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Regional patterns in foliar 15N across a gradient of nitrogen deposition in the northeastern US Texto completo
2007
Pardo, L.H. | McNulty, S.G. | Boggs, J.L. | Duke, S.
Recent studies have demonstrated that natural abundance 15N can be a useful tool for assessing nitrogen saturation, because as nitrification and nitrate loss increase, δ15N of foliage and soil also increases. We measured foliar δ15N at 11 high-elevation spruce-fir stands along an N deposition gradient in 1987-1988 and at seven paired northern hardwood and spruce-fir stands in 1999. In 1999, foliar δ15N increased from -5.2 to -0.7[per thousand] with increasing N deposition from Maine to NY. Foliar δ15N decreased between 1987-1988 and 1999, while foliar %N increased and foliar C:N decreased at most sites. Foliar δ15N was strongly correlated with N deposition, and was also positively correlated with net nitrification potential and negatively correlated with soil C:N ratio. Although the increase in foliar %N is consistent with a progression towards N saturation, other results of this study suggest that, in 1999, these stands were further from N saturation than in 1987-1988. Foliar δ15N increased with increasing N deposition from Maine to NY, but decreased between 1987-1988 and 1999
Mostrar más [+] Menos [-]Reduced nitrogen in ecology and the environment Texto completo
2007
Erisman, J.W. | Bleeker, A. | Galloway, J. | Sutton, M.S.
Since the beginning of the 19th century humans have increasingly fixed atmospheric nitrogen as ammonia to be used as fertilizer. The fertilizers are necessary to create amino acids and carbohydrates in plants to feed animals and humans. The efficiency with which the fertilizers eventually reach humans is very small: 5-15%, with much of the remainder lost to the environment. The global industrial production of ammonia amounts to 117 Mton NH3-N year-1 (for 2004). By comparison, we calculate that anthropogenic emissions of NH3 to the atmosphere over the lifecycle of industrial NH3 in agriculture are 45.3 Mton NH3-N year-1, about half the industrial production. Once emitted ammonia has a central role in many environmental issues. We expect an increase in fertilizer use through increasing demands for food and biofuels as population increases. Therefore, management of ammonia or abatement is necessary. Half of industrial ammonia production is eventually lost to the global environment with significant effects.
Mostrar más [+] Menos [-]Comparison of different stomatal conductance algorithms for ozone flux modelling Texto completo
2007
Büker, P. | Emberson, L.D. | Ashmore, M.R. | Cambridge, H.M. | Jacobs, C.M.J. | Massman, W.J. | Müller, J. | Nikolov, N. | Novak, K. | Oksanen, E.
Comparison of different stomatal conductance algorithms for ozone flux modelling Texto completo
2007
Büker, P. | Emberson, L.D. | Ashmore, M.R. | Cambridge, H.M. | Jacobs, C.M.J. | Massman, W.J. | Müller, J. | Nikolov, N. | Novak, K. | Oksanen, E.
A multiplicative and a semi-mechanistic, BWB-type [Ball, J.T., Woodrow, I.E., Berry, J.A., 1987. A model predicting stomatal conductance and its contribution to the control of photosynthesis under different environmental conditions. In: Biggens, J. (Ed.), Progress in Photosynthesis Research, vol. IV. Martinus Nijhoff, Dordrecht, pp. 221-224.] algorithm for calculating stomatal conductance (gs) at the leaf level have been parameterised for two crop and two tree species to test their use in regional scale ozone deposition modelling. The algorithms were tested against measured, site-specific data for durum wheat, grapevine, beech and birch of different European provenances. A direct comparison of both algorithms showed a similar performance in predicting hourly means and daily time-courses of gs, whereas the multiplicative algorithm outperformed the BWB-type algorithm in modelling seasonal time-courses due to the inclusion of a phenology function. The re-parameterisation of the algorithms for local conditions in order to validate ozone deposition modelling on a European scale reveals the higher input requirements of the BWB-type algorithm as compared to the multiplicative algorithm because of the need of the former to model net photosynthesis (An).
Mostrar más [+] Menos [-]Comparison of different stomatal conductance algorithms for ozone flux modelling Texto completo
2007
Buker, P. | Emberson, L.D. | Ashmore, M.R. | Cambridge, H.M. | Jacobs, C.M.J. | Massman, W.J. | Müller, J. | Nikolov, N. | Novak, K. | Oksanen, E. | Schaub, M. | Torre Llorente, Daniel de la
A multiplicative and a semi-mechanistic, BWB-type [Ball, J.T., Woodrow, I.E., Berry, J.A., 1987. A model predicting stomatalconductance and its contribution to the control of photosynthesis under different environmental conditions. In: Biggens, J. (Ed.), Progress in Photosynthesis Research, vol. IV. Martinus Nijhoff, Dordrecht, pp. 221–224.] algorithm for calculating stomatalconductance (gs) at the leaf level have been parameterised for two crop and two tree species to test their use in regional scale ozone deposition modelling. The algorithms were tested against measured, site-specific data for durum wheat, grapevine, beech and birch of different European provenances. A direct comparison of both algorithms showed a similar performance in predicting hourly means and daily time-courses of gs, whereas the multiplicative algorithm outperformed the BWB-type algorithm in modelling seasonal time-courses due to the inclusion of a phenology function. The re-parameterisation of the algorithms for local conditions in order to validate ozone deposition modelling on a European scale reveals the higher input requirements of the BWB-type algorithm as compared to the multiplicative algorithm because of the need of the former to model net photosynthesis (An)
Mostrar más [+] Menos [-]Evaluation of the treatment efficiencies of paper mill whitewaters in terms of organic composition and toxicity Texto completo
2007
Latorre, A. | Malmqvist, A. | Lacorte, S. | Welander, T. | Barcelo, D.
Evaluation of the treatment efficiencies of paper mill whitewaters in terms of organic composition and toxicity Texto completo
2007
Latorre, A. | Malmqvist, A. | Lacorte, S. | Welander, T. | Barcelo, D.
The efficiency of several lab scale treatments (aerobic, anaerobic and ozone or combination of these) was evaluated using two packaging board mill whitewaters. The effect of the different treatments on the elimination of the organic load, the chemical oxygen demand (COD) and the toxicity was tested as well as the relationship between these parameters. Biocides, phenolic compounds, surfactants, plasticiziers and wood extractives were identified in untreated and treated whitewaters by liquid chromatography coupled with mass spectrometry (LC-MS) or gas chromatography coupled with mass spectrometry (GC-MS). A strong dependency on the water type and treatment efficiency was observed, being the combination of anaerobic and aerobic treatments the best option to reduce the organic contaminants in these waters, although in some cases, the toxicity did not decrease. However, ozone as post-treatment permitted a further reduction of organic compounds, toxicity and COD. Aerobic and anaerobic treatments remove organic compounds in paper mill effluents but toxicity remains.
Mostrar más [+] Menos [-]Evaluation of the treatment efficiencies of paper mill whitewaters in terms of organic composition and toxicity Texto completo
2007
Latorre Fernández, Anna | Malmqvist, Asa | Lacorte Bruguera, Silvia | Welander, Thomas | Barceló, Damià
8 pages, 3 figures, 1 table.-- PMID: 17118260 [PubMed].-- Online version available Nov 20, 2006. | Issue title: Air Pollution and Climate Change: A Global Overview of the Effects on Forest Vegetation. | The efficiency of several lab scale treatments (aerobic, anaerobic and ozone or combination of these) was evaluated using two packaging board mill whitewaters. The effect of the different treatments on the elimination of the organic load, the chemical oxygen demand (COD) and the toxicity was tested as well as the relationship between these parameters. Biocides, phenolic compounds, surfactants, plasticiziers and wood extractives were identified in untreated and treated whitewaters by liquid chromatography coupled with mass spectrometry (LCeMS) or gas chromatography coupled with mass spectrometry (GCeMS). A strong dependency on the water type and treatment efficiency was observed, being the combination of anaerobic and aerobic treatments the best option to reduce the organic contaminants in these waters, although in some cases, the toxicity did not decrease. However, ozone as post-treatment permitted a further reduction of organic compounds, toxicity and COD. | Aerobic and anaerobic treatments remove organic compounds in paper mill effluents but toxicity remains. | This study has been supported by the EU Energy, Environmental and Sustainable Development Program (CLOSEDCYCLE, Contract No EVK1-2000-00749). The authors thank Riudesa factory (Catalonia, Spain) and Anox (Sweden) for supplying water samples and Merck for supplying the LC columns. | Peer reviewed
Mostrar más [+] Menos [-]Increasing risk for negative ozone impacts on vegetation in northern Sweden Texto completo
2007
Karlsson, P.E. | Tang, L. | Sundberg, J. | Chen, D. | Lindskog, A. | Pleijel, H.
Increasing risk for negative ozone impacts on vegetation in northern Sweden Texto completo
2007
Karlsson, P.E. | Tang, L. | Sundberg, J. | Chen, D. | Lindskog, A. | Pleijel, H.
Trends were found for increasing surface ozone concentrations during April-September in northern Sweden over the period 1990-2006 as well as for an earlier onset of vegetation growing season. The highest ozone concentrations in northern Sweden occurred in April and the ozone concentrations in April showed a strong increasing trend. A model simulation of ozone flux for Norway spruce indicated that the provisional ozone flux based critical level for forests in Europe is exceeded in northern Sweden. Future climate change would have counteracting effects on the stomatal conductance and needle ozone uptake, mediated on the one hand by direct effect of increasing air temperatures and on the other through increasing water vapour pressure difference between the needles and air. Thus, there is a substantial and increasing risk for negative impacts of ozone on vegetation in northern Sweden, related mainly to increasing ozone concentrations and an earlier onset of the growing season. Increasing risks for ozone impacts on vegetation in northern Sweden.
Mostrar más [+] Menos [-]Regional and local surface ozone variations in relation to meteorological conditions in Sweden Texto completo
Tang, Lin
Air quality is strongly dependent on meteorological conditions. Atmospheric circulation encapsulates general information about local meteorological variables to some extent, and can serve as an explanatory variable for air quality at a regional or local scale. Numerical models are another useful tool for understanding the influence of meteorological factors on the chemical and physical processes involved in regional and local air quality variations. The aims of this thesis have been to: (1) investigate regional surface ozone and its correlation to atmospheric circulations by making use of synoptic weather types in southern Sweden; (2) compare numerical models performances in simulating urban meteorological conditions and apply a numerical model to urban air quality study for Gothenburg. The study confirmed the influences of synoptic circulation on regional ozone concentrations by relating the Lamb Weather Types (LWTs) to surface ozone variations. Anticyclones, associated with atmospheric stagnation, tend to create whirling air masses and short trajectories from the European continent, which leads to effective long-range transport, enhanced local ozone photochemical production, and high-ozone levels. Cyclones, on the other hand, can also create high level ozone through frontal passages and enhanced vertical mixing. At the same time, the frequencies of cyclones and anticyclones in this region are highly anti-correlated, making cyclone frequency a skilful predictor of high ozone events. The frequency of cyclones over the past 150 years shows a high variability and showed significantly downward trend. Given the constant conditions from other factors for example emission, continuous decrease in the frequency of cyclones indicates the more occurrences of high-ozone events in southern Sweden. A numerical model - The Air Quality Model (TAPM) - was used to simulate the complex wind system and other meteorological variables needed for air quality applications in the Gothenburg area. Compared with The PSU/NCAR fifth-generation Mesoscale Model (MM5), TAPM is able to better reproduce near-surface air temperature and wind system in Gothenburg. Both MM5 and TAPM can simulate night-time vertical temperature gradient well, but underestimate daytime vertical temperature gradient and the occurrences of low wind speed situation at night. TAPM was then used to reproduce NOx−O3 reactions and investigate the wind speed effect on spatial differences of NO2 concentrations in the polluted urban landscape. TAPM satisfactorily simulated the relation of NO, NO2 and ozone as well as the site differences for different wind speed categories. However, TAPM underestimated NO at certain sites due to local scale sitespecific conditions and missing emissions from nearby roads and other emission sources.
Mostrar más [+] Menos [-]Intercontinental transport of aerosols and photochemical oxidants from Asia and its consequences Texto completo
2007
Wuebbles, D.J. | Lei, H. | Lin, JT.
The intercontinental transport of aerosols and photochemical oxidants from Asia is a crucial issue for air quality concerns in countries downwind of the significant emissions and concentrations of pollutants occurring in this important region of the world. Since the lifetimes of some important pollutants are long enough to be transported over long distance in the troposphere, regional control strategies for air pollution in downwind countries might be ineffective without considering the effects of long-range transport of pollutants from Asia. Field campaigns provide strong evidence for the intercontinental transport of Asian pollutants. They, together with ground-based observations and model simulations, show that the air quality over parts of North America is being affected by the pollutants transported from Asia. This paper examines the current understanding of the intercontinental transport of gases and aerosols from Asia and resulting effects on air quality, and on the regional and global climate system. Air quality over parts of North America is being affected by pollutants transported from Asia.
Mostrar más [+] Menos [-]Isozyme markers associated with O3 tolerance indicate shift in genetic structure of ponderosa and Jeffrey pine in Sequoia National Park, California Texto completo
2007
Staszak, J. | Grulke, N.E. | Marrett, M.J. | Prus-Glowacki, W.
Effects of canopy ozone (O3) exposure and signatures of genetic structure using isozyme markers associated with O3 tolerance were analyzed in 20-, 80-, and >200-yr-old ponderosa (Pinus ponderosa Dougl. ex Laws.) and Jeffrey pine (Pinus jeffreyi Grev. & Balf.) in Sequoia National Park, California. For both species, the number of alleles and genotypes per loci was higher in parental trees relative to saplings. In ponderosa pine, the heterozygosity value increased, and the fixation index indicated reduction of homozygosity with increasing tree age class. The opposite tendencies were observed for Jeffrey pine. Utilizing canopy attributes known to be responsive to O3 exposure, ponderosa pine was more symptomatic than Jeffrey pine, and saplings were more symptomatic than old growth trees. We suggest that these trends are related to differing sensitivity of the two species to O3 exposure, and to higher O3 exposures and drought stress that younger trees may have experienced during germination and establishment. Genetic variation in isozyme markers associated with ozone tolerance differed between parental trees and their progeny in two closely related species of yellow pine.
Mostrar más [+] Menos [-]Poplar for the phytomanagement of boron contaminated sites Texto completo
2007
Robinson, B.H. | Green, S.R. | Chancerel, B. | Mills, T.M. | Clothier, B.E.
Boron (B) is a widespread environmental contaminant that is mobile relative to other trace elements. We investigated the potential of hybrid poplar (Populus sp.) for B phytomanagement using a lysimeter experiment and a field trial on B-contaminated wood-waste. In both studies, poplars enhanced evapotranspiration from the wood-waste, reduced B leaching, and accumulated B in the aerial portions of the tree. When grown in a substrate containing 30 mg/kg B, poplar leaves had an average B concentration of 845 mg/kg, while the stems contained 21 mg/kg B. Leaf B concentrations increased linearly with leaf age. A decomposition experiment revealed that abscised leaves released 14% of their B during the winter months. Fertiliser application enhanced tree growth without decreasing the leaf B concentrations. Harvesting alternate rows of trees on a contaminated site would reduce leaching from the site while removing B. Harvested plant material may provide bioenergy, stock fodder, or an amendment for B-deficient soils. Poplars reduce boron leaching from contaminated sites.
Mostrar más [+] Menos [-]Phytotoxicity of nanoparticles: Inhibition of seed germination and root growth Texto completo
2007
Lin, D. | Xing, B.
Plants need to be included to develop a comprehensive toxicity profile for nanoparticles. Effects of five types of nanoparticles (multi-walled carbon nanotube, aluminum, alumina, zinc, and zinc oxide) on seed germination and root growth of six higher plant species (radish, rape, ryegrass, lettuce, corn, and cucumber) were investigated. Seed germination was not affected except for the inhibition of nanoscale zinc (nano-Zn) on ryegrass and zinc oxide (nano-ZnO) on corn at 2000 mg/L. Inhibition on root growth varied greatly among nanoparticles and plants. Suspensions of 2000 mg/L nano-Zn or nano-ZnO practically terminated root elongation of the tested plant species. Fifty percent inhibitory concentrations (IC50) of nano-Zn and nano-ZnO were estimated to be near 50 mg/L for radish, and about 20 mg/L for rape and ryegrass. The inhibition occurred during the seed incubation process rather than seed soaking stage. These results are significant in terms of use and disposal of engineered nanoparticles. Engineered nanoparticles can inhibit the seed germination and root growth.
Mostrar más [+] Menos [-]Future climate scenarios and rainfall-runoff modelling in the Upper Gallego catchment (Spain) Texto completo
2007
Burger, C.M. | Kolditz, O. | Fowler, H.J. | Blenkinsop, S.
Global climate change may have large impacts on water supplies, drought or flood frequencies and magnitudes in local and regional hydrologic systems. Water authorities therefore rely on computer models for quantitative impact prediction. In this study we present kernel-based learning machine river flow models for the Upper Gallego catchment of the Ebro basin. Different learning machines were calibrated using daily gauge data. The models posed two major challenges: (1) estimation of the rainfall-runoff transfer function from the available time series is complicated by anthropogenic regulation and mountainous terrain and (2) the river flow model is weak when only climate data are used, but additional antecedent flow data seemed to lead to delayed peak flow estimation. These types of models, together with the presented downscaled climate scenarios, can be used for climate change impact assessment in the Gallego, which is important for the future management of the system. Future climate change and data-based rainfall-runoff predictions are presented for the Upper Gallego.
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