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Ozone visible symptoms and reduced root biomass in the subalpine species Pinus uncinata after two years of free-air ozone fumigation Полный текст
2012
Díaz-de-Quijano, Maria | Schaub, Marcus | Bassin, Seraina | Volk, Matthias | Peñuelas, Josep
Concentrations of ozone often exceed the thresholds of forest protection in the Pyrenees, but the effect of ozone on Pinus uncinata, the dominant species in subalpine forests in this mountainous range, has not yet been studied. We conducted an experiment of free-air ozone fumigation with saplings of P. uncinata fumigated with ambient O₃ (AOT40 May–Oct: 9.2 ppm h), 1.5 × O₃ₐₘb (AOT40 May–Oct: 19.2 ppm h), and 1.8 × O₃ₐₘb (AOT40 May–Oct: 32.5 ppm h) during two growing seasons. We measured chlorophyll content and fluorescence, visible injury, gas exchange, and above- and below-ground biomass. Increased exposures to ozone led to a higher occurrence and intensity of visible injury from O₃ and a 24–29% reduction of root biomass, which may render trees more susceptible to other stresses such as drought. P. uncinata is thus a species sensitive to O₃, concentrations of which in the Pyrenees are already likely affecting this species.
Показать больше [+] Меньше [-]Ozone deposition to an orange orchard: Partitioning between stomatal and non-stomatal sinks Полный текст
2012
Fares, Silvano | Weber, Robin | Park, Jeong-Hoo | Gentner, Drew | Karlik, Jan | Goldstein, Allen H.
Orange trees are widely cultivated in regions with high concentrations of tropospheric ozone. Citrus absorb ozone through their stomata and emit volatile organic compounds (VOC), which, together with soil emissions of NO, contribute to non-stomatal ozone removal. In a Valencia orange orchard in Exeter, California, we used fast sensors and eddy covariance to characterize water and ozone fluxes. We also measured meteorological parameters necessary to model other important sinks of ozone deposition. We present changes in magnitude of these ozone deposition sinks over the year in response to environmental parameters. Within the plant canopy, the orchard constitutes a sink for ozone, with non-stomatal ozone deposition larger than stomatal uptake. In particular, soil deposition and reactions between ozone, VOC and NO represented the major sinks of ozone. This research aims to help the development of metrics for ozone-risk assessment and advance our understanding of citrus in biosphere-atmosphere exchange.
Показать больше [+] Меньше [-]Class 1 and 2 integrons, sul resistance genes and antibiotic resistance in Escherichia coli isolated from Dongjiang River, South China Полный текст
2012
Su, Hao-Chang | Ying, Guang-Guo | Tao, Ran | Zhang, Rui-Quan | Zhao, Jian-Liang | Liu, You-Sheng
Antibiotic susceptibility, detection of sul gene types and presence of class 1, 2 and 3 integrons and gene cassettes using PCR assays were investigated in 3456 Escherichia coli isolates obtained from 38 sampling sites of the Dongjiang River catchment in the dry and wet seasons. 89.1% of the isolates were resistant and 87.5% showed resistance to at least three antibiotics. sul2 was detected most frequently in 89.2% of 1403 SXT-resistant isolates. The presence of integrons (class 1 and 2) was frequently observed (82.3%) while no class 3 integron was found. In these integrons, 21 resistance genes of 14 gene cassette arrays and 10 different families of resistance genes were identified. Three gene cassette arrays, aac(6')-Ib-cr-aar-3-dfrA27-aadA16, aacA4-catB3-dfrA1 and aadA2-lnuF, were detected for the first time in surface water. The results showed that bacterial resistance in the catchment was seriously influenced by human activities, especially discharge of wastewater.
Показать больше [+] Меньше [-]Legacy and current-use flame retardants in house dust from Vancouver, Canada Полный текст
2012
Shoeib, Mahiba | Harner, Tom | Webster, Glenys M. | Sverko, Ed | Cheng, Yu
Fifteen polybrominated diphenyl ethers (PBDEs) and eighteen non-PBDEs were measured in 116 dust samples collected from homes in Vancouver, Canada during 2007–2008 as part of the Chemicals Health and Pregnancy (CHirP) study. The highest concentrations of PBDEs in house dust were observed for BDE 209, with a median concentration of 1350 ng/g. This is about two times greater than the median concentration of the PentaBDE (represented by the most abundant compounds in this formulation, ΣBDE 47, 99 and 100). In the case of non-PBDE FRs, a detection frequency between 81% and 100% was observed for nine analytes including: HBCD, BTBPE, BEHTBP, EHTBB, HBB, PBTO, PBBe, ATE and DP. The high detection of new FRs in indoor environments reflects their ubiquitous presence in indoor environment due to regulation of the PBDEs. Exposure to FRs are estimated based on these data for adults and toddlers.
Показать больше [+] Меньше [-]Bees, honey and pollen as sentinels for lead environmental contamination Полный текст
2012
Lambert, Olivier | Piroux, Mélanie | Puyo, Sophie | Thorin, Chantal | Larhantec, Michaëlle | Delbac, Frédéric | Pouliquen, Hervé
Three beehive matrices, sampled in eighteen apiaries from West France, were analysed for the presence of lead (Pb). Samples were collected during four different periods in both 2008 and 2009. Honey was the matrix the least contaminated by Pb (min = 0.004 μg g⁻¹; max = 0.378 μg g⁻¹; mean = 0.047 μg g⁻¹; sd = 0.057). The contamination of bees (min = 0.001 μg g⁻¹; max = 1.869 μg g⁻¹; mean = 0.223 μg g⁻¹; sd = 0.217) and pollen (min = 0.004 μg g⁻¹; max = 0.798 μg g⁻¹; mean = 0.240 μg g⁻¹; sd = 0.200) showed similar levels and temporal variations but bees seemed to be more sensitive bringing out the peaks of Pb contamination. Apiaries in urban and hedgerow landscapes appeared more contaminated than apiaries in cultivated and island landscapes. Sampling period had a significant effect on Pb contamination with higher Pb concentrations determined in dry seasons.
Показать больше [+] Меньше [-]A sediment ecotoxicity assessment platform for in situ measures of chemistry, bioaccumulation and toxicity. Part 1: System description and proof of concept Полный текст
2012
Burton, G. Allen, Jr | Rosen, Gunther | Chadwick, D Bart | Greenberg, Marc S. | Taulbee, W Keith | Lotufo, Guilherme R. | Reible, Danny D.
In situ-based testing using aquatic organisms has been widely reported, but is often limited in scope and practical usefulness in making decisions on ecological risk and remediation. To provide this capability, an integrated deployment system, the Sediment Ecotoxicity Assessment (SEA) Ring was developed, which incorporates rapid in situ hydrological, chemical, bioaccumulation, and toxicological Lines-of-Evidence (LoE) for assessing sediment and overlying water contamination. The SEA Ring system allows for diver-assisted, or diverless, deployment of multiple species of ecologically relevant and indigenous organisms in three different exposures (overlying water, sediment–water interface, and bulk sediment) for periods ranging from two days to three weeks, in a range of water systems. Measured endpoints were both sublethal and lethal effects as well as bioaccumulation. In addition, integrated passive sampling devices for detecting nonpolar organics (solid phase micro-extraction fibers) and metals (diffusive gradients in thin films) provided gradient measures in overlying waters and surficial sediments.
Показать больше [+] Меньше [-]The impact of organochlorines cycling in the cryosphere on global distributions and fate – 2. Land ice and temporary snow cover Полный текст
2012
Hofmann, Lorenz | Stemmler, Irene | Lammel, Gerhard
Global fate and transport of γ-HCH and DDT was studied using a global multicompartment chemistry-transport model, MPI-MCTM, with and without inclusion of land ice (in Antarctica and Greenland) or snow cover (dynamic). MPI-MCTM is based on coupled ocean and atmosphere general circulation models. After a decade of simulation 4.2% γ-HCH and 2.3% DDT are stored in land ice and snow. Neglection of land ice and snow in modelling would underestimate the total environmental residence time, τₒᵥ, of γ-HCH and overestimate τₒᵥ for DDT, both on the order of 1% and depending on actual compartmental distribution. Volatilisation of DDT from boreal, seasonally snow covered land is enhanced throughout the year, while volatilisation of γ-HCH is only enhanced during the snow-free season. Including land ice and snow cover in modelling matters in particular for the Arctic, where higher burdens are predicted to be stored.
Показать больше [+] Меньше [-]Toxicity assessment of simulated urban runoff containing polycyclic musks and cadmium in Carassius auratus using oxidative stress biomarkers Полный текст
2012
Chen, Fang | Gao, Jie | Zhou, Qixing
The objective of this study was to assess potential toxic effects of simulated urban runoff on Carassius auratus using oxidative stress biomarkers. The activity of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the content of malondialdehyde (MDA) in the liver of C. auratus were analyzed after a 7-, 14- and 21-day exposure to simulated urban runoff containing galaxolide (HHCB) and cadmium (Cd). The results showed that the activity of antioxidant enzymes and the content of MDA increased significantly exposed to the simulated urban runoff containing HHCB alone or mixture of HHCB and Cd. The activity of the investigated enzymes and the content of MDA then returned to the blank level over a longer period of exposure. The oxidative stress could be obviously caused in the liver of C. auratus under the experimental conditions. This could provide useful information for toxic risk assessment of urban runoff.
Показать больше [+] Меньше [-]Assessment of polybrominated diphenyl ethers (PBDEs) in serum from the Korean general population Полный текст
2012
Kim, Jongchul | Kang, Jung-Ho | Park, Hyokeun | Baek, Song-Yee | Kim, Yang-ho | Chang, Yoon Seok
In 2009 and 2010, 720 serum samples were collected from non-occupationally exposed study participants at four Korean locations and monitored for the presence of 27 polybrominated diphenyl ether (PBDE) congeners. The median concentrations of Σ₂₇PBDEs (the sum of 27 congeners) and Σ₃–₇PBDEs (the sum of tri- to hepta-BDE congeners) were 6.04 and 4.97 ng/g lipid, respectively. The most abundant congener detected in serum samples was BDE-153, followed by BDE-47 and BDE-99. The median value of Σ₃–₇PBDEs was similar to the median values observed in Asia and Europe, but much lower than that observed in North America. Some significant differences, based on geographic region and sex, were observed. We also observed a positive increase of BDE-153 with regard to age. In addition, we estimated the daily exposure to PBDEs from previously published reports of PBDE concentrations in food and dust, and determined the individual contributions of a variety of sources.
Показать больше [+] Меньше [-]Ammonium release from a blanket peatland into headwater stream systems Полный текст
2012
Daniels, S.M. | Evans, M.G. | Agnew, C.T. | Allott, T.E.H.
Hydrochemical sampling of South Pennine (UK) headwater streams draining eroded upland peatlands demonstrates these systems are nitrogen saturated, with significant leaching of dissolved inorganic nitrogen (DIN), particularly ammonium, during both stormflow and baseflow conditions. DIN leaching at sub-catchment scale is controlled by geomorphological context; in catchments with low gully densities ammonium leaching dominates whereas highly gullied catchments leach ammonium and nitrate since lower water tables and increased aeration encourages nitrification. Stormflow flux calculations indicate that: approximately equivalent amounts of nitrate are deposited and exported; ammonium export significantly exceeds atmospheric inputs. This suggests two ammonium sources: high atmospheric loadings; and mineralisation of organic nitrogen stored in peat. Downstream trends indicate rapid transformation of leached ammonium into nitrate. It is important that low-order headwater streams are adequately considered when assessing impacts of atmospheric loads on the hydrochemistry of stream networks, especially with respect to erosion, climate change and reduced precipitation.
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