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121.
P.R. Fresquez J.R. Biggs K.D. Bennett D.H. Kraig M.A. Mullen J.K. Ferenbaugh 《Journal of environmental science and health. Part. B》2013,48(5):901-915
Abstract This paper summarizes radionuclide concentrations (3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p<0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% on LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y‐1 (2.2 μSv y‐1), deer bone = 3.8 mrem y‐1 (38 μSv y‐1), elk muscle = 0.12 mrem y‐1 (1.2 μSv y‐1), and elk bone = 1.7 mrem y‐1 (17 μSv y‐1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y‐1 (1000 μSv y‐1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E‐06, which is far below the Environmental Protection Agency upper level guideline of 1E‐04. 相似文献
122.
将海藻酸钠与纳米α-Fe2O3制成微球,用于吸附U(Ⅵ)。探讨了纳米α-Fe2O3含量、交联时间、pH值、投加量、浓度、温度等对吸附的影响。结果表明,pH值对U(Ⅵ)的吸附过程影响显著,适宜pH值为3。U(Ⅵ)在微球上的吸附量随着吸附时间的增加而增大,初始阶段(1.5 h)反应进行得很快,9 h时达到吸附平衡。当U(Ⅵ)初始质量浓度为10mg/L时,其饱和吸附量为2.64mg/g。准二级动力方程很好地拟合了吸附动力学数据,且R2>0.99。吸附率与温度呈正相关,Lang-muir与Freundlich吸附等温方程均能较好地拟合固定化微球对U(Ⅵ)的吸附过程(R2>0.99),但Freundlich等温线效果更好。吸附反应中ΔG<0,ΔH>0且小于40 kJ/mol,ΔS>0,这表明吸附过程能自发进行,为吸热反应。 相似文献
123.
Roger F. Auch George Xian Christopher R. Laingen Kristi L. Sayler Ryan R. Reker 《Journal of Land Use Science》2018,13(1-2):32-58
Grassland to cropland conversion in the northern prairie of the United States has been a topic of recent land use change studies. Within this region more corn and soybeans are grown now (2017) than in the past, but most studies to date have not examined multi-decadal trends and the synergistic web of socio-ecological driving forces involved, opting instead for short-term analyses and easily targeted agents of change. This paper examines the coalescing of biophysical and socioeconomic driving forces that have brought change to the agricultural landscape of this region between 1980 and 2013. While land conversion has occurred, most of the region’s cropland in 2013 had been previously cropped by the early 1980s. Furthermore, the agricultural conditions in which crops were grown during those three decades have changed considerably because of non-biophysical alterations to production practices and changing agricultural markets. Findings revealed that human drivers played more of a role in crop change than biophysical changes, that blending quantitative and qualitative methods to tell a more complete story of crop change in this region was difficult because of the synergistic characteristics of the drivers involved, and that more research is needed to understand how farmers make crop choice decisions. 相似文献
124.
Craig Leohle 《Ecological modelling》1983,19(4):239-247
The concept of validation is inappropriate for the evaluation of ecological models. Classification of models into logical, theoretical, and calculation tool (predictive) types provides a sounder basis for choosing an evaluation technique. The dangers of model “tuning” are presented. 相似文献
125.
126.
Michael R. Patsfall Nickolaus R. Feimer Gregory J. Buhyoff J. Douglas Wellman 《Journal of environmental psychology》1984,4(1):7-26
Two studies were conducted to examine distance classes of vegetation (foreground, middleground and background) and scene composition (presence of vegetation in left, center or right section of the image) as predictors of perceived scenic beauty. In study one, 41 students rated 63 landscape scenes with regard to scenic beauty. The Scenic Beauty Estimation Method was used to derive interval scale beauty values (SBEs). For each landscape image, areal measures of vegetation in each distance class and for each vertical section were taken and used as predictors. Presence of haze, clouds and human impacts were also recorded. Among the most important contributors to scenic beauty were amount of center middleground vegetation, and center background vegetation. Left foreground vegetation and right foreground vegetation were found to have significant and opposing regression weight signs—negative for the left and positive for the right. Study two was conducted to determine whether these opposing regression weight signs for foreground vegetation were due to a perceptual right-left bias or to some specific content in the image itself. In the second study, the photographic slides used to present landscape scenes to subjects were reversed so that the content which was previously on the right was now left, and vice versa. Thirty-nine students rated the reversed slides with regard to their scenic beauty. The signs of the regression weights in study two shifted such that left foreground was now positively valued and right foreground was negatively valued. This finding suggests that viewers are sensitive to foreground content and its placement in the image, and not simply to one side of the field of vision. 相似文献
127.
Natural areas of national parks constitute unique ecological and aesthetic resources. Since the inception of national parks, it has been apparent that they are susceptible to threats that result in significant change and damage. Today, major issues concerning management of parks relate to questions of expanded visitor use and what types of facilities are to be deemed appropriate, that is, the dilemma of preservation versus use. In the United States of America, resolution of this dilemma must, strictly speaking, be based upon intent and meaning of Congressional legislation. The traditional interpretation of legislation in the U.S. has been to provide for a balance of use and preservation. However, extensive review of the literature of national park policy reveals a remarkable lack of elaboration and clarification of legislative meaning. Based upon a critical analysis of pertinent legislation, which has heretofore been ignored, we provide an interpretation of legislative meaning which strongly supports a policy of preservation of park resources. 相似文献
128.
Stephen R. Kessell Meredith W. Potter Collin D. Bevins Larry Bradshaw Bruhe W. Jeske 《Environmental management》1978,2(4):347-363
Recent advances in fire modeling permit quantitative estimations of fire behavior from quantitative inputs that describe the fuel array and conditions, such as weather and site data, under which it will burn. This paper describes the collection, analysis, and stratification of flammable forest fuels data for coniferous forest ecosystems in Montana and then illustrates the resource management application of these data in three areas: the development of the fire behavior model, a determination of the model's sensitivity to input errors as reflected by fire behavior prediction errors, and the development of a fire hazard simulator (TAROT). A new integrated stand simulator, GANDALF, is highlighted.Conclusions center on the need to integrate fire management into the land management planning decision-making process.This work was supported by a USDI National Park Service contract to Gradient Modeling, Inc., a nonprofit research foundation devoted to ecologic research and resource management applications, and by cooperative aid agreements between Gradient Modeling, Inc. and the USDA Forest Service, Intermountain Forest and Range Experiment Station, Northern Forest Fire Laboratory (Fire in Multiple Use Management, R, D, and A Program). 相似文献
129.
The tallgrass prairie version of the ELM Grassland Model was used to evaluate the potential impact of establishing a tallgrass prairie National Park in the Flint Hills region of Kansas. This total ecosystem model simulates (a) the flow of water, heat, nitrogen, and phosphorus through the ecosystem and(b) the biomass dynamics of plants and consumers. It was specifically developed to study the effects of levels and types of herbivory, climatic variation, and fertilization upon grassland ecosystems. The model was used to simulate the impact of building up herds of bison, elk, antelope, and wolves on a tallgrass prairie. The results show that the grazing levels in the park should not be decreased below the prepark grazing levels (moderate grazing with cattle) and that the final grazing levels in the park could be maintained at a slightly higher level than the prepark grazing levels. 相似文献
130.
Charles P. Becker Allender M. Griffin Carol S. Lown 《Journal of the American Water Resources Association》1973,9(5):963-975
ABSTRACT: Water resource and water quality management planning depend, to a large degree, on forecasts of industrial activity and population projections. A flexible economic data base is especially important where planning follows varying formats of geographical and industrial detail. Records of employment and payroll are collected in the administration of Unemployment Insurance (U.I.) programs and are available from State Employment Agencies. These statistics have been collected over a long period of record (thirty-five years). Many years of record are available on punched-cards or magnetic tape and may be arrayed and manipulated by computer. This basic approach has been followed in Virginia. Historical U.I. payroll and employment records for the period 1956 through 1970 were procured on magnetic tape. This data was arrayed by major hydrologic area and by regional planning district. Projections of manufacturing activity were then generated by fitting several exponential equations to annual payroll data in two-digit Standard Industrial Classifications. These exponentials were then extrapolated to provide a range of industrial projections. Other parameters of manufacturing activity were then correlated to the payroll data to generate projections of indexes such as employment, value-added, and gross manufacturing output. U.I. payroll data is now being correlated to parameters in non-manufacturing categories. Projections for industries such as trade and services will link extrapolated payroll data with benchmark correlations of payroll and sales receipts. 相似文献