Estimating Stream Temperature from Air Temperature: Implications for Future Water Quality

This study examines the air temperature/stream temperature relationship at a geographically diverse set of streams. We evaluate the general temperature relationships (both linear and nonlinear) that apply to these streams, and then examine how changes in stream temperature associated with climate variability or climate warming might affect dissolved oxygen levels. The majority of streams showed an increase in water temperature of about 0.6–0.8°C for every 1°C increase in air temperature, with very few streams displaying a linear 1:1 air/water temperature trend. For most of the streams, a nonlinear model produced a better fit than did a simple linear model. Understanding the relationship between air temperature and water temperature is important if people want to estimate how stream temperatures are likely to respond to anticipated future increases in surface air temperature. Surface water temperature in many streams will likely increase 2 to 3°C as air temperature increases 3 to 5°C. At sites with currently low dissolved oxygen content, an increase in summer stream temperatures could cause the dissolved oxygen levels to fall into a critically low range, threatening the health of many aquatic species.     

Thermal Reduction by an Underground Storm-Water Detention System

Increases in stream temperatures by heated storm-water runoff from impervious surfaces are a serious environmental problem. An underground detention with slow-release facility is a versatile storm-water best management practice (BMP) for buffering high flows. Temperature reductions in underground storm-water storage BMPs, however, have not been quantified. A field study on an underground detention BMP located in Maryland was undertaken to characterize its effect on storm-water runoff temperatures. In colder months, when the runoff temperature ranged from 5 to 15°C, small or no temperature change was observed. Runoff produced during summer storm events, however, with event mean temperatures over 20°C, exhibited mean temperature reductions of 1.6°C through the BMP. While statistically significant, the reductions were not sufficient to cool the summer runoff discharges below the Maryland Class III temperature standard (20°C) 100% of the time. The results indicate that underground facilities can moderate high runoff temperatures, but that more efficient designs are needed for heat transfer.     

Prestressed Carbon Fiber Reinforced Polymer Sheets for Strengthening Concrete Beams at Room and Low Temperatures

A technique for strengthening damaged concrete beams using prestressed carbon fiber reinforced polymer (CFRP) sheets was developed at Queen’s University and the Royal Military College of Canada. As part of this study, an anchorage system was developed to directly prestress the CFRP sheets by jacking and reacting against the strengthened concrete beam itself. The feasibility and effectiveness of using bonded prestressed CFRP sheets to strengthen precracked concrete beams at both room (+22°C,+72°F) and low (?28°C,?20°F) temperatures have been investigated experimentally. Materials and prestress changes due to temperature variations that would affect and cause changes in flexural behavior were studied. The strengthened beams showed significant increases in flexural stiffness and ultimate capacity as compared to the control-unstrengthened beams. The flexural behavior of the strengthened beams was not adversely affected by short-term exposure to reduced temperature (?28°C,?20°F). In addition to the experimental investigation, analytical models were developed to predict the overall flexural behavior of the strengthened beams during prestressing of the CFRP sheets and under external loading at both room and low temperatures. The model accurately predicted the flexural beam behavior. Improved serviceability behavior and higher strength were predicted for beams strengthened with the bonded prestressed CFRP sheets.     

Bioaugmentation with Nitrifying Bacteria Acclimated to Different Temperatures

A nitrifying biomass was produced from anaerobic sludge dewatering liquors for the purpose of bioaugmentation of sequencing batch reactors (SBRs). Nitrification of centrate was conducted at four temperatures (10, 20, 25, and 30°C) while the seeded SBRs were operated at 10°C with a solids retention time of approximately 4 days. The SBRs did not exhibit any nitrification before the onset of seeding. When the hydraulic retention time (HRT) was 24 h, partial removal of NH3–N occurred when seed acclimated to 20, 25, and 30°C was added. When the HRT was 12 h, only the SBR seeded with nitrifying biomass acclimated to 10°C achieved 50% NH3–N removal. Complete removal of NH3–N was not achieved in any of the seeded SBRs. The degree of NH3–N removal in the seeded SBRs was dependent on the initial temperature of the seed, and the observed growth rates of the nitrifying bacteria were inversely proportional to the change in temperature.     

Applications of Low-Temperature Regenerative Thermal Oxidizers to Treat Volatile Organic Compounds

A series of plant scale low temperature regenerative thermal oxidizers (LTRTOs) equipped with heating wires were constructed to treat volatile organic compounds (VOCs) laden gas streams. All regenerative beds were packed with gravel (approximate particle size 1.25 cm, specific area 205 m2/m3, and specific heat capacity 840 J/kg?°C) and equipped with K-type thermocouples for measuring gas temperatures. Test gas streams were extracted from manufacturing sections of varnishing, semiconductor packing, and petrochemical plants, representing a variety of gas-phase pollutants, including several commercial solvents. Experimental results indicate that 98% or greater treatment of VOCs with concentrations between 100 and 7,000 ppm as methane. Analysis of gas temperature variation with time at various bed depths confirm that VOC degradation occurs at temperatures ranging from 300 to 440°C, which are much lower than autoignition points of tested compounds. A 1.0 s gas residence time in the oxidation zone of regenerative beds is required for successful LTRTO operation.     

Thermal Analysis of Cover Systems in Municipal Solid Waste Landfills

Cover temperature variations were determined at four municipal solid waste landfills located in different climatic regions in North America: Michigan, New Mexico, Alaska, and British Columbia. Cover temperatures varied seasonally similarly to air temperatures and demonstrated amplitude decrement and phase lag with depth. Elevated temperatures in the underlying wastes resulted in warmer temperatures and low frost penetration in the covers compared to surrounding subgrade soils. The ranges of measured temperatures decreased and average temperatures generally increased (approximately 2°C/m) with depth. The ranges of measured temperatures (Tmax?Tmin) were 18–30°C and 13–21°C and the average temperatures were 13–18°C and 14–23°C at 1 and 2?m depths, respectively. For soil and geosynthetic barrier materials around 1?m depth, the maximum and minimum temperatures were 22–25°C and 3–4°C, respectively. Frost depths were determined to be approximately 50% of those for soils at ambient conditions. The main direction of heat flow in the covers was upward (negative gradients). The cover gradients varied between ?18 and 14°C/m, with averages of ?7?to?1°C/m. The gradients for soil and geosynthetic barrier materials around 1?m depth varied between ?11 and 9°C/m with an average of ?2°C/m. Cover thawing n-factors ranged between 1.0 and 1.4 and the cover freezing n-factor was 0.6. Design charts and guidelines are provided for cover thermal analyses for variable climatic conditions.     

Chloroquine resistance--discovering the missing link?

Toxicosis due to microcystin-containing blue-green algae has been sporadically reported in a variety of animal species. Most reports of intoxication involve algal blooms during periods of warm temperatures and abundant sunshine in the spring or early summer. A case of blue-green algae toxicosis with lesions attributable to toxins from Microcystis aeruginosa is described in 4 cattle from southern Georgia during November. The case was unusual in that characteristic hepatic necrosis was accompanied by severe mesenteric edema and peritoneal effusion. In addition, weather conditions and location were not expected to be conducive to algal blooms. Rapid diagnosis and identification of the probable source of intoxication allowed the owner to move the herd away from the affected pond. This action limited losses to only the 4 cattle.     

Deflection Response of Glass Fiber-Reinforced Pultruded Components in Hot Weather Climates

Presented in this paper are the experimental results pertaining to the deflection response of E-glass/polyester pultruded structural elements when subjected to bending and temperature profiles comparable to those encountered in hot weather conditions. Experiments were conducted on tubular components subjected to an applied force resulting in a maximum stress corresponding to 4% of the composite material strength. In one case, five component tests were carried out in an environmental condition in which the air temperature was first gradually increased from 20°±2°C?to?72°±2°C, then decreased to 60°±2°C in 1?h. In another case, one component was tested under an air temperature that was first gradually increased from 20?to?60°C, then kept at 60°±2°C for 215?h. Test results are compared with those obtained in another study at laboratory conditions (22°±2°C). It is concluded that the increase in the deflection of glass-reinforced pultruded components in hot climates is substantial and must always be accounted for in the design of pultruded structures.     

Cyclic Response of Reinforced Concrete Members at Low Temperatures

An experimental study was undertaken to investigate the influence of cold temperatures on the seismic behavior of reinforced concrete members. This paper summarizes the results of Phase I of a multiphase research project that consisted of the reversed cyclic testing of four identical large scale reinforced concrete circular columns subjected to temperatures ranging from ?40°C (?40°F) to 20°C (68°F). An extensive literary review is also presented. It was found that most of the past research focused on the material level, i.e., the independent behavior of plain concrete and reinforcing bars. Data collected from past works were complemented with the results obtained from the material tests performed in this research, and used to develop empirical equations for the estimation of the mechanical properties of concrete and steel reinforcement at low temperature. Past research shows an increase in strength without any loss in the deformation capacity of plain concrete and reinforcing steel bars tested at low temperatures. The results of this study show a reduction in the displacement capacity of reinforced concrete members tested at freezing temperatures.     

高温轴承钢M50连续冷却转变曲线的测定与分析

利用膨胀法在DIL805A型淬火膨胀仪对高温轴承钢M50（/%:0.82C,4.25Cr,4.17Mo,1.03V）开展了临界点测定及冷却速度0.02～40℃/s的连续冷却转变试验,并绘制了静态CCT曲线,结合室温下的显微组织以及维氏硬度分析,系统研究了冷却速率及奥氏体化温度（1 000℃和1 120℃）对高温轴承钢M50组织转变以及静态CCT曲线的变化影响。结果表明:高温轴承钢M50的临界点不受奥氏体化温度影响,A_c1与Accm温度分别为808℃和852℃;珠光体转变的临界冷速为0.05℃/s,奥氏体化温度的提高促进了马氏体转变起始温度的降低以及贝氏体转变区间在静态CCT曲线上的右移,并且显著提升了高温轴承钢M50在较低冷却速率条件下的室温硬度。     

Catalytic Oxidation of Volatile Organic Liquids

Metal oxide and supported-Pt catalysts were developed for complete oxidation of volatile organic compounds (VOCs) and other solvent-derived organic vapors (OVs) in air at relatively low temperatures. The goal for this work is to produce a simple, cost-effective technology for reducing the concentration of organic contaminants in air to acceptable levels before the air is released into the atmosphere or recirculated. Specific applications include ventilated work spaces for spray painting and engine maintenance, indoor air decontamination, dry cleaning, food processing, fume hoods, residential use, and solvent-intensive industrial processes. Catalyst powders and monolith-supported catalysts were screened for conversion of 1-butanol, toluene, and methyl ethyl ketone to carbon dioxide and water. The concentration of OVs in the feedstream was maintained at approximately 100 ppmv, and the space velocity was between 6,000 and 18,000 h?1. Metal oxide catalysts without Pt generated complete conversion of 1-butanol to CO2 at 150°C, 69% conversion at 100°C, and 15% conversion at 80°C. For toluene, complete conversion was achieved at 200°C, and greater than 75% conversion at 150°C. Addition of Pt to the metal oxide compositions typically lowered the temperature for a given OV oxidation rate by at least 20–50°C. Catalysts deposited onto standard commercial cordierite monoliths retained their composition and activity, and were stable in humid air, as well as nitrogen- and chlorine-containing OVs. However, the catalysts quickly deactivated in the presence of sulfur and phosphorus.     

Effect of Temperature on Ozone Inactivation of Cryptosporidium parvum in Oxidant Demand-Free Phosphate Buffer

Ozone inactivation of Cryptosporidium parvum oocysts was studied at bench-scale in 0.05 M phosphate buffer at 1 to 37°C, pH 6–8. Animal infectivity using neonatal CD-1 mice was used for evaluation of oocyst infectiousness following treatment. Survival curves of ozone inactivation were characterized by a tail-off effect, with an initial shoulder most evident at low temperature. Temperature was a critical factor for ozone inactivation kinetics with a significant decrease of ozone efficacy at low temperature. Accounting for ozone residual stability at different pH conditions, pH was found to have no significant effect on the activation of C. parvum by ozone. Inactivation kinetics at different temperatures were expressed as an Incomplete gamma Hom model with different reaction rate constants, adjusted for water temperature using the van't Hoff-Arrhenius relationship. Between 1 and 37°C, for every 10°C decrease in the water temperature, the inactivation rate constant decreased by a factor of 2.2, corresponding to activation energy of 51.7 kJ∕mol. Ozone disinfection design criteria for 1.0 and 2.0 log-units of inactivation of Cryptosporidium were developed for various water temperatures, and 90% confidence intervals are also provided.     

Treatment of MTBE-Contaminated Water in Fluidized Bed Bioreactor

Methyl tertiary-butyl ether (MTBE) biodegradation was evaluated in a laboratory-scale granular activated carbon (GAC)-based fluidized bed bioreactor system. The reactor was operated in seven distinct phases during which the MTBE loading rate, hydraulic retention time, cocontaminant loading [butyl, toluene, ethylbenzene, and xylene (BTEX) and tertiary-butyl alcohol (TBA)] and temperature were varied. The reactor was able to treat MTBE to less than 20 ug/L at 25°C and total organic carbon (TOC) loading rates between 0.01 and 1.1 kg/m3 of expanded GAC bed per day (kg/m3?day). Net biomass yield in the reactor under high loading conditions was approximately 0.55 g of total suspended solids (TSS) per gram of TOC consumed. This high yield under the higher loading rates necessitated that biomass be removed from the reactor to control bed expansion. At a loading rate of 1.5 kg/m3?day, MTBE effluents exceeded 20 ug/L. Reactor performance decreased as the reactor temperature was reduced from 25 to 15°C, but even at the lower temperatures MTBE removal efficiency exceeded 99%. Methyl tertiary-butyl ether treatment efficiency was not affected by the addition of TBA or BTEX under the conditions evaluated. Results of this study demonstrate that fluid bed bioreactors inoculated with an appropriate microbial culture can efficiently treat MTBE-contaminated water.     

The ontogeny of feeding in rats: III. Thermal determinants of early ingestive responding.

High ambient temperatures (38°C) stimulated high spontaneous levels of activity and high frequencies of behaviors normally associated with ingestion (mouthing and probing), particularly in young, 3- and 6-day-old Charles River CD rat pups (Exp I). The level of spontaneous behavior was highly correlated with body temperature and also depended on deprivation condition. Temperature played an important role in determining responses to food stimuli as well. When Ss were fed by oral infusion (Exp II) or by placing milk on the floor beneath them (Exp III), warm ambient temperatures were required for active ingestion. In Exp IV, body temperature and ambient temperature were manipulated independently to assess their relative importance for Ss' feeding behavior. Ss with a low (29°C) or normal (34°C) core temperature at the start of testing were fed in either a 24°C or a 34°C ambience. Regardless of body temperature, Ss' levels of intake, activity, mouthing, and probing were higher in a warm than in a cool ambience. Therefore, the suppressed ingestive behavior of Ss fed at cool temperatures occurred not simply because Ss became hypothermic and inactive. Perceived warmth appears to be a significant contextual cue that regulates pups' responses to food stimuli. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low-Temperature Soil Heating Using Renewable Energy

Data from a pilot study, in which renewable energy was used for low-temperature subsurface heating in a northern climate, suggests that such an approach may be useful for remediating low permeable soils. Low-temperature soil heating is expected to enhance remediation effectiveness by increasing contaminant volatility, diffusion, desorption, and microbiological activity. Direct and indirect solar energy was harvested with a hybrid photovoltaic/wind electric system. The electrical energy generated by the hybrid renewable energy system was distributed to the subsurface using a control system and wire, then converted to heat energy using a resistive element emplaced in an unsaturated silty layer 2.3?m below grade. Renewable energy system performance, soil temperature, and environmental data were collected. Ambient soil temperatures fluctuated seasonally within the silt layer from 4?to?15°C. The small renewable energy system performed as predicted and injected 441?kWh of energy into the soil over the eight-month study. This energy input translated to increased soil temperatures ranging from 7.7?to?19.4°C and from 3.3?to?4.3°C above ambient at distances 0.3 and 0.9?m from the heating well, respectively. The system supplied sufficient heat to maintain soil temperatures above ambient even in winter in Vermont, where low direct solar energy was available and sustained low ambient temperatures prevail.     

Wet Air Oxidation of Solid Waste Made of Polymers

Wet air oxidation was attempted on synthetic (mixture of plastics of various compositions) and natural (cellulose substances) solid polymers. The temperature was maintained at 270°C and the oxygen pressure varied from 0 to 2 MPa (from understoichiometric conditions to oxygen excess). No valorizable compounds were found, even in runs carried out under an oxygen deficit. Suitable conditions for the total destruction of the initial polymers were temperatures above 270°C, an excess of oxygen, and a residence time of less than 1 h. Only such degradable compounds as acetic and benzoic acids are found at low concentrations. Formation of chlorine and gaseous hydrochloric acid can be limited by adding CaCO3 as a neutralizing agent.     

Total Coliform Survival Characteristics in Frozen Soils

Survival characteristics of total coliform bacteria in soil samples, with different moisture contents (24–49%) and at different temperatures (from ?28 to 20°C), were studied. The study showed that a significant fraction of coliform bacteria survive for more than six months in soil at subfreezing temperatures. Survival of total coliform bacteria at subfreezing temperatures decreased with an increase in moisture content and an increase in temperature. For 24% moisture, approximately 66% of the coliforms survived at ?28°C after 170 days, whereas less than 0.1% survived at room temperature. First-order die-off rate constants varied between 0.041/day at room temperature and 0.002/day from ?15 to ?28°C (for 24% moisture). The impact of temperature on the die-off rate constant was described by the Arrhenius equation. The high survival at subfreezing temperatures indicates that fecal bacteria at honeybucket dumpsites may survive throughout the Alaskan winter which may lead to the contamination of water sources during spring thaw.     

Theoretical and Experimental Analysis of GFRP Bridge Deck under Temperature Gradient

The temperature difference between the top and bottom of a glass fiber reinforced polymer (GFRP) composite deck, ～ 65°C ( ～ 122°F), is nearly three times that of conventional concrete decks ～ 23°C ( ～ 41°F). Such a large temperature difference is attributed to the relatively lower thermal conductivity of GFRP material. In this study, laboratory tests were conducted on two GFRP bridge deck modules (10.2 and 20.3?cm deep decks) by heating and cooling the top surface of the GFRP deck, while maintaining ambient (room) temperature at the deck bottom. Deflections and strains were recorded on the deck under thermal loads. Theoretical results (using macro approach, Navier-Levy, and FEM) were compared with the laboratory test data. The test data indicated that the GFRP deck exhibited hogging under a positive temperature difference (i.e., Ttop>Tbottom, heating test; Ttop and Tbottom are temperatures at top and bottom of the deck, respectively) and sagging under a negative temperature difference (i.e., Ttop相似文献   

水电站用800 MPa级低焊接裂纹敏感性高强钢板SX780CF的开发

通过设计成分(/%：0. 09C,0. 15Si,l. 15Mn,0. 58Ni,0. 47Cr,0. 44Mo,0. 033V,0. 022Nb,0. 0012B, 0.036Al,0.014Ti),控制熔炼分析N含量≤20x10^-6冶炼,钢锭最高加热温度≤ 1 200℃ 轧制、930℃淬火、610℃回火,开发出的60 mm厚SX780CF钢板屈服强度780 MPa,抗拉强度887 MPa,延伸率18% ,5%应变250 °C时效后 -20 ℃冲击功(KV₂) 203 - 210 J,满足水电站用800 MPa级低焊接裂纹敏感性高强钢技术要求。     

The direction and range of ambient temperature change influences yawning in budgerigars (melopsittacus undulatus).

Comparative research suggests that yawning is a thermoregulatory behavior in homeotherms. Our previous experiments revealed that yawning increased in budgerigars (Melopsittacus undulatus) as ambient temperature was raised toward body temperature (22→34 °C). In this study, we identify the range of temperatures that triggers yawning to rule out the possible effect of changing temperature in any range. To corroborate its thermoregulatory function, we also related the incidence of yawning to other avian thermoregulatory behaviors in budgerigars (e.g., panting, wing venting). In a repeated measures design, 16 budgerigars were exposed to 4 separate 10-min periods of changing temperatures: (a) low-increasing (23→27 °C), (b) high-increasing (27→33 °C), (c) high-decreasing (34→28 °C), and (d) low-decreasing (28→24 °C). Birds yawned significantly more during the high-increasing temperature range, and yawning was positively correlated with ambient temperature across trials. Yawning was also positively correlated with other thermoregulatory behaviors. This research clarifies the previously demonstrated relationship between yawning rate and temperature by providing evidence that the physiological trigger for yawning is related to increasing body temperatures rather than the detection of changing external temperatures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)