Potential health risks from increased use of diesel light duty vehicles.
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Air Pollutants↗
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A new non-aerated illuminated packed-column reactor for the development of sulfide-oxidizing biofilms.
This paper describes an illuminated reactor that allows the spontaneous development of biofilms aimed at the treatment of sulfide-containing streams. The reactor operates as a sulfidostat and is composed of an illuminated packed-column, in which microorganisms are exposed to constant low substrate concentrations, thereby avoiding inhibition due to high sulfide concentrations. The control system allows highly polluted streams to be oxidized by the microbial biofilm while ensuring the quality of the effluent produced. Both monospecies and multispecies biofilms have been developed. Biofilms undergo changes in light irradiance and sulfide load while providing a consistent reduction of the sulfide levels, down to micromolar concentrations. Both types of biofilm developed differ from stirred reactors in that their specific activities are lower, constituting systems with a slow dynamic behavior and, therefore, they are less sensitive to sudden disturbances.
Biodegradation, Environmental↗
Motorcycle exhaust particulates enhance vasoconstriction in organ culture of rat aortas and involve reactive oxygen species.
The effects of motorcycle exhaust particulate on vasoconstriction were determined using rat thoracic aortas under organ culture conditions treated with organic extracts of motorcycle exhaust particulate from a two-stroke engine. The motorcycle exhaust particulate extract (MEPE) induced a concentration-dependent enhancement of vasoconstriction elicited by phenylephrine in the organ cultures of both intact and endothelium-denuded aortas for 18 h. Nifedipine (an L-type Ca2+ channel blocker), manganese acetate (an inorganic Ca2+ channel blocker), and staurosporine (a nonselective protein kinase C inhibitor), but not the selective protein kinase C inhibitor chelerythrine, inhibited the enhancement of vasoconstriction by MEPE. Staurosporine has also been reported as a myosin light chain kinase (MLCK) inhibitor, so we tested whether the MLCK pathway was involved in the effect of MEPE. The results showed that ML-9 (a selective MLCK inhibitor) could inhibit the enhancement of vasoconstriction by MEPE. The phosphorylation of a 20-kDa myosin light chain in a primary culture of rat vascular smooth muscle cells was also enhanced by MEPE. Moreover, we also examined the role of reactive oxygen species (ROS) in the stimulatory effect of MEPE on vasoconstriction. The antioxidant N-acetylcysteine significantly inhibited the enhancement of vasoconstriction by MEPE. A time-dependent increase in ROS production by MEPE was also detected in primary cultures of vascular smooth muscle cells. These results indicate that MEPE induces a marked enhancement of vasoconstriction in aortas under organ culture conditions and imply that a ROS-Ca2+-MLCK pathway may be involved in this MEPE-induced response.
Air Pollutants↗
Iron(III) photo-induced degradation of isoproturon: correlation between degradation and toxicity.
The degradation of isoproturon photoinduced by Fe(III) was investigated under both artificial and solar light. The monomeric species Fe(OH)2+ present under the experimental conditions ([Fe(III)] = 3 x 10(-4) M) is the main Fe(III) species responsible for the degradation of isoproturon. The process involves the attack on the pollutant by OH radicals generated by irradiation of Fe(OH)2+. The major primary photoproducts were identified; they accumulate in the solution medium before being degraded. The toxicity of the solution to marine bacterium Vibrio fisheri (Beijerinck) Lehmann & Neumann was monitored during the degradation process. It increased in the early stages of the reaction and, among the photoproducts, the N-formyl derivative appeared to be the major product responsible for the increase in toxicity.
Ferric Compounds↗
Chronobiometry with pocket calculators and computer systems.
Selected methods for the study of biologic time series are reviewed and their relative merits are discussed in the light of underlying assumptions. Their potential applications are exemplified in several fields of biology and medicine. The monitoring of environmental integrity, notably of pollution, is investigated. The need for specifying optimal sampling requirements is underlined. An individualized and time-qualified definition of health by the establishment of reference intervals is required for increasingly rational individualized program for the prevention and/or treatment of disease. With these reference intervals and rhythm characteristics available, one can better interpret with single samples or time series an increased risk of a certain disease or the inception of the disease. For all of these aims the monitoring of environmental and/or personal marker rhythms is essential--to obtain large data bases from which information can be more easily derived for monitoring personal health, to recognize risk as well as to diagnose disease early and to optimize treatment by timing according to rhythms.
Animals↗
Dyeless optical detection of ammonia in the gaseous phase using a pH-responsive polymer--characterization of the sorption process.
pH-responsive polymers enable the dyeless optical detection of acidic or basic pollutants in air. The characterization of the sorption process and the optimization of the response time of the sensitive layers were high-lighted. The swelling of a pH-responsive polysiloxane induced by sorption of gaseous ammonia was investigated by measurement techniques such as spectroscopic ellipsometry (SE) and infrared spectroscopy (IR). Furthermore, the pH-responsive polymer was applied for the detection of gaseous ammonia using the LED-based reflectometric interference spectroscopy set-up (RIfS4lambda). A limit of detection of 0.30 mg/m3 ammonia and a response time (t90%) of 35 s could be verified. The application of pH-responsive polymers can be a powerful alternative to dye-based optical sensing, since photobleaching or leaching of the sensitive functional unit cannot occur applying this approach, and since the properties of the sensitive layer proved to be very promising.
Journal Article↗
Photocatalytic degradation of cyanobacterial microcystin toxins in water.
The microcystins are hepatotoxins produced by a number of cyanobacterial species (blue green algae) in fresh water systems. The increasing eutrophication of natural waters has led to an increase in the incidence of algal blooms and the consequent increased risk of microcystin contamination of water resources. The removal of microcystins LR, YR and YA from contaminated water was investigated using an experimental laboratory-scale photocatalytic 'falling film' reactor in which an oxygen purge, UV radiation and semiconductor titanium dioxide (TiO2) catalyst were used to oxidatively decompose the microcystin pollutants. Preliminary studies, using algal extracts spiked into distilled water, indicated that the microcystins were rapidly decomposed in this reactor. The decomposition followed first order reaction kinetics with half-lives of less than 5 min with the reactor operating in a closed-loop mode. Reaction rates were strongly dependent on the amount of TiO2 catalyst (O-5 g/l), but only marginally influenced by a change in gas purge from oxygen to compressed air. The use of lake water, rather than distilled water, showed that this process is feasible in natural waters, although increased levels of catalyst (up to 5 g/l) were required to achieve comparable decomposition rates.
Bacterial Toxins↗
Use of an ipb-lux Fusion To Study Regulation of the Isopropylbenzene Catabolism Operon of Pseudomonas putida RE204 and To Detect Hydrophobic Pollutants in the Environment.
A DNA segment involved in the regulation of the isopropylbenzene (cumene) catabolism operon (ipb) of plasmid pRE4 from Pseudomonas putida RE204 and the Vibrio fischeri luciferase genes, luxCDABE, were used to create an ipbRo/pA(prm1)-luxCDABE reporter fusion plasmid, pOS25. Escherichia coli HMS174(pOS25) produces light in the presence of inducers of the ipb operon. These inducers were shown to be hydrophobic compounds and to include monoalkylbenzenes, substituted benzenes and toluenes, some alkanes and cycloalkanes, chlorinated solvents, and naphthalenes. Complex hydrocarbon mixtures, such as gasoline, diesel fuel, jet fuels (JP-4 and JP-5), and creosote, were also inducers of ipb-lux. Bacteria carrying the ipb-lux reporter may be useful as bioindicators of hydrocarbon pollution in the environment and may be particularly valuable for examining the bioavailability of inducing pollutants.
Journal Article↗
[Analysis of odoriferous pollutants in cooling water by on-line LC-GC/FTIR method].
The integration of two dimensional chromatography system (LC-GC) has ability for clean-up, enrichment, pre-separation and high resolution separation for the sample. The coupling of LC-GC with FTIR can notably improve the detection ability of conventional (light pipe) GC/FTIR system. The interface of LC-GC system employs retention gap technique (15 m x 0.53 mm i.d. retention gap column and 4 m x 0.25 mm i.d. precolumn) with on-column injection and partially concurrent solvent evaporation with early vapor exit. The applicability of the method is demonstrated by the analysis of odoriferous pollutants (phenolic compounds) in the cooling water with 15 cm x 2 mm i.d. silica LC column and 35 m x 0.25 mm i.d. OV-101GC column under the conditions of haxane/dichloromethane (80:20) as the mobile phase (0.3 mL/min) of LC, N2 as the carrier gas in GC and solvent evaporation temperature 80 degrees C, inlet pressure of 0.2 MPa etc. The method of on-line coupled LC-GC/FTIR is a reliable analytical tool for microcomponents in complex mixtures.
Chromatography, Gas↗
Investigation of the mechanism of action of atmospheric pollutants on the central nervous system and comparative evaluation of methods of study.
Some aspects of the mechanism of action of atmospheric pollutants (acetone, benzene, ammonia, formaldehyde, and ozone) on the central nervous system were studied by using methods of functional electroencephalography (analysis of the readjustment reaction to a rhythmic light stimulus, evoked potentials of the cerebral cortex, and determination of the photometrazol thresholds). Effects of the compounds were determined for the various structures of the cerebral cortex of experimental animals. The most sensitive structures were those which were first to associate in the reaction to toxic agents (the corticomedial nucleus of the amygdaloid complex and the olfactory bulb). EEG indices were observed which were indicative of an adverse effect (epileptoid activity in the most sensitive formations of the brain and a stable generalized stress rhythm in the neocortex and in the limbic ascending reticular system). During long-term action of toxic materials at low concentrations, changes were observed in the parameters of the primary and secondary responses of the visual evoked potential which were indicative of a disturbance of the cortical inhibition processes. This can be considered one effect of atmospheric pollutants at low concentrations. Problems of the comparative sensitivity of the various methods of studying the central nervous system are being investigated with a single compound: carbon bisulfide. In human experiments concerned with the fine coordination of measured movements such as writing and the solution of arithmetic problems, the subject-operator observed that repeated inhalation of subsensory concentrations of carbon bisulfide (0.08 mg/m3 level) disturbs the rate of execution of assigned motor processes. In tests with rats with developed instrument conditioned reflexes, it was shown that entire behavioral acts deteriorate under the effect of the same carbon bisulfide concentration. In tests on rabbits, simultaneous neurophysiological and neurochemical analyses were performed on the changes in the functional state of the central nervous system under chronic exposure to carbon bisulfide at various concentrations.
Acoustic Stimulation↗
Application of the Microtox test and pollution indices to the study of water toxicity in the Albufera Natural Park (Valencia, Spain).
The toxic effects of waters collected from irrigation channels in a Mediterranean wetland (Albufera Natural Park, Valencia, Spain) were tested with the Microtox assay and compared with six pollution indices (PIs) defined from analytical parameters. Chemical oxygen demand (COD), biological oxygen demand (BOD), nutrients, heavy metals and pesticides were measured. The bioassay result (concentrations of the water sample (% V/V) that reduced light emission to 10%, 20% and 50%, EC10, EC20 and EC50, respectively (ECs)) was compared with the PIs. This comparison has demonstrated a general agreement between ECs and PIs, except in the case of irrigation channels affected by herbicides used in rice farming (molinate and thiobencarb). No pronounced inhibition was detected in the bioluminescence in relation to the eutrophic parameters in the irrigation waters for EC50 values, indicating that this parameter does not suffice to detect eutrophic waters. Data derived from irrigation water pollution and bioassay were assembled by multivariate statistical techniques (principal component analysis). These components were associated with various contamination sources.
Agriculture↗
Single pollutant versus surrogate measure approaches: do single pollutant risk assessments underestimate the impact of air pollution on lung cancer risk?
Cancer risk as a result of air pollution may be quantified by different approaches. We compared the sum of unit risk based effects of single pollutants with an epidemiology-based method by using PM(10) as a surrogate of the total air pollution. The excess rate for lung cancer cases attributable to an increase of 10 microg/m3 in average PM(10) exposure was estimated from available cohort studies. Applying the epidemiology-based risk method to the air pollution situation in the Basel area (Switzerland) resulted in 13.3 (95% CI = 6.9-19.8) excess lung cancer cases per 100,000 person years. This estimate was considerably higher than the unit risk-based estimate yielding 1.1 (range, 0.45-2.8) cancer cases per 100,000 person years. We discuss these discrepancies in light of inherent differences between approaches in toxicology and epidemiology.
Air Pollutants↗
An analogy on assessment of urban air pollution in Turkey over the turn of the millennium (1992-2001).
Rapid industrialization and urbanization in Turkey, especially over the last twenty five years, has provided better living standards to its residents, but it also caused a decrease in environmental quality. In late 1970's, air quality monitoring activities were started in some major cities by individual researchers in Turkey. It was just around the 1990's that a countrywide program on continuous air pollution monitoring in major province centers and selected large towns was launched. The impact of air pollution on people depend on various factors, such as existence and magnitude of coal powered energy generation plants, type of urban heating and their efficiency, and the numbers and specifications of vehicles. In this study, current Turkish urban air quality over the turn of the Millennium (1992-2001) is studied in the light of the country's worst cities in terms of outdoor air quality, the number of upper respiratory diseases, sinusitis, bronchitis, and pneumonia cases in these provinces reported by the state medical treatment facilities in 2001. The population that is under outdoor urban air pollution hazard was computed. A comparative analysis between the provinces that use natural gas and others that use fossil fuels was also completed in order to project monetary gains if the studied provinces will transform their indoor heating and industrial operations to be run by natural gas or other cleaner energy sources. If natural gas use in air polluted urban centers could be realized in the near future, approximately 212 to 350 million US dollars per annum could to be saved just by reducing health related problems caused by outdoor air pollution.
Air Pollution↗
[Evolution of hydrocarbons and bacterial activity in the marine sediments contaminated by crude oil overflow and treated].
The fate of an experimental oil pollution of intertidal sediments in a sheltered beach of North Brittany (France) has been investigated over a 16-month period. Chemical treatments were applied to two of the three contaminated plots by pre-mixing oil respectively with dispersant and biodegrading agents. The physico-chemical and bacteriological characteristics of the polluted areas were followed with the purpose of identifying the limiting parameters for oil microbial degradation and the effect of treatment. The concentration of hydrocarbons in the oiled sediments did not change significantly during the experimental period. Spectrofluorimetric and chromatographic data showed that the main evolution of oil concerns the degradation of n-alkanes and the removal of light aromatics. Biodegradation of hydrocarbons occurred at a measurable rate only during the warm seasons (average temperature 18 +/- 2 degrees C) causing after sixteen months the disappearance of more than 80% of the n-alkanes fraction independently of the pollution sediment level and the chemical treatment of the experimental plots. However, the biodegradation of n-alkanes proceeded during the first months, at different rates, inversely depending on oil content in the collected samples. The main limiting factor is dissolved oxygen according to the fact that spilled oil was located at 3-5 cm depth in a poorly oxygenated zone characterized by low redox potential. Nutrients were not a limiting factor probably due to domestic and agricultural inputs in this area. A marked bacterial growth was observed two weeks after the oil spill with a relative increase in hydrocarbon degrading bacteria with respect to total heterotrophs. Degradation rates, based on C14 n-hexadecane experiments, seem to follow the same way than specific bacterial counts (plate technique). Specific bacteria are always high at the end of our 16 months' field experimentation. In the laboratory as well as in the field experiments, the same behaviour of untreated and chemically treated oil was observed in partially anaerobic sediment.
Bacteria↗
A study of the distribution of urban environmental lead levels in Cape Town, South Africa.
Epidemiological studies which have attempted to quantify the relationship between environmental lead and blood lead levels have been beset by numerous methodological problems, one of which has been the difficulty in assessing environmental exposure to lead. In Cape Town, South Africa, a comprehensive environmental lead monitoring programme was instituted in an inner city suburb where a blood lead screening study was in progress. The objective of the study was to examine the spatial and temporal variation in environmental lead levels, and to examine the role of potential influencing factors such as traffic. Results revealed substantial intra-urban variations in air lead levels, with annual means varying from less than 0.5 to over 2 micrograms/m3 at individual sites. Traffic density and the distance from heavily trafficked roads were important influencing factors within the area. Considerable seasonal as well as daily variations in air lead levels were also documented, and air lead levels were positively associated with dust lead levels. The spatial and temporal variations in environmental lead have implications for air monitoring strategies and epidemiological studies concerned with the relationship of exposure to lead and the health impact on populations. Micro variations in exposure need to be taken into account assessing exposure to environmental lead in epidemiological studies, in light of the considerable variations which may occur.
Air Pollutants↗
Structural effect of the in situ generated titania on its ability to oxidize and capture the gas-phase elemental mercury.
Structural effect of the in situ generated TiO(2) sorbent particle was examined for its ability to capture elemental mercury under UV irradiation in a simulated combustion flue gas. Titania particles were prepared by thermal gas-phase oxidation of Titanium (IV) isopropoxide (TTIP) using a high temperature electric furnace reactor. The structural characteristics of the in situ generated TiO(2) at various synthesis temperatures were investigated; size distribution and the geometric mean diameter were measured using a scanning mobility particle sizer, while fractal dimension and radius of gyration were evaluated from the transmission electron microscopy images. Results from the Hg(0) capture experiment show that with increasing titania synthesis temperature, the overall aggregate size increases and the morphology becomes more open-structured to gas-phase Hg(0) and UV light, resulting in the improved mercury removal capability.
Adsorption↗
Optimization of Fenton's oxidation of chemical laboratory wastewaters using the response surface methodology.
Establishing a treatment process for practical and economic disposal of laboratory wastewaters has become an urgent environmental concern of the Department of Chemical Engineering of the Universidade Estadual de Maringá (State University of Maringá), Brazil. Fenton and related reactions are potentially useful oxidation processes for destroying toxic organic compounds in water. In these reactions, hydrogen peroxide is combined with ferrous or ferric iron in the presence or absence of light to generate hydroxyl radicals (.OH). The feasibility of Fenton's reagent to treat waste chemicals from an academic research laboratory was investigated in this study. A response surface methodology was applied to optimize the Fenton oxidation process conditions using chemical oxygen demand (COD) removal as the target parameter to optimize, and the reagent concentrations, as related to the initial concentration of organic matter in the effluent, and pH as the control factors to be optimized. Maximal COD removal (92.3%) was achieved when wastewater samples were treated at pH 4 in the presence of hydrogen peroxide and iron in the ratios [COD]:[H2O2]=1:9 and [H2O2]:[Fe2+]=4.5:1. Under these conditions, it was possible to obtain simultaneously maximal COD removal and minimal chemical sludge after treatment, which is a residue that needs further processing.
Brazil↗
Process burner and combustion system hazards: 10 key issues that save lives.
Burner and combustion safety is crucial for the safe operation of fuel-fired heaters and boilers at process industry facilities. This paper discusses 10 of the most common burner and combustion system hazards that impact the safe operation of combustion equipment. The paper includes a discussion of three burner related explosion incidents that occurred at plants and how to avoid them. Strategies are also presented for training of maintenance and operations personnel on hazard recognition and avoidance. A protocol for walking down equipment prior to light offs is also presented as an extra safety step.
Air Pollutants↗