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121.
122.
Richard P. Morse Eileen Rawnsley Steven K. Sargent Dr. John M. Graham Jr. 《黑龙江环境通报》1987,7(9):631-638
Markedly decreased fetal activity (akinesia/hypokinesia) is usually readily apparent to experienced mothers, and frequently this concern leads to attempts at prenatal diagnosis. We report prenatal diagnosis of two fetuses with congenital contractures, markedly decreased fetal movement, and microcephaly due to severe holoprosencephaly. Such familial recurrence to phenotypically normal parents suggests a newly recognized autosomal recessive or X-linked syndrome that is readily detectable by prenatal ultrasonography. 相似文献
123.
Assefa M. Melesse Wendy D. Graham 《Journal of the American Water Resources Association》2004,40(4):863-879
ABSTRACT: In this study, remotely sensed data and geographic information system (GIS) tools were used to estimate storm runoff response for Simms Creek watershed in the Etonia basin in northeast Florida. Land cover information from digital orthophoto quarter quadrangles (DOQQ), and enhanced thematic mapper plus (ETM+) were analyzed for the years 1990, 1995, and 2000. The corresponding infiltration excess runoff response of the study area was estimated using the U.S. Department of Agriculture (USDA), Natural Resources Conservation Service Curve Number (NRCS‐CN) method. A digital elevation model (DEM)/GIS technique was developed to predict stream response to runoff events based on the travel time from each grid cell to the watershed outlet. A comparison of predicted to observed stream response shows that the model predicts the total runoff volume with an efficiency of 0.98, the peak flow rate at an efficiency of 0.85, and the full direct runoff hydrograph with an average efficiency of 0.65. The DEM/GIS travel time model can be used to predict the runoff response of ungaged watersheds and is useful for predicting runoff hydrographs resulting from proposed large scale changes in the land use. 相似文献
124.
Spatial and temporal drivers of zoonotic pathogen contamination of an agricultural watershed 总被引:1,自引:0,他引:1
Jokinen CC Edge TA Koning W Laing CR Lapen DR Miller J Mutschall S Scott A Taboada EN Thomas JE Topp E Wilkes G Gannon VP 《Journal of environmental quality》2012,41(1):242-252
In regions where animal agriculture is prominent, such as southern Alberta, higher rates of gastrointestinal illness have been reported when compared with nonagricultural regions. This difference in the rate of illness is thought to be a result of increased zoonotic pathogen exposure through environmental sources such as water. In this study, temporal and spatial factors associated with bacterial pathogen contamination of the Oldman River, which transverses this region, were analyzed using classification and regression tree analysis. Significantly higher levels of fecal indicators; more frequent isolations of Campylobacter spp., Escherichia coli O157:H7, and Salmonella enterica spp.; and higher rates of detection of pig-specific Bacteroides markers occurred at downstream sites than at upstream sites, suggesting additive stream inputs. Fecal indicator densities were also significantly higher when any one of these three bacterial pathogens was present and where there were higher total animal manure units; however, occasionally pathogens were present when fecal indicator levels were low or undetectable. Overall, Salmonella spp., Campylobacter spp., and E. coli O157:H7 presence was associated with season, animal manure units, and total rainfall on the day of sampling and 3 d in advance of sampling. Several of the environmental variables analyzed in this study appear to influence pathogen prevalence and therefore may be useful in predicting water quality and safety and in the improvement of watershed management practices in this and other agricultural regions. 相似文献
125.
Halihan T Paxton S Graham I Fenstemaker T Riley M 《Journal of environmental monitoring : JEM》2005,7(4):283-287
Present understanding of the earth's subsurface is most often derived from samples at discrete points (wells) and interpolations or models that interpret the space between these points. Electrical resistivity imaging techniques have produced an improved capability to map contaminants (especially NAPLs--NonAqueous Phase Liquids) away from traditional wells using actual field data. Electrical resistivity image data, confirmed by drilling, have demonstrated that LNAPL (Light NAPL--less dense than water, such as gasoline) contaminants exist outside of a delineated and remediated area in Golden, Oklahoma. The data also demonstrate that LNAPL exists between monitoring and remediation wells which indicate low contaminant levels when sampled. Additionally, the electrical images provided the drilling location with the highest concentration of hydrocarbon ever found on the site, even after two phases of remediation work had been performed, although the sampling protocols varied. The results indicate that current methods of post-remediation site characterization are inadequate for complete site characterization. 相似文献
126.
M. Anwar H. Khan M. M. Nazmul Hoque S. Shamsul Alam M. J. Ashfol Graham Nickless Dudley E. Shallcross 《环境科学学报(英文版)》2011,23(1):60-64
Night-time OH levels have been determined for UK urban surface environments using two methods, the decay and steady state
approximation methods. Measurement data from the UK National Environmental Technology Centre archive for four urban sites
(Bristol, Harwell, London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study. Three reactive
alkenes, namely isoprene, 1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method. Hourly
measurements of NO, NO2, O3, CO and 20 VOCs were used to determine night-time OH level using the steady state approximation
method. Our results showed that the night-time OH levels were in the range of 1 105–1 106 molecules/cm3 at these four urban sites in
the UK. The application of a t-test of these analyses indicated that except Bristol, there was no significant di erence between the OH
levels found from the decay and steady state approximation methods. Night-time levels of the OH radical appeared to peak in summer
and spring time tracking the night-time O3 levels which also passed through a maximum at this time. 相似文献
127.
Ruth Fernández Susana García-Tiscar M. Begoña Santos Alfredo López Jose A. Martínez-Cedeira Jason Newton Graham J. Pierce 《Marine Biology》2011,158(5):1043-1055
Skin and muscle from 43 bottlenose dolphins (38 juveniles/adults, 5 calves) stranded in NW Spain were analysed to determine
whether stable isotope ratios (δ13C and δ15N) could be used to assess dietary variation, habitat segregation and population substructure. Results were compared with
published stomach contents data. Stable isotope ratios from 17 known prey species were also determined. Isotope ratios of
the main prey (blue whiting, hake) varied significantly in relation to fish body size. Dolphin calves showed significant heavy
isotope enrichments compared to adult females. Excluding calves, δ15N decreased with increasing dolphin body size, probably related to an ontogenetic shift in diet towards species at lower trophic
levels, e.g. on blue whiting as suggested by stomach content results. Bottlenose dolphins were divided into two putative populations
(North, South) based on previous genetic studies, and values of δ13C and δ15N differed significantly between these two groups, confirming the existence of population structuring. 相似文献
128.
Graham Pinfield 《Local Environment》1996,1(2):151-163
Sustainability indicators are an increasingly popular tool for the identification of policies and monitoring of progress towards sustainable development. The need for indicators is clearly set out in Agenda 21 and has been taken up by the Commission for Sustainable Development. Devising alternative measures of progress to gross national product has been the subject of much research in the past few years. There are many local sustainability indicator initiatives now under way, co-ordinated by local authorities and involving local communities. However useful these exercises have been (not least to those engaged in them) there is little evidence, so far, that sustainability indicators are leading to substantial shifts in policy at national or local level. Evidence points, in fact, to substantial barriers to progress in several key areas: for example, the necessity for the greater integration of environmental, social and economic policy, the tackling of inequality and poverty and the encouragement of greater public participation in action on sustainable development. In order for indicators to make any progress in surmounting these barriers there is a need to address issues of trust and to examine existing institutional structures and practices. In parallel with the development of indicators, national, and particularly local, government will need to experiment with new and creative techniques for community participation in decision making, engage in dialogue with new cultural networks and implement practical initiatives to improve the quality of life in particular communities. 相似文献
129.
What do significance tests really tell us about the environment? 总被引:8,自引:0,他引:8
Routine application of significance tests does not extract the maximum information from environmental data and can lead to misleading conclusions. Reasons leading to this are: a significant result can often be reached merely by collecting enough samples; a statistically significant result is not necessarily practically significant; and reports of the presence or absence of statistically significant differences for multiple tests are not comparable unless identical sample sizes are used. These problems are demonstrated by application to pH data for grazed and retired fields, and by discussion of significance tests used in recent US regulations for groundwater quality. The advantages of equivalence tests, where the tester must state the difference of practical difference, are discussed and applied to the field pH problem. We recommend that environmental managers and scientists pay more attention to statistical power and decide on what is a practical difference. Confidence intervals for the size of the differences, accompanied where necessary by equivalence tests, are the preferred means of addressing the question: “is there a difference of practical significance?” 相似文献
130.
Carolyn Hunsaker Robin Graham Robert S. Turner Paul L. Ringold George R. Holdren Jr. Timothy C. Strickland 《Environmental management》1993,17(3):335-341
The United States Environmental Protection Agency, with support from the US Department of Energy and the National Oceanographic
and Atmospheric Administration, has been evaluating the feasibility of an effects-based (critical loads) approach to atmospheric
pollutant regulation and abatement. The rationale used to develop three of the six steps in a flexible assessment framework
(Strickland and others, 1992) is presented along with a discussion of a variety of implementation approaches and their ramifications.
The rationale proposes that it is necessary to provide an explicit statement of the condition of the resource that is considered
valuable (assessment end point) because: (1) individual ecosystem components may be more or less sensitive to deposition,
(2) it is necessary to select indicators of ecosystem condition that can be objectively measured and that reflect changes
in the quality of the assessment end point, and (3) acceptable status (i.e., value of indicator and quality of assessment
end point at critical load) must be defined. The rationale also stresses the importance of defining the assessment regions
and subregions to improve the analysis and understanding of the indicator response to deposition. Subregional definition can
be based on a variety of criteria, including informed judgment or quantitative procedures. It also depends on the geographic
scale at which exposure and effects models are accurate and on data availability, resolution, and quality.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental
Technology, Inc., and Interagency Agreement #1824-B014-A7 with the US Department of Energy and at Oak Ridge National Laboratory
managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental
Sciences Division Publication No. 3903. It has been subjected to the agency’s peer and administrative review and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. 相似文献