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We used the interdisciplinary model network REGFLUD to predict the actual mean nitrate concentration in percolation water at
the scale of the Weser river basin (Germany) using an area di erentiated (100 m 100 m) approach. REGFLUD combines the
agro-economic model RAUMIS for estimating nitrogen surpluses and the hydrological models GROWA/DENUZ for assessing the
nitrate leaching from the soil. For areas showing predicted nitrate concentrations in percolation water above the European Union (EU)
groundwater quality standard of 50 mg NO3-N/L, e ective agri-environmental reduction measures need to be derived and implemented
to improve groundwater and surface water quality by 2015. The e ects of already implemented agricultural policy are quantified by
a baseline scenario projecting the N-surpluses from agricultural sector to 2015. The REGFLUD model is used to estimate the e ects
of this scenario concerning groundwater and surface water pollution by nitrate. From the results of the model analysis the needs
for additional measures can be derived in terms of required additional N-surplus reduction and in terms of regional prioritization of
measures. Research work will therefore directly support the implementation of the Water Framework Directive of the European Union
in the Weser basin. 相似文献
24.
We used the interdisciplinary model network REGFLUD to predict the actual mean nitrate concentration in percolation water at the scale of the Weser river basin (Germany) using an area differentiated (100 m × 100 m) approach.REGFLUD combines the agro-economic model RAUMIS for estimating nitrogen surpluses and the hydrological models GROWA/DENUZ for assessing the nitrate leaching from the soil.For areas showing predicted nitrate concentrations in percolation water above the European Union (EU) groundwater quality standard of 50 mg NO 3 -N/L,effective agri-environmental reduction measures need to be derived and implemented to improve groundwater and surface water quality by 2015.The effects of already implemented agricultural policy are quantified by a baseline scenario projecting the N-surpluses from agricultural sector to 2015.The REGFLUD model is used to estimate the effects of this scenario concerning groundwater and surface water pollution by nitrate.From the results of the model analysis the needs for additional measures can be derived in terms of required additional N-surplus reduction and in terms of regional prioritization of measures.Research work will therefore directly support the implementation of the Water Framework Directive of the European Union in the Weser basin. 相似文献
25.
Chronosequences are useful to evaluate long-term changes in ecosystem services but assessing groundwater quality changes using this approach has rarely been done. In this study, groundwater level and quality comparisons were made in a watershed-scale reconstructed prairie chronosequence that extended back in time approximately 13 years at the Neal Smith National Wildlife Refuge (NSNWR) near Prairie City, Iowa. Our objectives were to determine whether groundwater conditions varied significantly across the chronosequence and quantify the rate of nitrate concentration reduction when row crop fields are replaced by prairie. We installed 19 groundwater wells at upland locations selected to provide similar soil type, landscape position and slope. Water samples were collected on five occasions in 2006 and 2007 and analyzed for field parameters, anions and NO3-N, NH4-N and PO4-P. Significant groundwater changes were primarily associated with groundwater levels, and groundwater nitrate and chloride concentrations. The groundwater was deeper under the older prairie plantings but fluctuated similarly among all well sites. Groundwater nitrate and chloride concentrations decreased 0.58 and 0.52 mg/l per year over the 13-year chronosequence, respectively. Results are seen to provide some guidance to land managers regarding possible nitrate concentration reductions achievable from converting cropland to perennial land cover in similar geomorphic settings. 相似文献
26.
D. James Baker Gary Richards Alan Grainger Patrick Gonzalez Sandra Brown Ruth DeFries Alexander Held Josef Kellndorfer Peter Ndunda Dennis Ojima Per-Erik Skrovseth Carlos Souza Fred Stolle 《Environmental Science & Policy》2010,13(3):249-260
International negotiations on the inclusion of land use activities into an emissions reduction system for the UN Framework Convention on Climate Change (UNFCCC) have been partially hindered by the technical challenges of measuring, reporting, and verifying greenhouse gas (GHG) emissions and the policy issues of leakage, additionality, and permanence. This paper outlines a five-part plan for estimating forest carbon stocks and emissions with the accuracy and certainty needed to support a policy for Reducing Emissions from Deforestation and forest Degradation, forest conservation, sustainable management of forests, and enhancement of forest carbon stocks (the REDD-plus framework considered at the UNFCCC COP-15) in developing countries. The plan is aimed at UNFCCC non-Annex 1 developing countries, but the principles outlined are also applicable to developed (Annex 1) countries. The parts of the plan are: (1) Expand the number of national forest carbon Measuring, Reporting, and Verification (MRV) systems with a priority on tropical developing countries; (2) Implement continuous global forest carbon assessments through the network of national systems; (3) Achieve commitments from national space agencies for the necessary satellite data; (4) Establish agreed-on standards and independent verification processes to ensure robust reporting; and (5) Enhance coordination among international and multilateral organizations. 相似文献
27.
Peter J. Silk Krista Ryall D. Barry Lyons Jon Sweeney Junping Wu 《Die Naturwissenschaften》2009,96(5):601-608
Analyses of the elytral hydrocarbons from male and female emerald ash borer, Agrilus planipennis Fairmaire, that were freshly emerged vs. sexually mature (>10 days old) revealed a female-specific compound, 9-methyl-pentacosane
(9-Me-C25), only present in sexually mature females. This material was synthesized by the Wittig reaction of 2-decanone with (n-hexadecyl)-triphenylphosphonium bromide followed by catalytic reduction to yield racemic 9-Me C25, which matched the natural compound by gas chromatography/mass spectrometry (retention time and EI mass spectrum). In field
bioassays with freeze-killed sexually mature A. planipennis females, feral males spent significantly more time in contact and attempting copulation with unwashed females than with females
that had been washed in n-hexane to remove the cuticular lipids. Hexane-washed females to which 9-Me-C25 had been reapplied elicited similar contact time and percentage of time attempting copulation as unwashed females, indicating
that 9-methyl-pentacosane is a contact sex pheromone component of A. planipennis. This is the first contact sex pheromone identified in the Buprestidae. 相似文献
28.
Sound stimulates the tympanic membrane (TM) of anuran amphibians through multiple, poorly understood pathways. It is conceivable
that interactions between the internal and external inputs to the TM contribute to the nonlinear effects that noise is known
to produce at higher levels of the auditory pathway. To explore this issue, we conducted measurements of TM vibration in response
to tones in the presence of noise in the frog Eupsophus calcaratus. Laser vibrometry revealed that the power spectra (n = 16) of the TM velocity in response to pure tones at a constant level of 80 dB sound-pressure level (SPL) had a maximum
centered at an average frequency of 2,344 Hz (range 1,700–2,990 Hz) and a maximum velocity of 61.1 dB re 1 μm/s (range 42.9–66.6
dB re 1 μm/s). These TM-vibration velocity response profiles in the presence of increasing levels of 4-kHz band-pass noise
were unaltered up to noise levels of 90 dB SPL. For the relatively low spectral densities of the noise used, the TM remains
in its linear range. Such vibration patterns facilitate the detection of tonal signals in noise at the tympanic membrane and
may underlie the remarkable vocal responsiveness maintained by males of E. calcaratus under noise interference. 相似文献
29.
Runoff and dissolved organic carbon loss from a paired-watershed study of three adjacent agricultural Watersheds 总被引:2,自引:0,他引:2
Kristen S. Veum Keith W. Goyne Peter P. Motavalli Ranjith P. Udawatta 《Agriculture, ecosystems & environment》2009,130(3-4):115-122
Organic matter plays several important roles in the biogeochemistry of terrestrial and aquatic ecosystems including the mobilization and transport of nutrients and pollutants. Cropping, tillage practices and vegetative buffer strip installation affect losses of dissolved organic carbon (DOC). While many studies show reductions in pollutant export from agroecosystems where vegetative buffers have been implemented, buffer strips may be a source of DOC and contribute to surface water pollution. Using a paired-watershed approach, the objectives of this study were to determine the effect of grass and agroforestry buffers on runoff and DOC loss, compare runoff and DOC losses between the growing and fallow seasons, and investigate crop effects on runoff and DOC losses. The study design consisted of three small agricultural Watersheds in a no-till, maize-soybean rotation located in the claypan region of northeast Missouri, USA; one watershed was planted with grass buffer strips, one with agroforestry buffer strips, and one unaltered watershed served as the control. Runoff and DOC loss were measured during a six-year calibration period (1991–1997) prior to buffer installation and for a nine-year treatment period (1997–2006). The grass buffer strips significantly decreased runoff by 8.4% (p = 0.015) during the treatment period while the agroforestry buffer system exhibited no significant change in runoff (p = 0.207). Loss of DOC was not significantly affected by grass or agroforestry buffer installation (p = 0.535 and p = 0.246, respectively). Additionally, no significant difference in runoff or DOC loss was found between crops (maize and soybean) or between seasons (growing and fallow). Overall, this study indicates that grass buffer systems are effective at reducing runoff and that DOC contamination of surface waters is not exacerbated by either type of vegetative buffer strip. 相似文献
30.
Götz Schroth Peter Laderach Jan Dempewolf Stacy Philpott Jeremy Haggar Hallie Eakin Teresa Castillejos Jaime Garcia Moreno Lorena Soto Pinto Ricardo Hernandez Anton Eitzinger Julian Ramirez-Villegas 《Mitigation and Adaptation Strategies for Global Change》2009,14(7):605-625
The mountain chain of the Sierra Madre de Chiapas in southern Mexico is globally significant for its biodiversity and is one of the most important coffee production areas of Mexico. It provides water for several municipalities and its biosphere reserves are important tourist attractions. Much of the forest cover outside the core protected areas is in fact coffee grown under traditional forest shade. Unless this (agro)forest cover can be sustained, the biodiversity of the Sierra Madre and the environmental services it provides are at risk. We analyzed the threats to livelihoods and environment from climate change through crop suitability modeling based on downscaled climate scenarios for the period 2040 to 2069 (referred to as 2050s) and developed adaptation options through an expert workshop. Significant areas of forest and occasionally coffee are destroyed every year by wildfires, and this problem is bound to increase in a hotter and drier future climate. Widespread landslides and inundations, including on coffee farms, have recently been caused by hurricanes whose intensity is predicted to increase. A hotter climate with more irregular rainfall will be less favorable to the production of quality coffee and lower profitability may compel farmers to abandon shade coffee and expand other land uses of less biodiversity value, probably at the expense of forest. A comprehensive strategy to sustain the biodiversity, ecosystem services and livelihoods of the Sierra Madre in the face of climate change should include the promotion of biodiversity friendly coffee growing and processing practices including complex shade which can offer some hurricane protection and product diversification; payments for forest conservation and restoration from existing government programs complemented by private initiatives; diversification of income sources to mitigate risks associated with unstable environmental conditions and coffee markets; integrated fire management; development of markets that reward sustainable land use practices and forest conservation; crop insurance programs that are accessible to smallholders; and the strengthening of local capacity for adaptive resource management. 相似文献