خيارات البحث
النتائج 1911 - 1920 من 3,208
Influence of advections of particulate matter from biomass combustion on specific-cause mortality in Madrid in the period 2004–2009 النص الكامل
2015
Linares, C. | Carmona, R. | Tobías, A. | Mirón, I. J. | Díaz, J.
Approximately, 20 % of particulate and aerosol emissions into the urban atmosphere are of natural origin (including wildfires and Saharan dust). During these natural episodes, PM₁₀and PM₂.₅levels usually exceed World Health Organisation (WHO) health protection thresholds. This study sought to evaluate the possible effect of advections of particulate matter from biomass fuel combustion on daily specific-cause mortality among the general population and the segment aged ≥75 years in Madrid. Ecological time-series study in the city of Madrid from January 01, 2004 to December 31, 2009. The dependent variable analysed was daily mortality due to natural (ICD-10:A00-R99), circulatory (ICD-10:I00-I99), and respiratory (ICD-10:J00-J99) causes in the population, both general and aged ≥75 years. The following independent and control variables were considered: a) daily mean PM₂.₅and PM₁₀concentrations; b) maximum daily temperature; c) daily mean O₃and NO₂concentrations; d) advection of particulate matter from biomass combustion (http://www.calima.ws/), using a dichotomous variable and e) linear trend and seasonalities. We conducted a descriptive analysis, performed a test of means and, to ascertain relative risk, fitted a model using autoregressive Poisson regression and stratifying by days with and without biomass advection, in both populations. Of the 2192 days analysed, biomass advection occurred on 56, with mean PM₂.₅and PM₁₀values registering a significant increase during these days. PM₁₀had a greater impact on organic mortality with advection (RRall ages = 1.035 [1.011–1.060]; RR ≥ 75 years = 1.066 [1.031–1.103]) than did PM₂.₅without advection (RRall ages = 1.017 [1.009–1.025]; RR ≥ 75 years = 1.012 [1.003–1.022]). Among specific causes, respiratory—though not circulatory—causes were associated with PM₁₀on days with advection in ≥75 year age group. PM₁₀, rather than PM₂.₅, were associated with an increase in natural cause mortality on days with advection of particulate matter from biomass combustion, particularly in the ≥75 year age group.
اظهر المزيد [+] اقل [-]Fuel nitrogen conversion and release of nitrogen oxides during coal gangue calcination النص الكامل
2015
Zhang, Yingyi | Ge, Xinlei | Liu, Lili | Wang, Xidong | Zhang, Zuotai
The pollution emission during the widespread utilization of coal gangue in construction industry has long been neglected. In present study, the NO ₓ release behaviors in a simulation experiment of coal gangue calcination in construction industry were systematically investigated. The corresponding evolution of nitrogen functionalities in coal gangue was also discussed. Results showed that pyrrolic (N-5) and pyridine N-oxide (N-6-O) forms nitrogen were relatively abundant in the raw gangue. During calcination, the N-5 and N-6-O form nitrogen greatly decreased and converted to quaternary nitrogen (N-Q). It was found that NO₂was formed under slowly heating-up condition and at 600 °C under isothermal condition, while only NO was detected with further increase of temperature. From 600 to 1000 °C, the conversion ratio of fuel nitrogen to NO ₓ increased from 8 to 12 %. The char nitrogen was found greatly contribute to NO formation, which may bring difficulty to the abatement of NO ₓ emission during coal gangue calcination.
اظهر المزيد [+] اقل [-]Effect of cadmium stress and inoculation with a heavy-metal-resistant bacterium on the growth and enzyme activity of Sorghum bicolor النص الكامل
2015
Muratova, Anna | Lyubun, Yelena | German, Kristina | Turkovskaya, Olga
In this study, the influence of the heavy-metal-resistant rhizobacterial inoculant Rhodococcus ruber N7 on the growth and enzyme activity of Sorghum bicolor (L.) Moench. under cadmium stress was investigated in quartz sand pot experiments. The effect of cadmium and bacterium on the plant biomass accumulation, photosynthetic pigments, protein content, and the activities of plant-tissue enzymes such as peroxidase, laccase, and tyrosinase were estimated. It was shown that the presence of cadmium in the sand influenced the roots to a greater extent than it influenced the aerial parts of sorghum. This is manifested as increased protein content, reduced activity of peroxidase, and increased activity of laccase. Compared with cadmium stress, inoculation of plants with rhizobacterium R. ruber N7 has a stronger (and often opposite) effect on the biochemical parameters of sorghum, including a decrease in the concentration of protein in the plant, but increased the activity of peroxidase, laccase, and tyrosinase. Under cadmium contamination of sand, R. ruber N7 successfully colonizes the roots of Sorghum bicolor, survives in its root zone, and contributes to the accumulation of the metal in the plant roots, thereby reducing the concentration of the pollutant in the environment.
اظهر المزيد [+] اقل [-]Effects of urbanization on gaseous and particulate polycyclic aromatic hydrocarbons and polychlorinated biphenyls in a coastal city, China: levels, sources, and health risks النص الكامل
2015
Hong, Youwei | Chen, Jinsheng | Zhang, Fuwang | Zhang, Han | Xu, Lingling | Yin, Liqian | Chen, Yanting
Gas/particle distributions of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) were measured in Xiamen from May 2009 to March 2010 to evaluate the impacts of urbanization on the fate of persistent organic pollutants (POPs) in the atmospheric environment. In a newly developing area (NDA), the concentrations of 16 PAHs (gas + particle) were significantly higher than that a historically urbanized area (HUA) (p value <0.05), while the trend of 28 PCBs was reversed. Diagnostic ratios and principle component analysis (PCA) implied that atmospheric PAHs in the NDA were mainly derived from petrogenic combustion, including mixed sources of vehicle emissions, biomass burning and oil combustion, while pyrogenic combustion (e.g., traffic and coal combustion) was considered the major source of PAHs in the HUA. Atmospheric PCBs in both HUA and NDA were dominated by TriCBs and PeCBs related to the use of commercial mixtures (Aroclors 1242 and 1254). Based on the toxicological equivalent factor (TEF) approach, total benzo[a]pyrene equivalent values in the HUA and NDA were 1.12 and 2.02 ng m⁻³, respectively, exceeding the standard threshold values (1.0 ng m⁻³) of China and WHO. Average daily intake of dioxin-like compounds was 0.2 pg kg⁻¹ day⁻¹ in the HUA, which are below the WHO tolerable daily intake level. The results showed that the contribution to the toxic equivalency (TEQ) was dominated by PCB169, PCB105, and PCB81.
اظهر المزيد [+] اقل [-]Extractive and oxidative removal of copper bound to humic acid in soil النص الكامل
2015
Hwang, Bo-Ram | Kim, Eun-jung | Yang, Jung-Seok | Baek, Kitae
Copper (Cu) is often found strongly bound to natural organic matter (NOM) in soil through the formation of strong Cu-NOM complexes. Therefore, in order to successfully remediate Cu-contaminated soils, effective removal of Cu bound to soil organic matter should be considered. In this study, we investigated soil washing methods for Cu removal from a synthetic Cu-contaminated model silica soil coated with humic acid (HA) and from field contaminated soil. Various reagents were studied to extract Cu bound to NOM, which included oxidant (H₂O₂), base (NaOH), and chelating agents (citric acid and ethylenediaminetetraacetic acid (EDTA)). Among the wash reagents, EDTA extracted Cu most effectively since EDTA formed very strong complexes with Cu, and Cu-HA complexes were transformed into Cu-EDTA complexes. NaOH extracted slightly less Cu compared to EDTA. HA was effectively extracted from the model soil under strongly alkaline conditions with NaOH, which seemed to concurrently release Cu bound to HA. However, chemical oxidation with H₂O₂was not effective at destroying Cu-HA complexes. Fourier transform infrared spectroscopy and elemental analysis revealed that chelating agents such as citrate and EDTA were adsorbed onto the model soil via possible complexation between HA and extraction agents. The extraction of Cu from a field contaminated soil sample was effective with chelating agents, while oxidative removal with H₂O₂and extractive removal with NaOH separated negligible amounts of Cu from the soil. Based on these results, Cu bound to organic matter in soil could be effectively removed by chelating agents, although remnant agents may remain in the soil.
اظهر المزيد [+] اقل [-]Analysis of predictors related to soil contamination in recreational areas of Romania النص الكامل
2015
Gagiu, C. | Pica, E. M. | Querol, X. | Botezan, C S
Soil contamination in recreational areas can considerably affect children’s health, as they are the segment of the population most sensitive to anthropogenic contamination. Soil contamination in recreational areas is influenced by a number of factors such as type and age of the recreational area, nearby traffic intensity, proximity to industrial areas, presence of vegetation, level of usage, treated wood structures, and the extent of maintenance operations carried out in the area. These can most often be observed during a simple site visit. The purpose of the present research is to analyze to which extent the presence of these factors can trigger an alarm signal, highlighting soil contamination in urban recreational areas. In this regard, soil contamination was scaled using the integrated pollution index applied on nine distinctive contaminants (As, Cu, Cd, Zn, Pb, Hg, Co, Ni, Mg) identified using inductively coupled plasma mass spectrometry (ICP-MS). Multiple linear regression analysis was performed in order to assess predictors of soil contamination. The research was carried out in a number of 88 recreational areas, parks, and playgrounds from 19 Romanian cities, revealing the fact that proximity to industrial areas and intensive traffic had statistically significant effects on soil contamination. Furthermore, it was observed that in 78 out of the 88 analyzed locations, the concentrations of contaminants exceeded the guidelines established through national legislation, thus confirming the presumption that high concentrations of contaminants exist in the parks and playgrounds of Romania.
اظهر المزيد [+] اقل [-]Dynamic water quality modelling and uncertainty analysis of phytoplankton and nutrient cycles for the upper South Saskatchewan River النص الكامل
2015
Akomeah, Eric | Chun, Kwok Pan | Lindenschmidt, Karl-Erich
The surface water quality of the upper South Saskatchewan River was modelled using Water Quality Analysis Simulation Program (WASP) 7.52. Model calibration and validation were based on samples taken from four long-term water quality stations during the period 2007–2009. Parametric sensitivities in winter and summer were examined using root mean square error (RMSE) and relative entropy. The calibration and validation results show good agreement between model prediction and observed data. The two sensitivity methods confirmed pronounced parametric sensitivity to model state variables in summer compared to winter. Of the 24 parameters examined, dissolved oxygen (DO) and ammonia (NH₃-N) are the most influenced variables in summer. Instream kinetic processes including nitrification, nutrient uptake by algae and algae respiration induce a higher sensitivity on DO in summer than in winter. Moreover, in summer, soluble reactive phosphorus (SRP) and chlorophyll-a (Chla) variables are more sensitive to algal processes (nutrient uptake and algae death). In winter however, there exists some degree of sensitivity of algal processes (algae respiration and nutrient uptake) to DO and NH₃-N. Results of this study provide information on the state of the river water quality which impacts Lake Diefenbaker and the need for additional continuous monitoring in the river. The results of the sensitivity analysis also provide guidance on most sensitive parameters and kinetic processes that affect eutrophication for preliminary surface water quality modelling studies in cold regions.
اظهر المزيد [+] اقل [-]Mercurial exposure of residents of Santarém and Oriximiná cities (Pará, Brazil) through fish consumption النص الكامل
2015
Bourdineaud, Jean-Paul | Durrieu, Gilles | Sarrazin, Sandra Layse Ferreira | da Silva, Wânia Cristina Rodrigues | Mourão, Rosa Helena Veras | de Oliveira, Ricardo Bezerra
A survey of the mercurial exposure of residents of Santarém and Oriximiná showed a differential mercurial impregnation between men and women. At the level of both cities, the mean hair mercury concentrations were 1.5 ± 0.5 (90th and 95th percentiles: 2.8 and 4.3) and 2.52 ± 0.09 μg g Hg/g (90th and 95th percentiles: 4.7 and 8.1) for women and men, respectively. The mercurial contamination appeared significantly closely linked to the daily amount of consumed fish. Carnivore species pescada branca (Plagioscion squamosissimus) and apapá (Pellona castelnaeana) and non-carnivore species pacú (Mylossoma duriventre) and aracú (Schizodon fasciatus) were consumed by 22, 19, 55 and 25 % of people, respectively, and the mean mercury concentrations within fish flesh were 1.44 ± 0.11, 1.66 ± 0.19, 0.48 ± 0.09 and 0.49 ± 0.06 μg/g dry weight, respectively. Men aged above 35 were significantly more contaminated than those below. The mean hair concentrations of men were 5.20 ± 1.25 and 1.50 ± 0.22 μg/g, for those aged above 35 and below, respectively. The probability for women of childbearing age from both cities to present a hair mercury concentration above 1 μg Hg/g (corresponding to the US Environmental Protection Agency reference dose) was equal to 0.30 (95 % confidence interval of 0.24–0.36). The probability of hair mercury concentration to be above the lowest observable adverse effect level (LOAEL) (0.3 μg Hg/g) was equal to 0.79 (95 % confidence interval: 0.73–0.86).
اظهر المزيد [+] اقل [-]Variation of levels and distribution of N-nitrosamines in different seasons in drinking waters of East China النص الكامل
2015
Li, Ting | Yu, Dian | Xian, Qiming | Li, Aimin | Sun, Cheng
We surveyed the occurrence of nine N-nitrosamine species in ten bottled drinking waters from supermarket and other water samples including raw waters, finished waters, and distribution system waters from nine municipal drinking water treatment plants in eight cities of Jiangsu Province, East China. N-nitrosodimethylamine (NDMA) was detected in one of ten bottled drinking water samples at concentration of 4.8 ng/L and N-nitrosomorpholine (NMor) was detected in four of the ten bottles with an average concentration and a standard deviation of 16 ± 15 ng/L. The levels of nitrosamines in the distribution system water samples collected during summer season ranged from below detection limit (BDL) to 5.4 ng/L for NDMA, BDL to 9.5 ng/L for N-nitrosomethylethylamine (NMEA), BDL to 2.7 ng/L for N-nitrosodiethylamine (NDEA) and BDL to 8.5 ng/L for N-nitrosopyrrolidine (NPyr). Samples of distribution system waters collected in winter season had levels of nitrosamines ranged from BDL to 45 ng/L for NDMA, BDL to 5.2 ng/L for NPyr, and BDL to 309 ng/L for N-nitrosopiperidine (NPip). A positive correlation of the concentration of NDMA as well as the total nine N-nitrosamines between finished waters and distribution system waters was observed. Both dissolved organic carbon and nitrite were found to correlate linearly with N-nitrosamine levels in raw waters.
اظهر المزيد [+] اقل [-]PFOS and PFOA in paired urine and blood from general adults and pregnant women: assessment of urinary elimination النص الكامل
2015
Zhang, Tao | Sun, Hongwen | Qin, Xiaolei | Gan, Zhiwei | Kannan, Kurunthachalam
Although levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in human blood are well documented, information on elimination of these chemicals is limited. In this study, PFOS and PFOA were analyzed in 81 whole blood–urine paired samples from general adults and pregnant women in Tianjin, China. PFOS and PFOA were detected in 48 and 76 % of adult urine (AU) samples, with geometric mean (GM) concentrations of 0.011 and 0.008 ng/mL, respectively; whereas relatively low PFOS and PFOA concentrations were found in maternal urine (MU) samples, with GM concentrations of 0.006 and 0.003 ng/mL, respectively. For PFOA, the coefficients of Pearson’s correlation between whole blood concentrations and creatinine-adjusted and creatinine-unadjusted urinary concentrations were 0.348 (p = 0.013) and 0.417 (p = 0.002), respectively. The GM urinary elimination rates of PFOS (PFOSUER) and PFOA (PFOAUER) were 16 and 25 %, respectively, for adults. These results indicate that urine is an important pathway of excretion of perfluoroalkyl substances (PFASs). The partitioning ratios of PFAS concentration between urine and whole blood (PFASU/B) in pregnant women (PFOSU/B, 0.0004; PFOAU/B, 0.0011) were significantly lower (p = 0.025 for PFOSU/B, p = 0.017 for PFOAU/B) than the ratios found in non-pregnant women (PFOSU/B, 0.0013; PFOAU/B, 0.0028). Furthermore, our results suggest a clear gender difference in the urinary elimination of PFOA, with male adults (31 %) having significantly higher PFOAUERthan that of female adults (19 %). PFOSUERwas significantly inversely correlated with age (r = −0.334, p = 0.015); these findings suggest that urinary elimination of PFOS is faster in young adults than in the elderly.
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