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991.
992.
To assist transport modeling in assessments of the radiological impact of a geological repository for radioactive wastes, the mobility of various elements was studied in arable and wetland soils in the Forsmark region, Sweden. Pore water and total element contents were determined for five types of unconsolidated deposits (regolith), spanning a wide range of soil properties with respect to pH and organic matter content. Two soil depths were sampled to capture element mobility in regolith layers affected and unaffected by soil-forming processes. The solid/liquid partition coefficients (K d values) for most elements varied significantly among regolith types. For most elements, the observed variations in K d values could be explained by variations in soil properties. For many elements, mobility increased with decreasing soil pH. The results provide a significant addition of data on radionuclide retention in soils, taking account of soil properties and processes. 相似文献
993.
There have been great transitions in the science of air pollution and science publishing since the journal began as the International Journal of Air Pollution in 1958. Atmospheric Environment witnessed the increased understanding of smog photochemistry in the late 1950s and the emerging fears of ozone depletion in the 1970s. The journal has grown, but not without the need to change and occasionally fragment only to reintegrate at a later date. At 9000 pages a year it represents an enormous editorial task that has had to be undertaken by more professional offices. This transition has been helped through the development of electronic tools, but the editorial offices strive to retain their personal relationship with authors and reviewers. An enhanced international perspective recognises the widening contributions made by scientists beyond Europe and North America. 相似文献
994.
Peter P.Zhou 《生态毒理学报》2001,23(4):42-46
研究了旨在东非和南非能够发生改善的许多举措.能够在这些国家明显地改善能源效率、减少温室气体的排放.从本地区缺乏资金来源的角度看,给需要的措施提供资金帮助仍然是个问题. 相似文献
995.
Kristen M. Waring Danielle M. Reboletti Lauren A. Mork Ching-Hsun Huang Richard W. Hofstetter Amanda M. Garcia Peter Z. Fulé T. Seth Davis 《Environmental management》2009,44(4):824-835
Predicted climate warming is expected to have profound effects on bark beetle population dynamics in the southwestern United
States. Temperature-mediated effects may include increases in developmental rates, generations per year, and changes in habitat
suitability. As a result, the impacts of Dendroctonus frontalis and Dendroctonus mexicanus on forest resources are likely subject to amplification. To assess the implications of such change, we evaluated the generations
per year of these species under three climate scenarios using a degree-day development model. We also assessed economic impacts
of increased beetle outbreaks in terms of the costs of application of preventative silvicultural treatments and potential
economic revenues forgone. Across the southwestern USA, the potential number of beetle generations per year ranged from 1–3+ under
historical climate, an increase of 2–4+ under the minimal warming scenario and 3–5+ under the greatest warming scenario. Economic
benefits of applying basal area reduction treatments to reduce forest susceptibility to beetle outbreaks ranged from 7.75/ha (NM) to7.75/ha
(NM) to 95.69/ha (AZ) under historical conditions, and 47.96/ha (NM) to47.96/ha (NM) to 174.58/ha (AZ) under simulated severe drought conditions.
Basal area reduction treatments that reduce forest susceptibility to beetle outbreak result in higher net present values than
no action scenarios. Coupled with other deleterious consequences associated with beetle outbreaks, such as increased wildfires,
the results suggest that forest thinning treatments play a useful role in a period of climate warming. 相似文献
996.
Michael Rizzo Peter Scheff Viswanathan Ramakrishnan 《Journal of the Air & Waste Management Association (1995)》2013,63(5):593-605
Abstract The objective of this project is to demonstrate how the ambient air measurement record can be used to define the relationship between O3 (as a surrogate for photochemistry) and secondary particulate matter (PM) in urban air. The approach used is to develop a time-series transfer-function model describing the daily PM10 (PM with less than 10 μm aerodynamic diameter) concentration as a function of lagged PM and current and lagged O3, NO or NO2, CO, and SO2. Approximately 3 years of daily average PM10, daily maximum 8-hr average O3 and CO, daily 24-hr average SO2 and NO2, and daily 6:00 a.m.-9:00 a.m. average NO from the Aerometric Information Retrieval System (AIRS) air quality subsystem are used for this analysis. Urban areas modeled are Chicago, IL; Los Angeles, CA; Phoenix, AZ; Philadelphia, PA; Sacramento, CA; and Detroit, MI. Time-series analysis identified significant autocorrelation in the O3, PM10, NO, NO2,CO, and SO2 series. Cross correlations between PM10 (dependent variable) and gaseous pollutants (independent variables) show that all of the gases are significantly correlated with PM10 and that O3 is also significantly correlated lagged up to two previous days. Once a transfer-function model of current PM10 is defined for an urban location, the effect of an O3-control strategy on PM concentrations is estimated by calculating daily PM10 concentrations with reduced O3 concentrations. Forecasted summertime PM10 reductions resulting from a 5 percent decrease in ambient O3 range from 1.2 μg/m3 (3.03%) in Chicago to 3.9 μg/m3 (7.65%) in Phoenix. 相似文献
997.
998.
Multivariate abundance data are commonly collected in ecology, and used to explore questions of “community composition”—how
relative abundance of different taxa changes with environmental conditions. In this paper, we propose a log-linear marginal
modeling approach for analyzing such compositional count data, via generalized estimating equations. This method exploits
the multiplicative nature of log-linear models for counts, by reparameterizing models that describe marginal effects on mean
abundance. This allows partitioning into “main effects” and compositional effects, which is appealing for interpretation.
We apply the proposed approach to reanalyze compositional counts of benthic invertebrates from Delaware Bay, and data of invertebrate
communities inhabiting Acacia plants in eastern Australia. In both cases we resort to a resampling approach to make inferences about regression parameters,
because the number of clusters was not large compared to cluster size. 相似文献
999.
1000.