Interactions between European agricultural policy and climate change: a Slovenian case study     

Emil Erjavec  Tina Volk  Miroslav Rednak  Barbara Zagorc  Ben Moljk 《Climate Policy》2013,13(8):1014-1030

This article analyses the interactions between agricultural policy measures in the EU and the factors affecting GHG emissions from agriculture on the one hand, and the adaptation of agriculture to climate change on the other. To this end, the article uses Slovenia as a case study, assessing the extent to which Slovenian agricultural policy is responding to the challenges of climate change. All agricultural policy measures related to the 2007–2013 programming period were analysed according to a new methodological approach that is based on a qualitative (expert evaluation) and a quantitative (budgetary transfers validation) assessment. A panel of experts reached consensus on the key factors through which individual measures affect climate change, in which direction and how significantly. Data on budgetary funds for each measure were used as weights to assess their relative importance. The results show that there are not many measures in (Slovenian) agricultural policy that are directly aimed at reducing GHG emissions from agriculture or at adaptation to climate change. Nevertheless, most affect climate change, and their impact is far from negligible. Current measures have both positive and negative impacts, but overall the positive impacts prevail. Measures that involve many beneficiaries and more budgetary funds had the strongest impact on aggregate assessments. In light of climate change, agricultural policy should pay more attention to measures that are aimed at raising the efficiency of animal production, as it is the principal source of GHG emissions from agriculture.

Policy relevance

Agricultural policy must respond to climate challenges and climate change impact assessment must be included in the process of forming European agricultural policy. Agricultural policy measures that contribute to the reduction of emissions and adaptation, whilst acting in synergy with other environmental, economic and social goals, should be promoted. The approach used in this study combines qualitative and quantitative data, yielding an objective assessment of the climate impact of agricultural policy measures and providing policy makers with a tool for either ex ante or ex post evaluations of climate-relevant policy measures.  相似文献   

Comment on Use of Single‐Well Tracer Dilution Tests to Evaluate LNAPL Flux at Seven Field Sites and Measurement of LNAPL Flux Using Single‐Well Intermittent Mixing Tracer Dilution Tests          下载免费PDF全文

Gabriel Paiva Lago  John H. Knight  John L. Rayner 《Ground water》2016,54(5):623-624

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Silicon isotopic fractionation of CAI-like vacuum evaporation residues     

Kim B. Knight  Noriko T. Kita  Frank M. Richter  Andrew M. Davis  John W. Valley 《Geochimica et cosmochimica acta》2009,73(20):6390-5891

Calcium-, aluminum-rich inclusions (CAIs) are often enriched in the heavy isotopes of magnesium and silicon relative to bulk solar system materials. It is likely that these isotopic enrichments resulted from evaporative mass loss of magnesium and silicon from early solar system condensates while they were molten during one or more high-temperature reheating events. Quantitative interpretation of these enrichments requires laboratory determinations of the evaporation kinetics and associated isotopic fractionation effects for these elements. The experimental data for the kinetics of evaporation of magnesium and silicon and the evaporative isotopic fractionation of magnesium is reasonably complete for Type B CAI liquids (Richter F. M., Davis A. M., Ebel D. S., and Hashimoto A. (2002) Elemental and isotopic fractionation of Type B CAIs: experiments, theoretical considerations, and constraints on their thermal evolution. Geochim. Cosmochim. Acta66, 521-540; Richter F. M., Janney P. E., Mendybaev R. A., Davis A. M., and Wadhwa M. (2007a) Elemental and isotopic fractionation of Type B CAI-like liquids by evaporation. Geochim. Cosmochim. Acta71, 5544-5564.). However, the isotopic fractionation factor for silicon evaporating from such liquids has not been as extensively studied. Here we report new ion microprobe silicon isotopic measurements of residual glass from partial evaporation of Type B CAI liquids into vacuum. The silicon isotopic fractionation is reported as a kinetic fractionation factor, α_Si, corresponding to the ratio of the silicon isotopic composition of the evaporation flux to that of the residual silicate liquid. For CAI-like melts, we find that α_Si = 0.98985 ± 0.00044 (2σ) for ²⁹Si/²⁸Si with no resolvable variation with temperature over the temperature range of the experiments, 1600-1900 °C. This value is different from what has been reported for evaporation of liquid Mg₂SiO₄ (Davis A. M., Hashimoto A., Clayton R. N., and Mayeda T. K. (1990) Isotope mass fractionation during evaporation of Mg₂SiO₄. Nature347, 655-658.) and of a melt with CI chondritic proportions of the major elements (Wang J., Davis A. M., Clayton R. N., Mayeda T. K., and Hashimoto A. (2001) Chemical and isotopic fractionation during the evaporation of the FeO-MgO-SiO₂-CaO-Al₂O₃-TiO₂-REE melt system. Geochim. Cosmochim. Acta65, 479-494.). There appears to be some compositional control on α_Si, whereas no compositional effects have been reported for α_Mg. We use the values of α_Si and α_Mg, to calculate the chemical compositions of the unevaporated precursors of a number of isotopically fractionated CAIs from CV chondrites whose chemical compositions and magnesium and silicon isotopic compositions have been previously measured.  相似文献   

Mapping and detection of land use change in a coal mining area using object-based image analysis     

Wenming Pei  Suping Yao  Joseph F. Knight  Shaochun Dong  Keith Pelletier  Lian P. Rampi  Yan Wang  Jim Klassen 《Environmental Earth Sciences》2017,76(3):125

Object-based image analysis was used to map land use in the Panxie coal mining area, East China, where long-term underground coal mines have been exploited since the 1980s. A rule-based classification approach was developed for a Pleiades image to identify the desired land use classes, and the same rule-based classification strategies, after the threshold values had been modified slightly, were applied to the Landsat series images. Five land use classes were successfully captured with overall accuracies of between 80 and 94%. The classification approach was validated for its flexibility and robustness. Multitemporal classification results indicated that land use changed considerably in the Panxie coal mining area from 1989 to 2013. The urban, coal and coal gangue, and water areas increased rapidly in line with the growth in mine production. Urban areas increased from 9.38 to 20.92% and showed a tendency to increase around the coal mines. From 1989 to 2013 the coal and coal gangue area increased by 40-fold, from 0.02 to 0.58%. Similarly, the water area increased from 2.77 to 7.84% over this time period, mainly attributable to the spread of waterlogged areas. The waterlogged areas increased to about 2900 ha in 2013, which was about 80 times more than their area in 1989. In contrast, the area of cultivated land was negatively related to the increase in mine production and decreased from 73.11 to 57.25%. The results of this study provide a valuable basis for sustainable land management and environmental planning in the Panxie coal mining area.  相似文献   

Bootstrap Calibration and Uncertainty Estimation of Downhole NMR Hydraulic Conductivity Estimates in an Unconsolidated Aquifer          下载免费PDF全文

A.D. Parsekian  K. Dlubac  E. Grunewald  J.J. Butler  R. Knight  D.O. Walsh 《Ground water》2015,53(1):111-121

Characterization of hydraulic conductivity (K) in aquifers is critical for evaluation, management, and remediation of groundwater resources. While estimates of K have been traditionally obtained using hydraulic tests over discrete intervals in wells, geophysical measurements are emerging as an alternative way to estimate this parameter. Nuclear magnetic resonance (NMR) logging, a technology once largely applied to characterization of deep consolidated rock petroleum reservoirs, is beginning to see use in near‐surface unconsolidated aquifers. Using a well‐known rock physics relationship—the Schlumberger Doll Research (SDR) equation—K and porosity can be estimated from NMR water content and relaxation time. Calibration of SDR parameters is necessary for this transformation because NMR relaxation properties are, in part, a function of magnetic mineralization and pore space geometry, which are locally variable quantities. Here, we present a statistically based method for calibrating SDR parameters that establishes a range for the estimated parameters and simultaneously estimates the uncertainty of the resulting K values. We used co‐located logging NMR and direct K measurements in an unconsolidated fluvial aquifer in Lawrence, Kansas, USA to demonstrate that K can be estimated using logging NMR to a similar level of uncertainty as with traditional direct hydraulic measurements in unconsolidated sediments under field conditions. Results of this study provide a benchmark for future calibrations of NMR to obtain K in unconsolidated sediments and suggest a method for evaluating uncertainty in both K and SDR parameter values.  相似文献   

A general model of lateral depth-averaged velocity distributions for open channel flows     

Xiaonan Tang  Donald W. Knight 《Advances in water resources》2008

This paper reviews a model, developed by Shiono and Knight [Shiono K, Knight DW. Two-dimensional analytical solution for a compound channel. In: Proceedings of the 3rd international symposium on refined flow modelling and turbulence measurements, Tokyo, Japan, July 1988. p. 503–10; Shiono K, Knight DW. Turbulent open channel flows with variable depth across the channel. J Fluid Mech 1991;222:617–46 [231:693]], which yields analytical solutions to the depth-integrated Navier–Stokes equations, and includes the effects of bed friction, lateral turbulence and secondary flows. Some issues about the original model developed by Shiono and Knight (1988, 1991) are highlighted and discussed. Based on the experimental data concerning the secondary flow, two assumptions are proposed to describe the contribution of the streamwise vorticity to the flow. Two new analytical solutions are compared with the conventional solution for three simple channel shapes and one trapezoidal compound channel to highlight their differences and the importance of the secondary flow and planform vorticity term. Comparison of the analytical results with the experimental data shows that the general SKM predicts the lateral distributions of depth-averaged velocity well.  相似文献   

A laboratory study of the effect of magnetite on NMR relaxation rates     

Kristina Keating  Rosemary Knight   《Journal of Applied Geophysics》2008,66(3-4):188

We conducted a laboratory study to measure the effect of magnetite concentration and grain size on proton nuclear magnetic resonance (NMR) relaxation rates of sand mixtures and to determine the dominant mechanism by which relaxation occurs. We measured mixtures of quartz and three different forms of magnetite: a powdered synthetic magnetite; a small-grained, natural magnetite; and a large-grained, natural magnetite. The powdered synthetic magnetite was mixed with quartz in five concentrations ranging from 0.14 to 1.4% magnetite by weight; both sizes of natural magnetite were mixed with quartz in concentrations of 1 and 2% magnetite by weight. The NMR response of the water-saturated samples was measured and used to calculate four averaged relaxation rates for each magnetite concentration: the total mean log, bulk fluid, surface, and diffusion relaxation rates. The results of this study show that: 1) surface relaxation was the dominant relaxation mechanism for all samples except the powdered synthetic magnetite sample containing 1.4% magnetite; 2) the surface relaxivity is a function of the fraction of the surface area in the sample composed of magnetite; 3) there is no clear dependence of the diffusion relaxation rate on the concentration of magnetite.  相似文献   

Low latitude density variations in the earth's neutral atmosphere between 200 and 400km,from August 1969 to May 1970     

D.E. Knight  R. Uribe  B.E. Woodgate 《Planetary and Space Science》1973,21(2):253-271

The daily averages of the dawn and dusk observed exospheric temperatures (deduced from solar EUV attenuation measurements between 250 and 400 km) are presented for 280 days from day 227, 1969. They are compared with the empirical model of the US Standard Atmosphere Supplements 1966 and the Jacchia 35 H model. Although consistently lower temperatures than either model were found, a better fit to the latter rather than the former was observed. The exospheric response to solar and geomagnetic activity is investigated, and refinements to the models are suggested.  相似文献   

Management procedures in the US fishery conservation zone     

H. Gary Knight 《Marine Policy》1978,2(1):22-29

The author provides an overview of the management process and indicates, on the basis of experience to date, how procedures are being developed to generate and implement fishery management plans. The article includes discussion of the Fishery Conservation and Management Act of 1976 and of the structure and operation of US regional fisheries commissions. It concludes with an analysis of potential problem areas that threaten the development of a sound management programme.  相似文献   

Controls on erosion patterns and sediment transport in a monsoonal,tectonically quiescent drainage,Song Gianh,central Vietnam          下载免费PDF全文

Tara N. Jonell  Peter D. Clift  Long V. Hoang  Tina Hoang  Andrew Carter  Hella Wittmann  Philipp Böning  Katharina Pahnke  Tammy Rittenour 《Basin Research》2017,29(Z1):659-683

The Song Gianh is a small‐sized (~3500 km²), monsoon‐dominated river in northern central Vietnam that can be used to understand how topography and climate control continental erosion. We present major element concentrations, together with Sr and Nd isotopic compositions, of siliciclastic bulk sediments to define sediment provenance and chemical weathering intensity. These data indicate preferential sediment generation in the steep, wetter upper reaches of the Song Gianh. In contrast, detrital zircon U‐Pb ages argue for significant flux from the drier, northern Rao Tro tributary. We propose that this mismatch represents disequilibrium in basin erosion patterns driven by changing monsoon strength and the onset of agriculture across the region. Detrital apatite fission track and ¹⁰Be data from modern sediment support slowing of regional bedrock exhumation rates through the Cenozoic. If the Song Gianh is representative of coastal Vietnam then the coastal mountains may have produced around 132 000–158 000 km³ of the sediment now preserved in the Song Hong‐Yinggehai Basin (17–21% of the total), the primary depocenter of the Red River. This flux does not negate the need for drainage capture in the Red River to explain the large Cenozoic sediment volumes in that basin but does partly account for the discrepancy between preserved and eroded sediment volumes. OSL ages from terraces cluster in the Early Holocene (7.4–8.5 ka), Pre‐Industrial (550–320 year BP) and in the recent past (ca. 150 year BP). The older terraces reflect high sediment production driven by a strong monsoon, whereas the younger are the product of anthropogenic impact on the landscape caused by farming. Modern river sediment is consistently more weathered than terrace sediment consistent with reworking of old weathered soils by agricultural disruption.  相似文献