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41.
Michael M. Pollock Timothy J. Beechie 《Journal of the American Water Resources Association》2010,46(4):843-847
Pollock, Michael M. and Timothy J. Beechie, 2010. Reply to Discussion –“Stream Temperature Relationships to Forest Harvest in Western Washington” by George Ice, George Brown, John Gravelle, C. Rhett Jackson, Jeff Light, Timothy Link, Douglas Martin, Dale McGreer, and Arne Skaugset. Journal of the American Water Resources Association (JAWRA) 46(4): 843-847. DOI: 10.1111/j.1752-1688.2010.00456.x 相似文献
42.
Shahla Hosseini Bai Zhihong Xu Timothy J. Blumfield Clyde H. Wild Chengrong Chen 《Environmental science and pollution research international》2014,21(7):5167-5176
During revegetation, the maintenance of soil carbon (C) pools and nitrogen (N) availability is considered essential for soil fertility and this study aimed to evaluate contrasting methods of site preparation (herbicide and scalping) with respect to the effects on soil organic matter (SOM) during the critical early establishment phase. Soil total C (TC), total N (TN), hot-water extractable organic C (HWEOC), hot-water extractable total N (HWETN), microbial biomass C and N (MBC and MBN), total inorganic N (TIN) and potentially mineralizable N (PMN) were measured over 53 weeks. MBC and MBN were the only variables affected by herbicide application. Scalping caused an immediate reduction in all variables, and the values remained low without any sign of recovery for the period of the study. The impact of scalping on HWETN and TIN lasted 22 weeks and stabilised afterwards. MBC and MBN were affected by both herbicide and scalping after initial treatment application and remained lower than control during the period of the study but did not decrease over time. While scalping had an inevitable impact on all soil properties that were measured, that impact did not worsen over time, and actually improved plant growth (unpublished data) while reducing site establishment costs. Therefore, it provides a useful alternative for weed control in revegetation projects where it is applied only once at site establishment and where SOM would be expected to recover as canopy closure is obtained and nutrient cycling through litterfall commences. 相似文献
43.
Timothy M. Gilmore Thomas R. Hanna 《Journal of the Air & Waste Management Association (1995)》2013,63(5):535-539
The so-called “Six Month Study” of the air toxics problem in the United States was initiated in November 1983 by the U.S. Environmental Protection Agency. The study focused on the magnitude, nature, and distribution of the problem—three major issues that were felt to be most useful to policy makers as they attempted to define the scope and direction of a national program for controlling toxic air pollutants. The following paper is based on a draft staff report on the study released for review in September 1984. The report has not been formally released by the U.S. EPA; a final report is due by late spring of 1985. 相似文献
44.
Timothy M. Gilmore Thomas R. Hanna 《Journal of the Air & Waste Management Association (1995)》2013,63(10):965-967
Recent investigations have indicated that ambient air CO measurements may not reflect population exposure to CO. The lack of correlation may be due to improper siting of CO instruments, improper interpretation of air quality data, or both. Studies of population carboxy-hemoglobin levels are evaluated and compared with ambient air data., No significant correlation was found between median population COHb levels and reductions in CO concentrations required to meet ambient air standards when calculations used to estimate reductions were based on the second highest 8 hour average. However, calculated reductions based on annual average concentrations and a trend analysis technique correlated significantly with COHb levels in five cities from which both CAMP and COHb data were available. Studies to determine the nature of the relationship between ambient air CO concentrations and population COHb levels are needed. The differences between the Occupational Safety and Health Act Regulations and the National Ambient Air Standards for carbon monoxide should be scrutinized to determine if a redefinition of the standards or their applicability is warranted. A reevaluation of the controls necessary to make reductions in population COHb burden may be necessary. 相似文献
45.
James N. Galloway Ellis B. Cowling 《Journal of the Air & Waste Management Association (1995)》2013,63(3):229-235
Precipitation is one of the most important factors determining the nature and productivity of terrestrial and aquatic ecosystems. Detailed historical and contemporary records are available indicating the amount of water deposited at thousands of locations throughout the world. Comparatively, however, knowledge of the changing chemistry of precipitation has developed only recently and is still very fragmentary. Our present ignorance of the total impact of changes in precipitation quality on the productivity and stability of ecosystems is especially profound. This paper has a fourfold purpose: (1) to describe the myriad of trace chemical constituents transferred from the atmosphere into the biosphere of the earth; (2) to define the range of beneficial and injurious ecological effects of perturbations in atmospheric deposition; (3) to explain the concepts of sensitive areas, life stages, and life forms; and (4) to describe briefly plans for a National Deposition Network and associated research on the terrestrial and aquatic ecosystems of the United States. 相似文献
46.
Howard M. Ellis Peter C. Liu Charles Runyon 《Journal of the Air & Waste Management Association (1995)》2013,63(6):670-675
The purpose of this study was to evaluate alternative prediction models for the SO2 concentrations produced in the vicinity of the Ohio Edison Company Sammis Power Plant. The plant is situated in the northeastern portion of the Ohio River Valley in complex terrain. Comparisons of the 16 highest predicted and measured short-term SO2 concentrations were conducted for a one year period for 58 alternative models. Several models were found to predict reasonably accurately the 16 highest measured 24-hour SO2 concentrations. Each of these models requires an upward adjustment in the plume centerline location as the plume is transported downwind in rising terrain. These same models overpredict by substantial margins the 16 highest measured 3-hour SO2 concentrations. Improvements in emissions inventory data and improvements in the prediction models used are believed necessary to increase prediction accuracy further. 相似文献
47.
Arijit Pakrasi Wayne T. Davis Gregory D. Reed Timothy C. Keener 《Journal of the Air & Waste Management Association (1995)》2013,63(7):987-992
The removal of SO2 with atomization of a slaked lime slurry and supplemental injection of gaseous NH3 were tested in a conventional spray dryer/baghouse system for SO2 concentrations of 2000 ppm and 3000 ppm and a 30° F approach to saturation. Results at 3000 ppm of SO2 showed an average SO2 removal efficiency of 90.3 percent at a combined stoichiometric ratio of 0.95-1.10 and an average overall sorbent utilization of 91.6 percent. The overall molal ratio of NH3/SO2 reaction was found to be 2:1 under the test conditions Particle size analyses, and EP toxicity tests were conducted on the products of the reactions. 相似文献
48.
Timothy L. Johnson David W. Keith 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1452-1459
ABSTRACT The decoupling of fossil-fueled electricity production from atmospheric CO2 emissions via CO2 capture and sequestration (CCS) is increasingly regarded as an important means of mitigating climate change at a reasonable cost. Engineering analyses of CO2 mitigation typically compare the cost of electricity for a base generation technology to that for a similar plant with CO2 capture and then compute the carbon emissions mitigated per unit of cost. It can be hard to interpret mitigation cost estimates from this plant-level approach when a consistent base technology cannot be identified. In addition, neither engineering analyses nor general equilibrium models can capture the economics of plant dispatch. A realistic assessment of the costs of carbon sequestration as an emissions abatement strategy in the electric sector therefore requires a systems-level analysis. We discuss various frameworks for computing mitigation costs and introduce a simplified model of electric sector planning. Results from a “bottom-up” engineering-economic analysis for a representative U.S. North American Electric Reliability Council (NERC) region illustrate how the penetration of CCS technologies and the dispatch of generating units vary with the price of carbon emissions and thereby determine the relationship between mitigation cost and emissions reduction. 相似文献
49.
Ryan Allen Michael Box Lee-Jane Sally Liu Timothy V. Larson 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1650-1653
ABSTRACT Particulate matter (PM) is a ubiquitous air pollutant that has been receiving increasing attention in recent years due in part to the association between PM and a number of adverse health outcomes, including mortality and increases in emergency room visits and respiratory symptoms, as well as exacerbation of asthma and decrements in lung function.1-5 As a result, the ability to accurately sample ambient PM has become important, both to researchers and to regulatory agencies. The federal reference method for the determination of fine PM as PM2.5 in the atmosphere recommends that particle-sampling filters be conditioned and weighed in an environment with constant temperature and relative humidity (RH).6 It is also recommended that vibration, electrostatic charges, and contamination of the filters from laboratory air be minimized to reduce variability in filter weight measurements. These controls have typically been maintained in small, environmentally controlled “cleanrooms.” As an alternative to constructing an elaborate cleanroom, we have designed, and presented in this paper, an inexpensive weighing chamber to maintain the necessary level of humidity control. 相似文献
50.
Stabilized landfill leachate is characterized by a high concentration of non-biodegradable organic matter, which is similar in chemistry to dissolved organic matter (DOM) in the natural aquatic environment. Magnetic ion exchange (MIEX) resin treatment is well-studied in drinking water for removal of DOM from natural waters. There are fewer studies evaluating MIEX treatment of waste waters, and there is no previous work evaluating MIEX treatment of landfill leachate. This work systematically evaluated MIEX treatment of stabilized landfill leachate and evaluated the results in the context of previous studies of MIEX treatment of natural and waste waters. Five leachates from four landfills were evaluated as a function of MIEX resin dose, mixing time, and regeneration efficiency. MIEX resin removed DOM from landfill leachate, even in the presence of a reported high background concentration of inorganic ions. MIEX resin that was exhausted with leachate DOM was effectively regenerated with a concentrated NaCl solution, and regenerated MIEX resin performed similarly to virgin resin. For a majority of the leachates, the removal trend for MIEX resin was color > UV-absorbing substances > dissolved organic carbon ≈ COD > total nitrogen. Finally, MIEX resin removed a wider range of DOM from leachate than coagulation. The most important contribution of this work is that MIEX treatment of leachate followed very similar trends as MIEX treatment of natural waters, which will allow previous MIEX data to be used to estimate the treatment efficiency of other waste waters. 相似文献