewaters are toxic organic contaminants for humans and aquatic life, to remove these compounds via the most efficient way is very important for environmental remediation treatment. In this context, almost all of the isotherm models (Freundlich, Langmuir, Temkin, Redlich–Peterson, Sips, and Khan) for adsorption in the literature were applied to explain the adsorption mechanism of 4-chlorophenol on activated carbon in this study. Also theoretical modeling data were obtained using model equations; interpolation and analysis of variance were made to compare data by using statistics software. In addition, the thermodynamic and kinetic studies for adsorption mechanism were included in the article. The adsorption of 4-chlorophenol on activated carbon fits well to the pseudo-first-order kinetic model than the pseudo-second-order, intraparticular diffusion and Bangham models. It is also indicated that 4-chlorophenol adsorption by granular activated carbon would be attributed to a type of transition between physical and chemical adsorption rather than a pure physical or chemical adsorption process. As a result, an environmental remediation problem and the adsorption mechanism on activated carbon that can be regarded as a solution to this problem are described and explained using the mathematical models and calculations in this study.     

Assessing the impact of chloroacetanilide herbicides and their metabolites on periphyton in the Leyre River (SW France) via short term growth inhibition tests on autochthonous diatoms

The Leyre River is the main tributary to the Bassin d'Arcachon lagoon. Herbicides belonging to the chloroacetanilide class have been found in the river (S-metolachlor and acetochlor) as well as some of their metabolites at higher concentrations. As the environmental toxicity of these molecules is not well known, ecotoxicological tests have been carried out on river periphyton at different levels of biological diversity: from the clone of one diatom species (Nitzschia nana) to the population of the same species (several clones) up to the multi-specific species community dominated by diatoms. Moreover, tests were performed on diatoms coming from an unpolluted upstream site and from a contaminated downstream site, in order to investigate possible tolerance acquisition to pollutants. The method consisted in measuring diatom growth inhibition at different doses of each substance from the increase of chlorophyll-a concentration after 4 days. It resulted that acetochlor was clearly more toxic than S-metolachlor at all levels of biological diversity. EC(50) values estimated from the tests suggest no effect of contaminants on diatom growth or biomass in the river. The toxicity of the metabolites appeared very low compared to that of their parent compounds. No difference in tolerance to the herbicides was demonstrated between summer diatom communities from the two sites in spite of different specific compositions. However, concerning the populations of N. nana isolated in winter following the highest herbicide concentrations in the river (about 0.5 μg L(-1)), the downstream population showed a higher tolerance to acetochlor but there was no co-tolerance to S-metolachlor. Thus, it appeared that acetochlor represents the highest toxic pressure on periphyton among the other contaminants in the Leyre River.     

Statistical modeling of crystalline silica exposure by trade in the construction industry using a database compiled from the literature

A quantitative determinants-of-exposure analysis of respirable crystalline silica (RCS) levels in the construction industry was performed using a database compiled from an extensive literature review. Statistical models were developed to predict work-shift exposure levels by trade. Monte Carlo simulation was used to recreate exposures derived from summarized measurements which were combined with single measurements for analysis. Modeling was performed using Tobit models within a multimodel inference framework, with year, sampling duration, type of environment, project purpose, project type, sampling strategy and use of exposure controls as potential predictors. 1346 RCS measurements were included in the analysis, of which 318 were non-detects and 228 were simulated from summary statistics. The model containing all the variables explained 22% of total variability. Apart from trade, sampling duration, year and strategy were the most influential predictors of RCS levels. The use of exposure controls was associated with an average decrease of 19% in exposure levels compared to none, and increased concentrations were found for industrial, demolition and renovation projects. Predicted geometric means for year 1999 were the highest for drilling rig operators (0.238 mg m(-3)) and tunnel construction workers (0.224 mg m(-3)), while the estimated exceedance fraction of the ACGIH TLV by trade ranged from 47% to 91%. The predicted geometric means in this study indicated important overexposure compared to the TLV. However, the low proportion of variability explained by the models suggests that the construction trade is only a moderate predictor of work-shift exposure levels. The impact of the different tasks performed during a work shift should also be assessed to provide better management and control of RCS exposure levels on construction sites.     

Soil and vegetation carbon stocks in Brazilian Western Amazonia: relationships and ecological implications for natural landscapes

The relationships between soils attributes, soil carbon stocks and vegetation carbon stocks are poorly know in Amazonia, even at regional scale. In this paper, we used the large and reliable soil database from Western Amazonia obtained from the RADAMBRASIL project and recent estimates of vegetation biomass to investigate some environmental relationships, quantifying C stocks of intact ecosystem in Western Amazonia. The results allowed separating the western Amazonia into 6 sectors, called pedo-zones: Roraima, Rio Negro Basin, Tertiary Plateaux of the Amazon, Javari-Juruá-Purus lowland, Acre Basin and Rondonia uplands. The highest C stock for the whole soil is observed in the Acre and in the Rio Negro sectors. In the former, this is due to the high nutrient status and high clay activity, whereas in the latter, it is attributed to a downward carbon movement attributed to widespread podzolization and arenization, forming spodic horizons. The youthful nature of shallow soils of the Javari-Juruá-Purus lowlands, associated with high Al, results in a high phytomass C/soil C ratio. A similar trend was observed for the shallow soils from the Roraima and Rondonia highlands. A consistent east–west decline in biomass carbon in the Rio Negro Basin sector is associated with increasing rainfall and higher sand amounts. It is related to lesser C protection and greater C loss of sandy soils, subjected to active chemical leaching and widespread podzolization. Also, these soils possess lower cation exchangeable capacity and lower water retention capacity. Zones where deeply weathered Latosols dominate have a overall pattern of high C sequestration, and greater than the shallower soils from the upper Amazon, west of Madeira and Negro rivers. This was attributed to deeper incorporation of carbon in these clayey and highly pedo-bioturbated soils. The results highlight the urgent need for refining soil data at an appropriate scale for C stocks calculations purposes in Amazonia. There is a risk of misinterpreting C stocks in Amazonia when such great pedological variability is not taken into account.     

Comparison of ALAD activities of Citrobacter and Pseudomonas strains and their usage as biomarker for Pb contamination

Delta-aminolevulinate dehydratase (ALAD) activity has been used in prokaryotes and eukaryotes as a biomarker for environmental lead (Pb) exposure and toxicity. Microorganisms are sensitive indicators of toxicity at the fundamental level of ecological organization, but bacterial biomarker studies are focused on the Pseudomonas strains in Group I and E coli. The objectives of the present work were to determine if Burkholderia gladioli belonging to group II, due to its 16SrRNA similarity, can be used as biomarker in metal contamination and compare its possible usage with Pseudomonas aeruginosa and Citrobacter freundii (previously known as Esherichia freundii) and Bacterium freundii which are classified in Group I. In this study, ALAD activity in an environmental strains of Burkholderia gladioli, Pseudomonas aeruginosa, Citrobacter freundii were investigated to evaluate potential inhibition by Pb and other toxic metals. When the ALAD activity of Burkholderia gladioli was tested, Co and Pb decreased activity by 27 and 71%, respectively. In addition to these findings, Zn increased the activity up to 26%. These effects were found to be statistically meaningful (p < 0.05). It was determined that the increase of lead concentration inhibites the ALAD activity at each of the three strains. There was a statistically significant dose–response relationship between ALAD activity in cells of Burkholderia gladioli and Pb (Pearson correlation coefficent = −0.665; r ² = 0.665, and p < 0.001). The strongest ALAD inhibition which was measured was 90% at Burkholderia gladioli when protein extracts were incubated with 750 μM of Pb. The relationship between Pb and ALAD activity was statistically described by [ALAD Activity] = 0.476−0.000597 × [Pb]. According to the obtained results, we suggest that the ALAD of Burkholderia gladioli can be used as a biomarker for lead contamination in the environment.     

Environmental assessment of trace element bioaccumulation in sipunculan from seagrass and wetland sediments

This study is the first measurement of trace elements in sipunculan and their surrounding sediments. The bioaccumulation characteristics of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), and zinc (Zn) were analyzed and compared in two sipunculan species, Sipuncula nudus and Siphonosoma vastum, which were collected from seagrass beds and wetlands in Taiwan. The sipunculan and sediment samples were analyzed using an inductively coupled plasma mass spectrometer. Both sipunculan in the wetlands and seagrass beds had a high Cu bioaccumulation mechanism. Multivariate analysis, principle component analysis, and partial least squares for discriminant analysis of trace element levels and bioaccumulation factors were used to distinguish the element distributions that corresponded to the two habitats (seagrass beds and wetlands). Different levels of certain trace elements in these two sipunculan species may result not only from the environmental factors of various habitats but also from the accumulation characteristics of various species. The As, Cd, Cr, Cu, Hg, and Zn concentrations were markedly lower in sipunculan than in other invertebrates from the adjacent polluted regions. The public health issues regarding the consumption of sipunculan are also discussed.     

Changes in the trade in native medicinal plants in Brazilian public markets

Plants continue to be an important source of new bioactive substances. Brazil is one of the world’s mega-diverse countries, with 20 % of the world’s flora. However, the accelerated destruction of botanically rich ecosystems has contributed to a gradual loss of native medicinal species. In previous study, we have observed a fast and intensive change in trade of medicinal plants in an area of Amazon, where human occupation took place. In this study, we surveyed 15 public markets in different parts of Brazil in search of samples of 40 plants used in traditional medicine and present in first edition of Brazilian Official Pharmacopoeia (FBRAS), published in 1926. Samples of plants commercialized as the same vernacular name as in Pharmacopoeia were acquired and submitted to analysis for authentication. A total of 252 plant samples were purchased, but the laboratory analyses showed that only one-half of the samples (126, 50.2 %) were confirmed as the same plant species so named in FBRAS. The high number of unauthenticated samples demonstrates a loss of knowledge of the original native species. The proximity of the market from areas in which the plant occurs does not guarantee that trade of false samples occurs. The impact of the commerce of the substitute species on their conservation and in public health is worrying. Strategies are necessary to promote the better use and conservation of this rich heritage offered by Brazilian biodiversity.