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النتائج 111 - 120 من 1,310
Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe النص الكامل
2011
Harmens, H. | Norris, D.A. | Cooper, D.M. | Mills, G. | Steinnes, E. | Kubin, E. | Thöni, L. | Aboal, J.R. | Alber R., | Carballeira, A. | Coşkun, M. | De Temmerman, L. | Frolova, M. | González-Miqueo, L. | Jeran, Z. | Leblond, S. | Liiv, S. | Maňkovská, B. | Pesch, R. | Poikolainen, J. | Rühling, Å | Santamaria, J.M. | Simonèiè, P. | Schröder, W. | Suchara, I. | Yurukova, L. | Zechmeister, H.G.
In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r² = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.
اظهر المزيد [+] اقل [-]Will PM control undermine China’s efforts to reduce soil acidification? النص الكامل
2011
Zhao, Yu | Duan, Lei | Lei, Yu | Xing, Jia | Nielsen, Chris P. | Hao, Jiming
China’s strategies to control acidifying pollutants and particulate matter (PM) may be in conflict for soil acidification abatement. Acidifying pollutant emissions are estimated for 2005 and 2020 with anticipated control policies. PM emissions including base cations (BCs) are evaluated with two scenarios, a base case applying existing policy to 2020, and a control case including anticipated tightened measures. Depositions of sulfur (S), nitrogen (N) and BCs are simulated and their acidification risks are evaluated with critical load (CL). In 2005, the area exceeding CL covered 15.6% of mainland China, with total exceedance of 2.2 Mt S. These values decrease in the base scenario 2020, implying partial recovery from acidification. Under more realistic PM control, the respective estimates are 17.9% and 2.4 Mt S, indicating increased acidification risks due to abatement of acid-neutralizing BCs. China’s anthropogenic PM abatement will have potentially stronger chemical implications for acidification than developed countries.
اظهر المزيد [+] اقل [-]Bioaccessibility and health risk of arsenic, mercury and other metals in urban street dusts from a mega-city, Nanjing, China النص الكامل
2011
Hu, Xin | Zhang, Yun | Luo, Jun | Wang, Tijian | Lian, Hongzhen | Ding, Zhuhong
The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level (<1 × 10⁻⁴). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults.
اظهر المزيد [+] اقل [-]Modelling arsenic toxicity in wheat: Simultaneous application of diffusive gradients in thin films to arsenic and phosphorus in soil النص الكامل
2011
Mojsilovic, Ognjen | McLaren, Ron G. | Condron, Leo M.
The diffusive gradients in thin films (DGT) technique was evaluated in modelling wheat (Triticum aestivum) arsenic toxicity using a dataset of As-contaminated soil samples (n=28) collected from former sheep dip sites. Above ground wheat biomass from a 21-day early growth bioassay was adopted as the response variable and the dose–response relationships were modelled using the three-parameter sigmoid equation. The DGT-derived effective soil solution As to P concentration ratios corresponded strongly to the differences in the response variable. With a single sample identified as an outlier, the 95% confidence interval for the effective soil solution As/P molar concentration ratio which resulted in a 50% reduction in the response (EC50) was 0.168–0.360. While the DGT-derived soil measure of As/P ratio was shown as a promising phytotoxicity predictor, the influence of P nutrition on the dose–response relationship deserves further consideration.
اظهر المزيد [+] اقل [-]The use of environmental metabolomics to determine glyphosate level of exposure in rapeseed (Brassica napus L.) seedlings النص الكامل
2011
Petersen, Iben Lykke | Tomasi, Giorgio | Sørensen, H. (Hilmer) | Boll, Esther S. | Hansen, Hans Christian Bruun | Christensen, Jan H.
Metabolic profiling in plants can be used to differentiate between treatments and to search for biomarkers for exposure. A methodology for processing Ultra-High-Performance Liquid Chromatography–Diode-Array-Detection data is devised. This methodology includes a scheme for selecting informative wavelengths, baseline removal, retention time alignment, selection of relevant retention times, and principal component analysis (PCA). Plant crude extracts from rapeseed seedling exposed to sublethal concentrations of glyphosate are used as a study case. Through this approach, plants exposed to concentrations down to 5 μM could be distinguished from the controls. The compounds responsible for this differentiation were partially identified and were different from those specific for high exposure samples, which suggests that two different responses to glyphosate are elicited in rapeseed depending on the level of exposure. The PCA loadings indicate that a combination of other metabolites could be more sensitive than the response of shikimate to detect glyphosate exposure.
اظهر المزيد [+] اقل [-]Characterization of PBDEs in soils and vegetations near an e-waste recycling site in South China النص الكامل
2011
Wang, Yan | Luo, Chunling | Li, Jun | Yin, Hua | Li, Xiangdong | Zhang, Gan
The concentration and composition of PBDEs in the soils and plants near a typical e-waste recycling site in South China were investigated. The total concentration of PBDEs (ΣPBDEs) in soil ranged from 4.8 to 533 ng/g dry wt. The ΣPBDEs in vegetation were from 2.1 to 217 ng/g dry wt. For the vegetable, the highest concentration of 19.9 ng/g dry wt. was observed in the shoot of Brassica alboglabra L. BDE 209 was the predominant congener in all samples. In comaprison with other e-waste contaminated sites in China, lower concentrations of PBDEs and higher concentrations of PCBs were observed in both soils and plants suggesting different e-waste types involved in the present study. The PBDEs contaminated vegetables around the e-waste dismantling site may pose a potential health risk to the local inhabitants.
اظهر المزيد [+] اقل [-]Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building النص الكامل
2011
Ni, Hong-Gang | Cao, Shan-Ping | Chang, Wen-Jing | Zeng, Hui
This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM₂.₅ (Particulate Matter up to 2.5 μm in size) bounded Σ₁₅PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM₁₀ (Particulate Matter up to 10 μm in size) bounded Σ₁₅PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of Σ₁₅PBDEs via dust inhalation and ingestion for adults reached ∼141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones.
اظهر المزيد [+] اقل [-]Urban and rural mortality rates during heat waves in Berlin and Brandenburg, Germany النص الكامل
2011
Gabriel, Katharina M.A. | Endlicher, Wilfried R.
In large cities such as Berlin, human mortality rates increase during intense heat waves. Analysis of relevant data from north-eastern Germany revealed that, during the heat waves that occurred between 1990 and 2006, health risks were higher for older people in both rural and urban areas, but that, during the two main heat waves within that 17-year period of time, the highest mortality rates were from the city of Berlin, and in particular from its most densely built-up districts. Adaptation measures will need to be developed, particularly within urban areas, in order to cope with the expected future intensification of heat waves due to global climate change.
اظهر المزيد [+] اقل [-]Urban nonpoint source pollution buildup and washoff models for simulating storm runoff quality in the Los Angeles County النص الكامل
2011
Wang, Long | Wei, Jiahua | Huang, Yuefei | Wang, Guangqian | Maqsood, Imran
Many urban nonpoint source pollution models utilize pollutant buildup and washoff functions to simulate storm runoff quality of urban catchments. In this paper, two urban pollutant washoff load models are derived using pollutant buildup and washoff functions. The first model assumes that there is no residual pollutant after a storm event while the second one assumes that there is always residual pollutant after each storm event. The developed models are calibrated and verified with observed data from an urban catchment in the Los Angeles County. The application results show that the developed model with consideration of residual pollutant is more capable of simulating nonpoint source pollution from urban storm runoff than that without consideration of residual pollutant. For the study area, residual pollutant should be considered in pollutant buildup and washoff functions for simulating urban nonpoint source pollution when the total runoff volume is less than 30mm.
اظهر المزيد [+] اقل [-]Differential accumulation of mercury and other trace metals in the food web components of a reservoir impacted by a chlor-alkali plant (Flix, Ebro River, Spain): Implications for biomonitoring النص الكامل
2011
Soto, David X. | Roig, Romero | Gacia, Esperança | Catalan, Jordi
Comparative studies of biomonitors of trace metal contamination are relatively scarce. We took advantage of a point source pollution in a reservoir (Flix, Spain) to compare trace metal (Hg, Pb, Cd, Se, As, Zn, Cu, Cr) bioaccumulation patterns among 16 food web components. Our results indicate that most organisms are suitable for Hg biomonitoring, whereas other metals are better monitored by only some of them. Biofilms and zebra mussel were the organisms with larger and more diverse biomonitoring capacity. However, we show that using groups of biomonitors increase the scope and strengths of the conclusions and specific goals can be better addressed. We conclude providing an overview of the strengths and weaknesses of the main organisms considered for biomonitoring trace metals in rivers and reservoirs.
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