The allelopathic potential of fescue (Festuca arundinacea Shreb.) was investigated under field and laboratory conditions. In the field, incorporation of fescue aboveground biomass
into the soil provided an effective weed control as it significantly reduced both the number and the dry weight of all weed
species. The effect on weeds was species specific. The reduction of the most abundant species, Picris echioides, with respect to the number of individuals and their dry weight was 67 and 45%. Fescue aboveground biomass, harvested immediately
before soil incorporation, was utilized in a bioassay-oriented fractionation, aimed at identifying the compounds in the toxic
extracts of the plant. While phytotoxic activity was detected for the n-butanol fraction, no activity was found for the aqueous one. Germination of an indicator species, lettuce (Lactuca sativa L.), was reduced by 33% at the higher extract concentration of 20 mg/mL, owing to the increase of the number of abnormal
seedlings. The LC/MS profile of the extract revealed the presence of two alkaloids, seven flavonol glycosides, and two flavonol
aglyca. Quercetin 3-O-rutinoside, isorhamnetin 3-O-rutinoside, and kaempferol 3-O-rutinoside were reported in fescue for the first time. 相似文献
During the Fifth Framework Programme (FP5) of the European Commission--according to an institutional programme in support to the policy of the European Commission for the implementation of Art. 35 and 36 of the Euratom Treaty as well as in the framework of the OSPAR Convention for the protection of marine environment of the north-east Atlantic--at the Institute for Transuranium Elements (ITU--General Directorate Joint Research Centre--European Commission), a reference laboratory for the measurement of radioactivity in the environment (MaRE laboratory) has been set up. In this paper, the principles and philosophy in order to improve the quality and reliability of analytical data for the measurement and monitoring of radioactivity in the environment under a quality assurance (QA) programme are presented. Examples of how a QA programme at the MaRE laboratory is developed and applied are given. Internal and external quality control (QC) programmes are also discussed. 相似文献
Land capability classification systems define and communicate biophysical limitations on land use, including climate, soils
and topography. They can therefore provide an accessible format for both scientists and decision-makers to share knowledge
on climate change impacts and adaptation. Underlying such classifications are complex interactions that require dynamic spatial
analysis, particularly between soil and climate. These relationships are investigated using a case study on drought risk for
agriculture in Scotland, which is currently considered less significant than wetness-related issues. The impact of drought
risk is assessed using an established empirical system for land capability linking indicator crops with water availability.
This procedure is facilitated by spatial interpolation of climate and soil profile data to provide soil moisture deficits
and plant available water on a regular 1-km grid. To evaluate potential impacts of future climate change, land capability
classes are estimated using both large-scale ensemble (multi-simulation) data from the HadRM3 regional climate model and local-scale
weather generator data (UKCP09) derived from multiple climate models. Results for the case study suggest that drought risk
is likely to have a much more significant influence on land use in the future. This could potentially act to restrict the
range of crops grown and hence reduce land capability in some areas unless strategic-level adaptation measures are developed
that also integrate land use systems and water resources with the wider environment. 相似文献
Natural resource degradation in highland regions is of increasing concern to the global community due to its role in aggravating poverty and the loss of environmental services to local and downstream users. The integration of trees into smallholder farming systems has been promoted as a means to enhance rural livelihoods while reversing the degradation of soil, water, biodiversity and related environmental services. Yet in addition to these benefits, negative impacts of trees on certain stakeholders or system components have also accompanied such efforts—suggesting that important trade-offs accompany afforestation. This paper presents a methodology for diagnosing problems stemming from cultivation of certain tree species in specific landscape niches. Data derived from the application of this methodology in two sites in the eastern African highlands are presented. Participatory diagnoses of landscape-level problems suggest that the negative impact of trees on water resource availability and crop yield are of critical concern to smallholder farmers. Ethnoecological data highlight the properties of different tree species that determine their suitability to specific farm and landscape niches. These data point to important opportunities for more socially- and environmentally-optimal integration of indigenous and exotic tree species into agricultural landscapes, and highlight the critical importance of local knowledge in forging solutions appropriate to contemporary realities. 相似文献
Ecotoxicological effects associated with contaminants present in dredged material from Spain were determined using a marine biotest based on the determination of metallothionein-like-protein concentrations (MTLPs) in the shore crab Carcinus maenas. Intermoult female C. maenas were exposed in the laboratory to sediments from three Spanish ports, Ría de Huelva (SW, Spain), La Coru?a (NW, Spain) and Bahía de Cádiz (SW, Spain) per replicate during 21 days. Hepatopancreas samples from crabs were taken for metallothioneins analysis on days 0, 7 and 21. Furthermore, chemical analysis was performed in the stations to determine the degree and nature of sediment contamination (Cr, Ni, Cu, Zn, Cd, Pb, Hg, As, PAHs and PCBs). A significant increase (p<0.05) in metallothionein concentration was observed over time in individuals exposed to sediment from the port Ría de Huelva characterized by high concentrations of metals. A toxicokinetic approach is proposed in this study related to the use of this biomarker in C. maenas to evaluate bioavailability associated with metals present in dredged material. As a first step, this toxicokinetic approach might reveal as a sensitive tool for evaluating bioavailability of contaminants present in dredged material. 相似文献
Conservation discourses tend to portray invasive species as biological entities temporally connected to colonial timelines, using terms such as “alien”, “colonizing”, “colonial”, and “native”. This focus on a colonial timeline emerges from scientific publications within conservation biology and invasion ecology and is enacted through invasive species management by state and NGO actors. Colonialism is influential for indigenous nations in myriad ways, but in what ways do indigenous understandings of invasive species engage with colonialism? We conducted ethnographic research with indigenous Anishnaabe communities to learn about the ways Anishnaabe people conceptualize invasive species as a phenomenon in the world and were gifted with three primary insights. First, Anishnaabe regard plants, like all beings, as persons that assemble into nations more so than “species”. The arrival of new plant nations is viewed by some Anishnaabe as a natural form of migration. The second insight highlights the importance of actively discovering the purpose of new species, sometimes with the assistance of animal teachers. Lastly, while Anishnaabe describe invasive species as phenomenologically entangled with colonialism, the multiple ways Anishnaabe people think about invasive species provide alternatives to native–non-native binaries that dominate much of the scientific discourse. 相似文献
Policy reform can be complex and fraught with contending arguments. Although much research has been conducted into the politics of coalition formation, less attention has been devoted to legitimating logics in policy reform. Drawing on the work of Boltanski and Thévenot, this exploratory study addresses this deficit by examining the influence of justifications deployed in policy debates. The paper analyses the role of shifting reasoning in contentious debates concerning attempts to reform water policy, including the introduction of domestic water charges in Ireland. Employing data from parliamentary deliberations, the paper traces the changing forms of justification used by those favouring and opposing the reforms. This examination suggests the importance of aligning an argument’s content with the shifting context into which it is introduced. The paper highlights the benefits of an investigative approach concerning policy justification for understanding policy reform dynamics at the intersection of politics and environmental communication. 相似文献
The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic matter content. Soils were spiked with the diphenyl-ether herbicide and irradiation experiments were performed either in the laboratory with a solar simulator (xenon lamp) or outside, under natural sunlight irradiation; other soil samples were kept in the dark to control the retention reaction. Kinetic parameters of both retention and photochemical reactions were calculated using zero-, first- and second- (Langmuir-Hinshelwood) order equations, and best fit was checked through statistical analysis. The soil behaviors were qualitatively similar but quantitatively different, with the soil sampled from the Nea Malgara region much more sorbent as compared with Preveza soil. All studied reactions followed second-order kinetics and photochemical reactions were influenced by retaining capability of the soils. The contributions of the photochemical processes to the global dissipation rates were also calculated. Two main metabolites were identified as 2-chloro-1-(3-ethoxy-4-hydroxyphenoxy)-4-(trifluoromethyl)benzene and 2-chloro-1- (3-hydroxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene. 相似文献
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
With the recognition that most global environmental problems are a result of human actions, there is an increasing interest in approaches which have the potential to influence human behaviour. Images have a powerful role in shaping persuasive messages, yet research on the impacts of visual representations of nature is a neglected area in biodiversity conservation. We systematically screened existing studies on the use of animal imagery in conservation, identifying 37 articles. Although there is clear evidence that images of animals can have positive effects on people’s attitudes to animals, overall there is currently a dearth of accessible and comparable published data demonstrating the efficacy of animal imagery. Most existing studies are place and context-specific, limiting the generalisable conclusions that can be drawn. Transdisciplinary research is needed to develop a robust understanding of the contextual and cultural factors that affect how animal images can be used effectively for conservation purposes.