Potential of dandelion (Taraxacum officinale) as a bioindicator of manganese arising from the use of methylcyclopentadienyl manganese tricarbonyl in unleaded gasoline

Methylcyclopentadienyl manganese tricarbonyl (MMT) is an organic manganese (Mn) compound currently added to unleaded gasoline in Canada. It has been suggested that the combustion of MMT containing Mn could cause various deleterious health effects in animals and humans at very high concentrations. This study evaluates the potential of dandelions (Taraxacum officinale) as bioindicators of Mn environmental contamination. Samples were picked at three different distances from a highway: a highly exposed site (E++), a lightly exposed site (E+) and a control site (E), located respectively at 10, 50 and 100 m. The total Mn, Mg, Ca, Al, Fe and Zn concentrations were measured in the soils and in the plants (flower, stem, leaves and root) by neutron activation analysis. Exchangeable Mn was measured in soils by atomic absorption spectrophotometry. Mn concentrations of the different parts of the plant and exchangeable Mn in soils were not correlated with distance from the roadway and, thus, do not seem to be a sensitive indicator of Mn contamination. Soil Mn concentrations were correlated with distance from the roadway. This suggests the hypothesis that the environmental fate of Mn from MMT sources could be associated with an increased total Mn in soil but does not lead to an increase in exchangeable Mn.     

Interaction between ozone and airborne particulate matter in office air

This study investigated the hypotheses that humans are affected by air pollution caused by ozone and house dust, that the effect of simultaneous exposure to ozone and dust in the air is larger than the effect of these two pollutants individually, and that the effects can be measured as release of cytokines and changes of the respiratory function. Experimental exposures of eight atopic but otherwise healthy subjects were performed in a climate chamber under controlled conditions. The three controlled exposures were about 75 microg/m3 total suspended particulate matter, 0.3 p.p.m. ozone, and the combination of these. The exposure duration was 3 h. The outcome measures were interleukins and cells in nasal lavages (NAL), respiratory function, bronchial metacholine responsiveness, rhinometry symptoms and general well-being in a questionnaire and time course of general irritation on a visual analogue scale. Indications of interactions between exposure types were demonstrated for peak expiratory flow (PEF) (P<0.05) and for discomfort symptoms (P<0.03). Non-significant interactions were found for the concentration of interleukin-8 in NAL. The combined exposure was found to cause significantly more effects than either ozone exposures or dust exposures. This is interpreted as indications of a potentiation caused by the combined exposures to dust and ozone. The findings in this study are based on a limited number of subjects and thus should not be over-interpreted. However, they support the hypothesis that ozone at relatively high concentrations interacts with dust exposures to cause decrements in PEF and increase in discomfort measures. PRACTICAL IMPLICATIONS: If confirmed at lower ozone and dust concentrations this finding could help to explain many problems with indoor air quality reported in offices throughout the world.     

Transport of exhaled particulate matter in airborne infection isolation rooms

The goal of this research was to examine the characteristics of the spatial velocity and concentration profiles which might result in health care workers’ exposure to a pathogenic agent in an airborne infection isolation room (AIIR). Computational fluid dynamics simulations were performed for this purpose. This investigation expanded on the work of Huang and Tsao [The influence of air motion on bacteria removal in negative pressure isolation rooms. HVAC & R Research 2005; 11: 563–85], who studied how ventilation conditions impact dispersion of pathogenic nuclei in an AIIR by investigating the airflow conditions impacting dispersion of infectious agents in the AIIR. The work included a careful quality assurance study of the computed airflow, and final simulations were performed on a fine tetrahedral mesh with approximately 1.3×10⁶ cells. The 1 μm diameter particles were released from a 0.001225 m² area representing the nose and mouth. Two cases were investigated during the current study: continuous exhalation of pathogen-laden air from the patient and expulsion of pathogenic particles by a single cough or sneeze. Slow decay of particle concentration in the AIIR during the single cough/sneeze simulation and tendency for particle accumulation near the AIIR walls observed in the continuous breathing simulation suggest that unintended exposures are possible despite the ventilation system. Based on these findings, it is recommended that extra care be taken to assure proper functionality of personal protective equipment used in an AIIR.     

Platinum and rhodium distribution in airborne particulate matter and road dust

In this work the platinum and rhodium content in the atmosphere of Madrid was monitored for 1 year at seven different sites. Samples were taken with medium volume PM-10 collectors (< 10 microm) for 48 h and analysed by ICP-MS. The Pt and Rh content was dependent on the sampling site, ranging from < 0.1 to 57.1 and < 0.2 to 12.2 pg m(-3) with a medium value of 12.8 and 3.3 pg m(-3), respectively. These results show that the Pt and Rh content in airborne samples depends on the traffic density per day and also on medium driving speed. Road dust < 63 microm was analysed at the same time and at the same location. The Pt and Rh content at the six sites analysed was in the 31-2252 and 11-182 ng g(-1) range with an average of 317 and 74 ng g(-1), respectively. The average Pt/Rh ratio obtained was 4.3. similar to that obtained for airborne particles (4.0), and agrees with that of the more commonly used gasoline car catalyst [J.J. Mooney, Encyclopaedia of Chemical Technology (1996) 982]. Platinum distribution as a function of particle size in airborne particulate matter was also studied, by sampling with two high-volume sample collectors, a five-stage WRAC (from 10 to 65.3 microm and total) and a seven-stages PM-10) cascade impactor (from 9 to < 0.39 microm). Platinum is associated with a wide range of particle diameters. Due to the ultratrace level of Pt in airborne samples, its distribution in the atmosphere could not be considered as homogeneous. No trend could be established in Pt distribution in the different fractions, except that in most cases the highest value of Pt was obtained in the < 0.39-microm fraction. The Pt content was usually high in airborne samples when the Pb, Ce, Zr and Hf content was also high, thus confirming that the source of these pollutants is from traffic.     

Monitoring children's personal exposure to airborne particulate matter in London, UK--method development and study design.

The paper outlines the methodology selected for identifying the personal exposure of children to airborne particulate matter in a UK urban environment.     

Trends in alkanes and PAHs in airborne particulate matter from Oporto and Vienna: identification and comparison.

A total of 56 weekly samples from Oporto and 40 from Vienna were collected and analysed, for 23 n-alkanes and 16 polycyclic aromatic hydrocarbons (PAH), by GC-MS after extraction with a toluene/methanol mixture. Total and elemental carbon were in the same range of values for both sampling sites. Although parts of the spectrum of species in both sampling sites were constant over the sampling period there is no evidence for suggesting a universal tracer for alkanes. For both Oporto and Vienna, Principal Component Analysis (PCA) identified two PCs and in both cases the first PC contained only PAHs while the second contained only alkanes. This separation between alkanes and PAHs and the observation of an alternating pattern with higher concentrations of odd carbon numbered from C27 to C30 (natural emissions from biological origin) is believed to result from a separation between anthropogenic and biological contributions associated with the first and second PC, respectively.     

Manganese and lead in children's blood and airborne particulate matter in Durban, South Africa

Despite the toxicity and widespread use of manganese (Mn) and lead (Pb) as additives to motor fuels and for other purposes, information regarding human exposure in Africa is very limited. This study investigates the environmental exposures of Mn and Pb in Durban, South Africa, a region that has utilized both metals in gasoline. Airborne metals were sampled as PM_2.5 and PM₁₀ at three sites, and blood samples were obtained from a population-based sample of 408 school children attending seven schools. In PM_2.5, Mn and Pb concentrations averaged 17 ± 27 ng m^− 3 and 77 ± 91 ng m^− 3, respectively; Mn concentrations in PM₁₀ were higher (49 ± 44 ng m^− 3). In blood, Mn concentrations averaged 10.1 ± 3.4 μg L^− 1 and 8% of children exceeded 15 μg L^− 1, the normal range. Mn concentrations fit a lognormal distribution. Heavier and Indian children had elevated levels. Pb in blood averaged 5.3 ± 2.1 μg dL^− 1, and 3.4% of children exceeded 10 μg dL^− 1, the guideline level. Pb levels were best fit by a mixed (extreme value) distribution, and boys and children living in industrialized areas of Durban had elevated levels. Although airborne Mn and Pb concentrations were correlated, blood levels were not. A trend analysis shows dramatic decreases of Pb levels in air and children's blood in South Africa, although a sizable fraction of children still exceeds guideline levels. The study's findings suggest that while vehicle exhaust may contribute to exposures of both metals, other sources currently dominate Pb exposures.     

The Salmonella mutagenicity of urban airborne particulate matter (PM2.5) from eight sites of the Emilia-Romagna regional monitoring network (Italy)

ARPA Emilia Romagna created, in 1997, a regional network for the continuous monitoring of the mutagenicity of PM(2.5) by short-term mutagenicity bioassays to guarantee a constant surveillance on the entire regional territory. The continuous monitoring of the PM mutagenicity provides essential information for a better understanding of the impact of air pollution on the health of the population, and allows one to better judge the efficiency of national and local efforts for urban air quality improvement (use of "green" petrol and ecodiesel, days during which traffic is prohibited, etc.). This article presents the results relating to the Network's activity between September 2000 and December 2002, on PM(2.5) fraction. The organic extracts of PM(2.5) were tested for mutagenicity using Salmonella tester strains TA98 and TA100 with and without metabolic activation (S9). The data obtained on the genotoxicity of air particulate extracts have revealed a constant presence of mutagenic substances adsorbed on particulate matter-with a prevalence of direct-acting mutagens than of promutagens-in a typical seasonal trend featuring higher levels in autumn-winter and lower in warmer periods of the year. In this work the evolution of PM(2.5) mutagenicity was compared with the particles, carbon monoxide (CO) and nitrogen dioxide (NO(2)) concentrations (monthly average); these comparisons revealed a quite good level of agreement on a local basis.     

Exposure of children to airborne particulate matter of different size fractions during indoor physical education at school

Although moderate regular aerobic exercise is recommended for good health, adverse health consequences may be incurred by people who exercise in areas with high ambient pollution, such as in the centres of large cities with dense traffic. The exposure of children during exercise is of special concern because of their higher sensitivity to air pollutants. The size-segregated mass concentration of particulate matter was measured in a naturally ventilated elementary school gym during eight campaigns, seven to ten days long, from November 2005 through August 2006 in a central part of Prague (Czech Republic). The air was sampled using a five-stage cascade impactor. The indoor concentrations of PM_2.5 recorded in the gym exceeded the WHO recommended 24-hour limit of 25 μg m⁻³ in 50% of the days measured. The average 24-h concentrations of PM_2.5 (24.03 μg m⁻³) in the studied school room did not differ much from those obtained from the nearest fixed site monitor (25.47 μg m⁻³) and the indoor and ambient concentrations were closely correlated (correlation coefficient 0.91), suggesting a high outdoor-to-indoor penetration rate. The coarse indoor fraction concentration (PM_2.5–10) was associated with the number of exercising pupils (correlation coefficient 0.77), indicating that human activity is its main source. Considering the high pulmonary ventilation rate of exercising children and high outdoor particulate matter concentrations, the levels of both coarse and fine aerosols may represent a potential health risk for sensitive individuals during their physical education performed in naturally ventilated gyms in urban areas with high traffic intensity.     

Measuring and modelling the airborne particulate matter mass concentration field in the street environment: model overview and evaluation.

This paper discusses the outline structure and preliminary evaluation of an emission-dispersion model for predicting the temporal and spatial distribution of vehicle-derived airborne particulate matter mass concentration in street canyons. The model is called Street Level Air Quality (SLAQ). SLAQ is semi-empirical, in that it uses not only results from field and wind tunnel experiments but also theory and models derived from multiple runs of numerical routines in order to simulate the basic physical processes within the street canyon. A combination of a plume model, for the direct contribution of vehicle exhaust, and a box model for the recirculating part of the pollutants in the street, is used to predict concentration for receptors within the canyon. Emission rates of vehicle-derived particulate matter are calculated within SLAQ, which serve as input to the dispersion module. Exhaust emission rates are scaled element by element along the street for each of the lanes according to the direction of traffic flow to account for modal operation of vehicles near signalised intersections. This refinement allows SLAQ to account for non-uniformity in along-canyon emission rates and to model a street that has several intersections along its length. Thermal turbulence due to environmental surface sensible heat and vehicle-generated heat is accounted for in the model. Other features of SLAQ include correction for the urban heat island effect, dry deposition, wet deposition, particle settling and estimation of wind direction standard deviation, when this latter data is not available. SLAQ has been evaluated in a street in Loughborough, Leicestershire, United Kingdom and correlation coefficient of 0.8 between the modelled and measured concentrations has been obtained.     

Chemical characteristics of airborne particulate matter near major roads and at background locations in Macao, China

PM10 and PM2.5 samples were collected near major roads and at the background locations in Macao using a TEOM1400a+ACCU system. The chemical analysis of these particles indicated the presence of 36 elements, water-soluble ions and carbonaceous species. The greatest contributors to total PM10 and PM2.5 mass were OC, sulfate, nitrate, ammonium, EC, Na, Cl and crustal elements including Si, Ca, Al, Fe, K and Mg. Organic material is the largest single fraction of airborne particulate matter in Macao. It contributes 32.8-41.5% and 38.2-48.4% of PM10 and PM2.5 at the roadsides, and as high as 29.7% and 33.4-39.4% of PM10 and PM2.5 at background locations, respectively. EC contributes 3.7-7.8% and 8.0-12.9% of PM10 and PM2.5, and crustal material is 10.2-15.4% and 7.6-12.2% of PM10 and PM2.5 near major roads, respectively. The share of EC at background locations is much lower than that at the roadsides, however, the contribution of crustal material is the same in both locations. At the roadsides, secondary aerosols, including sulfate, nitrate and ammonium, account for 16.6-29.0% and 15.8-38.0% of the total PM10 and PM2.5, respectively, as compared to 29.1-36.2% and 23.2-33.8% of total PM10 and PM2.5, respectively, at background locations. In PM2.5, Na and Cl contribute 1-3%, while the average amount of these two elements increase to 1-15% of the total PM10 in Macao.     

Some analytical problems encountered for trace elements determination in the airborne particulate matter of urban and rural areas

The determination of trace elements (TE) in airborne particulate matter collected onto filters requires an accurate evaluation of the entire analytical procedure. Since many elements have to be determined at a few milligrams of air dust at nanogram levels, possible sources of error can arise from uncontrolled parameters such as blank of the filters, sample homogeneity, pre-analytical treatment, primary and comparator standards. These potential critical points are presented here and discussed on the basis of the experience developed in our laboratory in previous studies where several TE monitoring campaigns have been performed for air particulate matter collected in urban as well as in rural residential areas of north Italy. Instrumental neutron activation analysis (INAA) and electrothermal atomic absorption spectroscopy (ET-AAS) have been used for the investigation of more than 30 trace elements.     

Seasonal variation of thallium, lead, and chromium concentrations in airborne particulate matter collected in an urban area

In November 1985 a research program started, with the aim to evaluate seasonal variations in the concentrations of organic and inorganic pollutants in the atmosphere of Genoa. The program provided for the collection of samples of airborne particulate in five different areas with distinct urban characteristics. First results for chromium, lead, and thallium concentrations in an industrial and in an urban area are reported. Lead showed the highest concentration at both locations (geometric mean: 1.037 and 0.476 microgram/m3, respectively) and appeared to be little affected by seasonal variation. Private traffic was confirmed as the main source of this pollutant. Chromium and thallium geometric mean concentrations were 0.006 and 0.014 microgram/m3 in site A and 0.017 and 0.015 microgram/m3 in site B, respectively. In the urban location a good negative linear correlation was found between chromium and thallium concentration and mean ambient temperature; the domestic heating plants were suspected as important emission sources of these two compounds.     

Lipid composition of suspended particulate matter (SPM) in a southeastern blackwater stream

Suspended particulate matter (SPM) was collected seasonally for 1 yr at third- and fifth-order sites in a blackwater stream on the coastal plain in South Carolina. Fatty acids with carbon chain lengths from C(12)-C(32) were the most abundant component among the lipid classes examined with total concentrations varying from 8.5 to 60.2 microgL(-1). Unsaturated fatty acids predominated while significant concentrations of the even-chained saturated components C(24)-C(30) derived from cuticular plant waxes were also found. Concentrations of aliphatic alcohols, with carbon chain lengths between C(16) and C(30), ranged from 0.52 to 2.73 microgL(-1) and was dominated by the higher molecular weight compounds (C(22)-C(30)) derived primarily from cuticular plant waxes. Total hydrocarbon concentrations ranged from 0.35 to 5.66 microgL(-1) and showed no discernible trends with time or consistent difference between sites. The hydrocarbon assemblage observed indicates that these components are entirely of biogenic origin with no detectable anthropogenic contribution.The ratios of unsaturated to saturated fatty acids and cuticular to noncuticular fatty acids and alcohols at both stream locations indicate that the organic detritus associated with SPM collected during November and January is of more recent origin and less processed than that collected in the spring and summer months. Lipid concentrations at the third-order site generally had higher and more variable concentrations of the lipid classes compared with the fifth-order site. The ratio of saturated to unsaturated fatty acids was higher at the third-order site indicating that the organic fraction of SPM at this site was of more recent origin and less decomposed. The ratios of cuticular to noncuticular fatty acids and alcohols support this conclusion. These results indicate an export of particulate lipids of higher carbon resource quality from upstream to lower stream reaches.     

Strength and deformability of an organic-calcareous lacustrine deposit (gyttja) in relation to its water content and colloid content

The purpose of this paper is to present the results of tests on the shear strength and compressibility of an organic-calcareous lacustrine deposit (gyttja). Physical and chemical properties of the detrital-calcareous gyttja of Grabowo are described herein. A ternary solid phase and colloidal liquid phase is a characteristic of gyttja. Deficiency of direct, rigid contacts among soil particles which are surrounded by colloidal films, being themselves elastically deformed, can be assumed as developing a low value of the angle of internal friction of gyttja. The leap compressibility is connected with heterogeneity of composition of the solid and liquid phase. Sufficiently strong structural bonds related to the specific mineralization of a pore-water, especially to the carbonate and non-carbonate hardness of gyttja, have an effect on the form of the compressibility diagrams. It is the nature of the matter, filling the macro- and micropopores, its types and chemical-mineral characteristic, which mainly exercises control over the sediment behaviour when its strength and compressibility are tested. While analysing and interpreting the results of triaxial and consolidation tests the processes which have occurred in colloids should be taken into consideration.     

Polynuclear aromatic hydrocarbon content of particulate matter suspended in the atmosphere of La Plata, Argentina

Twelve polynuclear aromatic hydrocarbons (PAH) were evaluated by chromatographic procedures using a HPLC-UV detector and a GC-FID detector. The PAH were evaluated in airborne particulate matter collected in La Plata, Argentina, over a period of 2 years (with sampling periods of approximately 4 months). The samples were size fractionated, and the PAH in each fraction determined. The analytical procedure used was as follows: extraction in benzene, concentration at room temperature, clean-up in a silica gel column and, finally, evaluation by chromatographic procedures. The extraction recovery was 76.2 +/- 5.8% for naphthalene and 96.0 +/- 6.2% for chrysene. Clean-up recovery was 87.8 +/- 7.15% for phenanthrene and 98.1 +/- 8.3% for anthracene. The largest PAH load was present in the smallest fractions. The smallest particles were carbonaceous in nature. The concentration peak was associated both with the total mass of airborne particulate matter and the reduction in amounts of coarse particles. The PAH distribution could not be correlated with characteristic physicochemical properties such as water solubility or the octanol-water distribution coefficient. The PAH load was greater in fall and winter than in spring and summer. This could be attributed to the reduction of photochemical processes during the cold seasons.     

Radioactive contamination of the Balchug (Upper Yenisey) floodplain, Russia in relation to sedimentation processes and geomorphology

The radioactive contamination of a riverine floodplain, heavily influenced by discharges from Krasnoyarsk-26, has been studied with respect to sedimentation processes and the geomorphology of the Upper Yenisey floodplain. The study was effected by implementation of a regime of in situ observations and measurements, sampling, and the interpretation of satellite images. The results of the study indicate that on the Balchug Bypass Floodplain, radionuclide contamination is primarily influenced by the thickness of the deposited sediments, and the area can be considered as two depositional environments. The Balchug floodplain area was contaminated due to sedimentation of radionuclide-contaminated alluvium, whose depositional regime significantly changed after the construction of a hydroelectric power station in 1967. Contamination levels are lower on the upstream part of the floodplain where sediment depth is less than 0.2-0.3 m, and this contamination started to accumulate in 1967, while the downstream part of the floodplain, exhibiting deeper deposits, displays higher levels of radionuclide contamination because radionuclides began to deposit here in 1958 when the Krasnoyarsk-26 Mining and Chemical Combine (KMCC) commenced operation. Radionuclide contamination of the floodplain is also related to the elevation of the floodplain, higher regions of the floodplain typically having lower contamination than low-lying areas, which tend to be frequently inundated with sediments being deposited during such inundations. Local relief, its orientation, and vegetation cover have also combined to form sediment traps with significantly higher radionuclide contamination. Lithological analysis combined with radiometric assay indicates a total 137Cs floodplain inventory of 33.7 GBq.     

盐渍土强度参数与含盐量、含水量关系初探

在室内试验条件下,以青海格尔木市郊土样为样品,研究了盐渍土抗剪力学性质的变化。试验结果表明,加入不同盐类和含量的氯盐及硫酸盐,土体粘聚力c和内摩擦角φ均与含盐量同含水量的比值m存在良好的线性关系。当m〈1.54时,加入的氯盐和硫酸盐所得c,φ值差异较大;当m〉1.54时,差异较小。经分析可以认为,盐渍土强度参数c,φ值的变化,主要是由土体中易溶盐相态变化所致。