Cadmium, zinc and copper levels were determined in the renal cortex and liver of 60 inhabitants of Cracow, Poland. Cadmium levels in the renal cortex were contained in broad limits of 5–176 g/g, mean 50.6 g/g (wet weight). Maximum levels were found in the age group of about 50–60 years. The levels were slightly higher in men (53 g/g) than in women (45 g/g), with no effect of location within the region. The levels in smokers (62 g/g) were much higher than in non-smokers (32 g/g). The above relations were less pronounced for cadmium levels in the liver. Whole body retention of cadmium followed the pattern of cadmium in renal cortex. The level of zinc in renal cortex reflected those of cadmium. A significant proportion of the population (54% in smokers, 9% in non-smokers) showed cadmium levels in renal cortex exceeding the reference level of 50 g/g recently accepted for general population. In the view of the authors the exposure to cadmium of the population of Cracow is excessive and calls for attention.The study was performed under a KBN grant No 40106 91 01. 相似文献
To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM2.5 data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM2.5 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 PM2.5 mass concentrations ranged from 5.7 to 9.6 µg/m3. Seven-year mean concentrations of SO42?, 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 PM2.5 mass. PM2.5 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 PM2.5 and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO42? 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 SO42? and NH4+ and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO42? and wintertime peaks for NO3?, but those of NH4+, OC, and EC exhibited different seasonality at different locations. 相似文献
Environmental Science and Pollution Research - The aim of the study was to compare the usefulness of 1 M HCl with aqua regia, EDTA, and CaCl2 for the extraction of phytoavailable forms of... 相似文献
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.
Passive sampling of pollutants in water has been gaining acceptance for environmental monitoring. Previously, an integrative passive sampler (the Chemcatcher) was developed and calibrated for the measurement of time weighted average concentrations of hydrophobic pollutants in water. Effects of physicochemical properties and environmental variables (water temperature and turbulence) on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water have been published. In this study, the effect of modification in sampler housing geometry on these calibration parameters was studied. The results obtained for polycyclic aromatic hydrocarbons show that reducing the depth of the cavity in the sampler body geometry increased the exchange kinetics by approximately twofold, whilst having no effect on the correlation between the uptake and offload kinetics of analytes. The use of performance reference compounds thus avoids the need for extensive re-calibration when the sampler body geometry is modified. 相似文献
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. 相似文献
This study reports ambient concentrations of 63 air toxics that were measured in Canada by the National Air Pollution Surveillance (NAPS) program over the period 2009–2013. Measured concentrations are compared with ambient air quality guidelines from Canadian jurisdictions, and compounds that exceeded guidelines are identified and discussed. Although this study does not assess risk or cumulative effects, air toxics that approached guidelines are also identified so that their potential contribution to ambient air toxics pollution can be considered. Eleven air toxics exceeded at least one guideline, and an additional 16 approached guidelines during the study period. Four compounds were measured using methods whose detection limits exceeded a guideline value, three of which could not be compared with guidelines, since they were not detected in any samples. The assessment of several metal(loid) concentrations is tentative, since they were measured only in fine particulate matter (PM) but compared with guidelines based on coarse or total PM. Improvements to sampling and analysis techniques for the latter compounds as well as for those whose methods are subject to known uncertainties would improve confidence in reported concentrations and their relation to applicable guidelines. Analysis of sampling strategies for all compounds found to exceed or approach guidelines would contribute to ensuring that their spatiotemporal coverage is adequate. Examination of the air toxics not measured by NAPS but having guidelines in Canadian jurisdictions or being included in other programs such as the U.S. National-Scale Air Toxics Assessment (NATA) would contribute to ensuring that the full suite of pollutants relevant to ambient air quality in Canada is subject to adequate study. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada.Implications: Recent measurements of 63 air toxics in Canada by the National Air Pollution Surveillance (NAPS) program showed that 11 compounds exceeded daily or annual ambient air quality guidelines and that an additional 16 compounds approached such guidelines within an order of magnitude. The results of this study can be applied to evaluating the effectiveness of toxic substances management in Canada and to identifying compounds that merit further investigation. 相似文献
Little is known about the level and content of exposure to fine particles (PM2.5) among persons who attend fireworks displays and those who live nearby. An evaluation of the levels of PM2.5 and their elemental content was carried out during the nine launches of the 2007 Montréal International Fireworks Competition. For each event, a prediction of the location of the firework plume was obtained from the Canadian Meteorological Centre (CMC) of the Meteorological Service of Canada. PM2.5 was measured continuously with a photometer (Sidepak?, TSI) within the predicted plume location (“predicted sites”), and integrated samples were collected using portable personal samplers. An additional sampler was located on a nearby roof (“fixed site”). The elemental composition of the collected PM2.5 samples from the “predicted sites” was determined using both a non-destructive energy dispersive ED-XRF method and an ICP-MS method with a near-total microwave-assisted acid digestion. The elemental composition of the “fixed site” samples was determined by the ICP-MS with the near-total digestion method. The highest PM2.5 levels reached nearly 10 000 μg m?3, roughly 1000 times background levels. Elements such as K, Cl, Al, Mg and Ti were markedly higher in plume-exposed filters. This study shows that 1) persons in the plume and in close proximity to the launch site may be exposed to extremely high levels of PM2.5 for the duration of the display and, 2) that the plume contains specific elements for which little is known of their acute cardio-respiratory toxicity. 相似文献
Background, aim, and scope Ionic liquids are regarded as essentially “green” chemicals because of their insignificant vapor pressure and, hence, are
a good alternative to the emissions of toxic conventional volatile solvents. Not only because of their attractive industrial
applications, but also due to their very high stability, ionic liquids could soon become persistent contaminants of technological
wastewaters and, moreover, break through into natural waters following classical treatment systems. The removal of harmful
organic pollutants has forced the development of new methodologies known as advanced oxidation processes (AOPs). Among them,
the Fenton and Fenton-like reactions are usually modified by the use of a higher hydrogen peroxide concentration and through
different catalysts. The aim of this study was to assess the effect of hydrogen peroxide concentration on degradation rates
in a Fenton-like system of alkylimidazolium ionic liquids with alkyl chains of varying length and 3-methyl-N-butylpyridinium chloride.
Materials and methods The ionic liquids were oxidized in dilute aqueous solution in the presence of two different concentrations of hydrogen peroxide.
All reactions were performed in the dark to prevent photoreduction of Fe(III). The concentrations of ionic liquids during
the process were monitored with high-performance liquid chromatography. Preliminary degradation pathways were studied with
the aid of 1H NMR.
Results Degradation of ionic liquids in this system was quite effective. Increasing the H2O2 concentration from 100 to 400 mM improved ionic liquid degradation from 57–84% to 87–100% after 60 min reaction time. Resistance
to degradation was weaker, the shorter the alkyl chain.
Discussion The compound omimCl was more resistant to oxidation then other compounds, which suggests that the oxidation rates of imidazolium
ionic liquids by OH· are structure-dependent and are correlated with the n-alkyl chain length substituted at the N-1-position. The level of degradation was dependent on the type of head group. Replacing
the imidazolium head group with pyridinium increased resistance to degradation. Nonetheless, lengthening the alkyl chain from
four to eight carbons lowered the rate of ionic liquid degradation to a greater extent than changing the head group from imidazolium
to pyridinium. 1H-NMR spectra show, in the first stage of degradation, that it is likely that radical attack is nonspecific,
with any one of the carbon atoms in the ring and the n-alkyl chain being susceptible to attack.
Conclusions The proposed method has proven to be an efficient and reliable method for the degradation of imidazolium ionic liquids by
a Fenton-like reagent deteriorated with lengthening n-alkyl substituents and by replacing the imidazolium head group with pyridinium. The enhanced resistance of 1-butyl-3-methylpyridinium
chloride when the resistance of imidazolium ionic liquids decreases with increasing H2O2 concentration is probably indicative of a change in the degradation mechanism in a vigorous Fenton-like system. H-NMR spectra
showed, in the first stage of degradation, that radical attack is nonspecific, with any one of the carbon atoms in the ring
and the n-alkyl chain being susceptible to attack.
Recommendations and perspectives Since ionic liquids are now one of the most promising alternative chemicals of the future, the degradation and waste management
studies should be integrated into a general development research of these chemicals. In the case of imidazolium and pyridinium
ionic liquids that are known to be resistant to bio- or thermal degradation, studies in the field of AOPs should assist the
future structural design as well as tailor the technological process of these chemicals 相似文献