خيارات البحث
النتائج 181 - 190 من 1,506
Brominated flame retardants in three terrestrial passerine birds from South China: Geographical pattern and implication for potential sources
2012
Sun, Yu-xin | Luo, Xiao-jun | Mo, Ling | Zhang, Qiang | Wu, Jiang-ping | Chen, She-jun | Zou, Fa-sheng | Mai, Bi-xian
Polybrominated diphenyl ethers (PBDEs), decabromodiphenyl ethane (DBDPE), polybrominated biphenyls (PBBs) and pentabromotoluene (PBT) were investigated in light-vented bulbul (LVB), long-tailed shrike (LTS) and oriental magpie-robin (OMR) collected from seven sampling sites in South China. ∑PBDEs, DBDPE, PBB 153, and PBT levels ranged from 35 to 15 000, no detected (nd)-130, nd-6800, and nd-6.8 ng/g lipid weight, respectively. Positive correlations were found between δ¹⁵N values and brominated flame retardant (BFR) concentrations. The BFR geographic pattern indicated that PBDEs were linked to e-waste recycling and local industry activities as well as urbanization; PBB 153 was derived from e-waste; DBDPE was mainly come from local industry activities; and no specific source was observed for PBT. PBDE congener profiles were found to be depended on bird species and sampling sites with relatively high abundances of lower brominated congeners in e-waste site and significantly higher abundance of BDE153 in LTS and OMR than in LVB.
اظهر المزيد [+] اقل [-]Occupational exposure to airborne particles and other pollutants in an aviation base
2012
Buonanno, Giorgio | Bernabei, Manuele | Avino, Pasquale | Stabile, Luca
The occupational exposure to airborne particles and other pollutants in a high performance jet engine airport was investigated. Three spatial scales were considered: i) a downwind receptor site, ii) close to the airstrip, iii) personal monitoring. Particle number, surface area, mass concentrations and distributions were measured as well as inorganic and organic fractions, ionic fractions and Polycyclic Aromatic Hydrocarbons. Particle number distribution measured at a receptor site presents a mode of 80 nm and an average total concentration of 6.5 × 10³ part. cm⁻³; the chemical analysis shows that all the elements may be attributed to long-range transport from the sea. Particle number concentrations in the proximity of the airstrip show short term peaks during the working day mainly related to takeoff, landing and pre-flight operations of jet engines. Personal exposure of workers highlights a median number concentration of 2.5 × 10⁴ part. cm⁻³ and 1.7 × 10⁴ part. cm⁻³ for crew chief and hangar operator.
اظهر المزيد [+] اقل [-]Dynamics of CH₄ oxidation in landfill biocover soil: Effect of O₂/CH₄ ratio on CH₄ metabolism
2012
Chi, Zi-Fang | Lu, Wen-Jing | Li, Huai | Wang, Hong-Tao
The CH₄ oxidation dynamics was investigated by observing the CH₄ oxidation rates at concentrations (from 1.0 × 10⁴ ppmv to 2.0 × 10⁵ ppmv) mixed with O₂ (from 5.0 × 10⁴ ppmv to 7.5 × 10⁵ ppmv). The CH₄–O₂ dual-substrate model based on Michaelis–Menten equation ( [Formula: see text] = 1.4 × 10⁵ ppmv; Vₘₐₓ = 7.6 × 10² μmol kg⁻¹ d⁻¹; [Formula: see text] = 5.5 × 10⁴ ppmv) was got and agreed well with the experimental data when the initial O₂/CH₄ ratio reached 3:1, indicating full aerobic CH₄ oxidization. Anoxic CH₄ oxidation gradually became predominant with decreasing O₂/CH₄ ratios. The effect of CH₄ is more significant than O₂, as evidenced by higher slope (0.58 kg⁻¹ d⁻¹) of [Formula: see text] line graph compared with that of [Formula: see text] line graph (0.062 kg⁻¹ d⁻¹). The paper presents the dynamics of CH₄ oxidation and proposes that ratio of O₂/CH₄ need to be considered for their dynamically changing in environmental habitats. The findings provide an important parameter for optimizing the operations of breathing biocover systems.
اظهر المزيد [+] اقل [-]The response of rice grain quality to ozone exposure during growth depends on ozone level and genotype
2012
Frei, Michael | Kohno, Yoshihisa | Tietze, Stefan | Jekle, Mario | Hussein, Mohammed A. | Becker, Thomas | Becker, Klaus
The effects of ozone exposure during the cropping season on rice grain quality were investigated in chamber experiments employing four ozone treatments (charcoal filtered air, ambient, 2× ambient, and 2.5× ambient concentration) and six genotypes. The concentrations of protein and lipids in brown rice increased significantly in response to ozone, while starch concentration and thousand kernel mass decreased. Other parameters, including the concentrations of iron, zinc, phenolics, stickiness and geometrical traits did not exhibit significant treatment effects. Total brown rice yield, protein yield, and iron yield were negatively affected by ozone. Numerous genotypic differences occurred in the response to ozone, indicating the possibility of optimizing the grain quality in high ozone environments by breeding. It is concluded that although the concentrations of two important macronutrients, proteins and lipids, increased in ozone treated grains, the implications for human nutrition are negative due to losses in total grain, protein and iron yield.
اظهر المزيد [+] اقل [-]Ecotoxicological effect characterisation of widely used organic UV filters
2012
Kaiser, D. | Sieratowicz, A. | Zielke, H. | Oetken, M. | Hollert, H. | Oehlmann, J.
Chemical UV filters are used in sun protection and personal care products in order to protect consumers from skin cancer induced by ultraviolet (UV) radiation. The present study aims to evaluate the effects of three common UV filters butyl-methoxydibenzoylmethane (B-MDM) ethylhexyl-methoxycinnamate (EHMC) and octocrylene (OCR) on aquatic organism, focussing particularly on infaunal and epibentic invertebrates (Chironomus riparius, Lumbriculus variegatus, Melanoides tuberculata and Potamopyrgus antipodarum). Due to their life habits, these organism are especially affected by lipophilic substances. Additionally, two direct sediment contact assays utilising zebra fish (Danio rerio) embryos and bacteria (Arthrobacter globiformis) were conducted. EHMC caused a toxic effect on reproduction in both snails with lowest observed effect concentrations (LOEC) of 0.4 mg/kg (Potamopyrgus antipodarum) and 10 mg/kg (Melanoides tuberculata). At high concentrations sublethal effects could be observed for D. rerio after exposure to EHMC (NOEC 100 mg/kg). B-MDM and OCR showed no effects on any of the tested organism.
اظهر المزيد [+] اقل [-]Observation of increases in emission from modern vehicles over time in Hong Kong using remote sensing
2012
Lau, Jason | Hung, W.T. | Cheung, C.S.
In this study on-road gaseous emissions of vehicles are investigated using remote sensing measurements collected over three different periods. The results show that a high percentage of gaseous pollutants were emitted from a small percentage of vehicles. Liquified Petroleum Gas (LPG) vehicles generally have higher gaseous emissions compared to other vehicles, particularly among higher-emitting vehicles. Vehicles with high vehicle specific power (VSP) tend to have lower CO and HC emissions while petrol and LPG vehicles tend to have higher NO emissions when engine load is high. It can be observed that gaseous emission factors of petrol and LPG vehicles increase greatly within 2 years of being introduced to the vehicle fleet, suggesting that engine and catalyst performance deteriorate rapidly. It can be observed that LPG vehicles have higher levels of gaseous emissions than petrol vehicles, suggesting that proper maintenance of LPG vehicles is essential in reducing gaseous emissions from vehicles.
اظهر المزيد [+] اقل [-]Atmospheric polybrominated diphenyl ethers (PBDEs) in the United Kingdom
2012
Birgul, Askin | Katsoyiannis, Athanasios | Gioia, Rosalinda | Crosse, John | Earnshaw, Mark | Ratola, Nuno | Jones, K. C. (Kevin C.) | Sweetman, A. J. (Andrew J.)
The occurrence of PBDEs has been studied in the atmosphere of four sites in the United Kingdom over a period of ten years. The concentrations have exhibited a sharp decrease after 2001–2003. This is evident in the urban sites of Manchester and London and at the semi-rural site of Hazelrigg. The average ΣPBDE half-lives for these three sites were 3.4, 2.0 and 3.5 years respectively. ΣPBDEs concentrations in the UK (in 2010 ΣPBDEs < 10 pg m⁻³) are among the lowest reported in literature. Comparison of concentrations to estimated emissions and employment of PBDE profiles suggest that PBDEs in the UK atmosphere originate from primary emissions from products that contain mainly the penta-BDE technical mixture. The detection of BDE-183 in the majority of samples hints that octa-bromodiphenylether has also been used extensively in the UK, however to a smaller extent than the penta- product.
اظهر المزيد [+] اقل [-]Spatial distribution of per- and polyfluoroalkyl compounds in coastal waters from the East to South China Sea
2012
Cai, Minghong | Zhao, Zhen | Yang, Haizhen | Yin, Zhigao | Hong, Qingquan | Sturm, Renate | Ebinghaus, Ralf | Ahrens, Lutz | Cai, Minggang | He, Jianfeng | Xie, Zhiyong
The spatial distribution of per- and polyfluoroalkyl compounds (PFCs) were investigated in coastal waters collected onboard research vessel Snow Dragon from the East to South China Sea in 2010. All samples were prepared by solid-phase extraction and analyzed using high performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(−)ESI-MS/MS). Concentrations of 9 PFCs, including C₄ and C₈ (PFBS, PFOS) perfluoroalkyl sulfonate (PFSAs), C₅–C₉ and C₁₃ (PFPA, PFHxA, PFHpA, PFOA, PFNA, PFTriDA) perfluoroalkyl carboxylates (PFCAs), and N-ethyl perfluorooctane sulfonamide (EtFOSA) were quantified. The ΣPFC concentrations ranged from 133 pg/L to 3320 pg/L, with PFOA (37.5–1541 pg/L), PFBS (23.0–941 pg/L) and PFHpA (0–422 pg/L) as dominant compounds. Concentrations of PFCs were greater in coastal waters along Shanghai, Ningbo, Taizhou, Xiamen and along coastal cities of the Guangdong province compared to less populated areas along the east Chinese coast. Additionally, the comparison with other seawater PFC measurements showed lower levels in this study.
اظهر المزيد [+] اقل [-]Coal fly ash basins as an attractive nuisance to birds: Parental provisioning exposes nestlings to harmful trace elements
2012
Bryan, A.L., Jr | Hopkins, W.A. | Parikh, J.H. | Jackson, B.P. | Unrine, J.M.
Birds attracted to nest around coal ash settling basins may expose their young to contaminants by provisioning them with contaminated food. Diet and tissues of Common Grackle (Quiscalus quiscala) nestlings were analyzed for trace elements to determine if nestlings were accumulating elements via dietary exposure and if feather growth limits elemental accumulation in other tissues. Arsenic, cadmium, and selenium concentrations in ash basin diets were 5× higher than reference diets. Arsenic, cadmium, and selenium concentrations were elevated in feather, liver, and carcass, but only liver Se concentrations approached levels of concern. Approximately 15% of the total body burden of Se, As, and Cd was sequestered in feathers of older (>5 days) nestlings, whereas only 1% of the total body burden of Sr was sequestered in feathers. Feather concentrations of only three elements (As, Se, and Sr) were correlated with liver concentrations, indicating their value as non-lethal indicators of exposure.
اظهر المزيد [+] اقل [-]The long-term impact of urbanization on nitrogen patterns and dynamics in Shanghai, China
2012
Gu, Baojing | Dong, Xiaoli | Peng, Changhui | Luo, Weidong | Chang, Jie | Ge, Ying
Urbanization is an important process that alters the regional and global nitrogen biogeochemistry. In this study, we test how long-term urbanization (1952–2004) affects the nitrogen flows, emissions and drivers in the Greater Shanghai Area (GSA) based on the coupled human and natural systems (CHANS) approach. Results show that: (1) total nitrogen input to the GSA increased from 57.7 to 587.9 Gg N yr⁻¹ during the period 1952–2004, mainly attributing to fossil fuel combustion (43%), Haber–Bosch nitrogen fixation (31%), and food/feed import (26%); (2) per capita nitrogen input increased from 13.5 to 45.7 kg N yr⁻¹, while per gross domestic product (GDP) nitrogen input reduced from 22.2 to 0.9 g N per Chinese Yuan, decoupling of nitrogen with GDP; (3) emissions of reactive nitrogen to the environment transformed from agriculture dominated to industry and human living dominated, especially for air pollution. This study provides decision-makers a novel view of nitrogen management.
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