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451.
Elizabeth J. Hilkert Colby Thomas M. Young Peter G. Green Jeannie L. Darby 《Journal of the American Water Resources Association》2010,46(6):1238-1254
Hilkert Colby, Elizabeth J., Thomas M. Young, Peter G. Green, and Jeannie L. Darby, 2010. Costs of Arsenic Treatment for Potable Water in California and Comparison to U.S. Environmental Protection Agency Affordability Metrics. Journal of the American Water Resources Association (JAWRA) 46(6):1238–1254. DOI: 10.1111/j.1752-1688.2010.00488.x Abstract: The United States (U.S.) federal standard for arsenic in potable water systems is only the second water quality standard in which the U.S. Environmental Protection Agency (USEPA) administrator used “discretionary authority to establish a less stringent standard” based on the results of cost-benefit analyses. Based on the findings that a “standard of 3 μg/l would be feasible but not justified,” the revised maximum contaminant level (MCL) lowered the allowable arsenic concentration from 50 to 10 μg/l in 2002. In 2009, approximately 145 systems in California were out of compliance. The objectives were to gather performance and cost data from arsenic treatment systems in California to compare with data from the USEPA demonstration sites as well as with the USEPA affordability metrics for drinking water. The median cost of compliance with the revised arsenic MCL for the 36 surveyed systems was $1.95/1,000 gallons (2008 dollars), which is 69% of the average cost of delivered tap water in the U.S. in 2008 ($2.81/1,000 gallons). Additionally, 22% of the surveyed systems in California paid more than the maximum predicted cost of compliance with the revised arsenic MCL ($5.05/1,000 gallons). The largest variation in cost was seen in the systems that treated <500 gpm. For the systems utilizing adsorption, systems obtained between 20 and 80% of the expected bed volumes prior to breakthrough, indicating the need for better prediction of performance. 相似文献
452.
Joshua Olusegun Okeniyi Uchechuckwu Eric Obiajulu Adedamola Oluwafisayo Ogunsanwo Nosadeba Wisdom Odiase Elizabeth Toyin Okeniyi 《Mitigation and Adaptation Strategies for Global Change》2013,18(3):325-335
The potential of CH4 (methane) greenhouse gas (GHG) emissions based on a model of prevailing behavioural pattern of livestock waste management in Nigerian local farms was investigated in this paper. Livestock waste, from Sus domesticus, pig, and Gallus domesticus, poultry, were employed as substrates in the study which uses water from a fish rearing farm as the matrix medium to simulate wastewater pool/river environment. A substrate to fish-water ratio of 1:3 by mass was used in developed laboratory-size digesting reactor system with U-tube water displacement, to facilitate volumetric readings of gas production, for each mix of the livestock waste. Volumetric readings from these, at ambient temperature conditions in the retention time of 32 days, follow the Normal probability density function, in accordance with Kolmogorov-Smirnov goodness-of-fit criteria. These readings showed that CH4-containing gas as high as 67.3?×?10?3 dm3 was produced on the 14th day from the pig and 86.8?×?10?3 dm3 on the 13th day from the poultry substrates. The overall CH4-containing gas productions of 255.4?×?10?3 dm3/kg and 323.58?×?10?3 dm3/kg were observed for the pig and the poultry substrates, respectively. A 70% scale-up analysis, modelled from these results, for the nation yield potential emission of about 4 kg CH4 (that could be as potent as 84 kg CO2-equivalent) annually. The environmental implications on global warming and possible prospects of recoverable domestic benefits from the waste through the adoption of sustainable policy of livestock waste managements for mitigating the CH4 emissions in Nigerian local farms are presented. 相似文献
453.
Megan E. Mach Elizabeth J. Sbrocco Lyndie A. Hice Tara A. Duffy David O. Conover Paul H. Barber 《Marine Biology》2011,158(3):515-530
The coastal marine environment of the Northwest Atlantic contains strong environmental gradients that create distinct marine
biogeographic provinces by limiting dispersal, recruitment, and survival. This region has also been subjected to numerous
Pleistocene glacial cycles, resulting in repeated extirpations and recolonizations in northern populations of marine organisms.
In this study, we examined patterns of genetic structure and historical demography in the Atlantic silverside, Menidia menidia, an annual marine fish with high dispersal potential but with well-documented patterns of clinal phenotypic adaptation along
the environmental gradients of the Northwest Atlantic. Contrary to previous studies indicating genetic homogeneity that should
preclude regional adaptation, results demonstrate subtle but significant (F
ST = 0.07; P < 0.0001) genetic structure among three phylogeographic regions that partially correspond with biogeographic provinces, suggesting
regional limits to gene flow. Tests for non-equilibrium population dynamics and latitudinal patterns in genetic diversity
indicate northward population expansion from a single southern refugium following the last glacial maximum, suggesting that
phylogeographic and phenotypic patterns have relatively recent origins. The recovery of phylogeographic structure and the
partial correspondence of these regions to recognized biogeographic provinces suggest that the environmental gradients that
shape biogeographic patterns in the Northwest Atlantic may also limit gene flow in M. menidia, creating phylogeographic structure and contributing to the creation of latitudinal phenotypic clines in this species. 相似文献
454.
Elizabeth K. O’Dea Edward Dwyer Valerie Cummins Dawn J. Wright 《Journal of Coastal Conservation》2011,15(4):607-627
A Coastal Web Atlas (CWA) is a valuable resource for a range of users including coastal managers as it provides easy access
to maps, spatial data, coastal information and tools. A trans-Atlantic workshop on “Potentials and Limitations of Coastal
Web Atlases”, held in Ireland in July 2006, brought together atlas developers and coastal data experts from Europe and the
United States to examine state-of-the-art developments in CWAs and future needs. This paper focuses on workshop outcomes,
including what defines a CWA and an overview of international, national, state and regional atlas case studies from both sides
of the Atlantic. Results of discussions are presented concerning issues related to design, data, technology and institutional
capacity for existing CWAs based on the collective experience of workshop participants. Directions in CWA development and
applications since the workshop are also discussed. A major outcome of the workshop was the initiation of an International
Coastal Atlas Network. The insights provided give a framework for CWA developers and a useful point of reference for coastal
managers and policy makers on atlas potentials and limitations. 相似文献
455.
Elizabeth?L.?Franklin Thomas?O.?Richardson Ana?B.?Sendova-Franks Elva?J.?H.?Robinson Nigel?R.?FranksEmail author 《Behavioral ecology and sociobiology》2011,65(4):569-579
During tandem runs, one ant worker recruits another to an important resource. Here, we begin to investigate how dependent
are tandem leaders and followers on visual cues by painting over their compound eyes to impair their vision. There are two
ways in which Temnothorax albipennis might use vision during tandem running. First, the follower might track the movements of the leader by keeping it in sight.
Our results suggest that the ants do not use vision in this way. For example, in all four classes of tandem run (those with
either leader or follower, both, or neither of their participants with visual impairments) progress was most smooth at about
3 mm/s. This suggests that communication between leaders and followers during tandem runs is not based on vision and is purely
tactile and pheromonal. Second, the leader and the follower might be using vision to navigate and our results support this
possibility but also suggest that these ants have other methods of navigation. Ants with visual impairments were more likely
to follow than to lead, but could occupy either role, even though they had many fully sighted nestmates. This might help to
explain why the ants did not focus grooming on their most visually impaired nestmates. Wild-type tandem runs, with both participants
fully sighted and presumably taking time to learn landmarks, were overall significantly slower, smoother, and a little less
tortuous, than the other treatments. All four classes of tandem run significantly increased mean instantaneous speeds and
mean absolute changes in instantaneous acceleration over their journeys. Moreover, tandems with sighted followers increased
their speed with time more than the other treatments. In general, our findings suggest that eyesight is used for navigation
during tandem running but that these ants also probably use other orientation systems during such recruitment and to learn
how to get to new nest sites. Our results suggest that the ants’ methods of teaching and learning are very robust and flexible. 相似文献
456.
Elizabeth A. Miesner Stephen N. Rudnick Fu-Chang Hu John D. Spengler Liesbeth Preller Halûk Özkaynak 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1577-1582
Abstract The purpose of this study was to characterize and measure indoor air quality in public facilities and office buildings. The pollutants of interest were particulate matter smaller than 2.5 μm in diameter, PM-2.5, and environmental tobacco smoke (ETS). Integrated PM- 2.5 samples were taken on Teflon membrane filters using Harvard Aerosol Impactors as a pre-size selector. Filters were analyzed by gravimetric analysis. Nicotine, which was used as a marker for ETS, was collected on sodium-bisulfate-impregnated, glass-fiber filters and was analyzed by gas chromatography. Twenty-one structures were monitored in Metropolitan Boston. Measured particle concentrations ranged from 6.0 μg/m3 to about 550 μg/m3. Nicotine concentrations were as high as 26 μg/m3 in a designated smoking room. Real-time measurements were also taken using two types of nephelometers; a Handheld Aerosol Monitor (HAM) and a Miniature Real-Time Aerosol Monitor (MINIRAM). Short-term field measurements with these instruments correlated better with the integrated PM-2.5 concentrations in smoking locations than with concentrations in non-smoking areas. 相似文献
457.
458.
459.
Robert L. Ficklin Elizabeth G. Dunn John P. Dwyer 《Journal of environmental management》1996,46(4):395-402
While there are increasing numbers of non-consumptive forest uses on public lands, some silvicultural management systems provide little flexibility for the realization of non-commodity values. Traditional economic decision-making tools, such as net present value, are often applied in a manner which inadequately accounts for the full value of the resource. As a result, sub-optimal management practices are often implemented. By applying a marginal analysis of the optimal externality of different silvicultural systems, it is possible to identify the optimal timber management strategy in terms of the total costs of the timber harvest under alternative uses. Although difficulties arise in valuing non-consumptive uses, contingent valuation with averting costs estimates can establish a lower bound on society's willingness to pay for foregone timber harvesting. Low impact harvest operations and “new forestry” techniques, such as selection harvest cuts, are helpful in reducing the external costs of timber cutting. Therefore, the implementation of such systems may actually increase the socially optimal area of public lands to be harvested under a multiple-use designation. 相似文献
460.