1,730 research outputs found

    Carbon Sequestration, Co-Benefits, and Conservation Programs

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    Land use changes to sequester carbon also provide モco-benefits,ヤ some of which (for example, water quality) have attracted at least as much attention as carbon storage. The non-separability of these co-benefits presents a challenge for policy design. If carbon markets are employed, then social efficiency will depend on how we take into account co-benefits, that is, externalities, in such markets. If carbon sequestration is incorporated into conservation programs, then the weight given to carbon sequestration relative to its co-benefits will partly shape these programs. Using the Conservation Reserve Program (CRP) as an example, we show that CRP has been sequestering carbon, which was not an intended objective of the program. We also demonstrate that more carbon would have been sequestered had CRP targeted this objective, although the モco-benefitsヤ would have increased or decreased.

    Environmental Conservation in Agriculture: Land Retirement Versus Changing Practices on Working Land

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    The study develops a conceptual framework for analyzing the allocation of conservation funds via selectively offering incentive payments to farmers for enrolling in one of two mutually exclusive agricultural conservation programs: retiring land from production or changing farming practices on land that remains in production. We investigate how the existence of a pre-fixed budget allocation between the programs affects the amounts of environmental benefits obtainable under alternative policy implementation schemes. The framework is applied to a major agricultural production region using field-scale data in conjunction with empirical models of land retirement and conservation tillage adoption, and a biophysical process simulation model for the environmental benefits of carbon sequestration and reduction in soil erosion.

    Thermodynamical Properties of a Rotating Ideal Bose Gas

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    In a recent experiment, a Bose-Einstein condensate was trapped in an anharmonic potential which is well approximated by a harmonic and a quartic part. The condensate was set into such a fast rotation that the centrifugal force in the corotating frame overcompensates the harmonic part in the plane perpendicular to the rotation axis. Thus, the resulting trap potential became Mexican-hat shaped. We present an analysis for an ideal Bose gas which is confined in such an anharmonic rotating trap within a semiclassical approximation where we calculate the critical temperature, the condensate fraction, and the heat capacity. In particular, we examine in detail how these thermodynamical quantities depend on the rotation frequency.Comment: Author Information under http://www.theo-phys.uni-essen.de/tp/ags/pelster_dir

    Collaborative Research: Origins of Cods on Georges Bank: Contributions of Early Developmental Stages for the Scotian Shelf

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    Recent work in the Georges Bank-Gulf of Maine area has documented significant, and apparently episodic, fluxes of Scotian Shelf Water (SSW) from the Nova Scotian continental shelf to Georges Bank. SSW is a relatively cold and fresh water mass with a significant component from the St. Lawrence River, and is commonly identifiable with temperature-salinity analyses of hydrographic data and in satellite images of sea surface temperature. One such flux episode was observed last March (1997) in satellite imagery and from shipboard hydrographic sampling on Georges Bank. Qualitative at-sea analyses of ichthyoplankton sampled on the March cruise revealed a remarkably tight association between abundances of gadid eggs and the distribution of SSW suggesting, along with other lines of evidence, that most of those eggs were spawned on the Scotian Shelf and were advected with the SSW water mass to Georges Bank. The fundamental question thus arises: to what extent are cod on Georges Bank imported to the Bank as early development stages by advection from Canadian waters to the east? The goal of this research is to answer the above question. The approach will be two tiered: (1) Drs. Townsend and Radtke will perform retrospective elemental analyses of otoliths from archived larval cod samples, as well as of ichthyoplankton samples to be collected in 1998 and 1999 as part of the continuing Georges Bank GLOBEC project, analyzing them for Sr/Ca ratios, using an X-ray electron microprobe, and elemental fingerprints , using UV lazer ablation inductively coupled plasma mass spectroscopy (ICPMS). (2) They will also assess the genetic identity of the larvae relative to larval and adult populations from Georges Bank and from the Scotian Shelf using nuclear DNA microsatellite techniques. They will first verify the elemental composition of otoliths from cod larvae known to have been spawned in the two locations. This elemental analyses will be combined with laboratory rearing experiments of larvae to determine the effects of temperature, salinity, feeding, and growth rates on the incorporation of elements in the otoliths. DNA based techniques will be used to identify individuals in these common-garden rearing experiments. The second step will be to identify the origin of larvae based on individual DNA profiles generated by characterizing nuclear DNA microsatellites, a new class of genetic markers that they have used to differentiate Georges Bank cod from those of Scotian Shelf waters.The intent in using the two different, independent approaches is to be able to identify the spawning locations of the larvae and track their transport in relation to hydrographic characteristics of water masses in the region

    Carbon Sequestration, Co-Benefits, and Conservation Programs

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    Land use changes to sequester carbon also provide co-benefits, some of which (for example, water quality) have attracted at least as much attention as carbon storage. The non-separability of these co-benefits presents a challenge for policy design. If carbon markets are employed, then social efficiency will depend on how we take into account co-benefits, that is, externalities, in such markets. If carbon sequestration is incorporated into conservation programs, then the weight given to carbon sequestration relative to its co-benefits will partly shape these programs. Using the Conservation Reserve Program (CRP) as an example, we show that CRP has been sequestering carbon, which was not an intended objective of the program. We also demonstrate that more carbon would have been sequestered had CRP targeted this objective, although the co-benefits would have increased or decreased

    Sny Magill Watershed Modeling Project: Final Report

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    Improved assessment of flow, sediment, and nutrient losses from watersheds with computer simulation models is needed in order to identify and control nonpoint source pollution. One model, currently under consideration by the U.S. Environmental Protection Agency for watershed assessments, is the Soil Water and Assessment Tool (SWAT). In this report, the authors describe an application of SWAT for the Sny Magill Creek Watershed (SMCW), which covers 7,100 hectares in northeastern Iowa. The authors conclude that the SWAT model was generally able to predict flow, sediment, and nutrient losses. Additionally, the SWAT model provided useful insights about the importance of accurate data inputs, weaknesses in some of the data collecting methodologies, and the impacts of best management practices (BMPs) on water quality

    Internal wave effects on photosynthesis: Experiments, theory, and modeling

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109941/1/lno20085310339.pd
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