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31.
Friedrich U von Oheimb G Dziedek C Kriebitzsch WU Selbmann K Härdtle W 《Environmental pollution (Barking, Essex : 1987)》2011,159(12):3553-3559
We analysed growth strategies (biomass allocation, nutrient sequestration and allocation) of heather (Calluna vulgaris) and purple moor-grass (Molinia caerulea) seedlings in monocultures and mixtures in relation to N, P, and N + P fertilisation in a greenhouse experiment in order to simulate a heath’s pioneer phase under high airborne nitrogen (N) loads. N fertilisation increased the total biomass of both species in monocultures. In mixtures, M. caerulea sequestered about 65% of the N applied, while C. vulgaris suffered from N shortage (halving of the total biomass). Thus, in mixtures only M. caerulea will benefit from airborne N loads, and competition will become increasingly asymmetric with increasing N availability. Our results demonstrate that the heath’s pioneer phase is the crucial tipping point at which the competitive vigour of M. caerulea (high belowground allocation, efficient use of belowground resources, shortened reproductive cycles) induces a shift to dominance of grasses under increased N availability. 相似文献
32.
Cornelia Meinert Emma Schymanski Eberhard Küster Ralph Kühne Gerrit Schüürmann Werner Brack 《Environmental science and pollution research international》2010,17(4):885-897
Background, aim and scope
The importance of groundwater for human life cannot be overemphasised. Besides fulfilling essential ecological functions, it is a major source of drinking water. However, in the industrial area of Bitterfeld, it is contaminated with a multitude of harmful chemicals, including genotoxicants. Therefore, recently developed methodologies including preparative capillary gas chromatography (pcGC), MOLGEN-MS structure generation and mutagenicity prediction were applied within effect-directed analysis (EDA) to reduce sample complexity and to identify candidate mutagens in the samples. A major focus was put on the added value of these tools compared to conventional EDA combining reversed-phase liquid chromatography (RP-LC) followed by GC/MS analysis and MS library search. 相似文献33.
34.
Scrano L Bufo SA D'Auria M Meallier P Behechti A Shramm KW 《Journal of environmental quality》2002,31(1):268-274
Photochemistry studies can be helpful in assessing the environmental fate of chemicals. Photochemical reactions lead to the formation of by-products that can exhibit different toxicological properties from the original compound. For this reason the photochemical behavior of the herbicide acifluorfen (5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid) in the presence of different solvents was studied. Photochemical reactions were carried out using a high-pressure mercury arc and a solar simulator. Kinetic parameters and quantum yields were determined. The identification of photoproducts was performed by mass spectrometry and [1H] nuclear magnetic resonance (NMR). Nitrofluorfen, hydroxy-nitrofluorfen, 2-chloro-4-(trifluoromethyl)phenol, 5-trifluoromethyl-5'-nitrodibenzofuran, and other derivatives were identified. The photochemical reactions were also carried out in the presence of either a singlet or a triplet quencher, and in the presence of either a radical initiator or a radical inhibitor. Substances used as inhibitors of the excited levels T1 and S1 showed that photodegradation of acifluorfen begins from a singlet state S1 through a pi,pi* transition. The role of free radicals in the photodegradation of acifluorfen was determined and a radical mechanism was proposed. Toxicity tests against Daphnia magna Strauss showed that acifluorfen was not toxic at a concentration of 0.1 mM; however, photoproducts formed after 36 h of UV exposure of the herbicide induced a remarkable toxicity to the test organism. 相似文献
35.
Astrid Wetzel Gabriela Klante D. Werner 《Umweltwissenschaften und Schadstoff-Forschung》1991,3(5):266-271
Im Zusammenhang mit der Umweltchemikalienprüfung und der Untersuchung und Kontrolle kontaminierter B?den besteht gro?er Bedarf
an Testverfahren mit h?heren Pflanzen, die schnell, einfach und preisgünstig durchzuführen sind und bereits bestehende Testverfahren
nach OECD- und BBA-Richtlinien sinnvoll erg?nzen k?nnen. Dieser Beitrag stellt einen Biotoxizit?tstest vor, der die Nodulation
in der Leguminosen-Kn?llchen-Symbiose als sensiblen Wirkungsparameter für die Belastung mit polyzyklischen aromatischen Kohlenwasserstoffen
(PAK) benutzt. Fremdstoff, Pflanze und Mikroorganismus werden dabei auf einer festen Matrix in Kontakt miteinander gebracht;
das axenische System erlaubt die Untersuchung der Fremdstoffwirkung sowohl auf den Gesamtorganismus Pflanze, als auch auf
die Interaktion von Pflanze und Mikroorganismus (Kn?llchenbildung). In Dose-Response-Versuchen zeigte sich der Wirkungsparameter
Nodulation, gemessen als Anzahl Wurzelkn?llchen pro Pflanze, sensibler als andere pflanzliche Wachstumsparameter.
There is great need for toxicity tests with higher plants for the investigation and monitoring of chemicals in the environment
— especially for tests which are quick, easy, and inexpensive. Such tests should add to and improve current guidelines, e.g.,
OECD- and BBA-Guidelines. This article describes the nodulation of leguminous plants withRhizobium bacteria used in a bioassay with polycyclic aromatic hydrocarbons (PAH). Plants growing on a solid medium were exposed simultaneously
to bacteria and PAH. This axenic culture system allows to observe the impact of PAH on plant growth and the interaction between
plant and bacteria (nodulation). Dose-response-experiments indicated that nodulation measured as number of nodules per plant,
was more sensitive to the inhibition by PAH than other plant growth parameters. 相似文献
36.
37.
Hussain Majid Khan Alam Pierre Madl Werner Hofmann 《Environmental monitoring and assessment》2013,185(6):5265-5276
Ambient aerosol concentrations along the roadside of metropolitan cities of Pakistan were measured using a Grimm 1.109 dust monitor. Considering the high ambient aerosol concentrations, regional lung deposition of aerosol particles in the human respiratory tract was calculated to assess extent of exposure. Lung deposition was computed in terms of mass concentration and the associated surface area for 12 male traffic wardens using the latest version of the stochastic lung deposition code Inhalation, Deposition, and Exhalation of Aerosols in the Lung. The results have revealed 4 to 10 times higher concentrations than recommended by WHO guidelines. The deposition results derived from the model disclose that extrathoracic deposition is in the range of 22 to 28 % with total lung deposition ranging from 40 to 44 % for the scanned particle window of 0.25–10 μm. Considering an average 8-h shift per day and an average breathing rate of 1.3 m3?h?1, it is approximated that in a worker, up to 1.6 mg of inhalable particle mass can deposit per day. 相似文献
38.
Surface water methane (CH4) and nitrous oxide (N2O) concentrations and fluxes were investigated in two subtropical coastal embayments (Bramble Bay and Deception Bay, which are part of the greater Moreton Bay, Australia). Measurements were done at 23 stations in seven campaigns covering different seasons during 2010-2012. Water-air fluxes were estimated using the Thin Boundary Layer approach with a combination of wind and currents-based models for the estimation of the gas transfer velocities. The two bays were strong sources of both CH4 and N2O with no significant differences in the degree of saturation of both gases between them during all measurement campaigns. Both CH4 and N2O concentrations had strong temporal but minimal spatial variability in both bays. During the seven seasons, CH4 varied between 500% and 4000% saturation while N2O varied between 128 and 255% in the two bays. Average seasonal CH4 fluxes for the two bays varied between 0.5 ± 0.2 and 6.0 ± 1.5 mg CH4/(m2·day) while N2O varied between 0.4 ± 0.1 and 1.6 ± 0.6 mg N2O/(m2·day). Weighted emissions (t CO2-e) were 63%-90% N2O dominated implying that a reduction in N2O inputs and/or nitrogen availability in the bays may significantly reduce the bays' greenhouse gas (GHG) budget. Emissions data for tropical and subtropical systems is still scarce. This work found subtropical bays to be significant aquatic sources of both CH4 and N2O and puts the estimated fluxes into the global context with measurements done from other climatic regions. 相似文献
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