Temporal variations in turbidity in an oil sands pit lake

Environmental Fluid Mechanics - We investigated temporal variations in turbidity in Base Mine Lake, an oil sands pit lake, located in northeast Alberta, Canada. The lake has a surface area of...     

Assessment of sociocultural acceptability of biogas from faecal waste as an alternative energy source in selected areas of Benin City,Edo State,Nigeria

Environment, Development and Sustainability - The use of wastes for biogas production has been restricted to few feedstock like cattle manure and food waste. Increasing the feedstock base for...     

Acid aerosols in the Pittsburgh Metropolitan area

This article presents data on ambient concentrations of selected acidic aerosols at four existing monitoring sites in the Pittsburgh PA metropolitan area. The data were collected by staff of the Allegheny County Health Department, Division of Air Quality during the summer and fall of 1993. The sampling protocol was focused on obtaining 24 h-average ammonia, ammonium, acidic sulfates, and particle strong acids data on a 2 to 3 day cycle. The data were obtained using Harvard University School of Public Health's “Short-HEADS” annular denuder sampling train. The Pittsburgh area is of interest because it is downwind of a major regional source of sulfur and nitrogen emissions from coal-burning power plants: the Ohio River Valley. The data presented here indicate that ground-level concentrations of acidic aerosols in Pittsburgh are highly correlated spatially and that many pollutants are higher on days when ground-level wind direction vectors indicate that wind is coming from the southwest rather than from the Pittsburgh source area itself. The monitoring site that is most upwind of the Pittsburgh source area – South Fayette – has particle strong acid levels about twice those of sites closer in to the Pittsburgh central business district.     

Laboratory testing of a continuous emissions monitor for hydrochloric acid

Continuous monitoring of exhaust flue gas has become a common practice in power plants in response to Federal Mercury and Air Toxics Standards (MATS) standards. Under the current rules, hydrochloric acid (HCl) is not continuously measured at most plants; however, MATS standards have been proposed for HCl, and tunable diode laser (TDL) absorption spectroscopy is one method that can be used to measure HCl continuously. The focus of this work is on the evaluation and verification of the operation performance of an HCL TDL over a range of real-world operating environments. The testing was conducted at the University of California at Riverside (UCR) spectroscopy evaluation laboratory. Laboratory tests were conducted at three separate temperatures, 25ºC, 100ºC, and 200ºC, and two distinct moisture levels for the enhanced temperatures, 0%, (2 tests) and 4%, over a concentration range from 0 ppmv to 25 ppmv-m at each of the elevated temperatures. The results showed good instrument accuracy as a function of changing temperature and moisture. Data analysis showed that the average percentage difference between the ammonia concentration and the calibration source was 3.33% for varying moisture from 0% to 4% and 2.69% for varying temperature from 25 to 100/200ºC. An HCl absorption line of 1.742 μm was selected for by the manufacturer for this instrument. The Hi Tran database indicated that CO₂ is probably the only major interferent, although the CO₂ absorption is very weak at that wavelength. Interference tests for NO, CO, SO₂, NH₃, and CO₂ for a range of concentrations typical of flue gasses in coal-fired power plants did not show any interference with TDL HCl measurements at 1.742 μm. For these interference tests, CO₂ was tested at a concentration of 11.9% concentration in N₂ for these tests. Average precision over the entire range for all 10 tests is 3.12%.

Implications: The focus of this study was an evaluation of the operation performance of a tunable diode laser (TDL) for the measurement of hydrochloric acid (HCl) over a range of real-world operating environments. The results showed good instrument accuracy as a function of changing temperature from 25ºC to 200ºC and moisture from 0% to 4%. Such as an instrument could be used for continuous monitoring of exhaust flue gas in power plants once the Federal Mercury and Air Toxics Standards (MATS) standards have been fully implemented.     

Planning theories and environmental impact assessment

The limited and sporadic interaction between EIA and planning theory has meant that EIA has largely failed to benefit from planning theory insights and lessons. Obstacles and dilemmas already encountered and addressed in planning theory are still hampering EIA theory building and practice. An overview of the characteristics, strengths, and limitations of five major planning theories—rationalism, pragmatism, socio-ecological idealism (SEI), political-economic mobilization (PEM), and communications and collaboration (CC) is presented in an effort to ameliorate this problem. EIA parallels to each planning theory and lessons for EIA are identified. Also addressed are the application of planning theories to different context types, overlaps, interconnections and middle ground concepts among theories, the integration of values, ethics, and postmodern perspectives and the potential to construct composite theories.     

Expected Decline in Carboxyhemogldbin Levels As Related to Automobile Carbon Monoxide Emission Standards

Carboxyhemoglobin (COHb) levels in blood are principally due to inhalation of carbon monoxide, although a low level (approximately 0.3%) of COHb is endogenous. A carboxyhemoglobin level above 1.5 % in non-smokers indicates exposure to CO in excess of the 10 mg/m³ air quality standard established under the Clean Air Act Amendments of 1970.

In most major U.S. cities, automobile emissions constitute the principal source of CO; in Chicago, according to EPA estimates,¹ light duty vehicles are responsible for 69.3% of all CO emissions. Thus as new automobiles incorporating emission controls enter the automotive fleet and older, emission-uncontrolled automobiles are phased out, ambient CO concentrations should decline and corresponding reductions in blood carboxyhemoglobin levels of nonsmokers can be expected.     

An Atmospheric Particulate Sampling Procedure For Gravimetric And Elemental Analyses

Large quantities of atmospheric aerosols with compositions SO₄ ⁼, NO₃ ^? and NH₄ ⁺ have been detected in highly industrialized areas. The major portions of aerosol products are the results of energyrelated fuel combustion. Both microphysical and macrophysical processes are considered in investigating the time dependent evolution of the saturation spectra of condensation nuclei associated with both polluted and clean atmospheres during the time periods of advection fog formation. The results show that the condensation nuclei associated with a polluted atmosphere provide more favorable conditions than condensation nuclei associated with a clean atmosphere to produce dense advection fog, and that attaining a certain degree of supersaturation is not necessarily required for the formation of advection fog with condensation nuclei associated with a polluted atmosphere for monodisperse distribution.     

The Use of Health Risk Assessment to Estimate Desirable Sampling Detection Limits

Abstract

The inclusion of non-detected chemicals in a health risk assessment may lead, in some cases, to estimated risks that exceed regulatory thresholds, because one must use the detection limit or half of the detection limit. This study presents a methodology which will allow one to estimate appropriate detection limits by conducting a health risk assessment prior to the source sampling program. The advantages and shortcomings of various levels of detail in the risk assessment to determine those detection limits are discussed. The application of the methodology is demonstrated with a case study of the potential health effects of power plant stack emissions.     

Size and Concentration Measurements of Particles Produced in Commercial Chromium Plating Processes

Abstract

Optical measurements of particle size and concentration were made at the chromium plating tank and exhaust system at a commercial hexavalent chromium plating facility. Particles were examined at three locations in the exhaust system: 1) directly at the hexavalent chromium plating bath surface, 2) at the exit of a cyclone separator located in the exhaust system approximately three to four meters downstream of the bath, and 3) in the exhaust stack, downstream of the induced draft fan and all abatement devices. Particle diameters at the bath surface ranged from 0.3 to 25 μm. Downstream of the cyclone exit and mesh pad filters, particle top sizes were approximately 5 and 0.7 mm, respectively. On a mass basis, the collection efficiency of all abatement devices was 99.997%. Assuming that droplets in the flow consist primarily of water and chromium, correcting the total particle mass flow against water content gives a chromium emission rate of 64,000 μg/hr, which compares favorably with a value of 77,000 μg/hr measured with EPA methods. This initial agreement, which should be validated through additional measurements over a broad range of flow conditions, raises the possibility of continuous monitoring for chromium metal emissions using particle size/mass as a surrogate.     

Day-of-Week Patterns of Particulate Matter and Its Chemical Components at Selected Sites in California

Abstract

This paper analyzes day-of-week variations in concentrations of particulate matter (PM) in California. Because volatile organic compounds (VOCs) and oxides of nitrogen (NO_x) are not only precursors of ozone (O₃) but also of secondary PM, it is useful to know whether the variations by day of week in these precursors are also evident in PM data. Concentrations of PM ≤10 μm (PM₁₀) and ≤2.5[H9262]m in aerodynamic diameter (PM_2.5) were analyzed. PM concentrations exhibit a general weekly pattern, with the maximum occurring late in the workweek and the minimum occurring on weekends (especially Sunday); however, this pattern does not prevail at all sites and areas. PM nitrate (NO₃ ^-) data from Size Selective Inlet (SSI) samplers in the South Coast Air Basin (SoCAB) tend to be somewhat lower on weekends compared with weekdays. During 1988–1991, the weekend average was lower than the weekday average at 8 of 13 locations, with an average decrease of 1%. During 1997–2000, the weekend average was lower than the weekday average at 10 of 13 locations, with an average decrease of 6%. The weekend averages are generally lower than weekday averages for sulfates, organic carbon, and elemental carbon. Because heavy-duty trucks typically represent a major source of elemental carbon, the weekend decrease in heavy-duty truck traffic may also result in a decrease in ambient elemental carbon concentrations.