Sorption of atmospheric ammonia by soil and perennial grass downwind from two large cattle feedlots

Livestock manure in feedlots releases ammonia (NH3), which can be sorbed by nearby soil and plants. Ammonia sorption by soil and its effects on soil and perennial grass N contents downwind from two large cattle feedlots in Alberta, Canada were investigated from June to October 2002. Atmospheric NH3 sorption was measured weekly by exposing air-dried soil at sampling points downwind along 1700-m transects. The amount of NH3 sorbed by soil was 2.60 to 3.16 kg N ha(-1) wk(-1) near the source, declining to about 0.25 kg N ha(-1) wk(-1) 1700 m downwind, reflecting diminishing atmospheric NH3 concentrations. Ammonia sorption at a control site away from NH3 sources was much lower: 0.085 kg N ha(-1) wk(-1). Based on these rates, about 19% of emitted NH3 is sorbed by soil within 1700 m downwind of feedlots. Field soil and grass samples from the transect lines were analyzed for total N (TN) and KCl-extractable N content (soil only). Nitrate N content in field soil followed a trend similar to that of atmospheric NH3 sorption. Soil TN contents, because of high background levels, showed no clear pattern. The TN content of grass, downwind of the newer feedlot, followed a pattern similar to that of NH3 sorption; downwind of the older feedlot, grass TN was correlated to soil TN. Our results suggest that atmospheric NH3 from livestock operations can contribute N to local soil and vegetation, and may need to be considered when determining fertilizer rates and assessing environmental impact.     

EFFECTS OF VARIABLE DISCHARGE SCHEMES ON DISSOLVED OXYGEN AT A HYDROELECTRIC STATION1

ABSTRACT: The effects of variable discharges during the summer on the dissolved oxygen (DO) content and water temperature upstream and downstream of the Conowingo Hydroelectric Power Station were investigated. The DO dynamics are controlled primarily by meteorological factors that are independent of the mode of hydrostation operation. DO stratification occurred during the summer in Conowingo Pond, but thermal stratification was not observed. The magnitude and duration of off-peak discharges including a run-of-the-river operation did not affect DO stratification in Conowingo Pond; little vertical mixing occurred. However, strong winds and/or high river flows temporarily destroyed DO stratification. The run-of-the-river operation or off-peak continuous discharge schemes did not provide better DO conditions downstream of the hydrostation than the peaking operation with intermittent off-peak releases. A statistical model predicted that a DO of 5 ppm occurs 0.6 miles downstream of the powerhouse when the natural river flow is consistently greater than 15,000 cfs and water temperature is less than 80°F. A mean daily DO of at least 4 ppm was predicted to occur over 80 percent of the time during the 92-day summer period. Farther downstream (1.3 miles from the powerhouse) a mean daily DO of at least 4 ppm was predicted to occur 90 percent of the time in summer.     

Use of Airborne Thermal Imagery to Detect and Monitor Inshore Oil Spill Residues During Darkness Hours

/ Trials were conducted using an airborne video system operating in the visible, near-infrared, and thermal wavelengths to detect two known oil spill releases during darkness at a distance of 10 nautical miles from the shore in St. Vincent's Gulf, South Australia. The oil spills consisted of two 20-liter samples released at 2-h intervals, one sample consisted of paraffinic neutral material and the other of automotive diesel oil. A tracking buoy was sent overboard in conjunction with the release of sample 1, and its movement monitored by satellite relay. Both oil residues were overflown by a light aircraft equipped with thermal, visible, and infrared imagers at a period of approximately 1 h after the release of the second oil residue. Trajectories of the oil residue releases were also modeled and the results compared to those obtained by the airborne video and the tracking buoy. Airborne imagery in the thermal wavelengths successfully located and mapped both oil residue samples during nighttime conditions. Results from the trial suggest that the most advantageous technique would be the combined use of the tracking beacon to obtain an approximate location of the oil spill and the airborne imagery to ascertain its extent and characteristics.KEY WORDS: Airborne video; Thermal imagery; Global positioning; Oil-spill monitoring; Tracking beacon     

The use of an atmospheric dispersion model to determine influence regions in the Prince George,B.C. airshed from the burning of open wood waste piles

A means of determining air emission source regions adversely influencing the city of Prince George, British Columbia, Canada from potential burning of isolated piles of mountain pine beetle-killed lodge pole pine is presented. The analysis uses the CALPUFF atmospheric dispersion model to identify safe burning regions based on atmospheric stability and wind direction. Model results show that the location and extent of influence regions is sensitive to wind speed, wind direction, atmospheric stability and a threshold used to quantify excessive concentrations. A concentration threshold based on the Canada Wide PM_2.5 Standard is used to delineate the influence regions while Environment Canada's (EC) daily ventilation index (VI) is used to quantify local atmospheric stability. Results from the analysis, to be used by air quality meteorologists in assessing daily requests for burning permits, are presented as a series of maps delineating acceptable burning locations for sources placed at various distances from the city center and under different ventilation conditions. The results show that no burning should be allowed within 10 km of the city center; under poor ventilation conditions, no burning should be allowed within 20 km of the city center; under good ventilation conditions, burning can be allowed within 10–15 km of the city center; under good to fair ventilation conditions, burning can be allowed beyond 15 km of the city center; and if the wind direction can be reliably forecast, burning can be allowed between 5 and 10 km downwind of the city center under good ventilation conditions.     

Fluoride removal and its impact on oral health in Sri Lanka's dry zone: Discussion and recommendation

Fifty percent of the dry zone areas in Sri Lanka have fluoride levels above 1 ppm. This paper discusses the ground conditions and recommends an appropriate range of fluoride in drinking water which can support preventive practices for improving the oral health of children 8-years old and younger. In efforts to address the Chronic Kidney Disease of Unknown etiology (CKDU), water treatment to reduce contaminant level in potable water has been implemented. Such treatment would also remove fluoride and has resulted in potable water with various fluoride levels, depending on concentrations in the raw water. While it is important to reduce fluoride levels, it is important to have appropriate residual levels for prevention of dental caries. It needs, however, to be noted fluoride in excess can cause dental fluorosis. In Sri Lanka's dry zone areas increasing prevalence of dental fluorosis with decreasing prevalence of dental caries has been noted. Consumption of tea and powdered milk could increase total intake of fluoride. Fluoridated toothpaste, when used properly, may, however, result in negligible intake of fluoride. Sri Lanka's hot tropical climate which results in substantial intake of fluids reinforces the need to consider reduction in water fluoride. Consideration of local studies and international standards indicate fluoride levels should be in the range of 0.225–0.500 ppm. In the range of 0.225–0.500 ppm, the prevalence of dental fluorosis and caries was only 14% and 8%, respectively, in an endemic district. When fluoride levels are above 0.500 ppm, the issue of dental fluorosis shall need to be addressed. When levels are below 0.225 ppm, oral health care services shall need to be directed at preventing dental caries.     

Odour-impact assessment around a landfill site from weather-type classification, complaint inventory and numerical simulation

Gases released from landfill sites into the atmosphere have the potential to cause olfactory nuisances within the surrounding communities. Landfill sites are often located over complex topography for convenience mainly related to waste disposal and environmental masking. Dispersion of odours is strongly conditioned by local atmospheric dynamics. Assessment of odour impacts needs to take into account the variability of local atmospheric dynamics. In this study, we discuss a method to assess odour impacts around a landfill site located over complex terrain in order to provide information to be used subsequently to identify management strategies to reduce olfactory nuisances in the residential neighbourhoods. A weather-type classification is defined in order to identify meteorological conditions under which olfactory nuisances are to be expected. A non-steady state Gaussian model and a full-physics meteorological model are used to predict olfactory nuisances, for both the winter and summer scenarios that lead to the majority of complaints in neighbourhoods surrounding the landfill site. Simulating representative scenarios rather than full years make a high resolution simulation of local atmospheric dynamics in space and time possible. Results underline the key role of local atmospheric dynamics in driving the dispersion of odours. The odour concentration simulated by the full-physics meteorological model is combined with the density of the population in order to calculate an average population exposure for the two scenarios. Results of this study are expected to provide helpful information to develop technical solutions for an effective management of landfill operations, which would reduce odour impacts within the surrounding communities.     

Behavioral Traits and Airport Type Affect Mammal Incidents with U.S. Civil Aircraft

Wildlife incidents with aircraft cost the United States (U.S.) civil aviation industry >US$1.4 billion in estimated damages and loss of revenue from 1990 to 2009. Although terrestrial mammals represented only 2.3 % of wildlife incidents, damage to aircraft occurred in 59 % of mammal incidents. We examined mammal incidents (excluding bats) at all airports in the Federal Aviation Administration (FAA) National Wildlife Strike Database from 1990 to 2010 to characterize these incidents by airport type: Part-139 certified (certificated) and general aviation (GA). We also calculated relative hazard scores for species most frequently involved in incidents. We found certificated airports had more than twice as many incidents as GA airports. Incidents were most frequent in October (n = 215 of 1,764 total) at certificated airports and November (n = 111 of 741 total) at GA airports. Most (63.2 %) incidents at all airports (n = 1,523) occurred at night but the greatest incident rate occurred at dusk (177.3 incidents/hr). More incidents with damage (n = 1,594) occurred at GA airports (38.6 %) than certificated airports (19.0 %). Artiodactyla (even-toed ungulates) incidents incurred greatest (92.4 %) damage costs (n = 326; US$51.8 million) overall and mule deer (Odocoileus hemionus) was the most hazardous species. Overall, relative hazard score increased with increasing log body mass. Frequency of incidents was influenced by species relative seasonal abundance and behavior. We recommend airport wildlife officials evaluate the risks mammal species pose to aircraft based on the hazard information we provide and consider prioritizing management strategies that emphasize reducing their occurrence on airport property.     

Reforming of CO2-containing natural gas with steam in AC gliding arc discharge for hydrogen production

In this study, a low-temperature gliding arc discharge system was used to investigate the effects of steam content and operational parameters, i.e. total feed flow rate, applied voltage, and input frequency, on the reforming performance of CO₂-containing natural gas. The addition of steam less than 10% was found to enhance both selectivities for hydrogen and carbon monoxide with a significant reduction of power consumptions. The highest hydrogen selectivity and yield with the lowest power consumptions were achieved at a steam content of 10 mol%, a total feed flow rate of 100 cm³/min (corresponding to a very short residence time of 1.37 s), an applied voltage of 13.5 kV and an input frequency of 300 Hz. Under these optimum conditions, the oxidative dehydrogenation reactions to produce hydrogen were dominant with the minimum activities of all undesired reactions of cracking and coupling. Both of the short residence time (1.37 s) with a low bulk temperature (lower than 200°C) in the plasma zone under atmospheric pressure, indicate that the studied plasma reactor (gliding arc system) is superior to conventional catalytic reactors for reforming of natural gas.     

A Quantitative Method for Estimating Probable Public Costs of Hurricanes

/ A method is presented for estimating probable public costs resulting from damage caused by hurricanes, measured as local government expenditures approved for reimbursement under the Stafford Act Section 406 Public Assistance Program. The method employs a multivariate model developed through multiple regression analysis of an array of independent variables that measure meteorological, socioeconomic, and physical conditions related to the landfall of hurricanes within a local government jurisdiction. From the regression analysis we chose a log-log (base 10) model that explains 74% of the variance in the expenditure data using population and wind speed as predictors. We illustrate application of the method for a local jurisdiction-Lee County, Florida, USA. The results show that potential public costs range from $4.7 million for a category 1 hurricane with winds of 137 kilometers per hour (85 miles per hour) to $130 million for a category 5 hurricane with winds of 265 kilometers per hour (165 miles per hour). Based on these figures, we estimate expected annual public costs of $2.3 million. These cost estimates: (1) provide useful guidance for anticipating the magnitude of the federal, state, and local expenditures that would be required for the array of possible hurricanes that could affect that jurisdiction; (2) allow policy makers to assess the implications of alternative federal and state policies for providing public assistance to jurisdictions that experience hurricane damage; and (3) provide information needed to develop a contingency fund or other financial mechanism for assuring that the community has sufficient funds available to meet its obligations. KEY WORDS: Hurricane; Public costs; Local government; Disaster recovery; Disaster response; Florida; Stafford Act     

Modeling Nutrient Release in the Tai Lake Basin of China: Source Identification and Policy Implications

Because nutrient enrichment has become increasingly severe in the Tai Lake Basin of China, identifying sources and loads is crucial for watershed nutrient management. This paper develops an empirical framework to estimate nutrient release from five major sectors, which requires fewer input parameters and produces acceptable accuracy. Sectors included are industrial manufacturing, livestock breeding (industrial and family scale), crop agriculture, household consumption (urban and rural), and atmospheric deposition. Results show that in the basin (only the five sectors above), total nutrient loads of nitrogen (N) and phosphorus (P) into aquatic systems in 2008 were 33043.2 tons N a^?1 and 5254.4 tons P a^?1, and annual area-specific nutrient loads were 1.94 tons N km^?2 and 0.31 tons P km^?2. Household consumption was the major sector having the greatest impact (46 % in N load, 47 % in P load), whereas atmospheric deposition (18 %) and crop agriculture (15 %) sectors represented other significant proportions of N load. The load estimates also indicate that 32 % of total P came from the livestock breeding sector, making it the second largest phosphorus contributor. According to the nutrient pollution sectors, six best management practices are selected for cost-effectiveness analysis, and feasible options are recommended. Overall, biogas digester construction on industrial-scale farms is proven the most cost-effective, whereas the building of rural decentralized facilities is the best alternative under extreme financial constraint. However, the reduction potential, average monetary cost, and other factors such as risk tolerance of policy makers should all be considered in the actual decision-making process.     

Ambient endotoxin concentrations and assessment of offsite transport at open-lot and open-freestall dairies

Endotoxins are derived from gram-negative bacteria and are a potent inducer of inflammatory reactions in the respiratory tract when inhaled. To assess daily fluctuations of airborne endotoxin and their potential for transport from dairies, endotoxin concentrations were monitored over an 8-h period at upwind (background) and downwind (5 m from edge of dairy) locations on three separate days at two dairies. The dairies consisted of an open-lot or an open-freestall production system, both of which were stocked with 10,000 milking cows. Upwind concentrations were stable throughout the sampling period, averaging between 1.2 and 36.8 endotoxin units (EU) m(-3), whereas downwind concentration averages ranged from 179 to 989 EU(-3). Downwind endotoxin concentrations increased with wind speed, animal activity, and lot management practices, resulting in concentrations up to 136-fold hi gher than upwind concentrations. An area-source model was used to predict downwind ground-level endotoxin concentrations at distances up to 2000 m from the production facilities. Predicted concentrations decreased with distance and reached background levels within 500 to 2000 m, depending on the source emision rate and meteorological conditions.     

SIMULATED EFFECTS OF ALTERED SPILLWAY RELEASES ON THERMAL STRUCTURE AND KOKANEE GROWTH IN A COLORADO RESERVOIR1

ABSTRACT: In‐reservoir thermal and ecological effects of releasing some flows over the surface spillway at Blue Mesa Reservoir, Colorado, rather than routing all releases through the hypolimnetic outlet were evaluated using a calibrated and validated one‐dimensional thermal model (CE‐THERM) with a set of ecological models. Thermal model output indicated that surface water temperatures were influenced primarily by atmospheric conditions, but the release of warmer water over the spillway resulted in a thinner epilimnion and cooler metalimnetic water temperatures. Ecological model predictions indicated that spillway releases and associated temperatures resulted in lower growth rates for young‐of‐year (YOY) kokanee salmon (Oncorhynchus nerka) in the reservoir by up to 9 percent when compared with growth rates under baseline operations with no releases over the spillway. Kokanee growth rates were reduced under spillway release scenarios because lower temperatures not only affected metabolic rates, but limited the productivity of the zooplankton as well. Thus, altering the release regime with spillway discharges could have deleterious effects on Blue Mesa's YOY kokanee. However, in other reservoirs, distributing discharges among different elevations may provide managers with a mechanism to regulate temperatures to benefit species of concern that are facing challenges imposed by environmental conditions such as global warming.     

Maximum ground level concentration for Gaussian plume formula using standard and Briggs methods

This work aims to determine the maximum concentration and downwind distance at the earth's surface in two methods Briggs and standard for two conditions are slightly unstable and neutral by using the Gaussian equation at different effective heights and wind seeped at (8.9, 8.5 and 8 m/s) under lateral and vertical dispersion coefficient measurement.     

Addressing Gaps in Environmental Emergency Planning: Hazardous Materials Releases during Earthquakes

Hazardous materials, in many forms, are ubiquitous in modern society. They are integrated into communities in the form of manufacturing and commercial establishments, medical facilities and laboratories-'hazmat' also circulates through communities in the transportation process, by rail, truck and pipeline. In areas vulnerable to earthquakes, hazmat releases constitute a secondary disaster that can be triggered by seismic action. This paper points out that little research and management attention have been given to the issue of earthquake-induced hazardous materials releases. The problem and its potential consequences are defined, and the history of hazmat releases in recent earthquakes is reviewed. Existing studies of earthquakeinduced hazardous materials releases are critiqued to identify gaps in knowledge that should be filled as a preface to meaningful efforts at planning for this hazard. Suggestions are outlined for the types of information needed to establish a database from which threat assessments, mitigation measures and emergency response strategies may be derived.     

Near-field dust exposure from cotton field tilling and harvesting

The frequency and intensities of dust exposures in and near farm fields, which potentially contribute to high intensity human exposure events, are undocumented due to the transient nature of local dust plumes and the difficulties of making accurate concentration measurements. The objective of this study is to measure near-field spatial concentrations of the dust plumes emitted during tilling and harvesting of an irrigated cotton field outside of Las Cruces, NM (soil class: fine-loamy, mixed, superactive, thermic Typic Calciargid). A comparison of remote lidar measurements of plumes emitted from cotton field operations with in situ samplers shows a strong agreement between the two techniques: r2 = 0.79 for total suspended particulates (TSP) and r2 = 0.61 for particulate matter with diameter less than or equal to 10 microm (PM10). Plume movement was dependent on the short-term wind field and atmospheric stability. Horizontal spread rate of the plumes, determined from lidar measured Gaussian dispersion parameters, was less than expected by a factor of 7. Thus, in-plume downwind concentrations were higher than expected. Vertical dispersion was dependent on the rise of "cells" of warm air convecting off the soil surface. On a windy day, discing the field showed TSP and PM10 concentrations at the source itself of up to 176 microg m(-3) and 120 microg m(-3), respectively. These resulted in in-plume peak TSP concentrations of about 1.22 microg m(-3) at 10 m downwind and 0.33 microg m(-3) at 100 m downwind. The measured concentrations highlight a potential exposure risk to people in and around farming operations.     

影响大气污染物散布的气象条件

大气污染物的空间分布以及随时间的变化，与气象条件密切相关。影响大气污染物散布的气象因子主要有：风、湍流，大气稳定度，太阳辐射，云，降水，天气形势，混合层高度及大气运动的尺度等。文章论述了风，大气稳定度，太阳辐射，云和天气形势对大气污染物散布的影响，以有复杂地形上的空气污染与局地气象条件的关系，目诉在于寻求有效防治大气污染的途径。     

环境空气质量评价方法改进研究

通过系统调研对比国内外环境空气质量评价标准,本文对2013—2018年全国主要城市的空气PM2.5浓度及气象数据进行分析,得到如下结论:采用环境空气中污染物浓度三年滑动均值作为空气质量评价标准是国际通行做法;2013—2018年我国大部分城市PM2.5浓度受气象等相关因素影响,年均值波动较大,采用PM2.5浓度三年滑动均值变化曲线更为平滑,且采用前两年及当年的年均值进行计算更切合实际需求;采用EMI指数法量化分析气象因素对环境空气质量的影响,表明大气污染气象条件的年际变化具有波动性且各重点区域变化趋势也有所不同。建议引进三年滑动均值作为PM2.5长期变化的考核依据之一,使空气质量评价考核方式更为公平合理。     

Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability

Since the late 1980s, our group has examined the effects of radiofrequency electromagnetic fields (RF-EMF), including pulse-modulated waves of the type emitted by mobile phones, upon the blood?Cbrain barrier. In more than 2,000 rats, we have repeatedly demonstrated a passage of the rats?? own albumin from the blood through the brain capillaries into the surrounding brain parenchyma at SAR values down to 0.1mW/kg. In most of these experiments, the animals were exposed in TEM-cells, ventilated by an external electrical fan at 50 Hz. In the present study, we examined whether the extremely low frequency (ELF) magnetic fields from the fan (50 Hz, 0.3?C1.5 ??T) might add to the RF effect. Sixty-four rats were divided into 4 groups: RF only, ELF only and RF + ELF exposure plus a sham group. The GSM-900 MHz RF exposure was at the very low, nonthermal, average whole-body SAR level 0.4 mW/kg. Demonstration of the normally occurring albumin extravasation in the basal hypothalamus is our inbuilt control proving that the staining is reliable. Two full series of staining of the whole material gave negative results for hypothalamus. Not until we changed to avidin, biotin, and antibodies from a third supplier, we received an acceptable staining. Twenty-five percent of the RF animals had a pathological albumin leakage, while the ELF and RF + ELF groups with three and two pathological findings, respectively, were not significantly different from the control group. We conclude that the use of external fans has had no major influence upon the result.     

PCM thermal conductivity effect on mechanism of PV/PCM thermal control characteristics

ABSTRACT

According to the structure of photovoltaic/phase change material (PV/PCM), the mechanism of internal heat transfer, transmission, storage, and temperature control is analyzed, and a two-dimensional finite element analysis model of PV/PCM structure is established. This study is carried out on the effect of PCM thermal conductivity on internal temperature distribution characteristics of PV/PCM and temperature control characteristics of solar cells. The results show that the increase in thermal conductivity of PCM can prolong the temperature control time of solar cell in PV/PCM system, for example, when the thermal conductivity is increased from 0.2 W/(m·K) to1.5 W/(m·K) under a thickness of 4 cm, the duration when PV/PCM solar cell temperature is controlled below 40°C and extended from 52 min to 184 min. In addition, PV/PCM experimental prototypes are designed with the LA-SA-EG composite PCM peak melting point of 46°C and thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K), respectively. The results indicate that compared with PCM-free solar cells, the maximum temperature of PV/PCM prototype solar cells with thermal conductivity of 0.8 W/(m·K) and 1.1 W/(m·K) is reduced by 10.8°C and 4.6°C, respectively, with average output power increased by 4.1% and 2.2%, respectively, under simulated light sources. Under natural light conditions, the average output power is increased by 6.9% and 4.3%, respectively. The results provide theoretical and experimental basis for the optimization of PV/PCM design by changing the thermal conductivity of PCM.