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Water, heat, and airborne pollutants effects on transpiration of urban trees 全文
2011
Wang, Hua | Ouyang, Z. (Zhiyun) | Chen, Weiping | Wang, Xiaoke | Zheng, Hua | Ren, Yufen
Transpiration rates of six urban tree species in Beijing evaluated by thermal dissipation method for one year were correlated to environmental variables in heat, water, and pollutant groups. To sort out colinearity of the explanatory variables, their individual and joint contributions to variance of tree transpiration were determined by the variation and hierarchical partitioning methods. Majority of the variance in transpiration rates was associated with joint effects of variables in heat and water groups and variance due to individual effects of explanatory group were in comparison small. Atmospheric pollutants exerted only minor effects on tree transpiration. Daily transpiration rate was most affected by air temperature, soil temperature, total radiation, vapor pressure deficit, and ozone. Relative humidity would replace soil temperature when factors influencing hourly transpiration rate was considered.
显示更多 [+] 显示较少 [-]Developments in greenhouse gas emissions and net energy use in Danish agriculture – How to achieve substantial CO₂ reductions? 全文
2011
Dalgaard, T. | Olesen, J.E. | Petersen, S.O. | Petersen, B.M. | Jørgensen, U. | Kristensen, T. | Hutchings, N.J. | Gyldenkærne, S. | Hermansen, J.E.
Developments in greenhouse gas emissions and net energy use in Danish agriculture – How to achieve substantial CO₂ reductions? 全文
2011
Dalgaard, T. | Olesen, J.E. | Petersen, S.O. | Petersen, B.M. | Jørgensen, U. | Kristensen, T. | Hutchings, N.J. | Gyldenkærne, S. | Hermansen, J.E.
Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990–2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50–70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers, optimization of animal feeding, cropping practices, and land use changes with more organic farming, afforestation and energy crops. In addition, the bioenergy production may be increased significantly without reducing the food production, whereby Danish agriculture could achieve a positive energy balance.
显示更多 [+] 显示较少 [-]Developments in greenhouse gas emissions and net energy use in Danish agriculture - How to achieve substantial CO2 reductions? 全文
2011
Dalgaard, Tommy | Olesen, Jørgen E. | Petersen, B.M. | Petersen, Søren O. | Jørgensen, Uffe | Kristensen, Troels | Hutchings, Nicholas J. | Gyldenkerne, Steen | Hermansen, J.E.
Greenhouse gas (GHG) emissions from agriculture are a significant contributor to total Danish emissions. Consequently, much effort is currently given to the exploration of potential strategies to reduce agricultural emissions. This paper presents results from a study estimating agricultural GHG emissions in the form of methane, nitrous oxide and carbon dioxide (including carbon sources and sinks, and the impact of energy consumption/bioenergy production) from Danish agriculture in the years 1990-2010. An analysis of possible measures to reduce the GHG emissions indicated that a 50-70% reduction of agricultural emissions by 2050 relative to 1990 is achievable, including mitigation measures in relation to the handling of manure and fertilisers, optimization of animal feeding, cropping practices, and land use changes with more organic farming, afforestation and energy crops. In addition, the bioenergy production may be increased significantly without reducing the food production, whereby Danish agriculture could achieve a positive energy balance.
显示更多 [+] 显示较少 [-]The role of root hairs in cadmium acquisition by barley 全文
2011
Zheng, Ruilun | Li, Huafen | Jiang, Rongfeng | Römheld, Volker | Zhang, Fusuo | Zhao, Fang-Jie
The role of root hairs in Cd acquisition from soil was investigated in three pot experiments using a root hairless mutant (bald root barley, brb) and its wild-type (WT) cultivar of barley (Hordeum vulgare). brb had significantly lower concentrations and lower total amounts of Cd in shoots than WT. The Cd uptake efficiency based on total root length was 8–45% lower in brb than in WT. The difference between brb and WT increased with increasing extractable Cd in soil under the experimental conditions used. Additions of phosphate to soil decreased Cd extractability. Both soil and foliar additions of phosphate decreased root length, and root hair formation in WT. These effects resulted in decreased Cd uptake with increasing P supply. Cd uptake in WT correlated significantly with root length, root hair length and density, and soil extractable Cd. Root hairs contribute significantly to Cd uptake by barley.
显示更多 [+] 显示较少 [-]Floodplain methylmercury biomagnification factor higher than that of the contiguous river (South River, Virginia USA) 全文
2011
Newman, Michael C. | Xu, Xiaoyu | Condon, Anne | Liang, Lian
Mercury biomagnification on the South River floodplain (Virginia, USA) was modeled at two locations along a river reach previously modeled for methylmercury movement through the aquatic trophic web. This provided an opportunity to compare biomagnification in adjoining trophic webs. Like the aquatic modeling results, methylmercury-based models provided better prediction than those for total mercury. Total mercury Food Web Magnification Factors (FWMF, fold per trophic level) for the two locations were 4.9 and 9.5. Methylmercury FWMF for the floodplain locations were higher (9.3 and 25.1) than that of the adjacent river (4.6). Previous speculation was not resolved regarding whether the high mercury concentrations observed in floodplain birds was materially influenced by river prey consumption by riparian spiders and subsequent spider movement into the trophic web of the adjacent floodplains. Results were consistent with a gradual methylmercury concentration increase from contaminated floodplain soil, to arthropod prey, and finally, to avian predators.
显示更多 [+] 显示较少 [-]Variations in concentrations and compositions of polycyclic aromatic hydrocarbons (PAHs) in coals related to the coal rank and origin 全文
2011
Laumann, S. | Micić, V. | Kruge, M.A. | Achten, C. | Sachsenhofer, R.F. | Schwarzbauer, J. | Hofmann, T.
The release of unburnt coal particles and associated polycyclic aromatic hydrocarbons (PAHs) may cause adverse impacts on the environment. This study assessed variations in the concentration and composition of PAHs in a set of fifty coal samples from eleven coal basins worldwide. The maximum PAH concentrations at high volatile bituminous rank were recorded in samples from a single basin. Considering the entire sample set, the highest PAH concentrations were in fact found outside of this rank range, suggesting that the maceral composition and thus the coal’s origin also influenced PAH concentrations. The examination of the PAH compositions revealed that alkylated 2–3 ring PAHs remain dominant compounds irrespective of coal rank or origin. Multivariate analysis based on PAH and maceral content, bulk and maturity parameters allowed the recognition of seven groups with different rank and origin within the coal sample set.
显示更多 [+] 显示较少 [-]Occurrence of polycyclic aromatic hydrocarbons in surface sediments of a highly urbanized river system with special reference to energy consumption patterns 全文
2011
Zhang, Kai | Wang, Ji-Zhong | Liang, Bo | Zeng, E. Y. (Eddy Y.)
Sediment samples collected from downstream of the Dongjiang River, a highly urbanized river network within the Pearl River Delta of South China, were analyzed for 28 polycyclic aromatic hydrocarbons (PAHs). Total concentrations of 28 PAHs, 16 priority PAHs designated by the United States Environmental Protection Agency (USEPA) and the seven carcinogenic PAHs classified by the USEPA ranged from 480 to 4600, 100 to 3400 and 10 to 1700 ng/g dry weight, respectively. Principal component analysis-based stepwise multivariate linear regression showed that sediment PAHs were predominantly derived from coal combustion, refined fossil fuel combustion and oil spills, accounting for 37%, 32% and 23%, respectively, of the total loading. The levels of sediment PAHs remained steady from 2002 to 2008, during which fossil fuel consumption had doubled, probably reflecting efforts to control PAH emissions from fossil fuel combustion. Finally, use of natural gas and liquefied petroleum gas in automobiles should be encouraged to improve environmental quality.
显示更多 [+] 显示较少 [-]Biofilm responses to marine fish farm wastes 全文
2011
Sanz-Lázaro, Carlos | Navarrete-Mier, Francisco | Marín, Arnaldo
Biofilm responses to marine fish farm wastes 全文
2011
Sanz-Lázaro, Carlos | Navarrete-Mier, Francisco | Marín, Arnaldo
The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems.
显示更多 [+] 显示较少 [-]Biofilm responses to marine fish farm wastes 全文
2011
Sanz-Lázaro, Carlos | Navarrete Mier, Francisco | Marín, Arnaldo | Universidad de Alicante. Departamento de Ciencias del Mar y Biología Aplicada | Biología Marina
The changes in the biofilm community due to organic matter enrichment, eutrophication and metal contamination derived from fish farming were studied. The biofilm biomass, polysaccharide content, trophic niche and element accumulation were quantified along an environmental gradient of fish farm wastes in two seasons. Biofilm structure and trophic diversity was influenced by seasonality as well as by the fish farm waste load. Fish farming enhanced the accumulation of organic carbon, nutrients, selenium and metals by the biofilm community. The accumulation pattern of these elements was similar regardless of the structure and trophic niche of the community. This suggests that the biofilm communities can be considered a reliable tool for assessing dissolved aquaculture wastes. Due to the ubiquity of biofilms and its wide range of consumers, its role as a sink of dissolved wastes may have important implications for the transfer of aquaculture wastes to higher trophic levels in coastal systems. | This work was funded by the project AGL2004-08350-C02-01/ACU from the Ministerio de Ciencia y Tecnología, a predoctoral grant to C. S. from the Ministerio de Educación y Ciencia (Spain) and another predoctoral grant to F. N. from the ALBAN programme (EU).
显示更多 [+] 显示较少 [-]An overview of experimental results and dispersion modelling of nanoparticles in the wake of moving vehicles 全文
2011
Carpentieri, Matteo | Kumar, Prashant | Robins, Alan
Understanding the transformation of nanoparticles emitted from vehicles is essential for developing appropriate methods for treating fine scale particle dynamics in dispersion models. This article provides an overview of significant research work relevant to modelling the dispersion of pollutants, especially nanoparticles, in the wake of vehicles. Literature on vehicle wakes and nanoparticle dispersion is reviewed, taking into account field measurements, wind tunnel experiments and mathematical approaches. Field measurements and modelling studies highlighted the very short time scales associated with nanoparticle transformations in the first stages after the emission. These transformations strongly interact with the flow and turbulence fields immediately behind the vehicle, hence the need of characterising in detail the mixing processes in the vehicle wake. Very few studies have analysed this interaction and more research is needed to build a basis for model development. A possible approach is proposed and areas of further investigation identified.
显示更多 [+] 显示较少 [-]Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. II. Zinc binding inside leaf cell organelles 全文
2011
Vollenweider, Pierre | Bernasconi, Petra | Gautschi, Hans-Peter | Menard, Terry | Frey, Beat | Günthardt-Goerg, Madeleine S.
The phytoextraction potential of plants for removing heavy metals from polluted soils is determined by their capacity to store contaminants in aboveground organs and complex them safely. In this study, the metal compartmentation, elemental composition of zinc deposits and zinc complexation within leaves from poplars grown on soil with mixed metal contamination was analysed combining several histochemical and microanalytical approaches. Zinc was the only heavy metal detected and was stored in several organelles in the form of globoid deposits showing β-metachromasy. It was associated to oxygen anions and different cations, noteworthy phosphorous. The deposit structure, elemental composition and element ratios indicated that zinc was chelated by phytic acid ligands. Maturation processes in vacuolar vs. cytoplasmic deposits were suggested by differences in size and amounts of complexed zinc. Hence, zinc complexation by phytate contributed to metal detoxification and accumulation in foliage but could not prevent toxicity reactions therein.
显示更多 [+] 显示较少 [-]Mineralisation of target hydrocarbons in three contaminated soils from former refinery facilities 全文
2011
Towell, Marcie G. | Bellarby, Jessica | Paton, Graeme I. | Coulon, Frédéric | Pollard, Simon J.T. | Semple, K. T. (Kirk T.)
This study investigated the microbial degradation of ¹⁴C-labelled hexadecane, octacosane, phenanthrene and pyrene and considered how degradation might be optimised in three genuinely hydrocarbon-contaminated soils from former petroleum refinery sites. Hydrocarbon mineralisation by the indigenous microbial community was monitored over 23 d. Hydrocarbon mineralisation enhancement by nutrient amendment (biostimulation), hydrocarbon degrader addition (bioaugmentation) and combined nutrient and degrader amendment, was also explored. The ability of indigenous soil microflora to mineralise ¹⁴C-target hydrocarbons was appreciable; ≥16% mineralised in all soils. Generally, addition of nutrients or degraders increased the rates and extents of mineralisation of ¹⁴C-hydrocarbons. However, the addition of nutrients and degraders in combination had a negative effect upon ¹⁴C-octacosane mineralisation and resulted in lower extents of mineralisation in the three soils. In general, the rates and extents of mineralisation will be dependent upon treatment type, nature of the contamination and adaptation of the ingenious microbial community.
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