Visible and near-infra-red transmission and reflectance measurements of the Luna 20 soil     

John B. Adams  Peter M. Bell  James E. Conel  H.K. Mao  Thomas B. McCord  Douglas B. Nash 《Geochimica et cosmochimica acta》1973,37(4):731-743

Visible and near-infra-red spectra of chemically analyzed grains of glass and minerals from the Luna 20 sample were compared with diffuse reflectance spectra of the bulk soil. As in the spectra of soil samples from other localities on the Moon, pyroxene contributes two broad absorption features near 1 μm and 2 μm. The soil has a high integral reflectance (or albedo) arising from plagioclase, which appears to be the dominant mineral in the lunar highlands. The Luna 20 soil curve is most similar to the reflectance curves of the non-rayed soils at Apollo 16, in agreement with the generally similar mineralogy of these samples. The average pyroxene composition in the Luna 20 soil, as determined from the absorption bands in the diffuse reflectance spectra, and analyses of single crystals, is more calcic than in the lithic fragments. Thus, the soil appears to have a few per cent of admixed material derived from mare basalts. Comparison of the soil spectrum with telescopic curves of nearby areas reveals a close similarity; however, the Luna 20 sample is slightly less mature than expected. Luna 20 may have sampled subsurface material that is fresher than the regional surface soil, or alternatively, the Luna 20 area may contain an admixture of relatively recently exposed material from a ray crater.  相似文献   

Artificial watershed acidification on the Fernow Experimental Forest, USA     

M. B. Adams  P. J. Edwards  F. Wood  J. N. Kochenderfer 《Journal of Hydrology》1993,150(2-4):505-519

A whole-watershed manipulation project was begun on the Fernow Experimental Forest in West Virginia, USA, in 1987, with the objective of increasing understanding of the effects of acidic deposition on forest ecosystems. Two treatment watersheds (WS9 and WS3) and one control watershed (WS4) were included. Treatments were twice-ambient N and S deposition, applied via NH₄SO₄ fertilizer, with three applications per year. Three years of pretreatment data were collected and used for calibration. Stream water chemistry data collected during 3 years of treatment were evaluated. Stream water pH and electrical conductivity were not significantly affected by the elevated N and S inputs on either treatment watershed. On WS9, there were no statistically significant treatment effects on stream water export of Ca, SO₄, or NO₃. On WS3, however, stream export of both NO₃ and Ca have increased as a result of acidification treatments. The implications of these results are discussed. Research is continuing so that the processes involved may be elucidated. In addition, effects on vegetation, aquatic invertebrates and amphibians also are being evaluated.  相似文献   

Closing the gaps in knowledge, policy and action to address water issues in forests     

Paul W. Adams 《Journal of Hydrology》1993,150(2-4):773-786

Water issues on forest lands involve many human elements and needs that are not addressed by advanced physical and biological research and technology. Major gaps in our knowledge of important patterns of climate, soils, and terrain can be filled by relatively basic data collection and monitoring programs. Careful analysis of existing data and field experience also can reveal appropriate directions for management. A focus on problem-solving can direct research more effectively towards the resolution of key issues. Despite their impact, resource policies have widely varying scientific foundations. Policy-makers need sound processes for policy development, including timely technical input that is clear, objective, and related to socio-economic considerations. Resource polices should be consistent and include not only regulation, but also research, education, assistance, and incentives. Knowledge and sound policies still may not produce the desired on-the-ground actions, however, because of variable awareness, understanding, skill, or supervision in the field. Education and training programs are important not only for resource technicians, but also for contractors, operators, and other forest workers. Good planning, communication, and field coordination further insure that problems are avoided and new opportunities for effective actions are identified.  相似文献   

Low pressure radon diffusion: a laboratory study and its implications for lunar venting     

Larry Jay Friesen  John A.S. Adams 《Geochimica et cosmochimica acta》1976,40(4):375-380

Results of a study of radon migration through columns of fine particulate materials, at total pressures of 2–20 × 10^?2 torr, are reported. Materials studied were: NBS Glass Spheres (SRM 1003), Emerson & Cuming Eccospheres (IG-101), activated coconut charcoal, Lipari obsidian, and W-1 Standard Diabase. Rates of diffusion were used to derive heats of adsorption for radon on the materials tested. The most reliable values found clustered around 8–9 kcal/mole.These high heats of adsorption, if typical for most materials, combined with low percentages of radon emanation by lunar soils found by other researchers, imply that random walk diffusion will not be an important mechanism for redistributing the radon and the radon daughters produced in the lunar regolith. In particular, since random walk migration is not a sufficient mechanism to account for localized high concentrations of radon-222 and its daughter polonium-210 observed by the Apollo 15 and 16 command modules, an alternative mechanism is proposed, in which radon would be swept to the surface by other gases during intermittent venting events.  相似文献   

MODEL HARBOUR WAVE FORM STUDIES BY SHORT RANGE PHOTOGRAMMETRY     

L. P. Adams  J. D. Pos 《The Photogrammetric Record》1981,10(58):457-470

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Earthquake source and propagation parameters in New Zealand     

R.D. Adams 《Tectonophysics》1978,49(3-4)

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Estimating palaeowind strength from beach deposits – Reply     

Kenneth D. Adams 《Sedimentology》2004,51(3):671-673

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Human Strategies for Coping with El Niño Related Drought in Amazônia     

Emilio F. Moran  Ryan Adams  Bryn Bakoyéma  Stefano Fiorini T.  Bruce Boucek 《Climatic change》2006,77(3-4):343-361

This article reports on findings of a research project examining farmers' coping strategies in the Brazilian Amazon in response to El Niño related weather events. We examine the extent of vulnerability of small and large farmers to these events in a tropical rainforest environment. Little attention has been given to the impact of ENSO events in Amazônia, despite evidence for devastating fires during ENSOs. Although we found a range of locally developed forecasting techniques and coping mechanisms, farmers have sustained significant losses, and we suggest that increased access to scientific forecasts would greatly enhance the ability of the farmers in our study area to cope with El Niño related weather events. In Amazônia the El Niño phase of the El Niño-Southern Oscillation (ENSO) climate pattern leads to an extended period of reduced rainfall (Hobbs et al., 1998). This period of reduced rainfall can result in significant agricultural losses for farmers and ranchers in the area and in increased forest flammability. We have found that the majority of our study population uses several methods of forecasting, coping with, and adapting to drought events – and they recognize the economic losses they can experience and the loss of forests through the accidental spread of fire. The poorest farmers in our study area experience El Niño related drought events as a serious threat to their livelihoods. Their vulnerability is heightened during extreme climate events and our observations revealed that all of the farmers in our study would benefit from increased availability of improved forecast information relevant to their locality and their current farming strategies. This paper examines the availability and use of forecasts, the occurrence of accidental fires and techniques to prevent fire related losses, and the coping mechanisms for dealing with El Niño related drought in the agricultural regions surrounding the cities of Altamira and Santarém, in Pará State, Brazil. Distribution of an El Niño Prediction Kit at the end of the study and a series of workshops may lead to better local information on rainfall variability and create a farmer-maintained grid of collecting stations to sensitize farmers to the variability of precipitation in the region, and on their property.  相似文献   

The olivine — clinopyroxene geobarometer: experimental results in the CaO-FeO-MgO-SiO2 system     

Gerald E. Adams  Finley C. Bishop 《Contributions to Mineralogy and Petrology》1986,94(2):230-237

The exchange of Ca and Mg between olivine and clinopyroxene has been studied in the CFMS system. Experiments were conducted in a piston-cylinder apparatus in the temperature range of 1,100–1,300° C and the pressure range 10–30 kbar. Results confirm the previous suggestion (Adams and Bishop 1982) that this reaction has a sufficiently large V° to be used as a geobarometer in several basic and ultrabasic systems. Experimental results were corrected for compositional effects using recent activity-composition models for quadrilateral pyroxenes and olivines. The corrected results indicate that the exchange reaction has aH _{1 bar} of 34,900 J, a S° of -7.25J/deg, and a V° of -0.489 J/bar. Corrected results agree well with calculations based on the thermodynamic properties of the endmembers.Application of the olivine-clinopyroxene geobarometer to many systems will require additional calibration of non CFMS components. Preliminary pressure estimates based on simple assumptions about the activity relations of these components have been made for spinel lherzolites from southwestern United States and coarse and porphyroclastic garnet lherzolites from southern Africa. A geotherm calculated from spinel lherzolites near the Rio Grande rift is consistent with a geophysical geotherm based on near-surface heat-flow measurements of 100 mW/m² or greater. Results on garnet lherzolites yield a southern African geotherm with no inflection which falls at somewhat higher temperatures than pyroxene geotherms calculated for the same area.  相似文献   

The environmental effects of dam construction in tropical Africa: Impacts and planning procedures     

W.M. Adams  F.M.R. Hughes   《Geoforum》1986,17(3-4)

Dam construction can have significant effects on downstream floodplain environments in tropical Africa. The impacts of river control on floodplain forests in the Tana River Valley in Kenya, and on floodplain agriculture in the Sokoto River Valley in Nigeria are described. The extent to which downstream impacts were understood or predicted in these case studies are described, and the implications of this for environmental appraisal in project planning are assessed.  相似文献