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Résultats 421-430 de 2,513
Cumulative risk assessment for plasticizer-contaminated food using the hazard index approach Texte intégral
2014
Chang, J.W. | Yan, B.R. | Chang, M.H. | Tseng, S.H. | Kao, Y.M. | Chen, J.C. | Lee, C.C.
Phthalates strongly and adversely affect reproduction, development and liver function. We did a cumulative risk assessment for simultaneous exposure to nine phthalates using the hazard index (HI) and the levels of nine phthalates in 1200 foodstuff samples. DEHP (di-2-ethylhexyl phthalate) present the highest level (mean: 0.443 mg/kg) in 1200 samples, and the highest average daily dose (ADD) was found in DEHP, ΣDBP(i + n) (the sum of dibutyl phthalate [DBP] isomers [DnBP + DiBP]) posed the highest risk potential of all the phthalates. In seven phthalates, the 95th percentiles of the ADDs for ΣDBP(i + n) in 0–6-yr-old children accounted for 91% (79–107%) of the tolerable daily intake, and the 95th percentiles of the HIs for the anti-androgenic effects of five phthalates in 0–3-yr-old children and 4–6-yr-old girls were >1. We conclude that the health of younger Taiwanese may be adversely affected by overexposure of phthalate-contaminated foods.
Afficher plus [+] Moins [-]Verification of NOx emission inventories over North Korea Texte intégral
2014
Kim, Na Kyung | Kim, Yong Pyo | Morino, Yu | Kurokawa, Jun-ichi | Ōhara, Toshimasa
In this study, the top-down NOx emissions estimated from satellite observations of NO2 vertical column densities over North Korea from 1996 to 2009 were analyzed. Also, a bottom-up NOx emission inventory from REAS 1.1 from 1980 to 2005 was analyzed with several statistics. REAS 1.1 was in good agreement with the top-down approach for both trend and amount. The characteristics of NOx emissions in North Korea were quite different from other developed countries including South Korea. In North Korea, emissions from industry sector was the highest followed by transportation sector in the 1980s. However, after 1990, the NOx emissions from other sector, mainly agriculture, became the 2nd highest. Also, no emission centers such as urban areas or industrial areas were distinctively observed. Finally, the monthly NOx emissions were high during the warm season.
Afficher plus [+] Moins [-]Are persistent organic pollutants and metals in eel muscle predictive for the ecological water quality? Texte intégral
2014
Van Ael, Evy | Belpaire, Claude | Breine, Jan | Geeraerts, Caroline | Van Thuyne, Gerlinde | Eulaers, Igor | Blust, Ronny | Bervoets, Lieven
Relationships between the presence of PCBs, OCPs and metals in aquatic ecosystems and the ecological water quality were investigated by combining datasets of long-term monitoring of chemicals in European eel (Anguilla anguilla, N = 1156) in Flanders (Belgium) and the Ecological Quality Ratio (EQR), based on the assessment of fish assemblages at 185 locations. For most pollutants, EQR scores were lower when pollutant levels were higher. Threshold concentrations for a good quality could be formulated for PCB's, most metals and OCPs. Mixed models suggested that the ecological water quality was significantly correlated with the presence of PCBs. However, the low R2 indicates that other environmental pressures may significantly influence the biotic integrity of fish communities. Empirical data and their analyses are essential to enable defining threshold values of bioaccumulated levels to allow better protection of the aquatic environment and its biota through associated food webs as demanded by the Water Framework Directive.
Afficher plus [+] Moins [-]Comparing black carbon types in sequestering polybrominated diphenyl ethers (PBDEs) in sediments Texte intégral
2014
Jia, Fang | Gan, Jay
Polybrominated diphenyl ethers (PBDEs) are widely found in sediments, especially congeners from the penta-BDE formula. Due to their strong affinity for black carbon (BC), bioavailability of PBDEs may be decreased in BC-amended sediments. In this study, we used a matrix-SPME method to measure the freely dissolved concentration (Cfree) of PBDEs as a parameter of their potential bioavailability and evaluated the differences among biochar, charcoal, and activated carbon. Activated carbon displayed a substantially greater sequestration capacity than biochar or charcoal. At 1% amendment rate in sediment with low organic carbon (OC) content (0.12%), Cfree of six PBDEs was reduced by 47.5–78.0%, 47.3–77.5%, and 94.1–98.3% with biochar, charcoal, and activated carbon, respectively, while the sequestration was more limited in sediment with high OC content (0.87%). Therefore, it is important to consider the type and properties of the BC and the sediment in BC-based remediation or mitigation.
Afficher plus [+] Moins [-]Occurrence and transport of 17 perfluoroalkyl acids in 12 coastal rivers in south Bohai coastal region of China with concentrated fluoropolymer facilities Texte intégral
2014
Wang, Pei | Lü, Yonglong | Wang, Tieyu | Fu, Yaning | Zhu, Zhaoyun | Liu, Shijie | Xie, Shuangwei | Xiao, Yang | Giesy, John P.
Perfluoroalkyl acids (PFAAs) are emerging contaminants that have raised great concern in recent years. While PFAAs manufacturing becomes regulated in developed countries, production has been partly shifted to China. Eight fluoropolymer manufacturing facilities located in the South Bohai coastal region, one of the most populated areas of China, have been used to manufacture PFAA-related substances since 2001. The environmental consequence of the intensive production of PFAAs in this region remains largely unknown. We analyzed 17 PFAAs in twelve coastal rivers of this region, and found staggeringly high concentrations of perfluorooctanoic acid (PFOA) ranging from 0.96 to 4534.41 ng/L. The highest concentration was observed in the Xiaoqing River which received effluents from certain fluoropolymer facilities. Principal component analysis indicated similar sources of several perfluoroalkyl carboxylic acids (PFCAs) in all rivers, which indicated that atmospheric transport, wastewater treatment and surface runoff also acted as important supplements to direct discharge to surface water.
Afficher plus [+] Moins [-]Characterizing the influence of highways on springtime NO2 and NH3 concentrations in regional forest monitoring plots Texte intégral
2014
Watmough, Shaun A. | McDonough, Andrew M. | Raney, Shanel M.
Highways are major sources of nitrogen dioxide (NO2) and ammonia (NH3). In this study, springtime NO2 and NH3 concentrations were measured at 17 Ontario Forest Biomonitoring Network (OFBN) plots using passive samplers. Average springtime NO2 concentrations were between 1.3 μg m−3 and 27 μg m−3, and NH3 concentrations were between 0.2 μg m−3 and 1.7 μg m−3, although concentrations measured in May (before leaf out) were typically twice as high as values recorded in June. Average NO2 concentrations, and to a lesser extent NH3, could be predicted by road density at all radii (around the plot) tested (500 m, 1000 m, 1500 m). Springtime NO2 concentrations were predicted for a further 50 OFBN sites. Normalized plant/lichen N concentrations were positively correlated with estimated springtime NO2 and NH3 concentrations. Epiphytic foliose lichen richness decreased with increasing NO2 and NH3, but vascular plant richness was positively related to estimated springtime NO2 and NH3.
Afficher plus [+] Moins [-]Risk assessment for cardiovascular and respiratory mortality due to air pollution and synoptic meteorology in 10 Canadian cities Texte intégral
2014
Vanos, Jennifer K. | Hebbern, Christopher | Cakmak, Sabit
Synoptic weather and ambient air quality synergistically influence human health. We report the relative risk of mortality from all non-accidental, respiratory-, and cardiovascular-related causes, associated with exposure to four air pollutants, by weather type and season, in 10 major Canadian cities for 1981 through 1999. We conducted this multi-city time-series study using Poisson generalized linear models stratified by season and each of six distinctive synoptic weather types. Statistically significant relationships of mortality due to short-term exposure to carbon monoxide, nitrogen dioxide, sulphur dioxide, and ozone were found, with significant modifications of risk by weather type, season, and mortality cause. In total, 61% of the respiratory-related mortality relative risk estimates were significantly higher than for cardiovascular-related mortality. The combined effect of weather and air pollution is greatest when tropical-type weather is present in the spring or summer.
Afficher plus [+] Moins [-]Analysis of Southeast Asian pollution episode during June 2013 using satellite remote sensing datasets Texte intégral
2014
Vadrevu, Krishna Prasad | Lasko, Kristofer | Giglio, Louis | Justice, C. O. (Christopher O.)
In this study, we assess the intense pollution episode of June 2013, in Riau province, Indonesia from land clearing. We relied on satellite retrievals of aerosols and Carbon monoxide (CO) due to lack of ground measurements. We used both the yearly and daily data for aerosol optical depth (AOD), fine mode fraction (FMF), aerosol absorption optical depth (AAOD) and UV aerosol index (UVAI) for characterizing variations. We found significant enhancement in aerosols and CO during the pollution episode. Compared to mean (2008–2012) June AOD of 0.40, FMF-0.39, AAOD-0.45, UVAI-1.77 and CO of 200 ppbv, June 2013 values reached 0.8, 0.573, 0.672, 1.77 and 978 ppbv respectively. Correlations of fire counts with AAOD and UVAI were stronger compared to AOD and FMF. Results from a trajectory model suggested transport of air masses from Indonesia towards Malaysia, Singapore and southern Thailand. Our results highlight satellite-based mapping and monitoring of pollution episodes in Southeast Asia.
Afficher plus [+] Moins [-]Stemflow acid neutralization capacity in a broadleaved deciduous forest: The role of edge effects Texte intégral
2014
Shiklomanov, Alexey N. | Levia, Delphis F.
Atmospheric deposition is an important pathway for moisture, nutrient, and pollutant exchange among the atmosphere, forest, and soils. Previous work has shown the importance of proximity to the forest edge to chemical fluxes in throughfall, but far less research has considered stemflow. This study examined the difference in acid neutralization capacity (ANC) of stemflow of nineteen Liriodendron tulipifera L. (yellow poplar) trees between the forest edge and interior in a rural area of northeastern Maryland. We measured ANC directly via potentiometric titration. Stemflow from trees at the forest edge was found to have significantly higher and more variable pH and ANC than in the forest interior (p < 0.01). No mathematical trend between ANC and distance to the forest edge was observed, indicating the importance of individual tree characteristics in stemflow production and chemistry. These results reaffirm the importance of stemflow for acid neutralization by deciduous tree species.
Afficher plus [+] Moins [-]Quantification of four artificial sweeteners in Finnish surface waters with isotope-dilution mass spectrometry Texte intégral
2014
Perkola, Noora | Sainio, Pirjo
The artificial sweeteners sucralose (SCL), acesulfame (ACS), saccharin (SAC), and cyclamate (CYC) have been detected in environmental waters in Europe and North America. Higher environmental levels are expected in view of the increasing consumption of these food additives. In this study, an isotope-dilution mass spectrometry (IDMS) LC–MS/MS method was developed and validated for quantifying the four artificial sweeteners in boreal lakes (n = 3) and rivers (n = 12). The highest concentrations of ACS, SAC, CYC and SCL were 9,600, 490, 210 and 1000 ng/L, respectively. ACS and SAC were detected in all studied samples, and CYC and SCL in 98% and 56% of the samples. Seasonal trends of ACS and SAC were observed in some rivers. ACS and SCL concentrations in rivers correlated linearly with population equivalents of the wastewater treatment plants in the catchment areas, whereas SAC and CYC concentrations depend more on the source.
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