Heavy metal distribution in dust from elementary schools in Hermosillo,Sonora, México

The city of Hermosillo, Sonora in northern Mexico was investigated for its heavy metals content. Samples of sedimented dust in roofs from 25 elementary schools were analyzed for their contents of Ni, Cr, Zn, Cd, Co, Ba, V, Pb, Fe and Cu after digestion with nitric acid. The results of the analysis were used to determine spatial distribution and magnitude of heavy metals pollution. The results of this study reveal that heavy metals distribution is different in two areas of the city. The southern area contains higher concentrations of heavy metals than the northcentral area. The mean level of Cd in exterior dust is 5.65 mg kg⁻¹ in the southern area whereas the mean level of Cd is 2.83 mg kg⁻¹ in the northcentral area. Elevated concentrations of Zn (2012 mg kg⁻¹), Pb (101.88 mg kg⁻¹), Cr (38.13 mg kg⁻¹) and Cd (28.38 mg kg⁻¹) in roof dust were found in samples located near industrial areas. Principal component analysis (PCA) was applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. PCA shows two main sources: (1) Pb, Cd, Cr and Zn are mainly derived from industrial sources, combined with traffic sources; (2) Fe, Co and Ba are mainly derived from natural sources. V and Ni are highly correlated and possibly related to fuel combustion processes. Enrichment factors were calculated, which in turn further confirms the source identification. Ba and Co are dominantly crustal. Anthropogenically added Cd, Pb, Zn and Cr show maximum enrichment relative to the upper continental crustal component. The distribution of the heavy metals in dust does not seem to be controlled only by the topography of the city, but also by the location of the emission sources.     

Real-world emission factors of fifteen carbonyl compounds measured in a Hong Kong tunnel

Real-world vehicle emissions of carbonyls were determined in summer and winter of 2003 at the Shing Mun Tunnel, Hong Kong. Fifteen carbonyl species have been analyzed in this study. The total measured carbonyls emission factors ranged from 21.7 to 68.9 mg veh⁻¹ km⁻¹ among different measurement periods, with an average of 35.8±11.9 mg veh⁻¹ km⁻¹. Higher carbonyl emissions were found to be associated with a high proportion of diesel-fueled vehicles. Total measured carbonyl emissions from Diesel-fueled Vehicle (DV, 71.5 mg veh⁻¹ km⁻¹) were about 7 times higher than those from Non-Diesel-fueled Vehicle (NDV, 10 mg veh⁻¹ km⁻¹). The five carbonyls with the largest DV emission factor were, in decreasing order, formaldehyde (38.3 mg veh⁻¹ km⁻¹), acetaldehyde (11.4 mg veh⁻¹ km⁻¹), acetone (5.3 mg veh⁻¹ km⁻¹), crotonaldehyde (5.2 mg veh⁻¹ km⁻¹) and benzaldehyde (2.0 mg veh⁻¹ km⁻¹). These five carbonyl compounds together accounted for 87% of the sum of all DV carbonyl emission factors. For NDV, the five most abundant carbonyls in NDV emission at the tunnel were, in decreasing order, formaldehyde (3.5 mg veh⁻¹ km⁻¹), acetone (1.8 mg veh⁻¹ km⁻¹), methyl ethyl ketone (1.6 mg veh⁻¹ km⁻¹), m,p-tolualdehyde (1.0 mg veh⁻¹ km⁻¹) and acetaldehyde (mg veh⁻¹ km⁻¹). They accounted for 85% of the sum of all NDV carbonyl emission factors.     

Removal of aqueous lead by poorly-crystalline hydroxyapatites

The use of a phosphorus amendment in altering Pb to a chemically less mobile phase is a promising strategy based on minimizing ecotoxicological risk and improving time and cost efficiency. This study evaluated crystalline and poorly-crystalline hydroxyapatite sorbents on removal of aqueous Pb in response to reaction time, solution pH, and Pb concentration. Batch experiments were conducted using a commercially-available crystalline hydroxyapatite (HA), and two poorly-crystalline hydroxyapatites synthesized from gypsum waste (CHA) and incinerated ash of poultry waste (MHA). Poorly-crystalline hydroxyapatites had greater capacity for Pb removal from a solution with a wider pH range as compared to a crystalline hydroxyapatite. The maximum sorption capacity of Pb determined by the Langmuir model was 500 mg g⁻¹ for CHA, 277 mg g⁻¹ for MHA and 145 mg g⁻¹ for HA. Removal of aqueous Pb by CHA was not dependent on solution pH, with a 98.8% reduction throughout the solution pH range of 2–9, whereas aqueous Pb removal by HA and MHA was pH-dependent with less removal in the neutral solution pH. Poorly-crystalline hydroxyapatites may provide an effective alternative to existing remediation technologies for Pb-contaminated sites.     

Emission factors of PAHs,methoxyphenols, levoglucosan,elemental carbon and organic carbon from simulated wheat and Kentucky bluegrass stubble burns

Emission factors (EFs) of pollutants from post-harvest agricultural burning are required for predicting downwind impacts of smoke and inventorying emissions. EFs of polycyclic aromatic hydrocarbons (PAH), methoxyphenols (MP), levoglucosan (LG), elemental carbon (EC) and organic carbon (OC) from wheat and Kentucky bluegrass (KBG) stubble burning were quantified in a US EPA test burn facility. The PAH and MP EFs for combined solid+gas phases are 17±8.2 mg kg⁻¹ and 79±36 mg kg⁻¹, respectively, for wheat and 21±15 mg kg⁻¹ and 35±24 mg kg⁻¹, respectively, for KBG. LG, particulate EC and artifact-corrected OC EFs are 150±130 mg kg⁻¹, 0.35±0.16 g kg⁻¹ and 1.9±1.1 g kg⁻¹, respectively, for wheat and 350±510 mg kg⁻¹, 0.63±0.056 g kg⁻¹ and 6.9±0.85 g kg⁻¹, respectively, for KBG. Positive artifacts associated with OC sampling were evaluated and remedied with a two-filter system. EC and OC accounted for almost two-thirds of PM_2.5 mass, while LG accounted for just under 3% of the PM_2.5 mass. Since EFs of these pollutants generally decreased with increasing combustion efficiency (CE), identifying and implementing methods of increasing the CEs of burns would help reduce their emissions from agricultural field burning. PAH, OC and EC EFs are comparable to other similar studies reported in literature. MP EFs appear dependent on the stubble type and are lower than the EFs for hard and softwoods reported in literature, possibly due to the lower lignin content in wheat and KBG.     

Decadal reductions of traffic emissions on a transit route in Austria – results of the Tauerntunnel experiment 1997

Real-world emissions of a traffic fleet on a transit route in Austria were determined in the Tauerntunnel experiment in October 1997. The total number of vehicles and the average speed was nearly the same on both measuring days (465 vehicles 30 min⁻¹ and 76 km h⁻¹ on the workday, 477 and 78 km h⁻¹ on Sunday). The average workday fleet contained 17.6% heavy-duty vehicles (HDV) and the average Sunday fleet 2.8% HDV resulting in up to four times higher emission rates per vehicle per km on the workday than on Sunday for most of the regulated components (CO₂, CO, NO_x, SO₂, and particulate matter-PM10). Emission rates of NMVOC accounted for 200 mg vehicle⁻¹ km⁻¹ on both days. The relative contributions of light-duty vehicles (LDV) and HDV to the total emissions indicated that aldehydes, BTEX (benzene, toluene, ethylbenzene, xylenes), and alkanes are mainly produced by LDV, while HDV dominated emissions of CO, NO_x, SO₂, and PM10. Emissions of NO_x caused by HDV were 16,100 mg vehicle⁻¹ km⁻¹ (as NO₂). Produced by LDV they were much lower at 360 mg vehicle⁻¹ km⁻¹. Comparing the emission rates to the results that were obtained by the 1988 experiment at the same place significant changes in the emission levels of hydrocarbons and CO, which accounted 1997 to only 10% of the levels in 1988, were noticed. However, the decrease of PM has been modest leading to values of 80 and 60% of the levels in 1988 on the workday and on Sunday, respectively. Emission rates of NO_x determined on the workday in 1997 were 3130 mg vehicle⁻¹ km⁻¹ and even higher than in 1988 (2630 mg vehicle⁻¹ km⁻¹), presumable due to the increase of the HD-traffic.     

Effect of natural compounds on reducing formaldehyde emission from plywood

The effects of natural compounds on reducing formaldehyde emission from plywood were investigated. Urea, catechin and vanillin were examined as the natural formaldehyde reducers. The microemission cell, with an internal volume of 35 ml, the maximum exposed test surface area of 177 cm² and an air purge flow rate of 50 ml min⁻¹, was used to measure specific emission rate (SER). In the case of no reducer treatment, formaldehyde emission from plywood was fast and SERs were 4.4 mg m⁻² h⁻¹ at 30 °C and 15 mg m⁻² h⁻¹ at 60 °C. When this plywood was treated with the natural compounds, the SERs of formaldehyde were decreased at all temperatures. In the case of urea treatment, the SERs of formaldehyde decreased to 0.30 mg m⁻² h⁻¹ at 30 °C and 0.65 mg m⁻² h⁻¹ at 60 °C. When the urea treatment was applied to the inside of kitchen cabinet (made from plywood; 270 cm wide, 60 cm deep, 250 cm high), the concentration of formaldehyde was reduced substantially from 1600 to 130 μg m⁻³. The reducing effect of formaldehyde continued during the observation period (6 months), with a mean concentration of 100 μg m⁻³. Reducers in the plywood would react with released formaldehyde. Application of natural compounds such as urea, catechin and vanillin could provide a simple and effective approach for suppressing formaldehyde emission from plywood.     

Methane emissions from lakes and floodplains in Pantanal,Brazil

To evaluate the tropical wetlands contribution to the methane (CH₄) burden better, field campaigns were performed during 2004 and 2005 near the Miranda River, in five sites inside the Brazilian Pantanal region. The CH₄ fluxes were determined using the static chamber technique. Environmental variables that may affect CH₄ emissions, as the water depth, the water and air temperatures were also measured. The overall average of the 320 individual CH₄ flux measurements made between March/2004 and March/2005 was 142±314 mg CH₄ m⁻² d⁻¹, which is a value near the ones observed in other tropical flooded regions. About 47% of the fluxes measurements presented nonlinear increases in the chamber concentrations, which were assumed to be linked to CH₄ losses through bubbles. The bubble flux represented about 90% of the total CH₄ losses in the measurements and ranged from 1 to 2187 mg CH₄ m⁻² d⁻¹ with an average of 292±410 mg CH₄ m⁻² d⁻¹ (median: 153 mg CH₄ m⁻² d⁻¹). The diffusive flux ranged from 1 to 124 mg CH₄ m⁻² d⁻¹, with an average of 10±17 mg CH₄ m⁻² d⁻¹ (median: 5 mg CH₄ m⁻² d⁻¹). The fluxes from lakes were smaller than those observed in the floodplains, where the flooding was more dependent on the seasonal cycle. The diffusive flux showed a slight, but not statistically significant seasonal variation, following the seasonal variation of the flooding of the Pantanal region. A rough estimative of the total annual CH₄ emission shows that the contribution of the Pantanal is about 3.3 Tg CH₄ yr⁻¹, which represents about 3.3% of the total CH₄ emissions estimated to be originated in wetlands ecosystems. It may be a conservative estimate, which may present a large interannual variation, since it was obtained during one of the lowest flood of the Pantanal in recent years.     

Responses of antioxidant status and Na+–K+-ATPase activity in gill of rainbow trout,Oncorhynchus mykiss,chronically treated with carbamazepine

In recent years, chemical pollution by the residual pharmaceuticals has been increasingly important issue due to its widely present in the aquatic environment. However, the toxicological effects of residual pharmaceuticals on fish have not been adequately researched. The aim of this work is to investigate the toxic effect of CBZ, an anticonvulsant drug commonly present in aquatic environment, on antioxidant status and Na⁺–K⁺-ATPase in gill of rainbow trout exposed to sublethal CBZ (1.0 μg L⁻¹, 0.2 mg L⁻¹ and 2.0 mg L⁻¹) for 7, 21 and 42 d. After prolonged exposure of CBZ at higher test concentration (0.2 or 2.0 mg L⁻¹), oxidative stress was apparent as reflected by the significant higher LPO and CP levels in fish gill, as well as the significant inhibition of antioxidant enzymes activities including SOD, CAT, GR and GPx. Besides, reduced glutathione level and Na⁺–K⁺-ATPase activity were significantly lower than those of the control after 42 d of exposure to CBZ at higher test concentration (0.2 or 2.0 mg L⁻¹). The results of this study indicate that chronic exposure of CBZ has altered multiple physiological indices in fish gill; however, before those parameters are used as special biomarkers for monitoring residual pharmaceuticals in aquatic environment, more detailed experiments in laboratory need to be performed in the future.     

Sulfuric odorous compounds emitted from pig-feeding operations

The objective of the study was to quantify the concentration and emission levels of sulfuric odorous compounds emitted from pig-feeding operations. Five types of pig-housing rooms were studied: gestation, farrowing, nursery, growing and fattening rooms. The concentration range of sulfuric odorous compounds in these pig-housing rooms were 30–200 ppb for hydrogen sulfide (H₂S), 2.5–20 ppb for methyl mercaptan (CH₃SH), 1.5–12 ppb for dimethyl sulfide (DMS; CH₃SCH₃) and 0.5–7 ppb for dimethyl disulfide (DMDS; CH₃S₂CH₃), respectively. The emission rates of H₂S, CH₃SH, DMS and DMDS were estimated by multiplying the average concentration (mg m⁻³) measured near the air outlet by the mean ventilation rate (m³ h⁻¹) and expressed either per area (mg m⁻² h⁻¹) or animal unit (AU; liveweight of the pig, 500 kg) (mg pig⁻¹ h⁻¹). As a result, the emission rates of H₂S, CH₃SH, DMS and DMDS in the pig-housing rooms were 14–64, 0.8–7.3, 0.4–3.4 and 0.2–1.9 mg m⁻² h⁻¹, respectively, based on pig's activity space and 310–723, 18–80, 9–39 and 5–22 mg AU⁻¹ h⁻¹, respectively, based on pig's liveweight, which indicates that their emission rates were similar, whether based upon the pig's activity space or liveweight. In conclusion, the concentrations and emission rates of H₂S were highest in the fattening room followed by the growing, nursery, farrowing and gestation rooms whereas those of CH₃SH, DMS and DMDS concentrations were largest in the growing room followed by the nursery, gestation and farrowing rooms.     

Preparation of controlled nano-MgO and investigation of its bactericidal properties

Nano-MgO is a good bactericide but with strong alkalinity in water due to its rapid hydrolysis. To control its hydrolysis rate and keep its bactericidal properties, we synthesized nano-MgO microspheres using chitosan–alginate system in this study. The synthesized nano-MgO release-controlled microspheres (nMgO-RCM) were with 0.98–1.20 mm of particle sizes. Also, their embedding ratio and loading percentage was 63.52% and 12.27%, respectively. Based on the characterization results, nano-MgO was only observed on surface of the nMgO-RCM. Its release rate from the nMgO-RCM could be controlled by the chitosan–alginate system, and the observed rate constant (k_obs) increased from 0.0289 h⁻¹ to 0.0358 h⁻¹ with the increment of the dosage from 10 mg L⁻¹ to 80 mg L⁻¹. Furthermore, the nMgO-RCM could maintain pH value lower than 8.5 and colony counts less than 20 CFU mL⁻¹ for at least 120 h.     

Characterization of emissions from portable household combustion devices: particle size distributions,emission rates and factors,and potential exposures

A series of source tests were conducted to characterize emissions of particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), and total hydrocarbon (THC ) from five types of portable combustion devices. Tested combustion devices included a kerosene lamp, an oil lamp, a kerosene space heater, a portable gas range, and four unscented candles. All tests were conducted either in a well-mixed chamber or a well-mixed room, which enables us to determine emission rates and emission factors using a single-compartment mass balance model. Particle mass concentrations and number concentrations were measured using a nephelometric particle monitor and an eight-channel optical particle counter, respectively. Real-time CO concentrations were measured with an electrochemical sensor CO monitor. CO₂, CH₄, and THC were measured using a GC-FID technique. The results indicate that all particles emitted during steady burning in each of the tested devices were smaller than 1.0 μm in diameter with the vast majority in the range between 0.1 and 0.3 μm. The PM mass emission rates and emission factors for the tested devices ranged from 5.6±0.1 to 142.3±40.8 mg h⁻¹ and from 0.35±0.06 to 9.04±4.0 mg g⁻¹, respectively. The CO emission rates and emission factors ranged from 4.7±3.0 to 226.7±100 mg h⁻¹ and from 0.25±0.12 to 1.56±0.7 mg g⁻¹, respectively. The CO₂ emission rates and emission factors ranged from 5500±700 to 210,000±90,000 mg h⁻¹ and from 387±45 to 1689±640 mg g⁻¹, respectively. The contributions of CH₄ and THC to emission inventories are expected to be insignificant due both to the small emission factors and to the relatively small quantity of fuel consumed by these portable devices. An exposure scenario analysis indicates that every-day use of the kerosene lamp in a village house can generate fine PM exposures easily exceeding the US promulgated NAAQS for PM_2.5.     

The effects of evaporating essential oils on indoor air quality

Essential oils, predominantly comprised of a group of aromatic chemicals, have attracted increasing attention as they are introduced into indoor environments through various forms of consumer products via different venues. Our study aimed to characterize the profiles and concentrations of emitted volatile organic compounds (VOCs) when evaporating essential oils indoors. Three popular essential oils in the market, lavender, eucalyptus, and tea tree, based on a nation-wide questionnaire survey, were tested. Specific aromatic compounds of interest were sampled during evaporating the essential oils, and analyzed by GC-MS. Indoor carbon monoxide (CO), carbon dioxide (CO₂), total volatile organic compounds (TVOCs), and particulate matters (PM₁₀) were measured by real-time, continuous monitors, and duplicate samples for airborne fungi and bacteria were collected in different periods of the evaporation. Indoor CO (average concentration 1.48 vs. 0.47 ppm at test vs. background), CO₂ (543.21 vs. 435.47 ppm), and TVOCs (0.74 vs. 0.48 ppm) levels have increased significantly after evaporating essential oils, but not the PM₁₀ (2.45 vs. 2.42 ppm). The anti-microbial activity on airborne microbes, an effect claimed by the use of many essential oils, could only be found at the first 30–60 min after the evaporation began as the highest levels of volatile components in these essential oils appeared to emit into the air, especially in the case of tea tree oil. High emissions of linalool (0.092–0.787 mg m⁻³), eucalyptol (0.007–0.856 mg m⁻³), d-limonene (0.004–0.153 mg m⁻³), ρ-cymene (0.019–0.141 mg m⁻³), and terpinene-4-ol-1 (0.029–0.978 mg m⁻³), all from the family of terpenes, were observed, and warranted for further examination for their health implications, especially for their potential contribution to the increasing indoor levels of secondary pollutants such as formaldehyde and secondary organic aerosols (SOAs) in the presence of ozone.     

Impact of PCB-118 and transformer oil toxicity on anaerobic digestion of sludge: Anaerobic toxicity assay results

In this study, possible toxicity of increasing doses of PCB-118 and transformer oil (TO) on anaerobic sludge digestion was investigated. For this purpose, five different sets of reactors were prepared in which four different PCB-118 concentration (1, 10, 20, and 30 mg L⁻¹) and three different TO concentration (0.38, 0.76, and 1.52 g L⁻¹) were applied. Throughout the study, biogas production and composition, pH, TS, VS, and COD as well as PCB concentration were monitored. Toxicity was investigated by anaerobic toxicity assay (ATA) evaluating the reduction in methane production. A notable inhibition was observed mostly in 30 mg L⁻¹ PCB reactors. A negative influence of PCB-118 and TO was observed on COD and solids removal. A maximum of 26.5% PCB-118 removal was attained.     

Effect of DTPA on Cd solubility in soil – Accumulation and subsequent toxicity to lettuce

In a controlled environment experiment, using Cd spiked soil, lettuce plants were grown under a range of DTPA levels and were subsequently harvested to determine levels of phytoaccumulation. Cadmium phytoaccumulation significantly increased with increasing soil Cd level (P < 0.05) but unexpectedly decreased with increasing DTPA levels, despite the fact that solubility of Cd was increased in the soil. Cadmium translocation (from root to shoot) increased after DTPA application. Lettuce growth was inhibited by both Cd and DTPA (at and above 10 and 500 mg kg^?1 respectively), as a result of higher Cd mobility and subsequent toxicity which was caused by DTPA higher dosages. Metal solubility in the soil (ranged between 2.8 and 26.5 mg kg^?1) was found to be significantly higher (P < 0.01) as compared to control with increasing DTPA levels even after 3 months of DTPA application. Cadmium tissue concentration in all DTPA treatments was less than in the corresponding control treatment, indicating a negative effect of DTPA application on Cd uptake. In conclusion, lettuce was an unsuitable plant species for Cd accumulation, at least when associated with a DTPA chelator.     

Removal of sulfamethoxazole and sulfapyridine by carbon nanotubes in fixed-bed columns

Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have gained increasing attention because of the ecological risks these substances pose to plants, animals, and humans. This work systematically investigated the removal of SMX and SPY by carbon nanotubes (CNTs) in fixed-bed columns under a broad range of conditions including: CNT incorporation method, solution pH, bed depth, adsorbent dosage, adsorbate initial concentration, and flow rate. Fixed-bed experiments showed that pH is a key factor that affects the adsorption capacity of antibiotics to CNTs. The Bed Depth Service Time model describes well the relationship between service time and bed depth and can be used to design appropriate column parameters. During fixed-bed regeneration, small amounts of SMX (3%) and SPY (9%) were irreversibly bonded to the CNT/sand porous media, thus reducing the column capacity for subsequent reuse from 67.9 to 50.4 mg g^?1 for SMX and from 91.9 to 72.9 mg g^?1 for SPY. The reduced column capacity resulted from the decrease in available adsorption sites and resulting repulsion (i.e., blocking) of incoming antibiotics from those previously adsorbed. Findings from this study demonstrate that fixed-bed columns packed with CNTs can be efficiently used and regenerated to remove antibiotics from water.     

Long-term measurements of SO2 dry deposition over Gansu Province,China

Potassium carbonate sulfation plates, monitored monthly for 11 years from 48 sites in 11 cities in Gansu Province, China, provide a crude estimate of cumulative SO₂ dry depositions. Measured SO₂ dry deposition rates were 1.6–472 mg m⁻² day⁻¹ and had seasonal variations with maxima in winter and minima mainly during summer as a result of higher winter and lower summer SO₂ concentrations. The 11-year monthly average SO₂ dry deposition rates are 23.2–248.97 and 11.7–175.6 mg m⁻² day⁻¹ in the eleven cities in winter and summer, respectively. A monthly average SO₂ deposition velocity was also estimated from 0.06 to 9.72 cm s⁻² in the 11 cities studied with a 11-year average maximum value of about 1.1–2.7 cm s⁻² in April and July and a 11-year average minimum value of about 0.2–1.0 cm s⁻¹ in January. The SO₂ dry deposition velocity also exhibits an increasing with wind speed in basins of less than 500 mm annual precipitation. In contrast, due to influences of the relative humidity in valleys of more than 500 mm annual precipitation, it shows a decreasing trend with wind speed increasing.     

Natural radioactivity levels in soil samples from some areas of Himachal Pradesh,India using γ-ray spectrometry

²²⁶Ra, ²³²Th and ⁴⁰K analysis has been carried out in soil samples collected from some areas of Himachal Pradesh, India using γ-ray spectrometry. The measured activity in soil ranges from 42.09 to 79.63 Bq kg⁻¹, 52.83 to 105.81 Bq kg⁻¹ and 95.33 to 160.30 Bq kg⁻¹ for ²²⁶Ra, ²³²Th and ⁴⁰K with the mean values of 57.34, 82.22 and 135.75 Bq kg⁻¹, respectively. The measured activity concentration of ²²⁶Ra and ²³²Th in soil samples collected from these areas is higher and for ⁴⁰K is lower than the world average. The radium equivalent activity in all the soil samples is lower than the safe limit set in the OECD report (370 Bq kg⁻¹). The value of the external exposure dose has been determined from the content of these radionuclides in soil. It has been observed that on the average, the outdoor terrestrial gamma air absorbed dose rate is about 83.28 nGy h⁻¹. The study yields an annual effective dose in the range of 0.07–0.13 mSv. The average value of annual effective dose lies in the global range of outdoor radiation exposure given in United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) [(2000). Effects and risks of ionizing radiations. UN, NY]. The activity concentration of ²³⁸U has also been determined using fission track technique and the values range from 3.26 to 7.71 mg kg⁻¹ with a mean value of 4.38 mg kg⁻¹.     

A novel field measurement method for determining fine particle and gas emissions from residential wood combustion

Emission data from residential wood combustion are usually obtained on test stands in the laboratory but these measurements do not correspond to the operational conditions in the field because of the technological boundary conditions (e.g. testing protocol, environmental and draught conditions). The field measurements take into account the habitual practice of the operators and provide the more reliable results needed for emission inventories. In this study, a workable and compact method for measuring emissions from residential wood combustion in winter conditions was developed. The emissions for fine particle, gaseous and PAH compounds as well as particle composition in real operational conditions were measured from seven different appliances. The measurement technique worked well and was evidently suitable for winter conditions. It was easy and fast to use, and no construction scaffold was needed. The dilution of the sample with the combination of a porous tube diluter and an ejector diluter was well suited to field measurement. The results indicate that the emissions of total volatile organic carbon (TVOC) (17 g kg⁻¹ (of dry wood burned)), carbon monoxide (CO) (120 g kg⁻¹) and fine particle mass (PM₁) (2.7 g kg⁻¹) from the sauna stove were higher than in the other measured appliances. In the masonry heaters, baking oven and stove, the emissions were 2.9–9 g kg⁻¹ TVOC, 28–68 g kg⁻¹ CO and 0.6–1.6 g kg⁻¹ PM₁. The emission of 12 PAHs (PAH₁₂) from the sauna stove was 164 mg kg⁻¹ and consisted mainly of PAHs with four benzene rings in their structure. PAH₁₂ emission from other appliances was, on average, 21 mg kg⁻¹ and was dominated by 2-ring PAHs. These results indicate that despite the non-optimal operational practices in the field, the emissions did not differ markedly from the laboratory measurements.     

Effects of aqueous stable fullerene nanocrystals (nC60) on Daphnia magna: Evaluation of sub-lethal reproductive responses and accumulation

Concerns exist regarding the inadvertent release of engineered nanomaterials into natural systems, and the possible negative ecosystem response that may occur. Understanding sub-lethal effects may be particularly important to determining ecosystem responses as current levels of nanomaterial release are low compared to levels projected for the future. In this work, the sub-lethal effects and bioaccumulation of water stable, nanocrystalline fullerenes as C₆₀, (termed nC₆₀) were studied in Daphnia magna, a globally distributed, parthenogenetic zooplankton. Sub-lethal concentrations were first determined for both mature mother (LD₅₀ = 0.4 mg L⁻¹) and neonate (gestating) daphnids (0.2 mg L⁻¹) in standard 48 h exposure tests. Subsequent experiments focused on the accumulation and effects (at temperatures of 18–28 °C) of nC₆₀, during the D. magna reproductive cycle. The results demonstrate that upon sub-lethal exposure, the mortality rates of gestating daphnids increased with time and developmental stage. The maturation of daughter daphnids was negatively impacted. The mother daphnids were unable to reproduce again after exposure during pregnancy, and differential bioaccumulation occurred as a function of lipid content in the daphnia with the highest accumulation level of 7000 mg kg⁻¹ wet weight. Taken together, these results not only describe the accumulation and sub-lethal effects of nC₆₀ on exposed daphnia, but also highlight the importance of sub-lethal exposure scenarios, which are critical to fully understanding the potential impact of fullerenes and other engineered nanoscale materials on natural systems.     

Importance of wet precipitation as a removal and transport process for atmospheric water soluble carbonyls

Carbonyl compounds exist in the atmosphere as either gases or aerosols. Some of them are water soluble and known as oxidation products of biogenic and/or anthropogenic hydrocarbons. Five carbonyl compounds, glyoxal (GO), 4-oxopentanal (4-OPA), glycolaldehyde (GA), hydroxyacetone (HA) and methylglyoxal (MG) have been identified in a temporal series of 12 rain samples. The concentrations of the compounds in the samples were high at the beginning of the rain event and decreased with time to relatively low and fairly constant levels, indicating that the compounds were washed out from the atmosphere at the start of the rain event. Possibly, these compounds also existed in the cloud condensation nuclei (CCN). Wet deposition rates of the carbonyl compounds were calculated for nine samples collected during a 20 h period. The deposition rates ranged from 0 (4-OPA) to 1.2×10⁻¹ mg C m⁻² h⁻¹ (MG) with the average of 2.9×10⁻² mg C m⁻² h⁻¹. Production rates of isoprene oxidation products (GA, HA and MG) in the area surrounding the sampling site were estimated with a chemical box model. The deposition rates exceeded the production rates in most samples. This indicates that the rainfall causes a large net flux of the water soluble compounds from the atmosphere to the ground. Insoluble carbonyl compounds such as n-nonanal and n-decanal were expected to be present in the atmosphere, but were not detected in the rain during the sampling period, suggesting that an aerosol containing these insoluble compounds does not effectively act as a CCN.