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Resultados 181-190 de 2,459
Air pollution and hospital admissions for respiratory diseases in Lanzhou, China
2014
Tao, Yan | Mi, Shengquan | Zhou, Shuhong | Wang, Shigong | Xie, Xiaoyun
Lanzhou is among the most seriously air-polluted cities in China as a whole, due to its unique topography, climate, industrial structure and so on. We studied the relationship between different air pollution and respiratory hospitalizations from 2001 to 2005, the total of respiratory hospital admissions were 28,057. The data were analyzed using Poisson regression models after controlling for the long time trend for air pollutants, the “day of week” effect and confounding meteorological factors. Three air pollutants (PM10, SO2, NO2) had a lag effect, the lag was 3–5 days for PM10, 1–3 days for SO2 and 1–4 days for NO2. The relative risks were calculated for increases in the inter-quartile range of the pollutants (139 μg/m3 in PM10, 61 μg/m3 in SO2 and 31 μg/m3 in NO2). Results showed that there were significant associations between air pollutants and respiratory hospital admissions, and stronger effects were observed for females and aged ≥65 yrs in Lanzhou.
Mostrar más [+] Menos [-]First measurements of source apportionment of organic aerosols in the Southern Hemisphere
2014
Crilley, Leigh R. | Ayoko, G. A. (Godwin A.) | Morawska, L. (Lidia)
An Aerodyne Aerosol Mass Spectrometer was deployed at five urban schools to examine spatial and temporal variability of organic aerosols (OA) and positive matrix factorization (PMF) used for the first time in the Southern Hemisphere to apportion the sources of the OA across an urban area. The sources identified included hydrocarbon-like OA (HOA), biomass burning OA (BBOA) and oxygenated OA (OOA). At all sites, the main source was OOA, which accounted for 62–73% of the total OA mass and was generally more oxidized compared to those reported in the Northern Hemisphere. This suggests that there are differences in aging processes or regional sources in the two hemispheres. Unlike HOA and BBOA, OOA demonstrated instructive temporal variations but not spatial variation across the urban area. Application of cluster analysis to the PMF-derived sources offered a simple and effective method for qualitative comparison of PMF sources that can be used in other studies.
Mostrar más [+] Menos [-]Persistent organic pollutant concentrations in fledglings of two arctic seabird species
2014
Guzzo, Matthew M. | Eckbo, Norith H. | Gabrielsen, Geir W. | Fisk, Aaron T. | Hylland, Ketil | Borgå, Katrine
Persistent organic pollutants (POPs) and stable isotopes were measured in muscle from fledglings of two arctic seabird species, Northern fulmar (Fulmarus glacialis) and Black-legged kittiwakes (Rissa tridactyla). The purpose was to compare POP concentrations between species, in an age class that is highly vulnerable to POPs but little studied, relate to diet using stable isotopes, and quantify differences across life stages (egg to adult). Northern fulmar fledglings had significantly higher POP concentrations than kittiwake, consistent with results reported for adults of these species. Surprisingly, carbon and nitrogen stable isotopes did not differ between species, which does not match data for, or the known feeding ecology, of the adults. Fulmar/kittiwake POP concentration ratios varied across life stages indicating variable POP exposure and accumulation with age in seabirds, indicating that of the use of avian species-specific thresholds should only be done with caution in ecosystem-based POP risk management.
Mostrar más [+] Menos [-]Ecological responses to contamination: A meta-analysis of experimental marine studies
2014
O'Brien, Allyson L. | Keough, Michael J.
Identifying general response patterns to contamination in the environment is critical for reliable assessments of ecosystem health. However, it is not often clear if there are biases in the information used to understand general effects of contamination. To investigate this we conducted a review of 314 studies that experimentally manipulated contaminants and measured the effects on marine invertebrate taxa. The majority of studies investigated the effects of metals (54%) on individual taxa (mainly bivalves, amphipods, copepods). Ecologically relevant responses to contamination were measured in only 22% of the studies. A meta-analysis using studies that measured ecological responses to copper illustrated a general negative effect of copper and highlighted the bias towards field or laboratory experiments that measure community or individual-level responses. There is a need for diversification of studies that investigate the ecological effects of contamination as an important advancement in ecotoxicology and ecological research and environmentally relevant risk assessments.
Mostrar más [+] Menos [-]Cumulative risk assessment for plasticizer-contaminated food using the hazard index approach
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.
Mostrar más [+] Menos [-]The kinetic and thermodynamic sorption and stabilization of multiwalled carbon nanotubes in natural organic matter surrogate solutions: The effect of surrogate molecular weight
2014
Li, Tingting | Lin, Daohui | Li, Lu | Wang, Zhengyu | Wu, Fengchang
Styrene sulfonate (SS) and polystyrene sulfonates (PSSs) were used as surrogates of natural organic matter to study the effect of molecular weight (from 206.2 to 70,000 Da) on their sorption by a multiwalled carbon nanotube (MWCNT) and an activated carbon (AC) and on their stabilization of MWCNT suspension. Results indicate that surface-diffusion through the liquid-sorbent boundary was the rate-controlling step of the kinetic sorption of both MWCNTs and AC, and surface-occupying and pore-filling mechanisms respectively dominated the thermodynamic sorption of MWCNTs and AC. Sorption rates and capacities of MWCNTs and AC in molecular concentration of SS and PSS decreased with increasing molecular weight. The PSSs but not SS facilitated the stabilization of MWCNT suspension because of the increased electrosteric repulsion. The PSSs with more monomers had greater capabilities to stabilize the MWCNT suspension, but the capabilities were comparable after being normalized by the total monomer number.
Mostrar más [+] Menos [-]Spatial distribution of PAH concentrations and stable isotope signatures (δ13C, δ15N) in mosses from three European areas – Characterization by multivariate analysis
2014
Foan, L. | Leblond, S. | Thöni, L. | Raynaud, C. | Santamaría, J.M. | Sebilo, M. | Simon, V.
Polycyclic aromatic hydrocarbon (PAH) concentrations and N, C stable isotope signatures were determined in mosses Hypnum cupressiforme Hedw. from 61 sites of 3 European regions: Île-de-France (France); Navarra (Spain); the Swiss Plateau and Basel area (Switzerland). Total PAH concentrations of 100–700 ng g−1, as well as δ13C values of −32 to −29‰ and δ15N values of −11 to −3‰ were measured. Pearson correlation tests revealed opposite trends between high molecular weight PAH (4–6 aromatic rings) content and δ13C values. Partial Least Square regressions explained the very significant correlations (r > 0.91, p < 0.001) between high molecular weight PAH concentrations by local urban land use (<10 km) and environmental factors such as elevation and pluviometry. Finally, specific correlations between heavy metal and PAH concentrations were attributed to industrial emissions in Switzerland and road traffic emissions in Spain.
Mostrar más [+] Menos [-]Identification of novel micropollutants in wastewater by a combination of suspect and nontarget screening
2014
Hug, Christine | Ulrich, Nadin | Schulze, Tobias | Brack, Werner | Krauss, Martin
To detect site-specific, suspected and formerly unknown contaminants in a wastewater treatment plant effluent, we established a screening procedure based on liquid chromatography–high resolution mass spectrometry (LC–HRMS) with stepwise identification schemes. Based on automated substructure searches a list of 2160 suspected site-specific and documented water contaminants was reduced to those amenable to LC–HRMS. After searching chromatograms for exact masses of suspects, presumably false positive detections were stepwise excluded by retention time prediction, the evaluation of isotope patterns, ionization behavior, and HRMS/MS spectra. In nontarget analysis, peaks for identification were selected based on distinctive isotope patterns and intensity. The stepwise identification of nontarget compounds was automated by a plausibility check of molecular formulas using the Seven Golden Rules, an exclusion of compounds with presumably low commercial importance and an automated HRMS/MS evaluation. Six suspected and five nontarget chemicals were identified, of which two have not been previously reported as environmental pollutants.
Mostrar más [+] Menos [-]Paddy field – A natural sequential anaerobic–aerobic bioreactor for polychlorinated biphenyls transformation
2014
Chen, Chen | Yu, Chunna | Shen, Chaofeng | Tang, Xianjin | Qin, Zhihui | Yang, Kai | Hashmi, Muhammad Zaffar | Huang, Ronglang | Shi, Huixiang
The environmental pollution and health risks caused by the improper disposal of electric and electronic waste (e-waste) have become urgent issues for the developing countries. One of the typical pollutants, polychlorinated biphenyls (PCBs), is commonly found in farmland in Taizhou, a major hotspot of e-waste recycling in China. This study investigated the amount of PCB residue in local farmlands. Biotransformation of PCBs was further studied under different water management conditions in paddy field with or without rice cultivation, with a special focus on the alternating flooded and drying processes. It was found that paddy field improved the attenuation of PCBs, especially for highly chlorinated congeners. In the microcosm experiment, 40% or more of the initial total PCBs was removed after sequential flood–drying treatments, compared to less than 10% in the sterilized control and 20% in the constant-drying system. Variation in the quantity of PCBs degrading and dechlorinating bacterial groups were closely related to the alteration of anaerobic–aerobic conditions. These results suggested that alternating anoxic–oxic environment in paddy field led to the sequential aerobic–anaerobic transformation of PCBs, which provided a favorable environment for natural PCB attenuation.
Mostrar más [+] Menos [-]High tolerance of subalpine grassland to long-term ozone exposure is independent of N input and climatic drivers
2014
Volk, Matthias | Wolff, Veronika | Bassin, Seraina | Ammann, Christof | Fuhrer, Jürg
In a seven-year study, we tested effects of increased N and O3 deposition and climatic conditions on biomass of subalpine grassland. Ozone risk was assessed as exposure (AOT40) and as stomatal flux (POD0,1). We hypothesized that productivity is higher under N- and lower under O3 deposition, with interactions with climatic conditions.Aboveground biomass was best correlated with growing-degree days for May (GDDMay). Nitrogen deposition increased biomass up to 60% in the highest treatment, and 30% in the lowest addition. Also belowground biomass showed a positive N-response. Ozone enrichment had no effect on biomass, and no interaction between O3 and N was observed. Growth response to N deposition was not correlated to GDDMay or precipitation, but indicated a cumulative effect over time.Productivity of subalpine grassland is tolerant to increasing ozone exposure, independent of N input and climatic drivers. N deposition rates at current critical loads, strongly increase the grassland yield.
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