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81.
Abichou T Chanton J Powelson D Fleiger J Escoriaza S Lei Y Stern J 《Waste management (New York, N.Y.)》2006,26(11):1305-1312
Methane emissions were measured on two areas at a Florida (USA) landfill using the static chamber technique. Because existing literature contains few measurements of methane emissions and oxidation in intermediate cover areas, this study focused on field measurement of emissions at 15-cm-thick non-vegetated intermediate cover overlying 1-year-old waste and a 45-cm-thick vegetated intermediate cover overlying 7-year-old waste. The 45 cm thick cover can also simulate non-engineered covers associated with older closed landfills. Oxidation of the emitted methane was evaluated using stable isotope techniques. The arithmetic means of the measured fluxes were 54 and 22 g CH(4) m(-2)d(-1) from the thin cover and the thick cover, respectively. The peak flux was 596 g m(-2)d(-1) for the thin cover and 330 g m(-2)d(-1) for the thick cover. The mean percent oxidation was significantly greater (25%) at the thick cover relative to the thin cover (14%). This difference only partly accounted for the difference in emissions from the two sites. Inverse distance weighing was used to describe the spatial variation of flux emissions from each cover type. The geospatial mean flux was 21.6 g m(-2)d(-1) for the thick intermediate cover and 50.0 g m(-2)d(-1) for the thin intermediate cover. High emission zones in the thick cover were fewer and more isolated, while high emission zones in the thin cover were continuous and covered a larger area. These differences in the emission patterns suggest that different CH(4) mitigation techniques should be applied to the two areas. For the thick intermediate cover, we suggest that effective mitigation of methane emissions could be achieved by placement of individualized compost cells over high emission zones. Emissions from the thin intermediate cover, on the other hand, can be mitigated by placing a compost layer over the entire area. 相似文献
82.
Reducing Nitrogen Export from the Corn Belt to the Gulf of Mexico: Agricultural Strategies for Remediating Hypoxia 下载免费PDF全文
Eileen McLellan Dale Robertson Keith Schilling Mark Tomer Jill Kostel Doug Smith Kevin King 《Journal of the American Water Resources Association》2015,51(1):263-289
SPAtially Referenced Regression on Watershed models developed for the Upper Midwest were used to help evaluate the nitrogen‐load reductions likely to be achieved by a variety of agricultural conservation practices in the Upper Mississippi‐Ohio River Basin (UMORB) and to compare these reductions to the 45% nitrogen‐load reduction proposed to remediate hypoxia in the Gulf of Mexico (GoM). Our results indicate that nitrogen‐management practices (improved fertilizer management and cover crops) fall short of achieving this goal, even if adopted on all cropland in the region. The goal of a 45% decrease in loads to the GoM can only be achieved through the coupling of nitrogen‐management practices with innovative nitrogen‐removal practices such as tile‐drainage treatment wetlands, drainage–ditch enhancements, stream‐channel restoration, and floodplain reconnection. Combining nitrogen‐management practices with nitrogen‐removal practices can dramatically reduce nutrient export from agricultural landscapes while minimizing impacts to agricultural production. With this approach, it may be possible to meet the 45% nutrient reduction goal while converting less than 1% of cropland in the UMORB to nitrogen‐removal practices. Conservationists, policy makers, and agricultural producers seeking a workable strategy to reduce nitrogen export from the Corn Belt will need to consider a combination of nitrogen‐management practices at the field scale and diverse nitrogen‐removal practices at the landscape scale. 相似文献
83.
William S. Linn Edward L. Avol Deborah A. Shamoo Jill D. Whynot Karen R. Anderson Jack D. Hackney 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1323-1328
Young asthmatic adult volunteers (N = 27) were exposed in an environmental chamber to sulfuric acid aerosol at concentrations near 0, 122, 242, and 410 μg/m3, in purified background air at 22° C and 50 percent relative humidity. The polydisperse aerosol had a mass median aerodynamic diameter near 0.6 μm. Exposures occurred in random order at one-week intervals. Each lasted 1 h, during which subjects exercised (mean ventilation 42 L/min) and rested during alternate 10-min periods. Specific airway resistance and forced expiratory function were measured pre-exposure, after the initial exercise, and at end-exposure. Bronchial reactivity was determined by challenge with cold air immediately post-exposure. Symptoms were monitored during exposure for one week afterward. Exercise-induced bronchospasm was observed under all conditions. Physiologic and symptom changes possibly attributable to sulfuric acid exposure were small and not statistically significant. Our largely negative results contrast with positive findings elsewhere at lower acid doses. Possible explanations include different clinical characteristics of subjects and different routes of breathing. 相似文献
84.
Lynne A. Isbell Jill D. Pruetz Truman P. Young 《Behavioral ecology and sociobiology》1998,42(2):123-133
The effect of food resources on behavior has been difficult to measure. Here we use animals themselves to describe “effective”
food abundance and distribution by comparing, relative to where individuals stopped to eat, movements of (1) adult females
living in a small group of vervet monkeys (Cercopithecus aethiops) with those living in a large group and (2) vervets and patas monkeys (Erythrocebus patas). Although females in the large vervet group travelled farther and stopped to eat more often than females in the small vervet
group, these differences resulted from foraging in Acacia drepanolobium habitat. In A. xanthophloea habitat, females in the large group travelled less far, travelled shorter distances between foods, and stopped as often as
females in the small group. Greater foraging costs of females in larger vervet groups may be offset by access to home ranges
of better quality. Compared to patas, vervets travelled shorter distances, moved shorter distances between food sites, stopped
less often, and had longer feeding bouts, suggesting that foods of vervets are denser and larger, overall, than foods of patas.
When vervets foraged in A. drepanolobium habitat, also the habitat of patas, their foraging behavior became more like that of patas. Vervets travelled farther, stopped
more often, and spent less time at food sites in A. drepanolobium habitat than in A. xanthophloea habitat, suggesting that foods are smaller and less usurpable in A. drepanolobium habitat. Distance between foods, a component of food distribution, did not increase, however. The critical variable underlying
usurpability of foods may be food site depletion time, a temporal measure.
Received: 14 March 1997 / Accepted after revision: 19 October 1997 相似文献
85.
Andrew B. Sparks Eric T. Wang Craig A. Struble Wade Barrett Renee Stokowski Celeste McBride Jacob Zahn Kevin Lee Naiping Shen Jigna Doshi Michel Sun Jill Garrison Jay Sandler Desiree Hollemon Patrick Pattee Aoy Tomita-Mitchell Michael Mitchell John Stuelpnagel Ken Song Arnold Oliphant 《黑龙江环境通报》2012,32(1):3-9
86.
Jill K. Tjon Melinda M. E. H. Witbreuk Peter A. A. Struijs Bloeme J. van der Knoop Ingeborg H. Linskens Johanna I. P. de Vries 《黑龙江环境通报》2023,43(8):1056-1065
Objective
Children and adults with talipes equinovarus (TEV) have smaller calves and shorter feet compared to non-affected controls. Do these changes have a prenatal onset?Methods
A prospective cohort study (January 2020–July 2021) was conducted with serial ultrasonographic measurements at 20 and 28 weeks gestation and measurements directly and 6 weeks after birth. Calf circumference and width, foot length and length of humerus, ulna, radius, femur, tibia and fibula were measured in TEV and were compared to a control population. Calculated sample size necessitated a minimal population of 10 cases with TEV and 50 controls.Results
Twenty cases with TEV and 62 controls were included. Fetal calf circumference (p < 0.001) and width (p < 0.001) were smaller in the TEV group in comparison to the control group, which persisted after birth. Growth in foot length (p < 0.001) and calf width (p 0.003) declined prenatally over time. The bone lengths and upper leg circumference were not smaller or shorter in TEV compared to controls.Conclusion
This prospective cohort study demonstrated the prenatal onset of reduced calf and foot size in fetuses with TEV from 20 weeks and onwards, which persists directly after birth. To investigate whether reduction in circumference initiates TEV or is caused by TEV, further examination is needed. 相似文献87.
Jason Chibuk Jill Rafalko Theresa Boomer Ron McCullough Graham McLennan Philip Wyatt Eyad Almasri 《黑龙江环境通报》2020,40(10):1321-1329
Objective
Outcome data from cell-free DNA (cfDNA) screening in twin gestations are limited. This study adds an appreciable number of confirmed outcomes to the literature, and assesses performance of cfDNA screening in twins over a 4.5-year period at one large clinical laboratory.Method
Prenatal cytogenetic and SNP microarray results were cross-referenced with cfDNA results for twin pregnancies, yielding 422 matched cases. Using diagnostic results as truth, performance of cfDNA screening in this population was assessed.Results
Of the 422 twin pregnancies with both cfDNA and diagnostic results, 3 specimens failed amniocyte analysis, and 48 samples (11.5%) were nonreportable from the initial cfDNA draw. Analysis of the 371 reportable samples demonstrated a collective sensitivity of 98.7% and specificity of 93.2% for trisomies 21/18/13. Positive predictive values (PPVs) in this study population, which is enriched for aneuploidy, were 78.7%, 84.6%, and 66.7% for trisomy 21, 18, and 13, respectively.Conclusion
CfDNA screening in a cohort of twin pregnancies with matched diagnostic results showed superior performance compared to traditional serum biochemical screening in twins. This study adds to a growing body of evidence suggesting that cfDNA is an accurate and reliable screening tool for the major trisomies in twin pregnancies.88.
Jill S Baron 《Ecological applications》2006,16(2):433-439
Using an estimated background nitrogen (N) deposition value of 0.5 kg N x ha(-1) x yr(-1) in 1900, and a 19-year record of measured values from Loch Vale (Colorado, USA; NADP site CO98), I reconstructed an N-deposition history using exponential equations that correlated well with EPA-reported NO(x) emissions from Colorado and from the sum of emissions of 11 western states. The mean wet N-deposition values for the period 1950-1964 was approximately 1.5 kg N x ha(-1) x yr(-1), corresponding to the reported time of alteration of diatom assemblages attributed to N deposition in alpine lakes in Rocky Mountain National Park (USA). This value becomes the critical load defining the threshold for ecological change from eutrophication. Thus if an N-deposition threshold for ecological change can be identified, and the date at which that threshold was crossed is known, hindcasting can derive the amount of atmospheric deposition at the time of change, at least for alpine lakes. Independent support for the technique and the deposition amount comes from experimental studies, ecosystem modeling, and paleolimnological records from northern Wyoming (USA). 相似文献
89.
Integrated assessment (IA) can be defined as a structured process of dealing with complex issues, using knowledge from various
scientific disciplines and/or stakeholders, such that integrated insights are made available to decision makers (J. Rotmans,
Enviromental Modelling and Assessment 3 (1998) 155). There is a growing recognition that the participation of stakeholders
is a vital element of IA. However, only little is known about methodological requirements for such participatory IA and possible
insights to be gained from these approaches. This paper summarizes some of the experiences gathered in the ULYSSES project,
which aims at developing procedures that are able to bridge the gap between environmental science and democratic policy making
for the issue of climate change. The discussion is based on a total of 52 IA focus groups with citizens, run in six European
and one US city. In these groups, different computer models were used, ranging from complex and dynamic global models to simple
accounting tools. The analysis in this paper focuses on the role of the computer models. The findings suggest that the computer
models were successful at conveying to participants the temporal and spatial scale of climate change, the complexity of the
system and the uncertainties in our understanding of it. However, most participants felt that the computer models were less
instrumental for the exploration of policy options. Furthermore, both research teams and participants agreed that despite
considerable efforts, most models were not sufficiently user-friendly and transparent for being accessed in an IA focus group.
With that background, some methodological conclusions are drawn about the inclusion of the computer models in the deliberation
process. Furthermore, some suggestions are made about how given models should be adapted and new ones developed in order to
be helpful for participatory IA.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
90.
Jill Baron A. Scott Denning Keith Schoepflin 《Environmental monitoring and assessment》1989,12(3):293-293
Contribution from Fourth World Wilderness Congress-Acid Rain Symposium, Denver (Estes Park), Colorado, September 11–18, 1987. 相似文献