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401.
Eighteen percent and 47% of two populations of Ophiocoma echinata in the Florida Keys were undergoing regeneration. An individual would take approximately 720 days to completely regenerate three arms. Regeneration of three arms had a greater effect on gonad production in females than in males, and reduced storage material in the stomach of both. Regeneration in O. echinata was estimated to be 0.07 kJ m-2 day-1, which could provide the equivalent of 0.07% of primary production on a reef to higher trophic levels per day. 相似文献
402.
Sotiriou M Ferguson SF Davey M Wolfson JM Demokritou P Lawrence J Sax SN Koutrakis P 《Environmental monitoring and assessment》2008,137(1-3):351-361
Particles in a dental office can be generated by a number of instruments, such as air-turbine handpieces, low-speed handpieces,
ultrasonic scalers, bicarbonate polishers, polishing cups, as well as drilling and air sprays inside the oral cavity. This
study examined the generation of particles during dental drilling and measured particle size, mass, and trace elements. The
air sampling techniques included both continuous and integrated methods. The following particle continuous measurements were
taken every minute: (1) size-selective particle number concentration (Climet); (2) total particle number concentration (PTRAK),
and; (3) particle mass concentration (DustTrak). Integrated particle samples were collected for about 5 h on each of five
sampling days, using a PM2.5 sampler (ChemComb) for elemental/organic carbon analysis, and a PM10 sampler (Harvard Impactor) for mass and elemental analyses. There was strong evidence that these procedures result in particle
concentrations above background. The dental procedures produced number concentrations of relatively small particles (<0.5 μm)
that were much higher than concentrations produced for the relatively larger particles (>0.5 μm). Also, these dental procedures
caused significant elevation above background of certain trace elements (measured by X-ray fluorescence) but did not cause
any elevation of elemental carbon (measured by thermal optical reflectance). Dental drilling procedures aerosolize saliva
and products of drilling, producing particles small enough to penetrate deep into the lungs. The potential health impacts
of the exposure of dental personnel to such particles need to be evaluated. Increased ventilation and personal breathing protection
could be used to minimize harmful effects. 相似文献
403.
404.
Tamara Mittman Lawrence E. Band Taehee Hwang Monica Lipscomb Smith 《Journal of the American Water Resources Association》2012,48(3):546-557
Mittman, Tamara, Lawrence E. Band, Taehee Hwang, and Monica Lipscomb Smith, 2012. Distributed Hydrologic Modeling in the Suburban Landscape: Assessing Parameter Transferability from Gauged Reference Catchments. Journal of the American Water Resources Association (JAWRA) 48(3): 546-557. DOI: 10.1111/j.1752-1688.2011.00636.x Abstract: Distributed, process-based models of catchment hydrologic response are potentially useful tools for the assessment of Low Impact Development (LID) techniques in urbanized catchments. Their application is often limited, however, by the lack of continuous streamflow records to calibrate poorly constrained parameters. This article examines the transferability of soil and groundwater parameters from a forested reference catchment to a nearby suburban catchment. We use the Regional Hydro-Ecologic Simulation System (RHESSys) to develop hydrologic models of one gauged forested and one ungauged suburban catchment within the Baltimore Ecosystem Study (BES) study area. We use a parameter uncertainty framework to calibrate soil and groundwater parameters for the forested catchment, and discrete measurements of streamflow from the suburban catchment to assess parameter transferability. Results indicate that the transfer of soil and groundwater parameters from forested reference to nearby suburban catchments is viable, with performance measures for the suburban catchment often exceeding those for the forested catchment. We propose that the simplification of hydrologic processes in urbanized catchments may account for the increase in model performance in the suburban catchment. 相似文献
405.
Hamilton Lawrence C. Hartter Joel Keim Barry D. Boag Angela E. Palace Michael W. Stevens Forrest R. Ducey Mark J. 《Regional Environmental Change》2016,16(6):1819-1832
Regional Environmental Change - Wildfire poses a rising threat in the western USA, fueled by synergies between historical fire suppression, changing land use, insects and disease, and shifts toward... 相似文献
406.
Lyman A. Ripperton Lawrence Kornreich James J.B. Worth 《Journal of the Air & Waste Management Association (1995)》2013,63(9):589-592
Measurement of NO2 and NO has been carried out in Piedmont, N. C. and in the southern Appalachian Mountains. Average values for the Piedmont were: continuous NO2 measured 30 ft above surface, 0.76 pphm (14.3 μg/m3), 1 20 ft, 0.61 pphm (11.5 μg/m3); simultaneous values (also Piedmont) (2-hr discrete samples) taken at an earlier time at 4 ft, NO2, 0.56 pphm (10.6 μg/m3), NO, 0.19 pphm (2.34 μg/m3). The mountain top values (5120 ft, 1573 m) were: NO2, 0.46 pphm (6.4 μg/m3), NO, 0.26 pphm (2.72 μg/m3). The results of this study furnish further proof that tropospheric NO and NO2 are produced at the surface of the earth. Data obtained are consistent with the belief that a major sink for NOx is reaction with O3 and ultimate conversion to nitrate. Ozone values frequently increased and NOx values decreased ahead of cold fronts, probably as a result of deep vertical mixing. Also, in small scale turbulence the changes in NOx values and in the O3 values tended to be “out of phase,” i.e., as O3 concentration increased, NOx concentration decreased and vice versa. Values of NOx from Green Knob, N. C. (mountain top) also tended to be higher at times when O3 values were lowest. The NO2 hourly average values in Piedmont, N. C, demonstrated a diurnal cycle reminiscent of diurnal urban changes. An early morning peak was followed by a minimum in mid-afternoon. Next, the values rose to a broad evening peak and then decreased slowly during the night. Reported urban concentrations are usually about ten times those found in Piedmont, N. C. 相似文献
407.
Jack M. Leavîtt Lawrence A. George Robert E. Clark 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1133-1140
TVA is conducting a program of intermittent control of SO2 emissions at nine of its coal-fired power plants.The program is designed to limit SO2 emissions by reducing generation during adverse atmospheric conditions to avoid exceeding ambient SO2 standards. Each is identified as a Class I or Class II program—based primarily on its design and operational complexity. The four Class I programs (Paradise, Cumberland, Allen, Gallatin) operate 7 days/week from early morning through mid-afternoon. The five Class II programs (Kingston, Widows Creek, Colbert, Johnsonville, Shawnee) operate 24 hours/day and 7 days/week. Environmental data stations (EDS) are located at each plant site; the staff has the responsibility for the collection and validation of the onsite meteorological data, the SO2 mobile and fixed monitoring network data, the plant operational data, and the meteorological forecast data from the Meteorological Forecast Center in Muscle Shoals, AL. At the EDS, the data are entered into a computer operating model for scheduling plant generation reductions. 相似文献
408.
David T. Alien Terry Foecke Howard Klee Jr. W. B. Beck Lawrence L. Ross Arthur H. Purcell 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1159-1167
The 1992 A&WMA Critical Review was authored by Harry Freeman and members of his staff at the Pollution Prevention Research Branch, Risk Reduction Engineering Laboratory, U.S. Environmental Protection Agency in Cincinnati, Ohio. Mr. Freeman presented the paper "Industrial Pollution Prevention," at the Critical Review session held during the 85th Air & Waste Management Association Annual Meeting in Kansas City, Missouri. Prepared discussions and invited comments presented during the session are published here, as well as closing remarks by Mr. Freeman. 相似文献
409.
Constantina Alina Hossu Ioan Cristian Ioja Lawrence E. Susskind Denisa L. Badiu Anna M. Hersperger 《Ambio》2018,47(7):816-830
A critical challenge in natural resource management is to bring all stakeholders together to negotiate solutions to critical problems. However, various collaborative approaches to heading off conflicts and resolving natural resource management disputes have been used. What drives these efforts, however, still needs further research. Our study provides a systematic look at the drivers likely to initiate collaborative problem-solving efforts in four cases in Romania. We use Emerson’s et al. (2012) framework for collaborative governance and multi-value qualitative comparative analysis (mvQCA) to analyze cases involving endangered species, restrictions on forest harvest, conflicts associated with infrastructure development projects, and disputes over the management of environmentally sensitive areas. Our findings contribute to the already existing collaborative governance literature indicating which of the four factors: uncertainty, interdependence, consequential incentives, and leadership, in which combination, are necessary and sufficient to spur collaborative resource management efforts. Our results showed that in Romania the initiation of collaboration is best explained by positive consequential incentives (i.e., financial opportunities) which has determined leaders to take initiative. This study provides additional information for the complicated process of natural resource management which is often overriding collaboration by investigating what enables and constrains collaborative efforts in a country where natural resources were managed and used according to the principles of central planning. 相似文献
410.
Alexandra P. Pinho Lawrence A. Morris C. Rhett Jackson W. James White Parshall B. Bush Antônio T. Matos 《Journal of the American Water Resources Association》2008,44(6):1564-1577
Abstract: It is common practice in the United States and elsewhere to maintain vegetated filter strips adjacent to streams to retain contaminants in surface runoff. Most research has evaluated contaminant retention in managed agricultural field strips, while relatively few studies have quantified retention in forested filter strips, particularly for dissolved contaminants. Plot‐scale overland flow experiments were conducted to evaluate the efficiency of natural forested filter strips established as streamside management zones (SMZs) for retaining phosphorus (P), atrazine, and picloram transported in runoff. Retention was evaluated for five different slope classes: 1‐2, 5‐7, 10‐12, 15‐17, and 20‐22%; two cover conditions: undisturbed forest floor (O horizon intact) and forest floor removed by raking; and two periods with contrasting soil moisture conditions: summer‐dry and winter‐wet season. Surface flow was collected at 0, 2, 4, 6, and 10 m within the filter strip to evaluate changes in solution concentration as it moved through the O horizon and the surface soil horizon mixing zone. On average, a 10 m length of forested SMZ with an undisturbed forest floor reduced initial solution concentration of total dissolved P by 51%, orthophosphate P by 49%, atrazine by 28%, and picloram by 5%. Percentages of mass retention through infiltration of water plus concentration reductions in runoff were 64% for total dissolved P, 62% for orthophosphate P, 47% for atrazine, and 28% for picloram for undisturbed forest floor conditions. Lower retention occurred following forest floor removal, particularly for P. Average dissolved P retention was 16% lower following forest floor removal. For undisturbed sites, differences in retention were more closely related to forest floor depth than to slope or antecedent soil moisture. These results indicate that forested SMZ filter strips provide a significant measure of surface water protection from dissolved P and herbicide delivery to surface water. 相似文献