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981.
V.N. Finelii M. Karaffa M. Malanchuk R.M. Danner L. McMillan S.D. Lee 《Journal of the Air & Waste Management Association (1995)》2013,63(3):231-233
The introduction of oxidizing catalytic converters in the exhaust system of automobiles has been found to be effective in reducing carbon monoxide, total hydrocarbons, and some other components of tailpipe emissions. The utilization of these converters, however, has also caused further oxidation of sulfur compounds producing an increased amount of sulfur trioxide (SO3) which yields sulfuric acid and sulfates.1 Studies on the biological effects of these sulfur compounds are in progress in our laboratory and preliminary findings are reported separately. This paper compares the biological effects of exposure to whole emissions from engines with and without converter and exposure to carbon monoxide alone. 相似文献
982.
M. Mansi V. Romano F. Senatore 《Journal of the Air & Waste Management Association (1995)》2013,63(8):881-882
ABSTRACT In this paper, assumptions regarding future land use as a key uncertainty is considered and its impact on risk analysis for contaminated sites is assessed. Risks are assessed for two land use scenarios (current-use industrial and future-use residential) using probabilistic models that incorporate uncertainty and variability in the exposure parameters. Residual risks are calculated for both industrial and residential cleanup standards. A Superfund site in northern California is considered. In general, for the unremediated case, the future-use residential scenarios produce larger risks (1 to 3 orders of magnitude) than current- (continued) use industrial scenarios. For the Superfund site studied, the residual risks calculated for the remedy selected was not sufficiently protective of future-use residents in that it did not meet .S. Environmental Protection Agency (EPA) risk goals, but was protective of current-use workers, even though the cleanup criteria were based on residential use. Alternative risk management practices, such as deed restrictions, can be used in such cases. 相似文献
983.
G. B. Howe R. K. M. Jayanty A. V. Rao W. F. Gutknecht C. E. Decker D. J. von Lehmden 《Journal of the Air & Waste Management Association (1995)》2013,63(9):823-826
A repository of 38 gaseous organic compounds in compressed gas cylinders has been established by EPA. This repository was established to provide standards for source test performance audits, that is, quantitative quality assurance tests. Among these compounds are ten halogenated organic species, which are the focus of this paper. Stability studies of all ten compounds have been performed to determine the feasibility of using them as performance audit standards. Results indicate that all of the halocarbons tested are adequately stable to be used as reliable audit standards. Subsequent to completion of stability studies, four of the ten halocarbons were used in source test performance audits. Results are available at this time for two of the four compounds; the results show agreement within 10% of the concentrations previously established by Research Triangle Institute. 相似文献
984.
Alfred V. Mollitor Dudley J. Raynal 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1032-1036
Major mechanisms for input of ions to forest ecosystems in the central Adirondack Mountains of New York State were studied. Precipitation and throughfall in adjacent northern hardwood and lake margin coniferous forests were continuously sampled from May 2, 1979 to May 7, 1980. Important mechanisms for transport of ions from atmosphere to forest floor were identified using regression analyses and the assumption that deciduous and coniferous forests capture particulates and aerosols with differing efficiencies. Sodium was delivered in precipitation and dry-fall and interacted little with the forest canopies. Hydrogen, potassium, and magnesium were also deposited primarily by bulk precipitation but hydrogen was retained by foliage while additional quantities of potassium and magnesium were leached from tree canopies. Impaction of suspended particulates and/or aerosols on forest vegetation was an important source of additional sulfate and nitrate, and these ions contributed to the leaching of calcium from foliage. 相似文献
985.
Ecosystem services and hydroelectricity in Central America: modelling service flows with fuzzy logic and expert knowledge 总被引:1,自引:0,他引:1
Bruno Locatelli Pablo Imbach Raffaele Vignola Marc J. Metzger Efraín José Leguía Hidalgo 《Regional Environmental Change》2011,11(2):393-404
Because ecosystem services are generally not produced and used in the same place, their assessment should consider the flows
of services from ecosystems to users. These flows depend on the characteristics and spatial distribution of ecosystems and
users, the spatial relationships between them, and the presence of filters or barriers between ecosystems and users. The objective
of this paper is to map the ecosystem services provided to the Costa Rican and Nicaraguan hydroelectric sectors, which are
crucial sectors for national sustainable development and depend directly on hydrological ecosystem services. The paper presents
an approach for modelling the flows of multiple services from diverse ecosystems to diverse users through different kinds
of filters in a landscape. The approach uses expert knowledge and fuzzy numbers to handle uncertainties. The analyses for
Costa Rica and Nicaragua show how the approach helps identify priority areas for the conservation and restoration of forests
for the services they provide to the hydroelectric sector. As such, it is a useful tool for defining spatially targeted policies
for the conservation of ecosystem services and for involving the users of ecosystem services in ecosystem management. 相似文献
986.
Andrea M. Bassi 《Regional Environmental Change》2011,11(2):285-295
Observing the many and varied reactions to the Kyoto Protocol, it becomes clear that different governments find themselves
in different contexts that eventually direct them toward taking dissimilar positions on energy issues. This paper, through
five integrated studies, investigates whether contextualizing energy issues is (are) relevant to support energy policy formulation
and evaluation and provides insights into how to operationalize the contextualization. Instead of considering the most widely
accepted tools currently used to assess and evaluate energy policy, this research proposes the utilization of a holistic framework
that incorporates social, economic and environmental factors as well as their relations to the energy sector to better contextualize
global, regional and national energy issues. This framework, which accounts for feedback loops, delays and non-linearity,
is applied to case studies to investigate the longer-term performance of selected energy policies. Results of the study indicate
the likely emergence of various unexpected side effects and elements of policy resistance over the medium and longer term
due to the interrelations existing between energy and society, economy and environment. Furthermore, while side effects and
unintended consequences may arise both within the energy sector and in the other sectors, they simultaneously influence society,
economy and environment. 相似文献
987.
This study projected responses of forest net primary productivity (NPP) to three climate change scenarios at a resolution
of 5 km × 5 km across the state of Louisiana, USA. In addition, we assessed uncertainties associated with the NPP projection
at the grid and state levels. Climate data of the scenarios were derived from Community Climate System Model outputs. Changes
in annual NPP between 2000 and 2050 were projected with the forest ecosystem model PnET-II. Results showed that forest productivity
would increase under climate change scenarios A1B and A2, but with scenario B1, it would peak during 2011–2020 and then decline.
The projected average NPP under B1 over the years from 2000 to 2050 was significantly different from those under A1B and A2.
Forest NPP appeared to be primarily a function of temperature, not precipitation. Uncertainties of the NPP projection were
due to large spatial resolution of the climate variables. Overall, this study suggested that in order to project effects of
climate change on forest ecosystem at regional level, modeling uncertainties could be reduced by increasing the spatial resolution
of the climate projections. 相似文献
988.
Long-term (1860–2010) catchment mass balance calculations rely on models and assumptions which are sources of uncertainty
in acidification assessments. In this article, we report on an application of MAGIC to model acidification at the four Swedish
IM forested catchments that have been subject to differing degrees of acidification stress. Uncertainties in the modeled mass
balances were mainly associated with the deposition scenario and assumptions about sulfate adsorption and soil mass. Estimated
base cation (BC) release rates (weathering) varied in a relatively narrow range of 47–62 or 42–47 meq m−2 year−1, depending on assumptions made about soil cation exchange capacity and base saturation. By varying aluminum solubility or
introducing a dynamic weathering feedback that allowed BC release to increase at more acidic pHs, a systematic effect on predicted
changes in acid neutralizing capacity (ΔANC ca. 10–41 μeq l−1) and pH (ca. ΔpH = 0.1–0.6) at all sites was observed. More robust projections of future changes in pH and ANC are dependent
on reducing uncertainties in BC release rates, the timing, and extent of natural acidification through BC uptake by plants,
temporal changes in soil element pools, and fluxes of Al between compartments. 相似文献
989.
James S. Risbey 《Regional Environmental Change》2011,11(1):197-203
Water resources in Australia are sensitive to changes in rainfall. Ongoing droughts in south-west and south-east Australia are stressing water resources in the major cities and in agricultural regions. Climate change scenarios for Australia include reasonable prospects of long-term drying, which would exacerbate these issues. The dryer scenarios would entail major readjustments and costs on natural and human systems. 相似文献
990.