Robert B. Jacko

Model for Forecasting Expressway Fine Particulate Matter and Carbon Monoxide Concentration: Application of Regression and Neural Network Models

Abstract The Borman Expressway is a heavily traveled 16-mi segment of the Interstate 80/94 freeway through Northwestern Indiana. The Lake and Porter counties through which this expressway passes are designated as particulate matter <2.5 µm (PM2.5) and ozone 8-hr standard nonattainment areas. The Purdue University air quality group has been collecting PM2.5, carbon monoxide (CO), wind speed, wind direction, pressure, and temperature data since September 1999. In this work, regression and neural network models were developed for forecasting hourly PM2.5 and CO concentrations. Time series of PM2.5 and CO concen trations, traffic data, and meteorological parameters were used for developing the neural network and regression models. The models were compared using a number of statistical quality indicators. Both models had reasonable accuracy in predicting hourly PM2.5 concentration with coefficient of determination ~0.80, root mean square error (RMSE) <4 µg/m3, and index of agreement (IA) >0.90. For CO prediction, both models showed moderate forecasting performance with a coefficient of determination ~0.55, RMSE ~0.50 ppm, and IA ~0.85. These models are computationally less cumbersome and require less number of predictors as compared with the deterministic models. The availability of real time PM2.5 and CO forecasts will help highway managers to identify air pollution episodic events beforehand and to determine mitigation strategies.

Determination of polycyclic aromatic hydrocarbons in biomass gasifier effluents with liquid chromatography/diode array spectroscopy.

Liquid chromatography/diode array spectroscopy (LC/DAS) is used for the determination of polycyclic aromatic hydrocarbons (PAH) isolated from the emissions of biomass gasifiers. The spectrometer is capable of obtaining complete absorption spectra of components as they elute from the chromatograph, thus confirming the identities of pure peaks and mixed or poorly resolved peaks. This technique is especially well suited for the determination of polynuclear aromatics, where many isomers difficult to resolve chromatographically are easily distinguished by their electronic spectra. The instrument is also capable of differentiating between unsubstituted PAH and their methylated analogues, even though methylation does not greatly perturb the electronic nature of the parent hydrocarbon.

A model to estimate mixing height and its effects on ozone modeling

Abstract A mixing height estimation model (PMH) whose output can be used in air quality models, especially the Urban Airshed Model (UAM-IV), is developed. The evaluation of the performance of the PMH shows that the predictions match the observations very well. The average geometric mean of the predicted to observed hourly mixing height ratios is equal to 0.99. The outputs of the PMH along with those of the mixing height model incorporated in the UAM-IV package (RAMMETX) are used in the UAM-IV to simulate hourly average concentrations of tropospheric ozone (O3) in the Indianapolis metropolitan statistical area (MSA). A comparative study performed to assess the effects of mixing height shows that the UAM-IV performs better when the mixing height fields are from the PMH. For example, the episodic mean of the average normalized bias and the average normalized absolute bias of predicted to observed O3 concentrations are 1.2% and 18.6%, respectively, when the mixing height fields are from the PMH. They are 6.6% and 20.1%, respectively, when the mixing height fields are from RAMMETX.

Trace Metal Particulate Emission Test Results from a Number of Industrial and Municipal Point Sources

As part of a Purdue University study of the environmental flow of cadmium and other trace metals, source emission sampling for par-ticulates has been conducted at a number of industrial and municipal plants. The emission samples from each plant were analyzed for Cd, Pb, Zn, Cu, and in some cases Fe and Ni by atomic absorption spectroscopy. Atmospheric mass emission rates and emission factors are reported for total particulates and for each metal. Cadmium emission factors were found to be substantially different from those estimated by Davis in an earlier report. Aerodynamic particle size distributions were measured at each source using an Andersen im-pactor. A comparison of the total particulate size distributions with the trace metal size distributions revealed that the metals are not evenly distributed among the particle sizes. In every case the trace metals were found predominantly in the respirable particulate fraction even when the bulk of the emissions were non-respirable.

A Wind Tunnel Study into the Effects of Raised Intakes and Parapets on Fresh Air Intake Contamination by a Rooftop Stack

A wind tunnel study was completed to determine the effects the presence of a parapet and raised intake configurations have on the dilution of a pollutant between a rooftop stack and building intake. This study was the first to address the effects of building parapets and varying intake configurations. A study of this kind is desirable because it is common practice for architects to attempt to hide stacks with the use of a parapet in order to make industrial buildings more aesthetically pleasing. This is done with no thought to the effect it may have on the intended function of the stacks, which is dispersing gases away from the building to avoid contamination of ventilation air. Three parapet configurations (no parapet and two different parapet heights) and two intake configurations (flush and raised) were investigated. The relative effects of the parapets and the raised intake configurations were also compared and contrasted for five stack heights, two stack locations, and four intake locations. The parapets were found to produce a cavity zone that extends above the buildings roof by as much as two times the physical height of the parapet; increasing stack height had little effect on dispersion until the stack extended beyond this cavity region. The independent use of the parapets and raised intake configuration decreased the number of dilutions occurring between stack and intake when compared to the no parapet and flush intake configurations in all cases. Also substantiated in this study is the widely accepted view that the effect of the parapet addition is to decrease the effective stack height by the parapet height itself. The results of this investigation were then compared to existing wind tunnel-derived empirical models. The models tested were not able to predict the effects of varying stack height and of varying the relative distance between stack and intake on the dilution of a pollutant between stack and intake under the tested configurations.

Odor and odorous chemical emissions from animal buildings: Part 2- odor emissions

This study was an add-on project to the National Air Emissions Monitoring Study (NAEMS) and focused on comprehensive measurement of odor emissions. Odor emissions from two animal species (dairy and swine) from four sites with nine barns/rooms (two dairy barns in Wisconsin, two dairy barns and two swine rooms in Indiana, and three swine barns in Iowa) during four cycles (13-week periods) were measured. Odor samples were analyzed in three olfactometry laboratories and no significant difference was found among these laboratories. The highest ambient odor concentrations and barn odor emissions were measured for the Iowa swine site. The most intense odor and the least pleasant odor were also measured for this site. Ambient odor concentrations were the lowest for the Wisconsin dairy site. But the lowest barn odor emission rates were measured for the Indiana dairy site. Significantly higher odor emissions were measured in summer.

Stochastic Model for Estimating Impact of Highway Incidents on Air Pollution and Traffic Delay

A stochastic model was developed to estimate the average excess emission of carbon monoxide (CO), volatile organic compounds (VOC), oxides of nitrogen (NOx), and particulate matter (PM2.5) and the traffic delay due to incidents. This work models incident characteristics such as incident clearance time, degree of capacity reduction, and the demand-to-capacity ratio as random variables to derive the statistical characteristics of the excess emissions and traffic delays. It was found that estimated excess CO and traffic delay could be modeled as lognormal distributions. Excess VOC and NOx distributions were found to have the characteristics of a three-parameter lognormal distribution. Excess PM2.5 distribution was found to have gamma distribution characteristics. Average incident clearance time for this study was found to be 26 min. The average degree of capacity reduction and demand-to-capacity ratio were assumed to be 63% and 71%, respectively. An incident with these characteristics is estimated to result in 126.9 kg of excess CO, 20.8 kg of excess VOC, 8.8 kg of excess NOx, 0.27 kg of excess PM2.5 emissions, and 630 vehicle hours of traffic delay. This represents a 138% increase in CO emissions, a 500% increase in VOC emissions, a 26% increase in NOx emissions, and a 43% increase in PM2.5 emissions compared with the normal traffic emissions. Sensitivity analysis of incident management strategies revealed that air pollutant emissions and traffic delay could be reduced by as much as 30% by detouring as little as 5% of the incoming traffic.

A banded double ring electrodynamic balance for the suspension of submillimeter sized particles

Abstract A banded double ring electrodynamic balance (BDRB) has been developed at Purdue University and utilized to electrodynamically suspend droplets > 750 μ m in diameter. This represents a three fold increase in diameter and thirty fold increase in mass from prior electrodynamic suspension devices. The balance geometry and some construction details are presented. Numeric modelling of the equations of motion is shown to be superior to the traditional Mathieu approach for determining the onset of particle stability. The charge simulation technique (CST) was used to determine the electric field within the balance environment. Results indicate that the difference between Mathieu stability and numeric calculations result from the assumption of Stokes drag, which is necessary for the Mathieu solution. Particle Reynolds numbers for a droplet are numerically computed to be as high as 10.

Odor and Chemical Emissions from Dairy and Swine Facilities: Part 1 – Project Overview and Collection Methods

Livestock facilities have received numerous criticisms due to their emissions of odorous air and chemicals. Hence, there is a significant need for odor emission factors and identification of principle odorous chemicals. Odor emission factors are used as inputs to odor setback models, while chemical emission factors may be compared with regulations to demonstrate possible health impacts.

Odor and odorous chemical emissions from animal buildings: Part 4- correlations between sensory and chemical measurements

This study supplemented the National Air Emissions Monitoring Study (NAEMS) by making comprehensive measurements, over a full calendar year, of odor emissions from five swine and four dairy rooms/buildings (subset of the total number of buildings monitored for the NAEMS project). The measurements made in this project included both standard human sensory measurements using dynamic forced-choice olfactometer and a novel chemical analysis technique for odorous compounds found in these emissions. Odor and hydrogen sulfide (H2S) and ammonia (NH3) concentrations for all dairy and swine buildings had a statistically significant correlation. A higher number of correlations between odor and volatile organic compounds (VOCs) were found for the five swine rooms/buildings (two rooms in a pig finishing barn, two sow gestation barns, and a farrowing room) compared to the four dairy buildings. Phenol and 4-methyl phenol (p-cresol) concentrations were well correlated (R2 > 50%) with odor concentrations in the five swine rooms/buildings but not significantly correlated in the four dairy buildings.