Spatiotemporal trends of PM2.5 and its major chemical components at urban sites in Canada

To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_2.5 data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_2.5 collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_2.5 mass concentrations ranged from 5.7 to 9.6 µg/m³. Seven-year mean concentrations of SO₄^2?, NO₃^?, NH₄⁺, organic carbon (OC), and elemental carbon (EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 µg /m³, accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_2.5 mass. PM_2.5 and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_2.5 and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO₄^2? and NH₄⁺ were comparable, while those of NO₃^?, OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO₄^2? and NH₄⁺ and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO₄^2? and wintertime peaks for NO₃^?, but those of NH₄⁺, OC, and EC exhibited different seasonality at different locations.     

Urinary level of homovanillic acid and mercury in autistic children

Catecholamines and their metabolites affect children's nervous system. Dopamine is an important neurotransmitter in the brain. In the routine analysis for diagnostics of diseases, the dopamine metabolite homovanillic acid (HVA) is determined. Mercury is a neurotoxic agent and can cause different undesirable effects on the brain. In the present work a putative correlation between HVA, the main metabolite of dopamine, and mercury in urine of healthy and autistic children was studied. The level of HVA was higher in the urine of autistic children (14.5 ± 8.3 mg L^?1) compared to generally healthy children (4.4 ± 0.5 mg L^?1). The level of mercury in the urine of autistic children was lower (0.36 ± 0.24 µg L^?1) than in the urine of healthy children (2.1 ± 1.0 µg L^?1) showing that there is no correlation between HVA and mercury.     

Development and application of cross-linked polyethylenimine for trace metal and metalloid removal from mining and industrial wastewaters

Pollution of water bodies by trace metals is an established problem and several studies have been conducted to deal with it. South Africa is amongst those countries whose water systems are most affected as a result of intensive mining activities. This research was dedicated to the development of an insoluble chelating polymer for use as an adsorbent for abstraction of metal ions from mining and industrial wastewaters. Polyethylenimine (PEI), well known for its metal chelating potential, was cross-linked by epichlorohydrin (ECH) in order to convert it into a water-insoluble form for direct use as an adsorbent. The binding affinity of the cross-linked polyethylenimine (CPEI) to heavy metal ions was assessed as well as its ability to be regenerated for re-use. CPEI exhibited good complexation ability to metal ions with high affinity to Cr and most divalent metal ions. The observed order of complexation was: Cr?>?Zn>?Fe?>?Ni?>?Mn?>?Pb. On the other hand, it showed very poor ability to bind oxo-anions such as SeO₃ ^2? and AsO₂ ^? which has been attributed to the unavailability of suitable functional groups to interact with these ions.     

Dust-particle migration around flotation tailings ponds: pine needles as passive samplers

The potential use of dust particles trapped on Scots pine needles for tracking dust migration around flotation tailings ponds in the Silesian-Krakowian ore district, Southern Poland was tested. 1-, 2- and 3-years old needles were studied using a scanning electron microscope and energy dispersive X-ray microanalysis. Particle sizes and morphologies, and the nature of the compounds hosting metals ions, were examined. A large majority of the particles examined are <10 microm in size. Almost 80% of particles represent respirable dust. All the components in the flotation wastes appear among the chemical compounds identified in particles on the pine needles. The quantity of the waste particles decreases with distance from the flotation tailings ponds. The analysis of dust particles on pine needles could be a useful method for estimating vectors and travel distances of suspended dust migrating around open flotation tailings ponds and around other point sources emitting dust particles with chemical compositions differing from the environmental background.     

Heavy metal accumulation and distribution in Phragmites australis seedlings tissues originating from natural and urban catchment

The retention of heavy metal (HM) was studied in root and rhizomes (BLG), stems (ST), and leaves (LF) of Phragmites australis (common reed) seedlings collected from different locations, differing in the scale of anthropogenic interference. The analysis includes the reference samples of sediments in uncontaminated lake Garczonki and contaminated roadside ditch in Cieplewo. The concentrations of Zn, Cu, Pb, Cd, Ni, and Cr were analyzed in plant tissues and sediments using the atomic absorption spectrometry and inductively coupled plasma mass spectrometry. The general assessment of sediments collected in the Garczonki lake showed a good environmental status; while in the roadside ditch in Cieplewo, the sediments were considerably polluted with HM. In the first stage of plant growth, all of the analyzed HMs are mainly inhibited by BLG system. The decreasing trend of elements was as follows: BLG > ST > LF. The organs followed different decreasing trends of HM concentration; the trend Zn > Cu > Ni > Cr > Pb > Cd was found in ST and LF for the Garczonki lake seedlings and for BLG and LF for the roadside ditch in Cieplewo seedlings. Zn showed the highest concentration, while Cd the lowest concentration in each of the examined organs. The bioaccumulation factor indicated the higher mobility of HM in seedlings in the Garczonki lake than in the roadside ditch in Cieplewo. The morphological studies suggest the good state and health of seedling from both sites; however, the reduction of root hair surface was observed for the roadside ditch seedlings. The anatomical studies present changes in the size of the nucleus and count of chloroplasts in LF. No reaction on HM contamination sediments in the seedlings from the roadside ditch in Cieplewo in the aerenchyma was noted. Potentially, both types of seedlings can be used to decontaminate environments rich in HM. However, the level of HM absorbed by seedlings (in the first stage of growth) should be considered due to the behavior in the target phytoremediation site.

     

Proposal of new convenient extractant for assessing phytoavailability of heavy metals in contaminated sandy soil

Environmental Science and Pollution Research - The aim of the study was to compare the usefulness of 1&nbsp;M HCl with aqua regia, EDTA, and CaCl2 for the extraction of phytoavailable forms of...     

Genotoxicological effects of some phenoxyherbicides and their metabolites on Bacillus subtilis M45 Rec- and H17 Rec+ strains

Because they are used in a number of commercial preparations phenoxyacetic acids and their salts can occur in wastewater. During their degradation genotoxic substances may be created. The results of investigations of biodegradability and genotoxicity of some phenoxyherbicides are presented. Commercial formulations of 2,4-D (Aminopielik 720) and MCPA (Chwastox Extra) were the substrates studied. Biodegradation tests were conducted according to OECD guidelines for testing of chemicals--confirmatory test (OECD Method 303 A). Genotoxicity tests were conducted with Bacillus subtilis strains according to the method of [Chemical Mutagens, vol. 6, Plenum Press. New York, 1980, p. 149]. Genotoxicity of biodegradation products was also studied. Both commercial formulations were biodegradable. Aminopielik 720 was potentially genotoxic but only at great concentrations while Chwastox Extra was not genotoxic. Biodegradation products of neither compound were genotoxic.     

Novel Tough Crystalline Blends of Polylactide with Ethylene Glycol Derivative of POSS

Blending of polylactide (PLA) with low stereoregularity and polyhedral oligomeric silsesquioxane grafted with arms of poly(ethylene glycol) methyl ether, acting as a plasticizer, allowed us previously to obtain a novel stable elastomeric-like material. The present contribution focuses on the properties of semi-crystalline PLA plasticized with this compound. Melt blends of PLA with 5–15 wt% of the plasticizer, were compression molded, quenched and annealed, which enabled cold-crystallization. The glass transition temperature of the blends and their drawability depended on their crystallinity and plasticizer content. The best ductility was reached at the plasticizer content of 15 wt%; the achieved strain at break was 6.5 (650%) and 1.3 (130%), for the quenched and annealed material, respectively. The latter value exceeded 20 times the strain at break of neat crystalline PLA. The tensile toughness of the annealed 15 wt% blend was 12 times larger than that of crystalline PLA. Moreover, annealing of 15 wt% blend improved its yield strength by 40%. Despite the two peaks of the loss modulus, indicating the two glass transitions in this blend, no heterogeneities were found by scanning electron microscopy, indicating that the plasticizer enriched phase formed instead of distinct inclusions of the plasticizer.     

Occupational Exposure to Polycyclic Aromatic Hydrocarbons During Diesel Combustion

Identification and determination of polycyclic aromatic hydrocarbons (PAHs) in Diesel exhaust in the working environment and assessment of workers’ occupational exposure to these suspected human carcinogens were the aim of this experimental investigation.

The range of exposure factors calculated on the basis of 9 individual PAH concentrations determined in personal air samples shows that time-averaged concentration of these compounds did not exceed the Polish Maximum Admissible Concentration (MAC) value for PAHs, that is, 2 μg·m^–3. The highest concentrations of PAHs were determined in the breathing zone of forklift operators. The maximum exposure factor was 0.427 μg·m^–3 (about 1/4 of MAC).