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Результаты 271-280 из 2,500
Reduced climate sensitivity of carbon, oxygen and hydrogen stable isotope ratios in tree-ring cellulose of silver fir (Abies alba Mill.) influenced by background SO2 in Franconia (Germany, Central Europe)
2014
Boettger, Tatjana | Haupt, Marika | Friedrich, Michael | Waterhouse, John S.
The climate sensitivity of carbon (δ13C), oxygen (δ18O) and hydrogen (δ2H) isotope signatures in tree-ring cellulose of Abies alba Mill. from a marginally industrialized area of Franconia (Germany) was analysed for the last 130 years. All isotopes preserve climatic signals up to c. 1950 AD. After 1950 we observe a clear reduction in climate sensitivity of δ13C and δ2H while δ18O – climate relations remain well pronounced. Nevertheless statistical tests implied that SO2 background emissions of West Germany had influenced isotope signatures long before 1950. The relationships between isotope values and concentrations of SO2, dust, O3 and NO2 at the regional level during the period 1979–2006 indicate that δ13C and δ18O were influenced primarily by SO2. The impact of SO2 on δ2H was negligible, but the observed reduction of climate sensitivity may be caused by synergic influences. The results have significant implications if isotope signatures from tree-rings from anthropogenic influenced regions are used to reconstruct past climate.
Показать больше [+] Меньше [-]A new analytical approach for monitoring microplastics in marine sediments
2014
Nuelle, Marie-Theres | Dekiff, Jens H. | Rémy, Dominique | Fries, Elke
A two-step method was developed to extract microplastics from sediments. First, 1 kg sediments was pre-extracted using the air-induced overflow (AIO) method, based on fluidisation in a sodium chloride (NaCl) solution. The original sediment mass was reduced by up to 80%. As a consequence, it was possible to reduce the volume of sodium iodide (NaI) solution used for the subsequent flotation step. Recoveries of the whole procedure for polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene and polyurethane with sizes of approximately 1 mm were between 91 and 99%. After being stored for one week in a 35% H2O2 solution, 92% of selected biogenic material had dissolved completely or had lost its colour, whereas the tested polymers were resistant. Microplastics were extracted from three sediment samples collected from the North Sea island Norderney. Using pyrolysis gas chromatography/mass spectrometry, these microplastics were identified as PP, PVC and PET.
Показать больше [+] Меньше [-]Atmospheric polycyclic aromatic hydrocarbons in rural and urban areas of northern China
2014
Li, Wei | Wang, Chen | Wang, Hongqijie | Chen, Jiwei | Shen, Huizhong | Shen, Guofeng | Huang, Ye | Wang, Rong | Wang, Bin | Zhang, Yanyan | Chen, Han | Chen, Yuanchen | Su, Shu | Lin, Nan | Tang, Jianhui | Li, Qingbo | Wang, Xilong | Liu, Junfeng | Tao, Shu
Air pollution in rural China has often been ignored, especially for the less developed west China. Atmospheric polycyclic aromatic hydrocarbons (PAHs) were measured monthly at 11 rural sites (5 rural villages and 6 rural fields) together with 7 urban stations in northern China between April 2010 and March 2011. PAH concentrations at rural village sites were similar to those in urban areas and significantly higher than those in rural fields, indicating severe contamination in rural villages. PAH concentrations in the west were similar to those in the more developed North China Plain, and higher than those along the coast. Such a geographical distribution is mainly caused by the differences in residential energy consumption and meteorological conditions, which can explain approximately 48% of the total variation in PAH concentrations. With heavy dependence on biofuel combustion for heating, seasonality in rural areas is more profound than that in urban areas.
Показать больше [+] Меньше [-]Methylated and unsubstituted polycyclic aromatic hydrocarbons in street dust from Vietnam and India: Occurrence, distribution and in vitro toxicity evaluation
2014
Tuyen, Le Huu | Tue, Nguyen Minh | Takahashi, Shin | Suzuki, Go | Viet, Pham Hung | Subramanian, Annamalai | Bulbule, Kesav A. | Parthasarathy, Peethambaram | Ramanathan, Alagappan | Tanabe, Shinsuke
Methylated polycyclic aromatic hydrocarbons (MePAHs), unsubstituted PAHs and AhR-mediated activities were determined in street dust collected from Vietnam and India using a combined approach of chemical analysis and in vitro reporter gene assay. MePAHs and PAHs diagnostic ratios indicated that the main sources of MePAHs in Vietnam were pyrogenic emissions, whereas in India there were mixed sources of pyrogenic and petrogenic emissions. AhR-mediated activities determined by using DR-CALUX assay were observed in urban street dust at mean 40, 29 and 20 ng CALUX-TEQ/g dw for Hanoi, Bangalore and New Delhi, respectively. MePAHs and PAHs contributed only 5% or less to AhR-mediated activity in street dust, indicating the occurrence of unknown AhR agonists. The principal contributors to Theoretical-TEQs among target compounds were methyl benz[a]anthracene, benzo[b]- and benzo[k]fluoranthene. The present study indicates importance of MePAHs in evaluation of toxic risk related to AhR-mediated activity in urban polluted areas.
Показать больше [+] Меньше [-]Characterization of polybrominated diphenyl ethers (PBDEs) and hydroxylated and methoxylated PBDEs in soils and plants from an e-waste area, China
2014
Wang, Sen | Zhang, Shuzhen | Huang, Honglin | Niu, Zhenchuan | Han, Wei
In order to characterize polybrominated diphenyl ethers (PBDEs), and hydroxylated and methoxylated PBDEs (OH-PBDEs and MeO-PBDEs) in the soil–plant system, soil and plant samples were collected from an e-waste recycling area in China. Forty one PBDEs, twelve OH-PBDEs and MeO-PBDEs were detected in the soil and plant samples. Concentrations of PBDEs in roots were significantly correlated to their concentrations in the soils, but the percentages of lower brominated congeners in the plants were higher than those in the soils. Significant positive linear relationships exist between concentrations of ∑OH-PBDEs and ∑MeO-PBDEs with higher levels of ∑MeO-PBDEs than those of ∑OH-PBDEs in the soils, plant roots and leaves. A majority of the OH-/MeO-PBDEs had the hydroxyl or methoxy group at the ortho-positions to the biphenyl bond for most of the plant species. However the occurrence of meta- and para- substituted OH-/MeO-PBDEs in soils and plants were also confirmed.
Показать больше [+] Меньше [-]Cadmium contamination of agricultural soils and crops resulting from sphalerite weathering
2014
Robson, T.C. | Braungardt, C.B. | Rieuwerts, J. | Worsfold, P.
The biogeochemistry and bioavailability of cadmium, released during sphalerite weathering in soils, were investigated under contrasting agricultural scenarios to assess health risks associated with sphalerite dust transport to productive soils from mining. Laboratory experiments (365 d) on temperate and sub-tropical soils amended with sphalerite (<63 μm, 0.92 wt.% Cd) showed continuous, slow dissolution (0.6–1.2% y−1). Wheat grown in spiked temperate soil accumulated ≈38% (29 μmol kg−1) of the liberated Cd, exceeding food safety limits. In contrast, rice grown in flooded sub-tropical soil accumulated far less Cd (0.60 μmol kg−1) due to neutral soil pH and Cd bioavailability was possibly also controlled by secondary sulfide formation. The results demonstrate long-term release of Cd to soil porewaters during sphalerite weathering. Under oxic conditions, Cd may be sufficiently bioavailable to contaminate crops destined for human consumption; however flooded rice production limits the impact of sphalerite contamination.
Показать больше [+] Меньше [-]Possible causes of the recent rapid increase in the radial increment of silver fir in the Western Carpathians
2014
Bošeľa, Michal | Petráš, Rudolf | Sitková, Zuzana | Priwitzer, Tibor | Pajtík, Jozef | Hlavatá, Helena | Sedmák, Róbert | Tobin, Brian
Silver fir is one of the most productive and ecologically valuable native European tree species, however, it has been experiencing decline which has periodically occurred over its natural range. This paper aims to investigate the recent climate–growth relationships of silver fir (Abies alba Mill.) and its temporal change along the course of its life. Long-term tree-ring databases, as well as records on climate, atmospheric SO2, NO3 and acid concentrations from four different regions in the Western Carpathians were used. The results provide clear evidence of significant increase of silver fir's radial increment over the entire Western Carpathian area since 1970–1980. The results indicated that the most probable factors behind the rapid recovery of tree radial increment were reductions in emissions of NO3 and SO2, alongside a significant increase in mean June, July and April temperatures.
Показать больше [+] Меньше [-]Year-round grazing to counteract effects of atmospheric nitrogen deposition may aggravate these effects
2014
van Dobben, H.F. | Wamelink, G.W.W. | Klimkowska, A. | Slim, P.A. | van Til, M.
Excessive nitrogen input in natural ecosystems is a major threat to biodiversity. A coastal dune area near Amsterdam in the Netherlands suffers from high atmospheric nitrogen deposition affecting sensitive habitats such as fixed coastal dunes with herbaceous vegetation (‘grey dunes’). To mitigate its effect year round grazing was applied from 2007 until 2012. In winter, when natural food supply is low, the cattle received supplementary hay that caused additional inputs of nitrogen. Estimates based on nitrogen contents of hay, as well as of manure, showed the input through winter feeding (c. 3–14 kg N ha-1.y-1) is in the same order of magnitude as both the actual deposition (c. 17 kg N ha-1.y-1) and the critical load for a number of herbaceous habitat types (10–15 kg N ha-1.y-1). Locally, the effect of winter feeding adds to the effect of nitrogen redistribution within the area caused by the cattle's terrain usage. We conclude that winter feeding may aggravate effects of atmospheric nitrogen deposition. Keywords: Vegetation management; Manure; Nitrogen; Eutrophication; Natura 2000; Grey dune
Показать больше [+] Меньше [-]Concentrations of polybrominated diphenyl ethers (PBDEs) in central air-conditioner filter dust and relevance of non-dietary exposure in occupational indoor environments in Greece
2014
Besis, Athanasios | Katsoyiannis, Athanasios | Botsaropoulou, Elisavet | Samara, Constantini
Polybrominated Diphenyl Ethers (PBDEs) are ubiquitous in the indoor environment owing to their use in consumer products and various studies around the world have found higher concentrations indoors than outdoors. Central air conditioner (A/C) systems have been widely used in many workplaces, therefore, studying of PBDEs in central A/C filter dust is useful to better understand the occurrences and health implications of PBDEs in indoor environments. The present study examined the occurrence of PBDEs in central A/C filter dust collected from various workplaces (n = 20) in Thessaloniki, Greece. The sum concentrations of 21 target congeners (∑21PBDE) in A/C dust ranged between 84 and 4062 ng g−1 with a median value of 1092 ng g−1, while BDE-209 was found to be the most abundant BDE congener. The daily intake via dust ingestion of PBDEs estimated for the employees of the occupational settings ranged from 3 to 45 ng day−1 (median 12 ng day−1).
Показать больше [+] Меньше [-]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.
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