Perceptions and responses to climate policy risks among California farmers     

Meredith T. Niles  Mark Lubell  Van R. Haden 《Global Environmental Change》2013,23(6):1752-1760

This paper considers how farmers perceive and respond to climate change policy risks, and suggests that understanding these risk responses is as important as understanding responses to biophysical climate change impacts. Based on a survey of 162 farmers in California, we test three hypotheses regarding climate policy risk: (1) that perceived climate change risks will have a direct impact on farmer's responses to climate policy risks, (2) that previous climate change experiences will influence farmer's climate change perceptions and climate policy risk responses, and (3) that past experiences with environmental policies will more strongly affect a farmer's climate change beliefs, risks, and climate policy risk responses. Using a structural equation model we find support for all three hypotheses and furthermore show that farmers’ negative past policy experiences do not make them less likely to respond to climate policy risks through participation in a government incentive program. We discuss how future research and climate policies can be structured to garner greater agricultural participation. This work highlights that understanding climate policy risk responses and other social, economic and policy perspectives is a vital component of understanding climate change beliefs, risks and behaviors and should be more thoroughly considered in future work.  相似文献   

A comparison of the diets of Gulf killifish,Fundulus grandis Baird and Girard,entering and leaving a Mississippi brackish marsh     

Lawrence P. Rozas  Mark W. LaSalle 《Estuaries and Coasts》1990,13(3):332-336

We examined the diets of Gulf killifish,Fundulus grandis Baird and Girard, collected monthly from March through July 1988 with unbaited minnow traps during two sampling periods: (1) on flood tides before they reached the marsh surface, and (2) on ebb tides as they left the marsh. Thirty-five prey taxa, plant parts, and detritus were identified from the stomach contents of 110 Gulf killifish (mean SL = 55 mm, range = 30?82 mm). Fiddler crabs,Uca longisignalis Salmon and Atsaides; amphipods, mostlyCorophium louisianum Shoemaker; tanaidaceans,Hargeria rapax (Harger); and hydrobiids,Littoridinops palustris Thompson, were their most important prey. Killifish diets differed both quantitatively and qualitatively relative to the habitat in which they were feeding. Fiddler crabs and polychaetes were consumed more frequently and in greater numbers in the intertidal zone, whereas more amphipods were eaten by killifish feeding in subtidal and low intertidal areas. Gulf killifish consumed a greater volume of food when they had access to the marsh surface than when they were confined to subtidal areas.  相似文献   

Acidic deposition impacts mediated by sulfur cycling in a coastal plain forest ecosystem     

Mark D. Morgan  Ralph E. Good  Henry G. Spratt Jr. Dr. 《GeoJournal》1988,17(2):183-187

Deposition in the New Jersey Pinelands was very acidic (pH=4.17) and contained high levels of SO₂ ⁻² based on bulk deposition measurementsfrom July 1984–July 1986. Streamwater over the same interval in undisturbed watersheds was less acidic (pH =4.52) and had proportionately less SO₄ ⁻². A preliminary alkalinity budget for undisturbed watersheds suggested that SO₄ ⁻² retention within Pinelands watersheds accounted for a large portion of the total alkalinity generated and thereby lessened the impact of acidic deposition on surface waters. The only process capable of explaining the retention of SO₄ ⁻² was microbial sulfate reduction in the extensive wetlands surrounding Pinelands streams which occurred at high rates.  相似文献   

Variational stabilization of the ionic charge densities in the electron-gas theory of crystals: Applications to MgO and CaO     

George H. Wolf  Mark S. T. Bukowinski 《Physics and Chemistry of Minerals》1988,15(3):209-220

The electron-gas theory of crystals is extended to include the effects of many-body forces that arise from both electrostatic and overlap interactions. These effects are incorporated through a self-consistent spherical relaxation of the ionic charge distributions such that the crystal binding energy is minimized. This variational model is used to compute the elastic constants and equations of state of MgO and CaO, and we compare its results to those derived from earlier electron-gas models. In the variational model, the anion charge distributions are markedly more sensitive to the local crystal environment than they are in the PIB or other electron-gas models. We find that for these oxides the variational model gives the best overall agreement with experiment for lattice constants, equations of state, dissociation energies, and elastic moduli.  相似文献   

A MEG study of the olivine and spinel forms of Mg2SiO4     

Mark D. Jackson  Roy G. Gordon 《Physics and Chemistry of Minerals》1988,15(6):514-520

In this paper we present a theoretical investigation of the structures and relative stability of the olivine and spinel phases of Mg₂SiO₄. We use both a purely ionic model, based on the Modified Electron Gas (MEG) model of intermolecular forces, and a bond polarization model, developed for low pressure silica phases, to investigate the role of covalency in these compounds. The standard MEG ionic model gives adequate structural results for the two phases but incorrectly predicts the spinel phase to be more stable at zero pressure. This is mainly because the ionic modeling of Mg₂SiO₄ only accounts for 95 percent of the lattice energy. The remainder can be attributed to covalency and many-body effects. An extension of the MEG ionic model using “many-body” pair potentials corrects the phase stability error, but predicts structures which are in poorer agreement with experiment than the standard ionic approach. In addition, calculations using these many-body pair potentials can only account for 10 percent of the missing lattice energy. This model predicts an olivine-spinel phase transition of 8 GPa, below the experimental value of 20 GPa. Therefore, in order to understand more fully the stability of these structures we must consider polarization. A two-shell bond polarization model enhances the stability of both structures, with the olivine structure being stabilized more. This model predicts a phase transition at about 80 GPa, well above the observed value. Also, the olivine and spinel structures calculated with this approach are in poorer agreement with experiment than the ionic model. Therefore, based on our investigations, to properly model covalency in Mg₂SiO₄, a treatment more sophisticated than the two-shell model is needed.  相似文献   

Sediment transport,biotic modifications and selection of grain size in a surface deposit-feeder     

Mark W. Luckenbach  Douglas V. Huggett  Erik C. Zobrist 《Estuaries and Coasts》1988,11(2):134-139

Deposit-feeders often select for particles on the basis of grain size. The available pool of particles at the sediment surface may be modified both by deposit-feeder activity and by sediment transport, but the effects of these alterations on deposit-feeder diet composition have received little attention. In laboratory experiments the spionid polychaeteParaprionospio pinnata altered the grain-size composition in its foraging area, and these alterations were reflected in grain-size changes in the diet. After simulated transport of fine-grain sediments,P. pinnata diets also changed in grain-size composition. Field data were collected from 9 m depth in the lower Chesapeake Bay. A video camera, deployed near the bottom, identified times of sediment transport over a 6-h Period;P. pinnata were collected concurrently for gut analysis. Consistent with predictions from the laboratory experiments,P. pinnata ingested primarily small-grain sizes. During periods of no sediment transport this feeding pattern reduced the relative availability of small particles; larger sediments were incorporated into the diet. Sediment transport may resupply the foraging area with fine-grain particles which are then incorporated into the diet. On these small spatial and time scales, deposit-feeder activity may affect the availability of food resources.  相似文献   

Activity-composition relations in FeTiO3-MnTiO3 ilmenite solid solutions from EMF measurements at 1050–1300 K     

Hugh St. C. O'Neill  Mark I. Pownceby  Victor J. Wall 《Contributions to Mineralogy and Petrology》1989,103(2):216-222

The activity of FeTiO₃ in the binary ilmenitepyrophanite (FeTiO₃-MnTiO₃) solid solution has been determined for the temperature range 1050–1300 K by displacement of the reaction: 2 FeTiO₃=2 Fe+2 TiO₂+O₂ in T-O₂ space, using an electrochemical technique with calcia- and yttria-stabilized zirconia solid electrolytes. The activities show small positive deviations from ideality, which, although the data are unusually precise, may be perfectly described by the simple regular solution model, with an interaction parameter, W _Fe-Mn ^ilm , of 2.2±0.3 kJ g-atom^–1, which is independent of temperature. This value, together with the experimental data on the partitioning of Fe and Mn between ilmenite and garnet (Pownceby et al. 1987), gives W _Fe-Mn ^gt =1.2±0.5 kJ g-atom^–1 for the almandine-spessartine (Fe₃Al₂Si₃O₁₂-Mn₃Al₂Si₃O₁₂) solid solution.  相似文献   

Doppler sounder observations of trade winds and sea breezes along the African west coast near 34 ° S, 19 ° E     

Mark Jury  Garth Spencer-Smith 《Boundary-Layer Meteorology》1988,44(4):373-405

Summer weather conditions along the west coast of Africa near 34 ° S, 18 ° E are investigated using doppler acoustic sounder profiles. Case studies were selected from a two-year record to form composite analyses over the diurnal cycle. The SE trade wind exhibited a low level jet at the level of the temperature inversion due to a sharp reversal in the thermal wind vector aloft. Mean wind speeds reached 14 m s^–1 just before midnight as the surface and upper inversions strengthened. Seabreezes were categorised by the supporting gradient wind and found to have mean depths of 400 m, speeds of over 6 m s^–1 at the 200 m level, and advance/retreat times of 09 hr and 16–20 hr. During seabreezes and weak on-shore gradient flow conditions, the thermal internal boundary layer (TIBL) was monitored with sounder transects in the first 12 km of the coastal zone. The growth height was observed to be 1:20 in the first 5 km and 1:50 farther inland. The sounder climatology, together with surface network and aerial survey results, illustrate the four-dimensional characteristics of trade winds and seabreezes near Cape Town.  相似文献   

Earth pillar formation on the Mountain Pine Ridge,Belize     

Mark Francek 《地球表面变化过程与地形》1988,13(2):183-186

The roadcuts of Belize's Mountain Pine Ridge feature numerous coarsely textured earth pillars less than 10 cm in height. Preferential impregnation of iron occurs over a buried pebble resulting in a dripline. The higher concentration of iron along the buried pebble's dripline is later oxidized and exposed to the surface by rainsplash erosion. For slopes greater than five degrees, the intensity of sheetwash erosion is great enough to remove pillars. Earth pillar genesis thus seems a function of laterization, slope angle, and sheetwash intensity.  相似文献   

Statistical methods for investigating quiescence and other temporal seismicity patterns     

Mark V. Matthews  Paul A. Reasenberg 《Pure and Applied Geophysics》1988,126(2-4):357-372

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