Modification in the soil and traffic-related sources of particle matter between 1998 and 2007 in Santiago de Chile

Santiago de Chile is one of the most polluted South American cities, concentrating its pollution episodes during winter. Daily PM2.5 (particulate matter [PM] < or = 2.5 microm in aerodynamic diameter) concentrations over 80 microg/m3 have been reached frequently since 1998. Despite several regulations introduced over the past 20 yr to improve the air quality, PM concentration levels remain high. In this work, sampling in downtown Santiago was conducted from April 1998 to August 2007 for PM2.5 and from October 2003 to March 2006 for PM10-2.5 (PM between 2.5 and 10 microm in aerodynamic diameter) with dichotomous samplers. Elemental analysis was performed on the samples with X-ray fluorescence. The resuming series of 859 samples and 216 elements identified were divided into semiannual periods and analyzed with factor analysis. Five factors are clearly discerned: soil, motor vehicles, residual oil, marine aerosols, and secondary sulfates. The soil factor in the fine fraction shows a clear increase from 2002 to 2006, whereas the coarse fraction of this factor shows a stable trend. The most probable cause for this trend is the growth in the number of vehicles in Santiago (6.5%/yr), which increases the resuspension of particles from the ground. Another cause for the increase is the growth in the construction activity (4.2%/yr). The motor vehicle factor in the fine fraction shows a decrease between 1998 and 2006. The decrease in the apportionment of this factor can be explained by the improvement in the vehicle fleet. In Santiago, the number of noncatalytic vehicles has been reduced from 389,000 in 2001 to 275,000 in 2006. The residual oil factor also shows a decrease between 1998 and 2006. The decrease could be attributed to the adoption of cleaner technologies and norms regarding gasoline and diesels.     

Temporal dynamics and plasticity in the cellular immune response of the sea fan coral, Gorgonia ventalina

The temporal dynamics of the invertebrate immune response often determines an organism’s success in responding to physiological stress, physical damage, and pathogens. To date, most immune challenge studies have been conducted under highly controlled laboratory conditions, with few attempts to study immune function in the wild. In this study, we characterized the temporal dynamics of the Caribbean sea fan, Gorgonia ventalina, cellular immune response [granular amoebocyte aggregation and prophenoloxidase (PPO) activation] to allogenic grafts in the laboratory and field using a clonally replicated design. Amoebocyte reaction time differed markedly between the lab (% amoebocyte surface area in tissue sections peaked at 2 days) and field (peak at 6 days). PPO activity decreased between 0 and 6 days after grafting in both ungrafted and grafted tissue, suggesting PPO is decoupled from other cellular components. The reaction norms of the fold induction in % amoebocyte area between disease-grafted and healthy-grafted tissue of each colony across time indicate high intercolony plasticity in cellular immune response. The plasticity between colonies was also evident in the magnitude of cellular immune response, ranging from a 0.88- to 1.60-fold increase in amoebocyte area between initial and 6 days for the disease-grafted tissue. With the demonstration of highly dynamic cnidarian cellular immune responses, our study expands understanding of the evolutionary ecology of metazoan immune defense mechanisms.     

Interactions between diesel emissions and gaseous copollutants in photochemical air pollution: Some health implications

A complete assessment of the health effects of diesel emissions must take into account the possible chemical transformations (and associated biological impacts) of particulate organic matter (POM) due to reactions with the many gaseous copollutants which have now been unambiguously demonstrated to be present in atmospheres burdened by photochemical air pollution. These copollutants include the “trace” species, nitric (HNO₃) and nitrous (HONO) acids, the nitrate radical (NO₃), formaldehyde (H₂CO) and formic acid (HCOOH), as well as the criteria pollutants, ozone (O₃) and nitrogen dioxide (NO₂). Techniques for establishing the atmospheric concentrations of the trace pollutants (and their spatial and temporal variations) are briefly described, and we present results of investigations into the reactions of polycyclic aromatic hydrocarbons (PAH) coated on filters and exposed to ambient concentrations of O₃ and NO₂. Environmental health implications of these results are discussed and include the potential for sampling “artifacts” and their possible effects on the correlation (or lack thereof) between ambient PAH levels and urban lung cancer rates, as well as the problems associated with understanding the appropriate POM “dose” to be employed in animal testing and assessments of impacts on human health.     

Wastewater treatment with a double-layer submerged biological aerated filter,using waste materials as biofilm support

The aim of this research was to determine the performance of a submerged biological aerated filter, composed of a double-layer bed. This bed is made up of a top layer of ceramic material and a bottom layer of plastic material (both from previously used waste material). Effluent concentrations are presented related to the volumetric and hydraulic loads applied. The results were very satisfactory. If effluent concentrations of under 20 mg TBOD5/L and 25 mg SS/L are to be achieved, 4.87 kg TBOD5/m3/d and 3.0 kg SS/m3/d could be applied, respectively. For that maximum TBOD5 volumetric load that can be applied, a very reasonable consumption value of 1.0 kg O2/kg TBOD5, eliminated was obtained. The counter-current flow system outperformed the co-current flow system with respect to TBOD5 and SS removal. The tests were performed at a pilot plant with full scale height. The influent used was primary effluent of a conventional treatment plant. A multivariant analysis (ANOVA) was applied to the results.     

Microfibrous mesh coated with titanium dioxide: a self-sterilizing,self-cleaning filter

The utility of metal microfibrous mesh coated with titanium dioxide as a self-sterilizing, self-cleaning filter for air is explored. The low-cost mesh is produced via a roll-to-roll process similar to paper manufacturing. The titanium dioxide is applied by spraying an aqueous suspension of the photocatalyst on the surface of the mesh using an airbrush. Photocatalytic activity comparable to a powder layer is achieved at one quarter of the mass loading. The coating enhanced the separation of Escherichia coli (E. coli) from aqueous suspension, but also led to an increase in pressure drop in an air stream flowing through the mesh. The self-cleaning property of the coated mesh is established by recovery of pressure drop performance lost due to biofilm buildup. This is accomplished via a photocatalytic regeneration process involving exposing the mesh to ultraviolet light in air. Oxidation is confirmed by monitoring CO2 evolution during the regeneration. Scanning electron photomicrographs also provide visual evidence of successful regeneration via photocatalysis.     

(210)Pb content in natural gas pipeline residues ("black-powder") and its correlation with the chemical composition

The present work was carried out to assess the (210)Pb content in "black-powder" found in pigging operations on gas pipelines in Brazil, in particular, on the Campos Basin gas pipeline. Additionally, the chemical composition of such deposits was determined and an eventual correlation with (210)Pb concentration evaluated. Typical "black-powder" generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide ( approximately 81%) and residual organic matter ( approximately 9%). The (210)Pb content ranges from 4.9 to 0.04k Bqkg(-1) and seems to be inversely correlated with the distance to the platforms. On the other hand, (226)Ra concentration is higher on the pipeline branch between the platform and the onshore installations. (228)Ra was only observed in few samples, in particular, in the samples with the highest (226)Ra content.     

Chemical studies on Indopacific Ceratosoma nudibranchs illuminate the protective role of their dorsal horn

Summary. Two Ceratosoma species, C. trilobatum and C. gracillimum (Mollusca: Gastropoda: Opistobranchia), collected along the South China Sea coast, have been studied in order to investigate their defensive strategies. Both species contain four typical sponge furanosesquiterpenoids, probably with a dietary origin. The tissue distribution of these compounds has been studied by ¹H-NMR analysis and preliminary bioassays have been carried out in order to evaluate the ecological role of the isolated metabolites. The main sesquiterpene component in both species was (–)-furodysinin (2), which showed significant feeding-deterrent and ichthyotoxic properties in bioassays with freshwater organisms. The work has been performed studying a very limited number of molluscs that prevented the realization of ecologically relevant experiments. However, the almost exclusive presence of compound 2 in the crude extract of the mantle glands concentrated in the dorsal horn of C. gracillimum strongly supports the defensive role of that dorsal protuberance, which probably acts as a defensive lure attracting potential predators to the part of the animal that contains the distasteful chemicals.     

Behavioral and life-history components of division of labor in honey bees (Apis mellifera L.)

Variability exists among worker honey bees for components of division of labor. These components are of two types, those that affect foraging behavior and those that affect life-history characteristics of workers. Variable foraging behavior components are: the probability that foraging workers collect (1) pollen only; (2) nectar only; and (3) pollen and nectar on the same trip. Life history components are: (1) the age the workers initiate foraging behavior; (2) the length of the foraging life of a worker; and (3) worker length of life. We show how these components may interact to change the social organization of honey bee colonies and the lifetime foraging productivity of individual workers. Selection acting on foraging behavior components may result in changes in the proportion of workers collecting pollen and nectar. Selection acting on life-history components may affect the size of the foraging population and the distribution of workers between within nest and foraging activities. We suggest that these components define possible sociogenic pathways through which colony-level natural selection can change social organization. These pathways may be analogous to developmental pathways in the morphogenesis of individual organisms because small changes in behavioral or life history components of individual workers may lead to major changes in the organizational structure of colonies. Correspondence to: R.E. Page, Jr.     

Can a marine pest reduce the nutritional value of Mediterranean fish flesh?

Biological invasions are deemed as one of the most severe threats to biodiversity and can result in huge economic impacts on natural resources. Many studies have assessed structural changes caused by the introduction of nonindigenous species, but urgent questions remain to be answered about the complex indirect effects of invasive pests on marine biodiversity at the species and ecosystem level. Previous investigations focusing on the biological invasion by Caulerpa racemosa in the Mediterranean indicated that the lipophilic algal metabolite caulerpin accumulates in the tissues of the native edible white sea bream Diplodus sargus feeding on the exotic alga. The level of caulerpin in D. sargus has been thus used as an indicator of the trophic exposure of the fish to the seaweed and related with adverse effects on the fish health. In the present study, we show that the C. racemosa-based diet can also alter muscle fatty acids composition in the white sea bream by reducing the percentage of polyunsaturated fatty acids of the n-3 and n-6 series, such as eicosapentaenoic (C20:5), docosahexaenoic (C22:6) and arachidonic acids (C20:4). This represents both a real threat to the health of fish unable to biosynthesize these essential fatty acids and an impoverishment of an important source of essential fatty acids for human nutrition, which helps to prevent cardiovascular diseases, diabetes, hepatic steatosis, cancer and neurological disorders. On the whole, this work sheds light on an unexplored and critical aspect of biological invasions with implication on the health of both humans and the environment.     

Spatial and temporal variability of atmospheric mercury concentrations emitted from a coal-fired power plant in Mexico

Atmospheric mercury in the environment as a result of the consumption of fossil fuels, such as coal used in electricity generation, has gained increased attention worldwide because of its toxicity, atmospheric persistence, and bioaccumulation. Determining or predicting the concentration of this pollutant in ambient air is essential for determining sensitive areas requiring health protection. This study investigated the spatiotemporal variability of gaseous elemental mercury (GEM) concentrations and its dry deposition surrounding the Presidente Plutarco Elías Calles (CETEPEC) coal-fired power plant, located on Mexico’s Pacific coast. The CALPUFF dispersion model was applied on the basis of the daily consumption of coal during 2013 for each generating unit in the power plant and considering the local scale. The established 300-ng/m³ annual average risk factor considered by the U.S. Department of Health and Human Services (U.S. DHHS) and Integrated Risk Information System (IRIS) must not be exceeded to meet satisfactory air quality levels. An area of 65 × 60 km was evaluated, and the results show that the risk level for mercury vapor was not exceeded because the annual average concentration was 2.8 ng/m³. Although the predicted risk level was not exceeded, continuous monitoring studies of GEM and of particulates in the atmosphere, soil, and water may be necessary to identify the concentration of this pollutant, specifically that resulting from coal-fired power plants operated in environmental areas of interest in Mexico. The dry mercury deposition was low in the study area; according to the CALPUFF model, the annual average was 1.40E?2 ng/m²/sec. These results represent a starting point for Mexico’s government to implement the Minamata Convention on Mercury, which Mexico signed in 2013.

Implications: The obtained concentrations of mercury from a bigger coal-fired plant in Mexico, through the application of the CALPUFF dispersion model by the mercury emissions, are below the level recommended according to the US Department of Health and Human Services and Integrated Risk Information System. These results provide evidence of important progress in the planning and installation to the future of monitoring mercury stations in the area of interest.