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321.
322.
William A. McClenny S. Mark Schmidt Keith G. Kronmiller 《Journal of the Air & Waste Management Association (1995)》2013,63(1):64-69
ABSTRACT Dalton's law of partial pressures and the hypothesis that water vapor equilibrium in a canister is identical to that established above liquid water are used to predict the variation of the percent relative humidity (%RH) of air released from canisters used in ambient air sampling, typically 6-L canisters pressurized with 18 L of air. When (and if) the water vapor partial pressure in a canister exceeds its saturation vapor pressure, water vapor condensation begins and the condensation rate equals the sampling rate of water vapor into the canister. Under constant temperature conditions, the air subsequently released from the canister is less humid than the original sample, following the relationship %RH = 100% (6 L/Vs) for Vs> Vr, where Vs is the residual air volume (referenced to atmospheric pressure), and Vr is shown to depend on the %RH of the ambient air sample. Vr is the residual air volume at which water is completely removed (except for adsorbed water vapor) from the canister wall. For Vs < Vr, the predicted %RH is constant and equal to its value at Vr. Experimental values agree reasonably well with predictions at both high (90%) and low (34%) RH. However, experimental values are often slightly displaced (usually towards lower values of %RH) for mid-range %RH (61%) and variations in %RH near Vr change from canister to canister. 相似文献
323.
Alistair J. Wilson Mark Dean James P. Higham 《Behavioral ecology and sociobiology》2013,67(9):1399-1415
Over the last few decades the animal communication community has become increasingly aware that much communication occurs using multiple signals in multiple modalities. The majority of this work has been empirical, with less theoretical work on the advantages conferred by such communication. In the present paper, we ask: Why should animals communicate with multiple signals in multiple modalities? To tackle this question we use game theoretic techniques, and highlight developments in the economic signaling literature that might offer insight into biological problems. We start by establishing a signaling game, and investigate signal honesty under two prevailing paradigms of honest communication – costly signaling and cheap talk. In both paradigms, without further constraint, it is simple to show that anything that can be achieved with multiple signals can be achieved with one. We go on to investigate different sets of possible constraints that may make multiple signals and multimodal signals in particular more likely to evolve. We suggest that constraints on cost functions and bandwidths, orthogonal noise across modalities, strategically distinct modes, multiple qualities, multiple signalers, and multiple audiences, all provide biologically plausible scenarios that theoretically favor multiple and multimodal signaling. 相似文献
324.
Kees van Leeuwen 《Environmental management》1990,14(6):779-792
In a recently published annex to the National Environmental Policy Plan of the Netherlands (1989), attention was paid to ecotoxicological
effects assessment. The proposed procedure was based on the advice of the Health Council of the Netherlands (1989) on risk
assessment of toxic chemicals for ecosystems. The various extrapolation methods described by the Health Council are critically
discussed in this paper. The extrapolation method of Van Straalen and Denneman (1989) is evaluated for eight chemicals and
11 aquatic species. Conclusions are drawn about the quality and quantity of the ecotoxicological data needed for aquatic effects
assessment. For the soil—a compartment that is often at risk—ecotoxicological effects assessment is not possible because suitable
ecotoxicological test methods still have to be developed. 相似文献
325.
The premise of this article is that the planning and design of new rest camps in conservation areas should be based on ecological
principles in such a way that the plant ecology within the camp be an integral part and extension of the natural ecology of
its immediate vicinity. This is desirable so that visitors to the camp will be provided not only with facilities for resting,
eating, and sleeping, but also be able to enjoy and study the natural environment in a relaxed atmosphere. The Berg-en-Dal
rest camp, which was established in Kruger National Park, was planned in such a way and designed according to the principles
outlined by the authors in a companion article.
The planning included six zones: a control zone, day visitor zone, overnight visitor zone, staff accommodation zone, recreation
zone, and service zone. The point is stressed that plant species selected to be used as additional vegetation to those already
growing in the camp were endemic to the nine landscape facets identified in the camp. The design allowed for separation of
the various land-use zones in such a way that they would complement each other rather than be a hindrance to each other. The
camp has been built according to the plans included in this article and has proved to be a great success. The conclusion is
drawn that the planning principles are sound and should be used in the future for the planning and design of rest camps for
conservation areas in South Africa. 相似文献
326.
Gregory J. McCabe David M. Wolock Lauren E. Hay Mark A. Ayers 《Journal of the American Water Resources Association》1990,26(4):633-643
ABSTRACT: The Thornthwaite moisture index is a useful indicator of the supply of water (precipitation) in an area relative to the demand for water under prevailing climatic conditions (potential evapotranspiration). This study examines the effects of changes in climate (temperature and precipitation) on the Thornthwaite moisture index in the conterminous United States. Estimates of changes in mean annual temperature and precipitation for doubled-atmospheric CO2 conditions derived from three general circulation models (GCMs) are used to study the response of the moisture index under steady-state doubled-CO2 conditions. Results indicate that temperature and precipitation changes under doubled-CO2 conditions generally will cause the Thornthwaite moisture index to decrease, implying a drier climate for most of the United States. The pattern of expected decrease is consistent among the three GCMs, although the amount of decrease depends on which GCM climatic-change scenario is used. Results also suggest that changes in the moisture index are related mainly to changes in the mean annual potential evapotranspiration as a result of changes in the mean annual temperature, rather than to changes in the mean annual precipitation. 相似文献
327.
328.
Gregory J. McCabe Mark A. Ayers 《Journal of the American Water Resources Association》1989,25(6):1231-1242
ABSTRACT: The Thornthwaite water balance and combinations of temperature and precipitation changes representing climate change were used to estimate changes in seasonal soil-moisture and runoff in the Delaware River basin. Winter warming may cause a greater proportion of precipitation in the northern part of the basin to fall as rain, which may increase winter runoff and decrease spring and summer runoff. Estimates of total annual runoff indicate that a 5 percent increase in precipitation would be needed to counteract runoff decreases resulting from a warming of 2°C; a 15 percent increase for a warming of 4°C. A warming of 2° to 4°C, without precipitation increases, may cause a 9 to 25 percent decrease in runoff. The general circulation model derived changes in annual runoff ranged from ?39 to +9 percent. Results generally agree with those obtained in studies elsewhere. The changes in runoff agree in direction but differ in magnitude. In this humid temperate climate, where precipitation is evenly distributed over the year, decreases in snow accumulation in the northern part of the basin and increases in evapotranspiration throughout the basin could change the timing of runoff and significantly reduce total annual water availability unless precipitation were to increase concurrently. 相似文献
329.
The U.S. Environmental Protection Agency has developed regulations under the Hazardous and Solid Waste Amendments (HSWA) of 1984 to restrict the land disposal of hazardous wastes. As a result of the regulations, all hazardous wastes to be placed on the land must meet treatment standards based on the performance of the best demonstrated available technology (BDAT) identified for individual waste classifications. The Marathon Oil Company is currently evaluating innovative technologies for managing listed waste materials, with a focus on waste minimization and recycling. Remediation Technologies, Inc. (ReTeC) has conducted testing on wastewater treatment sludges from three Marathon refineries using a proprietary thermal desorption technology. The results from these tests have demonstrated that the technology has the ability to consistently meet BDAT treatment standards, while preferentially separating and condensing residual moisture and oils from the material. 相似文献
330.
Saud A. Amer Timothy O. Keefer Mark A. Weltz David C. Goodrich Leslie B. Bach 《Journal of the American Water Resources Association》1994,30(1):69-83
ABSTRACT: Certain physical and chemical properties of soil vary with soil water content. The relationship between these properties and water content is complex and involves both the pore structure and constituents of the soil solution. One of the most economical techniques to quantify soil water content involves the measurement of electrical resistance of a dielectric medium that is in equilibrium with the soil water content. The objective of this research was to test the reliability and accuracy of fiberglass soil-moisture electrical resistance sensors (ERS) as compared to gravimetric sampling and Time Domain Reflectometry (TDR). The response of the ERS was compared to gravimetric measurements at eight locations on the USDA-ABS Walnut Gulch Experimental Watershed. The comparisons with TDR sensors were made at three additional locations on the same watershed. The high soil rock content (≥45 percent) at seven locations resulted in consistent overestimation of soil water content by the ERS method. Where rock content was less than 10 percent, estimation of soil water was within 5 percent of the gravimetric soil water content. New methodology to calibrate the ERS sensors for rocky soils will need to be developed before soil water content values can be determined with these sensors. 相似文献