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النتائج 51 - 60 من 456
Levels and bioaccumulation of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) in fishes from the Pearl River estuary and Daya Bay, South China النص الكامل
2008
Guo, L. | Qiu, Y. | Zhang, G. | Zheng, G.J. | Lam, P.K.S. | Li, Xunjing
Fifty fish samples were collected from the Pearl River estuary (PRE) and Daya Bay, South China and were analyzed for DDTs, HCHs, chlordanes and polybrominated biphenyl ethers (PBDEs). Except the high concentrations of DDT observed in fishes, the concentrations of HCHs, chlordanes and PBDEs were low when compared to other regions. BDE-47 was the predominant PBDE congener and the BDE-209 concentrations were relatively low, despite its high concentration in surface sediments. The absence of significant increase of DDT, HCH, chlordane and PBDE concentrations towards higher δ15N values, as well as the lack of a significant correlation (p < 0.1) between log concentrations (lipid normalized) and δ15N, may indicate a weak biomagnification of these chemicals in the food webs. Good agreement was observed between their concentrations and lipid contents of the organisms. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms in the studied subtropical waters. Bioconcentration was suggested to be responsible for the accumulation of OCPs and PBDEs in the lower trophic organisms of subtropical waters.
اظهر المزيد [+] اقل [-]Slow growth of Empetrum nigrum in industrial barrens: Combined effect of pollution and age of extant plants النص الكامل
2008
Zverev, Vitali E. | Zvereva, Elena L. | Kozlov, Mikhail V.
We studied the impact of industrial pollution on population demography (age structure), growth and reproduction of crowberry, Empetrum nigrum L. Crowberry growing in severely polluted sites near non-ferrous smelters (at Harjavalta, Monchegorsk and Nikel) was on average twice as old as in unpolluted habitats, as indicated by the number of annual rings at root collar. Shoot length decreased both with plant ageing and due to pollution impact, while neither the proportion of generative plants nor berry production was affected by pollution or plant age. Our results suggest that death of the extant individuals of E. nigrum near the non-ferrous smelters is to a large extent explained by age-related damage of the main stem accelerated by pollution. Since vegetative propagation, seed germination and seedling establishment are hampered by soil toxicity, E. nigrum populations near the smelters continue to decline with ageing in spite of the gradual decline of emissions. Both older age of crowberry in heavily polluted sites and pollution-induced environmental disturbance contributed to slower growth, but had no effect on fructification.
اظهر المزيد [+] اقل [-]Simultaneous monitoring of profiles of polycyclic aromatic hydrocarbons in contaminated air with semipermeable membrane devices and spruce needles النص الكامل
2008
Zhu, Xiuhua | Pfister, Gerd | Henkelmann, Bernhard | Kotalik, Jarmila | Bernhöft, Silke | Fiedler, Stefan | Schramm, Karl-Werner
Gaseous emissions of combusted electronic scrap, PVC, carpet and wood were monitored for polycyclic aromatic hydrocarbons (PAHs) by simultaneous use of semipermeable membrane devices (SPMDs) and shoots of spruce needles (Picea abies). It was found that phenanthrene, acenaphthylene and fluorene were the dominating PAHs in all samples. SPMDs and needles mainly sequestered PAH associated with the vapor phase. Particle-bound PAHs were only detected in small amounts, at which the needles tended to uptake more of these compounds in comparison to the SPMDs. Nevertheless, the logarithm of the concentrations of PAHs analyzed in both passive samplers after the same sampling period exhibited a significant linear correlation with correlation coefficients larger than 0.8073. SPMDs and spruce needles can complement each other in passive air sampling for compounds with a preference to the gas phase rather than aerosols.Relationship of PAHs in SPMDs and spruce needles at the same sampling time was found.
اظهر المزيد [+] اقل [-]Metals in particle-size fractions of the soils of five European cities النص الكامل
2008
Ajmone-Marsan, F. | Biasioli, M. | Kralj, T. | Grčman, H. | Davidson, C.M. | Hursthouse, A.S. | Madrid, L. | Rodrigues, S.
Soils from Aveiro, Glasgow, Ljubljana, Sevilla and Torino have been investigated in view of their potential for translocation of potentially toxic elements (PTE) to the atmosphere. Soils were partitioned into five size fractions and Cr, Cu, Ni, Pb and Zn were measured in the fractions and the whole soil. All PTE concentrated in the <10 μm fraction. Cr and Ni concentrated also in the coarse fraction, indicating a lithogenic contribution. An accumulation factor (AF) was calculated for the <2 and <10 μm fraction. The AF values indicate that the accumulation in the finer fractions is higher where the overall contamination is lower. AF for Cr and Ni are particularly low in Glasgow and Torino. An inverse relationship was found between the AF of some metals and the percentage of <10 μm particles that could be of use in risk assessment or remediation practices.
اظهر المزيد [+] اقل [-]Biomonitors and the assessment of ecological impacts: Distribution of herbivorous epifauna in contaminated macroalgal beds النص الكامل
2008
Roberts, David A. | Johnston, Emma L. | Poore, Alistair G.B.
We determined metal contents of co-occurring algae Padina crassa and Sargassum sp. in Port Jackson (Australia), and relationships between metal levels and the abundance of epifaunal amphipods. Copper, lead and zinc concentrations were amongst the highest yet recorded in these algae. Copper, manganese and lead concentrations were far greater in P. crassa than Sargassum sp., possibly due to the low growth of P. crassa in proximity to contaminated sediments. However, in manipulative experiments the proximity of algae to sediments did not explain these differences. The abundance of herbivorous amphipods correlated negatively with the copper content of P. crassa, but not with the lower concentrations in Sargassum sp. The greater contamination of P. crassa led to patchy distributions of metals in algal beds and recolonisation experiments showed Sargassum sp. acts as a refuge from contaminants for epifauna. The contamination of macroalgae may pose threats to epifauna in harbours around the world. The accumulation of metals by macroalgae may pose ecological threats to herbivorous epifauna in ports and harbours worldwide.
اظهر المزيد [+] اقل [-]Phthalate esters (PAEs): Emerging organic contaminants in agricultural soils in peri-urban areas around Guangzhou, China النص الكامل
2008
Zeng, Feng | Cui, Kunyan | Xie, Zhiyong | Wu, Linuo | Liu, Min | Sun, Guoquan | Lin, Yujun | Luo, Danling | Zeng, Zunxiang
This study reports the first data on the concentrations and distribution of phthalate esters (PAEs) in the agricultural soils from the peri-urban areas of Guangzhou city. Σ16PAEs concentrations ranged from 0.195 to 33.6 μg g−1-dry weight (dw). Elevated levels of PAEs were recorded in the vegetable fields located next to the urban districts, and a decreasing trend exists following the distance away from the urban center. Diisobutyl phthalate (DiBP), Di-n-butyl phthalate (DnBP), and Di(2-ethylhexyl) phthalate (DEHP) dominated the PAEs in the agricultural soils. Significant relationship (correlation coefficient R2 = 0.85, p < 0.01, n = 40) was present between the accumulation of PAEs and total organic carbons in agricultural soils. In addition, both pH and texture of soils are found to be important factors affecting the level of PAEs. This study shows that the agricultural soils in the peri-urban area of Guangzhou city were moderately polluted by PAEs. PAEs are determined in agricultural soils at high concentration levels, which imply a potential risk for the food chain.
اظهر المزيد [+] اقل [-]Bulk deposition of polycyclic aromatic hydrocarbons (PAHs) in an industrial site of Turkey النص الكامل
2008
Esen, F. | Cindoruk, S.S. | Tasdemir, Y.
Ambient air and deposition samples were collected in the period of July 2004-May 2005 in an industrial district of Bursa, Turkey and analyzed for polycyclic aromatic hydrocarbon (PAH) compounds. The overall average of fourteen bulk deposition fluxes for PAHs was 3300 ± 5100 ng m-2 d-1. PAH depositions showed a seasonal variation and they were higher in winter months. This was probably due to increases in residential heating activities and decreases in atmospheric mixing layer levels. Ambient air samples, measured with a high volume air sampler, were collected from the same site. The average total concentration including gas and particulate phase was about 300 ± 420 ng m-3 and it was in the range of previously reported values. Some of the ambient air and bulk deposition samples were collected simultaneously in dry periods. Both concurrently measured values were used to calculate the dry deposition velocities whose overall average value was 0.45 ± 0.35 cm s-1. Bulk deposition fluxes of PAHs were measured in an industrial area and deposition velocities of PAHs were reported.
اظهر المزيد [+] اقل [-]Spatial and temporal variations of mercury levels in Okefenokee invertebrates: Southeast Georgia النص الكامل
2008
George, B.M. | Batzer, D.
Accumulation of mercury in wetland ecosystems has raised concerns about impacts on wetland food webs. This study measured concentrations of mercury in invertebrates of the Okefenokee Swamp in Georgia, focusing on levels in amphipods, odonates, and crayfish. We collected and analyzed total mercury levels in these invertebrates from 32 sampling stations across commonly occurring sub-habitats. Sampling was conducted in December, May, and August over a two-year period. The highest levels of mercury were detected in amphipods, with total mercury levels often in excess of 20 ppm. Bioaccumulation pathways of mercury in invertebrates of the Okefenokee are probably complex; despite being larger and higher in the food chain, levels in odonates and crayfish were much lower than in amphipods. Mercury levels in invertebrates varied temporally with the highest levels detected in May. There was a lack of spatial variation in mercury levels which is consistent with aerial deposition of mercury. This study measured mercury levels in invertebrates and found the highest levels in amphipods.
اظهر المزيد [+] اقل [-]Field comparison of disjunct and conventional eddy covariance techniques for trace gas flux measurements النص الكامل
2008
Rinne, J. | Douffet, T. | Prigent, Y. | Durand, P.
A field intercomparison experiment of the disjunct eddy covariance (DEC) and the conventional eddy covariance (EC) techniques was conducted over a grass field. The half-hourly water vapor fluxes measured by the DEC were within the estimated uncertainty from the fluxes measured by the EC. On the average there was a slight overestimation (<10%) of the fluxes measured by the DEC during the day and underestimation during the night as compared to the fluxes measured by the EC. As this bias does not appear in the simulated DEC measurements it is likely to be due to instrumental problems. The insensitivity of the quality of the fluxes measured by the DEC method to the deficiencies in the gas analysis shows the robustness of this new approach for measuring the surface-atmosphere exchange of trace gases. Results from the first field intercomparison between a new state-of-the-art trace gas flux measurement technique and the direct eddy covariance measurements are reported in this paper.
اظهر المزيد [+] اقل [-]Passive sampling of selected endocrine disrupting compounds using polar organic chemical integrative samplers النص الكامل
2008
Arditsoglou, Anastasia | Voutsa, Dimitra
Two types of polar organic chemical integrative samplers (pharmaceutical POCIS and pesticide POCIS) were examined for their sampling efficiency of selected endocrine disrupting compounds (EDCs). Laboratory-based calibration of POCISs was conducted by exposing them at high and low concentrations of 14 EDCs (4-alkyl-phenols, their ethoxylate oligomers, bisphenol A, selected estrogens and synthetic steroids) for different time periods. The kinetic studies showed an integrative uptake up to 28 days. The sampling rates for the individual compounds were obtained. The use of POCISs could result in an integrative approach to the quality status of the aquatic systems especially in the case of high variation of water concentrations of EDCs. The sampling efficiency of POCISs under various field conditions was assessed after their deployment in different aquatic environments. Calibration and field performance of polar organic integrative samplers for monitoring EDCs in aquatic environments.
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