Daniel A. Burgard

Spectroscopy applied to on-road mobile source emissions.

Not to be confused with emission spectroscopy, the detection of mobile source emissions by means of a remote sensing device (RSD) is almost entirely an application of absorption spectroscopy. In this article we discuss the application to measurement of individual vehicle emissions remotely as the vehicle drives by in its normal driving mode. Most studies and commercial implementation have involved automobiles and light duty trucks. However, the same technology has been applied to heavy duty trucks, locomotives, snowmobiles and airplanes in taxi and takeoff modes. The challenge in all these applications is to make precisely collocated absorption measurements at 100 Hz in both the UV and IR regions of the spectrum with low noise. The ability to measure 1/1000 absorbance units is necessary. The only compensating advantage is that an individual vehicle measurement cycle is over in one second or less, such that slow instrument drift becomes unimportant. The results are all measured as a ratio to the measured emission of CO2 and calibrated by means of a certified cylinder with known ratios. Using these ratios, the end result for each vehicle can be expressed as mass emissions per kg or per L of fuel as well as the emissions % which would be measured were the vehicle equipped with a tailpipe probe and emissions measurement system (corrected for any excess air which might be in the exhaust manifold).

Nitrogen dioxide, sulfur dioxide, and ammonia detector for remote sensing of vehicle emissions

A remote sensor for measuring on-road vehicles passing the sensor in real time is described. This sensor expands upon previous technology that measured carbon monoxide, carbon dioxide, and exhaust hydrocarbons in the IR and nitric oxide in the UV. The design adds the capability to measure nitrogen dioxide in the UV with one spectrometer and to measure SO2 and NH3 along with NO in a second UV spectrometer. With these units operating side by side, the major mobile source precursors to secondary aerosol production can be measured simultaneously and in real time. Detection limits for NO2, SO2, and NH3 are 1.2, 0.72, and 0.78 g pollutant per kilogram of fuel, respectively.

Working Upstream: How Far Can You Go with Sewage-Based Drug Epidemiology?

The field of drug epidemiology based upon sewer sampling has only emerged in the last 10 years and has great potential to aid in drug epidemiological studies. This rapidly expanding field can provide an unbiased look into the illicit drug habits of large populations as well as specific, smaller groups. How far the field has evolved is discussed as well as where the future for these types of monitoring studies could go.

Chemiluminescent Reactions of Nickel, Iron, and Cobalt Carbonyls with Ozone:

Metal carbonyls have been historically used for metal purification but are becoming increasingly used in chemical vapor deposition and preparation of nanomaterials. Metal carbonyls are toxic and therefore, when used industrially, the area in which they are used must be monitored in case of unintended leakage. Nickel and iron carbonyls were first reported to chemiluminesce with ozone by Morris and Niki and the emission spectra reported by Groth et al. A fast, sensitive, and portable chemiluminescent monitor for nickel carbonyl was developed by Stedman et al. based on these initial observations. The detectors are configured either with a broad band pass filter to monitor both nickel and iron carbonyls, or with selective optical filters and a pre-reactor to monitor only one. The selective optical filters are based on the published spectra. The system was later adapted by Houpt et al. to remove the interference of iron carbonyl by making use of the difference in chemiluminescent lifetimes from the two metal carbonyls. Cobalt carbonyl and cobalt nitrosyl carbonyl have been shown to induce a signal in commercial filter-based detectors. The cobalt carbonyls may be an impurity in nickel carbonyl detection or a detector specific to cobalt may be needed. Therefore, the chemiluminescence spectra from these cobalt compounds needed to be determined. Charge-coupled device (CCD) technology now provides the ability to monitor all wavelengths at once and thus preserve accurate relative intensities. This feature also allows pressure dependence studies to be conducted relatively easily in order to observe the extent to which the intensity distributions change with reaction pressure. New monitoring instruments for metal carbonyls would be simpler and less expensive if inexpensive vacuum pumps and thus higher pressures could be used in the reactor. Therefore, a study concerning intensity as a function of pressure was also carried out.

Remote sensing of emissions from in-use small engine marine vessels.

This paper reports the first use of a remote sensing device to measure emissions from in-use marine vessels. Emissions from 307 small marine vessels were measured as they passed through the Hiram M. Chittenden locks near Seattle, WA. Of these vessels, 89 were matched to state registration information to allow for further analysis of emissions vs model year, fuel type, and engine type. Emission factors are reported for CO, HC, and NOx in grams of pollutant per kilogram of fuel. The measured emission factors generally agreed with those derived from laboratory studies. HC emissions are disproportionately skewed across the fleet where 40% of the emissions come from just 10% of the fleet. These are most likely due to the remaining two-stroke engines in the fleet. CO and HC emissions show no improvement with newer vessels.

Improving wastewater-based epidemiology to estimate cannabis use : focus on the initial aspects of the analytical procedure

Wastewater-based epidemiology is a promising and complementary tool for estimating drug use by the general population, based on the quantitative analysis of specific human metabolites of illicit drugs in urban wastewater. Cannabis is the most commonly used illicit drug and of high interest for epidemiologists. However, the inclusion of its main human urinary metabolite 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in wastewater-based epidemiology has presented several challenges and concentrations seem to depend heavily on environmental factors, sample preparation and analyses, commonly resulting in an underestimation. The aim of the present study is to investigate, identify and diminish the source of bias when analysing THC-COOH in wastewater. Several experiments were performed to individually assess different aspects of THC-COOH determination in wastewater, such as the number of freeze-thaw cycles, filtration, sorption to different container materials and in-sample stability, and the most suitable order of preparatory steps. Results highlighted the filtration step and adjustment of the sample pH as the most critical parameters to take into account when analysing THC-COOH in wastewater. Furthermore, the order of these initial steps of the analytical procedure is crucial. Findings were translated into a recommended best-practice protocol and an inter-laboratory study was organized with eight laboratories that tested the performance of the proposed procedure. Results were found satisfactory with z-scores ≤ 2.

High-Mileage Light-Duty Fleet Vehicle Emissions: Their Potentially Overlooked Importance

State and local agencies in the United States use activity-based computer models to estimate mobile source emissions for inventories. These models generally assume that vehicle activity levels are uniform across all of the vehicle emission level classifications using the same age-adjusted travel fractions. Recent fuel-specific emission measurements from the SeaTac Airport, Los Angeles, and multi-year measurements in the Chicago area suggest that some high-mileage fleets are responsible for a disproportionate share of the fleets emissions. Hybrid taxis at the airport show large increases in carbon monoxide, hydrocarbon, and oxide of nitrogen emissions in their fourth year when compared to similar vehicles from the general population. Ammonia emissions from the airport shuttle vans indicate that catalyst reduction capability begins to wane after 5-6 years, 3 times faster than is observed in the general population, indicating accelerated aging. In Chicago, the observed, on-road taxi fleet also had significantly higher emissions and an emissions share that was more than double their fleet representation. When compounded by their expected higher than average mileage accumulation, we estimate that these small fleets (<1% of total) may be overlooked as a significant emission source (>2-5% of fleet emissions).

On-Road, In-Use Gaseous Emission Measurements by Remote Sensing of School Buses Equipped with Diesel Oxidation Catalysts and Diesel Particulate Filters

Abstract A remote sensing device was used to obtain on-road and in-use gaseous emission measurements from three fleets of schools buses at two locations in Washington State. This paper reports each fleet’s carbon monoxide (CO), hydrocarbon (HC), nitric oxide (NO), and nitrogen dioxide (NO2) mean data. The fleets represent current emission retrofit technologies, such as diesel particulate filters and diesel oxidation catalysts, and a control fleet. This study shows that CO and HC emissions decrease with the use of either retrofit technology when compared with control buses of the same initial emission standards. The CO and HC emission reductions are consistent with published U.S. Environmental Protection Agency verified values. The total oxides of nitrogen (NOx), NO, and the NO2/NOx ratio all increase with each retrofit technology when compared with control buses. As was expected, the diesel particulate filters emitted significantly higher levels of NO2 than the control fleet because of the intentional conversion of NO to NO2 by these systems. Most prior research suggests that NOx emissions are unaffected by the retrofits; however, these previous studies have not included measurements from retrofit devices on-road and after nearly 5 yr of use. Two 2006 model-year buses were also measured. These vehicles did not have retrofit devices but were built to more stringent new engine standards. Reductions in HCs and NOx were observed for these 2006 vehicles in comparison to other non-retrofit earlier model-year vehicles.