首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Ambient concentrations and the elemental composition of particles less than 2.5 microm in diameter (PM2.5), as well as carbon monoxide (CO) concentrations, were measured at ground-level in three Guatemalan cities in summer 1997: Guatemala City, Quetzaltenango, and Antigua. This pilot study also included quantitative and qualitative characterizations of microenvironment conditions, e.g., local meteorology, reported elsewhere. The nondestructive X-ray fluorescence elemental analysis (XRF) of Teflon filters was conducted. The highest integrated average PM2.5. concentrations in an area (zona) of Guatemala City and Quetzaltenango were 150 microg m(-3) (zona 12) and 120 microg m(-3) (zona 2), respectively. The reported integrated average PM2.5 concentration for Antigua was 5 microg m(-3). The highest observed half-hour and monitoring period average CO concentrations in Guatemala City were 10.9 ppm (zona 8) and 7.2 ppm (zonas 8 and 10), respectively. The average monitoring period CO concentration in Antigua was 2.6 ppm. Lead and bromine concentrations were negligible, indicative of the transition to unleaded fuel use in cars and motorcycles. The XRF results suggested sources of air pollution in Guatemala, where relative rankings varied by city and by zonas within each city, were fossil fuel combustion emitting hydrocarbons, combustion of sulfurous conventional fuels, soil/roadway dust, farm/agricultural dust, and vehicles (evaportion of gas, parts' wear).  相似文献   

2.
A variety of models for predicting the behaviour of radionuclides in fresh water ecosystems have been developed and tested during recent decades within the framework of many international research projects. These models have been implemented in Computerised Decision Support Systems (CDSS) for assisting the appropriate management of fresh water bodies contaminated by radionuclides. The assessment of the state-of-the-art and the consolidation of these CDSSs has been envisaged, by the scientific community, as a primary necessity for the rationalisation of the sector. The classification of the approaches of the various models, the determination of their essential features, the identification of similarities and differences among them and the definition of their application domains are all essential for the harmonisation of the existing CDSSs and for the possible development and improvement of reference models that can be widely applied in different environmental conditions. The present paper summarises the results of the assessment and evaluation of models for predicting the behaviour of radionuclides in lacustrine ecosystems. Such models were developed and tested within major projects financed by the European Commission during its 4th Framework Programme (1994-1998). The work done during the recent decades by many modellers at an international level has produced some consolidated results that are widely accepted by most experts. Nevertheless, some new results have arisen from recent studies and certain model improvements are still necessary.  相似文献   

3.
The mathematical model used by Repace and Lowrey to arrive at the quantitative estimate of five lung cancer deaths per year 100, 000 persons exposed to ETS is questioned based on data from published international studies. A challenge of the Repace and Lowrey calculations is necessary to allay the concern which has arisen from the uncritical acceptance of the preliminary accusative estimates.  相似文献   

4.
In the present paper a generic model for predicting the long-term migration of radionuclides and heavy metals from catchments is described. The model subdivides the catchment into a number of homogeneous, infinitesimal sub-catchments and integrates the radionuclide contributions from such sub-catchments to calculate the total flux of contaminant. It relates the radionuclide behaviour to the statistical distribution of the pollutant partition coefficient on the "ensemble" of sub-catchments. The methodology was validated for 90Sr and 137Cs by using data for water contamination in some European rivers. Values of migration parameters for Pu, Tc, I and Cd isotopes were obtained.  相似文献   

5.
As far as the impact of air pollutants on human health being is concerned, ozone (O3) is one of the most pollutant sources, and, in particular, the ground level ozone is responsible for a variety of adverse effects on both human being and plant life. To protect the population from such adverse health effects, early information and precautions about the high ozone level need to be ascertained. In this study, statistical characteristics of ground level ozone is analyzed according to field monitoring data in mixed residential, commercial and industrial areas, e.g., Tsuen Wan area in Hong Kong. The study deals with the characteristics of hourly and daily mean ozone levels under different climatic conditions such as temperature, solar radiation (SR), wind speed (WS), and other pollutant concentration levels. The study aims to investigate the importance of meteorological factors and their impact on relevant pollutant concentration levels from a chemical aspect. Further, reasons for the spatial and temporal variation of ozone levels are discussed. All these results will provide a physical basis for accurately predicting ozone concentration in similar research.  相似文献   

6.
Fluorinated organic compounds (FOCs) are a group of chemicals widely used as surfactants, lubricants, polymers, and fire-fighting foams. Recent studies have shown the ubiquitous distribution of FOCs in the environment, wildlife, and humans. We here report the results of a pilot study conducted to provide preliminary data on the levels of 13 FOCs in the blood of 48 residents in Catalonia, Spain, in relation to gender and age (25+/-5 and 55+/-5 years). The highest mean concentration was obtained for perfluorooctane sulfonate (PFOS, 7.64 ng/ml), followed by perfluorohexane sulfonate (PFHxS, 3.56 ng/ml) and perfluorooctanoic acid (PFOA, 1.80 ng/ml). Four other FOCs showed mean levels between 0.30 and 0.44 ng/ml, whereas those of the remaining 6 compounds were below the detection limit. Regarding gender, the blood levels of PFHxS and PFOA were significantly higher (p<0.05) in men than in women, while differences according to age were only noted for PFHxS (p<0.05) and perfluorooctane sulfonamide (PFOSA) (p<0.001), for which the levels were higher in the younger (25+/-5 years) group of subjects. A significant correlation between PFOS levels and those of the remaining detected FOCs (except PFDA) was found. In general terms, the current FOC concentrations were lower than those found in recent studies concerning levels of these chemicals in human blood and serum of subjects from different countries.  相似文献   

7.
The radiological assessment of the impact of nuclear weapon's testing on the Semipalatinsk Test Site (STS) on the local population requires comprehensive site-specific information on radionuclide behaviour in the environment. However, information on radionuclide behaviour in the conditions of the STS is rather sparse and, in particular, there are no data in the literature on parameters of radionuclide transfer from feed to horse products proofed to be important contributors to the internal dose to the local population. The transfer of 137Cs and 90Sr to horse milk and meat was studied under laboratory and field conditions: in controlled experiment with three lactating horses maintained in the Kazakh Agricultural Research Institute, and in field measurements of horse products taken from horses grazing at the Semipalatinsk Test Site. The equilibrium transfer factors from feed to horse milk and meat were estimated to be 0.012 dl(-1) and 0.035 dkg(-1) for (137)Cs and 0.0022 dl(-1) and 0.003 dkg(-1) for (90)Sr, respectively. The biological half-lives were approximated by a sum of two exponentials amounting to 3 (85%) and 15 (15%) days for 137Cs and 3.5 (70%) and 100 (30%) days for 90Sr. The highest 137Cs transfer has been found to be to spleen, followed by lung, heart, muscles, kidneys, intestine, and finally skin and bones. For90Sr, the maximum activity concentration was observed in bones; contamination of other tissues is rather uniform except for liver and intestine with a factor of about 2 higher than muscles.  相似文献   

8.
In vitro assays have been developed to determine metal bioaccessibility in contaminated soils; however, their application to Cd is limited. To assess their suitability to determine Cd relative bioavailability (RBA), Cd-RBA in 12 contaminated soils containing 3.00–296 mg kg 1 Cd were determined using a mouse model and compared with Cd bioaccessibility data based on four assays including the UBM, SBRC, IVG, and PBET. After being administered feed amended with soil or CdCl2 for 10-day, the Cd concentrations in the mouse liver and/or kidneys were used as biomarkers to estimate Cd-RBA. Cd-RBA was comparable at 34–90% and 40–78% based on mouse liver and kidneys with RSD of 7.10–8.99%, and 37–84% based on mouse liver plus kidneys with lower RSD of 5.8%. Cadmium bioaccessibility in soils varied with assays, with 61–99, 59–103, 54–107, and 35–97% in the gastric phase and 20–56, 38–77, 42–88, and 19–64% in the intestinal phase of the UBM, SBRC, IVG and PBET assays. Based on the combined biomarker of liver plus kidneys, better correlation was observed for PBET (r2 = 0.61–0.70) than those for IVG, UBM and SBRC assays (0.12–0.52). The monthly Cd intake in children was 0.24–23.9 μg kg 1 using total Cd concentration in soils, which was reduced by 43% to 0.18–12.3 μg kg 1 using bioavailable Cd. Our data suggest it is important to consider Cd-RBA to assess risk associated with contaminated soils and the PBET may have potential to predict Cd-RBA in contaminated soils.  相似文献   

9.
OBJECTIVE: This November 2003 pilot study investigates the correlation between serum IgE and residential endotoxin levels from a group of 18 pregnant women living in Trujillo, Peru, and investigates the impact of the demographic and lifestyle factors of this group on the IgE and endotoxin levels measured. METHODS: Serum samples were collected from 19 subjects and analyzed for IgE. Dust samples were collected from the mattresses of 18 subjects and measured for endotoxin levels. A questionnaire was used to obtain demographic, socioeconomic, and lifestyle information for each subject. RESULTS: Geometric means for IgE and endotoxin were 246.8 (GSD=4.3, n=19) IU/mL and 66.5 EU/mg (GSD=1.7, n=18), respectively. Log-transformed IgE and endotoxin were not correlated (R2=0.02; p=0.60). CONCLUSIONS: Residential endotoxin and serum IgE were not correlated in this group. Potential selection bias and sample size are major limitations of the study. However, 74% (14/19) of the subjects in this study had an IgE over 100 IU/mL, a level generally considered elevated.  相似文献   

10.
A study of daily and seasonal variations of radon concentrations in underground buildings in major cities of China was carried out. According to the data from the Model 1027 continuous monitor, radon concentrations in the underground buildings changed through two cycles each day. The first cycle was from 12:00 to 0:00 and the highest or lowest value, depending on location, was at about 19:00. The second cycle had a little change. Based on the data from solid state nuclear detectors (SSNTDs), it was concluded that the radon concentrations in underground buildings in winter were lower than in summer, which was opposite to that above the ground level. Similar to that above the ground level, the radon concentrations in spring were close to the year-round average radon concentrations.  相似文献   

11.
The present study aims to analyse the influences of five meteorological parameters (temperature, wind speed, barometric pressure, rainfall, and solar radiations) on ground-level ozone (GLO) concentrations over the region of Ranchi Municipal Corporation (Jharkhand, India). The diurnal variation of GLO concentration and the meteorological parameters were analysed in each month to understand the associations. The results indicated that the correlation coefficients of GLO concentration with SR, AT, and DPT are found to be positive in each month and also statistically significant. But, the association between WS and GLO concentration was not uniform between the study days. Furthermore, the study also demonstrates an approach for identifying the hot spots that are having the higher level of GLO concentration. The hot spot maps were produced for each month to understand the shifting of the locations of hot spot locations. The results reveal that the hot spot locations are changes frequently in each case. Since the hot spot analysis was conducted with limited data, the presented hot spots are indicative and dependent on the meteorological conditions of the specific period and cannot be considered as a robust epidemiological study.  相似文献   

12.
Climate adaptation is a complex task surrounded by uncertainty. To support climate adaptation policies, a new scenario approach is pursued to explore possible discontinuous future developments of societal perspectives on climate adaptation issues. The scenario approach was tested for a case study on Dutch river management. In a series of scenario development workshops, a select group of stakeholders explored the perspectives on the management of the River Meuse in the past, present, and future. The process was supported by an analytical perspectives mapping tool to illustrate and analyze the development of perspectives over time. The process and analytical tools contributed to insight into the drivers of perspective change for the case study at hand. Moreover, the stakeholders highlighted the potential of the approach for water management policy for creating awareness about the plurality of perspectives and the dynamics of perspective change, monitoring perspectives and perspective change as part of a flexible policy approach, and anticipating on the occurrence of shock events. Further work is required to better represent the social dynamics of perspectives change, to better empirically ground the perspective change model, and to apply integrated water models in the scenario development process to assess water–society interactions.  相似文献   

13.
BackgroundPhthalates can disrupt endocrine function and induce reproductive and developmental toxicity in laboratory animals. Few studies have evaluated exposure to phthalates in pregnant women, despite the potential sensitivity of the developing fetus to adverse effects of phthalates.MethodsWe measured urinary concentrations of 11 phthalate metabolites in 19 pregnant women, recruited in Jerusalem, Israel in 2006, and collected questionnaire data on demographic factors and consumer habits from these women. We compared geometric mean concentrations in subgroups and used the Mann–Whitney U-test for independent samples to determine significant differences between groups.ResultsNine metabolites were detected in at least 95% of the samples: mono(2-ethyl-5-carboxypentyl) phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate, mono(3-carboxypropyl) phthalate, mono(n-butyl) phthalate, monobenzyl phthalate (MBzP), monoethyl phthalate (MEP), mono(2-ethylhexyl) phthalate and monoisobutyl phthalate. Phthalate metabolite concentrations in these pregnant women were remarkably similar to those in the general United States female population. MBzP geometric mean concentrations were higher in women living in buildings existing 40 years or more (P = 0.04). In women who used four or more personal care products (perfume, deodorant, lipstick, nail polish, or hand/face cream) in the 48 h prior to providing the urine sample, geometric mean MEP concentrations were more than 4 times higher than concentrations in women using only two or three of the aforementioned products (P = 0.07).ConclusionsPregnant women in Jerusalem are exposed to a wide range of phthalates. Building materials used in old constructions may be a source of exposure to benzylbutyl phthalate, the parent compound of MBzP. Personal care products may be sources of exposure to diethyl phthalate, the parent compound of MEP.  相似文献   

14.
All full-time residents (N = 24) from six homes with urea formal dehyde foam insimulation underwent standardized allergy, respiratory, and neuropsychiatric tests. Skin testing did not reveal an increased prevalence of atopy or reaction to 4% formalin. Spirometry was normal in all subjects, and bronchial reactivity was not significantly different from a population-based response to the same challenge. Memory difficulty was a frequently reported symptom. Memory storage deficits could not be documented, but 11 of 14 subjects had abnormal tests of attention span. Eight of the 11 subjects with attention span deficits had elevated depression scores. Chronic low level exposure to formaldehyde may cause significant mental status changes, but further testing of a larger, randomly population is necessary to evaluate this question.  相似文献   

15.
16.
Arsenic level of hair samples of apparently healthy Egyptian was measured by means of hydride atomic absorption spectrophotometery. It ranged between 0.04 and 1.04 mg As/kg hair, about 55% of the analysed hair samples were within the range of allowable values (0.08-0.25 mg As/kg hair), but 45% were not. There were no considerable sex-related differences (0.303 and 0.292 mg As/kg hair for males and females, respectively). Different educational levels did not influence it either, when the effect of the age had been excluded. Children and adolescents proved to be more susceptible to arsenic as their mean levels (0.353 microg/g), and were significantly higher than those in the adults (0.233 microg/g). Smoking and some dietary habits had an important role in the elevation of arsenic levels among the nonoccupational Egyptian population: 60% of smokers and 66.7% of indoor passive smokers had arsenic levels >0.25 mg As/kg hair. Arsenic levels were also dependent on the kind of smoking, as hair arsenic of the subject smoking molasses tobacco was found to be significantly higher than that of cigarette smokers (0.459 and 0.209 mg As/kg hair, respectively). The frequency of meat and fish consumption per week was also found to be positively, significantly correlated with arsenic levels. On the other hand, the frequency of consumption of fruits, fresh and cooked vegetables, milk and milk products per week beneficially influenced the arsenic level of the hair samples examined. Arsenic content of the consumed water in Egypt was 0.001 mg/l, which is below the maximum drinking water level allowed by World Health Organisation (WHO). Therefore, the arsenic content of domestic tap water hardly contributed to the arsenic exposure of the Egyptian population in the regions of the study. It is likely that exposure routes by smoking, fish and animal protein consumption are the principal cause of arsenic accumulation in the general Egyptian population.  相似文献   

17.
Environmental contamination caused by extra heavy oil-based drill cuttings (DCs) is a major problem in the Liaohe Oilfield, northeastern China. To study the potential effectiveness of the mature reed wetland in removing extra heavy oil contained in drill cuttings, biodegradation of extra heavy oils and study of the effects on soil property and ecophysiological and quality indices of reeds were carried out in a 2-year in situ pilot experiment. In the wetland, four reed beds were used to treat drill cuttings in various loadings: 0 (control), 5, 20, and 40 kg/m(2), corresponding to 150, 600, and 1200 g/m(2) extra heavy oil hydrocarbons (HCs). The obtained results demonstrate that the mature reed wetland was effective at degrading extra heavy oils without extra fertilization. Removal efficiencies of reed bed 2 in the 0- to 80-cm soil profile increased with time, from 90.1% (first harvest season) to 95.8% (second harvest season). After 2 years, only 4.2% of the initial hydrocarbons residual was retained in the surface soil. There was no apparent adverse effects on the surface soil property during degradation of extra heavy oils and, actually, the deeper soil property and reed quality indices were improved at the end of the experiment. Phytotoxicity, resulting in reduction of reed yield, was observed in the most heavily treated beds in the first year. However, long-term reed yield recovered robustly. During the 2-year period, reed height and leaf number were slightly inhibited.  相似文献   

18.
In a published controlled dosing experiment, a single individual consumed 5 mg each of labeled di-n-butyl phthalate (DnBP) and diisobutyl phthalate (DiBP) on separate occasions and tracked metabolites in his blood and urine over 48 h. Data from this study were used to structure and calibrate simple pharmacokinetic (PK) models for these two phthalates, which predict urine and blood metabolite concentrations with a given phthalate intake scenario (times and quantities). The calibrated models were applied to a second published experiment in which 5 individuals fasted over the course of a 48-h weekend (bottled water only), and their full urine voids were captured and measured for DnBP and DiBP metabolites. One goal of this model application was to confirm the validity of the calibrated models — their validity would be demonstrated if a profile of intakes could be found which adequately duplicated the metabolite concentrations measured in the urine. A second goal was to study patterns of exposure for this group. It was found that all metabolites could be duplicated very well with individual-specific “best-fit” intake scenarios, with one exception. It appears that the model predicted much lower concentrations of the metabolite, 3carboxy-mono-propylphthalate (MCPP), than were observed in all individuals. Modeled as a metabolite of DnBP, this suggests that DnBP was not the major source of MCPP in the urine. For all 5 individuals, the reconstructed dose profiles of the two phthalates were similar: about 6 small bolus doses per day and an intake of about 0.5 μg/kg-day. The intakes did not appear to be associated with diary-reported activities (personal hygiene and medication) of the participants. The modeled frequent intakes suggested one (or both) of two possibilities: ongoing exposures such as an inhalation exposure, or no exposure but rather an ongoing release of body stores of the phthalate metabolites from past exposures.  相似文献   

19.
We review studies of the effects of low ambient ozone concentrations on morbidity that found a negative coefficient for ozone concentration. We call this a Paradoxical Ozone Association (POA). All studies were in regions with methyl ether in gasoline. All but one study carefully controlled for the effects of other criterion pollutants, so the phenomenon cannot be attributed to them. One was in southern California in mid-summer when ozone levels are highest. Because ozone is created by sunlight, the most plausible explanation for a POA would be an ambient pollutant that is rapidly destroyed by sunlight, such as methyl nitrite (MN). A previously published model of engine exhaust chemistry suggested methyl ether in the fuel will create MN in the exhaust. MN is known to be highly toxic, and closely related alkyl nitrites are known to induce respiratory sensitivity in humans. Support for the interpretation comes from many studies, including three linking asthma symptoms to methyl tertiary butyl ether (MTBE) and the observation that a POA has not been seen in regions without ether in gasoline. We also note that studies in southern California show a historical trend from more significant to less significant ozone-health associations. The timing of those changes is consistent with the known timing of the introduction of gasoline oxygenated with MTBE in that region.  相似文献   

20.
Background and goalsAs part of the authorization process for the solid waste incinerator (SWI) in Modena, Italy, a human biomonitoring cross-sectional pilot study was conducted to investigate the degree to which people living and working in the proximity of the plant were exposed to SWI emissions.MethodsBetween May and June 2010, 65 subjects living and working within 4 km of the incinerator (exposed) and 103 subjects living and working outside this area (unexposed) were enrolled in the study. Blood, serum and urinary metals (Pb, Cd, Cu, Zn, Hg, Mn, Ni), urinary benzene, toluene, xylene (BTEX), S-phenylmercapturic acid (SPMA), and urinary polycyclic aromatic hydrocarbons (PAHs) were analysed. Information about lifestyle, anthropometric characteristics, residence, and health status was collected by a self-administered questionnaire. Exposure to particulate matter (PM) emitted from the SWI was estimated using fall-out maps from a quasi-Gaussian dispersion model. A multiple linear regression analysis investigated the relationship between biomarkers and the distance of a subject's place of residence from the SWI plant or the exposure to PM.ResultsUrinary BTEX and SPMA and blood, serum and urinary metals showed no differences between exposed and unexposed subjects. PAHs were higher in exposed than in unexposed subjects for phenanthrene, anthracene, and pyrene (median levels: 9.5 vs. 7.2 ng/L, 0.8 vs. < 0.5 ng/L and 1.6 vs. 1.3 ng/L, respectively, p < 0.05). Multiple linear regression analysis showed that blood Cd and Hg and urinary Mn, fluorene, phenanthrene, anthracene and pyrene were inversely correlated to the distance of a subject's residence from the SWI. Urinary Mn, fluorene and phenanthrene were directly correlated to PM exposure.ConclusionsThis study, although not representative of the general population, suggests that specific biomarkers may provide information about the degree of exposure the subjects working and living in the proximity of the SWI plant may have to emissions from that facility.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号