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111.
Xiying Hao Chi Chang H. Henry Janzen Brett R. Hill Troy Ormann 《Agriculture, ecosystems & environment》2005,110(3-4):185-194
Elevated atmospheric NH3 levels near intensive livestock operations can add significant N to local agroecosystems. In this study, the potential atmospheric NH3 sorbed by soil and water was assessed over a 2-year period starting October 2000 in an intensive livestock production area in southern Alberta, Canada. Fifty-two uneven grid sampling sites were selected in the 53,905 ha study area. The sorption rate of atmospheric NH3 was estimated weekly by exposing distilled water and air-dried soil samples to the atmosphere at the sampling sites. The increases in NH4–N content in the samples after 1-week exposure was regarded as an index of the atmospheric NH3 sorbed for that week. The NH3 sorption rates were highly variable across the 52 sites, with water ranging from 4 to 125 kg ha−1 year−1 with a mean of 22 kg N ha−1 year−1 and soil from 5 to 84 kg N ha−1 year−1 with a mean of 20 kg N ha−1 year−1. Considerable variation in NH3–N sorption across the study area reflects the effects of size, direction (upwind or downwind) and proximity of nearby livestock operations or other NH3 sources and operators’ activities around the sampling sites. The NH3 sorption rate at each site also varied considerably in response to weather conditions. The high rate of NH3 input poses a direct risk of surface water eutrophication in intensive livestock operation areas. If fertilizer recommendations are not reduced to account for NH3 sorption by soil, excess N may also contribute to eutrophication through runoff and leaching. 相似文献
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Darek?J.?NalleEmail author Jeffrey?L.?Arthur 《Environmental Modeling and Assessment》2005,10(3):229-238
The efficacy of simultaneously advancing two distinct conceptual designs (referred to here as fixed-site and non-fixed-site)
for species conservation and protection is addressed. In the literature, numerous models can be found that typically stem
from a particular design, but rarely are comparisons made between approaches. This paper presents a more integrated optimization
framework that models landowner behavior and species viabilities at a landscape scale. Regional demand for resource extraction
is used as the economic driver, a variant of simulated annealing is used to solve the model under different species protection
approaches, and a detailed species population simulator is utilized to measure biological responses. When directly comparing
the outcomes of different species protection strategies from a case study in Oregon (USA), it was found that neither approach
was universally superior in terms of financial value or degree of protection for two late seral forest dependent species. 相似文献
114.
A Nationwide Analysis of U.S. Army Corps of Engineers Reservoir Performance in Meeting Operational Targets
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Lauren A. Patterson Martin W. Doyle 《Journal of the American Water Resources Association》2018,54(2):543-564
The United States (U.S.) Army Corps of Engineers operates reservoirs across the U.S. with 89% of reservoirs constructed prior to 1980. Many reservoirs have experienced changes in environmental conditions (e.g., climate and sediment yield) and societal conditions (e.g., water/energy demand and ecological flows) since construction. These changes may challenge the potential for reservoirs to meet their operational targets (OTs) (management goals). Historic daily reservoir data and OTs were collected for 233 reservoirs. Analyses were developed to identify when and where reservoirs may be systematically departing from OTs in terms of the frequency and magnitude of departure. Fifty‐six percent of reservoirs consistently met operating targets, 30% were borderline, and 13% experienced frequent and large magnitude departures. Fifty‐two percent of reservoirs with large departures were due to shortages and were located in the South Pacific and Southwestern divisions. This work provides a framework to identify reservoir performance in relation to management goals, a necessary step for moving toward adaptive management under changing conditions. All individual reservoir analyses are provided via an interactive data visualization tool: https://nicholasinstitute.duke.edu/reservoir-data . 相似文献
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Tom Myers 《Journal of the American Water Resources Association》2013,49(5):1213-1224
As demand for water in the southwestern United States increases and climate change potentially decreases the natural flows in the Colorado River system, there will be increased need to optimize the water supply. Lake Powell is a large reservoir with potentially high loss rates to bank storage and evaporation. Bank storage is estimated as a residual in the reservoir water balance. Estimates of local inflow contribute uncertainty to estimates of bank storage. Regression analyses of local inflow with gaged tributaries have improved the estimate of local inflow. Using a stochastic estimate of local inflow based on the standard error of the regression estimator and of gross evaporation based on observed variability at Lake Mead, a reservoir water balance was used to estimate that more than 14.8 billion cubic meters (Gm3) has been stored in the banks, with a 90% probability that the value is actually between 11.8 and 18.5 Gm3. Groundwater models developed by others, observed groundwater levels, and simple transmissivity calculations confirm these bank storage estimates. Assuming a constant bank storage fraction for simulations of the future may cause managers to underestimate the actual losses from the reservoir. Updated management regimes which account more accurately for bank storage and evaporation could save water that will otherwise be lost to the banks or evaporation. 相似文献
118.
优势菌处理高浓度苯胺工业废水的研究 总被引:7,自引:0,他引:7
本文叙述了从自然界分离选育出能降解苯胺的优势菌种,经人工驯化,构建出具有高效降解性能的微生物体系的试验过程,研究确立了优势菌———活性污泥组合技术工艺,并成功地将其用于含苯胺类工业废水的处理。 相似文献
119.
基于可靠性为中心的航空保障系统特种装置维修决策研究 总被引:2,自引:2,他引:0
目的研究航空保障系统维修决策。方法通过对俄罗斯航母航空保障系统特种装置主要功能和系统组成的分析,探索特种装置维修技术保障特点,并以可靠性为中心的维修理论,研究航空保障特种装置重要功能部件,分析其故障模式及产生原因。结果通过RCM进行逻辑决断,确定了航空保障特种装置预防性维修工作类型、维修等级和维修间隔期等。结论 RCM可有效应用于航空保障特种装置维修分析中,为机关决策提供理论参考。 相似文献
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