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111.
We analyzed the past and current distribution and abundance of vegetation and wildlife to develop a wildlife habitat restoration
plan for the Sweetwater Regional Park, San Diego County, California. Overall, there has been a substantial loss of native
amphibians and reptiles, including four amphibians, three lizards, and 11 snake species. The small-mammal community was depauperate
and dominated by the exotic house mouse (Mus musculus) and the native western harvest mouse (Reithrodontomys megalotis). It appeared that either house mice are exerting a negative influence on most native species or that they are responding
positively to habitat degradation. There has apparently been a net loss of 13 mammal species, including nine insectivores
and rodents, a rabbit, and three large mammals. Willow (Salix) cover and density and cottonwoods (Populus fremontii) had the highest number of positive correlations with bird abundance. There has been an overall net loss of 12 breeding bird
species; this includes an absolute loss of 18 species and a gain of six species. A restoration plan is described that provides
for creation and maintenance of willow riparian, riparian woodland, and coastal sage scrub vegetation types; guides for separation
of human activities and wildlife habitats; and management of feral and exotic species of plants and animals. 相似文献
112.
Melvin W. Anderson Ronald F. Giovannelli 《Journal of the American Water Resources Association》1980,16(1):93-99
ABSTRACT: A common problem encountered during regional planning and development of ground water dependent communities is the difficulty in deciding which areas should be preserved for aquifer recharge purposes. This paper describes the development and application of a digital overlay technique for objective evaluation and ranking of potential infiltration and potential recharge areas. Equations are developed which relate the hydrologic parameters pertaining to infiltration and recharge in a surface aquifer-confined aquifer system. These equations make use of discrete data, yet by application in a digital overlay technique results are obtained in the form of spatial distributions in order for regional trends and conditions to be examined. An application of this procedure to the 551,000 acre region of central Florida, known as the Green Swamp, is discussed. The results are presented in the form of computer generated maps which identify and rank areas of potential recharge to the aquifer system. 相似文献
113.
Self-insurance against natural disasters 总被引:1,自引:0,他引:1
Expenditures on self-insurance to mitigate the effects of natural disasters on the value of private assets are examined in a model where individuals are partially insured against financial loss by a public relief program and where private insurance is unavailable. The model predicts that optimal private expenditures on self-insurance will be excessive or insufficient according to the nature of the technology by which individuals protect their assets. The comparative static effects of variations in the level of public compensation, individual wealth, and attitudes toward risk and the degree of environmental uncertainty on self-insurance expenditures and on the magnitude and frequency of public compensation are also characterized and their implications for remedial government policies are examined. 相似文献
114.
Robert L. Thomson Veli-Matti Pakanen Diane M. Tracy Laura Kvist David B. Lank Antti Rönkä Kari Koivula 《Behavioral ecology and sociobiology》2014,68(8):1261-1272
Males of many species theoretically face a fitness tradeoff between mating and parental effort, but quantification of this is rare. We estimated the magnitude of the mating opportunity cost paid by incubating male Temminck’s stints (Calidris temminckii), taking advantage of uniparental care provided by both sexes in this species. “Incubating males” provide all care for an early clutch, limiting subsequent mating possibilities. “Non-incubating” males include males that failed to obtain, lost to predation, or actively avoided incubating clutches. These males were free to pursue extrapair copulations and to mate with females laying later clutches, which females usually incubate themselves. Male incubation classes did not differ in measures of quality, and many individuals changed classes between years, suggesting the use of conditional reproductive tactics. However, specialist non-incubators may also exist. Using microsatellites to assign parentage, we compare males’ total fertilizations and the subset “free of care” fertilizations between incubation classes. Incubators were more likely to gain at least one fertilization per season and averaged one more per season than non-incubators. However, successful non-incubators were more likely to gain “free of care” fertilizations, averaging two more than successful incubators. The relative success of male incubation classes also changed with local sex ratios. With higher female proportions, non-incubators gained disproportionately more offspring, suggesting that the use of tactics should be partly determined by the availability of potentially incubating females. Overall, we estimate the opportunity cost of incubating to be 13–25 % of the potential annual reproductive output. 相似文献
115.
Market-based approaches to environmental regulation (such as tradable permits or transferable quotas) are frequently offered
as innovative solutions to many environmental problems. Globally, one of the most well-established forms of this approach
is individual transferable quotas (or ITQs) in fisheries management. Within the natural resource management community, there
is considerable debate over the effects ITQs have on the fishing industry and fisher behavior although this approach is not
well-established in the United States. The previously imposed moratorium on ITQs in the United States has expired and the
2006 reauthorization of the Magnuson-Stevens Act explicitly provides for limited access privileges (LAPs). A variety of fishers,
regulators, and conservation organizations are enthusiastically seeking to introduce ITQ management. With debate over whether
and how ITQs should be used in American fisheries reinvigorated, it is timely to examine the evidence on the social and economic
effects of ITQs in other nations’ fisheries. After briefly summarizing the debate on ITQs, we examine the case of New Zealand,
one of the earliest and longest-lived ITQ-based fisheries regimes. We use multiple data sources and methods to analyze the
extent to which industry consolidation and aggregation has occurred, including surveys of industry participants, expert interviews,
reviews of academic reports and analyses, analysis of trade publications, and direct analysis of quota ownership patterns.
This analysis shows a more complex outcome than recent debates in the ITQ literature would predict. These findings suggest
that policy makers considering ITQs can learn from the experiences of other countries related to key issues such as quota
allocation, aggregation limits, transferability, cost recovery, and resource sustainability when designing ITQ and other LAP
systems. It is also important to explicitly identify economic and social objectives and then carefully design ITQ regimes
to meet these objectives. 相似文献
116.
J.-F. Mercier B.L. Tracy R. d'Amours F. Chagnon I. Hoffman E.P. Korpach S. Johnson R.K. Ungar 《Journal of environmental radioactivity》2009
It has long been observed that the environmental gamma-ray dose rate increases noticeably during precipitation intervals. This increase, due to the presence of radon progeny in the rain droplets (or snow flakes), can affect the reliability of the monitoring of artificial radioactivity and long term estimates of exposure to ambient natural radionuclides in surveillance network. Predicting the amplitude of the dose increase has been shown to be surprisingly challenging. In this work, standard air mass back trajectory analysis is used to show that the amplitude of the increase can be quantitatively linked to the history of the air mass where the precipitation is occurring. Furthermore, we show how back trajectory analysis, environmental gamma and rain data can be used to obtain estimations of relative radon emanation rates for locations far from the actual point of detection. 相似文献
117.
Injury severity related to overturn characteristics of tractors 总被引:1,自引:0,他引:1
Melvin L. Myers Author VitaeAuthor Vitae Susan C. Westneat Author Vitae 《Journal of Safety Research》2009,40(2):165-170
Introduction
Early studies of injuries associated with overturns indicate that more fatalities occurred when a tractor overturned beyond 90° (continuous roll) relative to the impact plane. Recently, the principle of preventing continuous rolls has re-emerged for the protection of riding lawnmower operators.Method
Related to tractors, a population-based study was conducted that compared the severity of fatal and nonfatal injuries between a 90° and continuous roll for tractors equipped with rollover protective structures (ROPS) and not equipped with a ROPS (non- ROPS). In 2002, the Kentucky Farm Tractor Overturn Survey was administered to an 8% random sample (6,063) of Kentucky farm operators. The farmers responded to questions that differentiated between the types of overturns and operator injury outcomes for ROPS-equipped and non-ROPS tractors during overturn events. Overturn characteristics were collected that included 90° to the side, beyond 90° to the side, and to the rear for both ROPS-equipped and non-ROPS tractors.Results
Of the 541 overturns reported in this study, 535 (99%) of the respondents reported the most recent overturn characteristics of the tractor: 92 (17%) were ROPS-equipped and 443 (83%) were non-ROPS. For side overturns, 67% of the rolls occurred with ROPS-equipped tractors, and 54% occurred with non-ROPS tractors. The percentages of deaths related to rolls to the side for ROPS-equipped and non-ROPS tractors were, respectively, 1.6% and 3.7%. There was one (2%) deaths related to 90° rolls for ROPS-equipped tractors, whereas for continuous rolls there were 6.4% fatalities related to side overturns, 13% resulted in non-fatal injuries with an average of 1 day of hospitalization for ROPS-equipped tractors, and 39% resulted in non-fatal injuries with an average of 18 days of hospitalization for non-ROPS tractors. The results from this study indicated that a ROPS was more effective at stopping an overturn at 90° than no ROPS, with an associated reduction in the severity of injury in the event of a tractor overturn. 相似文献118.
Chambers AK Strosher M Wootton T Moncrieff J McCready P 《Journal of the Air & Waste Management Association (1995)》2008,58(8):1047-1056
Refineries are a source of emissions of volatile hydrocarbons that contribute to the formation of smog and ozone. Fugitive emissions of hydrocarbons are difficult to measure and quantify. Currently these emissions are estimated based on standard emission factors for the type and use of equipment installed. Differential absorption light detection and ranging (DIAL) can remotely measure concentration profiles of hydrocarbons in the atmosphere up to several hundred meters from the instrument. When combined with wind speed and direction, downwind vertical DIAL scans can be used to calculate mass fluxes of the measured gas leaving the site. Using a mobile DIAL unit, a survey was completed at a Canadian refinery to quantify fugitive emissions of methane, C2+ hydrocarbons, and benzene and to apportion the hydrocarbon emissions to the various areas of the refinery. Refinery fugitive emissions as measured with DIAL during this demonstration study were 1240 kg/hr of C2+ hydrocarbons, 300 kg/hr of methane, and 5 kg/hr of benzene. Storage tanks accounted for over 50% of the total emissions of C2+ hydrocarbons and benzene. The coker area and cooling towers were also significant sources. The C2+ hydrocarbons emissions measured during the demonstration amounted to 0.17% of the mass of the refinery hydrocarbon throughput for that period. If the same loss were repeated throughout the year, the lost product would represent a value of US$3.1 million/yr (assuming US$40/bbl). The DIAL-measured hourly emissions of C2+ hydrocarbons were 15 times higher than the emission factor estimates and gave a different perspective on which areas of the refinery were the main source of emissions. Methods, such as DIAL, that can directly measure fugitive emissions would improve the effectiveness of efforts to reduce emissions, quantify the reduction in emissions, and improve the accuracy of emissions data that are reported to regulators and the public. 相似文献
119.
Chowdhury Z Edwards RD Johnson M Naumoff Shields K Allen T Canuz E Smith KR 《Journal of environmental monitoring : JEM》2007,9(10):1099-1106
We have developed a small, light, passive, inexpensive, datalogging particle monitor called the "UCB" (University of California Berkeley particle monitor). Following previously published laboratory assessments, we present here results of tests of its performance in field settings at high particle concentrations. We demonstrate the mass sensitivity of the UCB in relation to gravimetric filter-based PM(2.5) mass estimates as well as commercial light-scattering instruments co-located in field chamber tests and in kitchens of wood-burning households. The coefficient of variation of the unadjusted UCB mass response in relation to gravimetric estimates was 15%. Although requiring adjustment for differences in sensitivity, inter-monitor performance was consistently high (r(2) > 0.99). Moreover, the UCB can consistently estimate PM(2.5) mass concentrations in wood-burning kitchens (Pearson r(2) = 0.89; N = 99), with good agreement between duplicate measures (Pearson r(2) = 0.94; N = 88). In addition, with appropriate cleaning of the sensing chamber, UCB mass sensitivity does not decrease with time when used intensively in open woodfire kitchens, demonstrating the significant potential of this monitor. 相似文献
120.
David Leith Melvin W. First 《Journal of the Air & Waste Management Association (1995)》2013,63(8):754-758
Performance data for fabric filters using either woven or felt bags can be better understood when fault processes such as pinhole bypass and seepage are considered. Penetration straight through the dust cake and fabric may not be important by comparison. Observed trends of increased penetration with increased filtration velocity, constant or slightly increased penetration with increasing particle diameter, and constant penetration with additional dust loading can be explained by fault processes. The pulse-jet experimental work described here, done over many filtration and cleaning cycles, shows that penetration increases substantially with increasing filtration velocity and that this increase is due entirely to seepage. 相似文献