Methane, Volatile Organic Compounds, and Nitrogen

 Oxides at the City of Boulder Reservoir (Colorado)                                                                                                   


This site presents preliminary results of atmospheric near-real time monitoring at the Boulder Reservoir. This monitoring is sponsored by Boulder County Public Health and conducted by researchers from the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado in partnership with the State of Colorado Department of Public Health and the Environment (CDPHE).

Methane (CH4) During the Past Three Days                                                             Back to Top


Methane is a potent greenhouse gas. It has an atmospheric lifetime of about a decade and is distributed globally. Methane emissions in our area mainly come from oil and gas. Livestock, landfills, and wastewater treatment plants are also sources of methane in northeastern Colorado.

All times are reported in Mountain Standard Time (MST). Data during Daylight Savings Time (March-November) will have to be corrected by adding one hour.

Click here to see graphical analyses of all monthly data since February 2017.


Selected Volatile Organic Compounds (VOCs) During the Past Three Days        Back to Top



Ethane and propane have atmospheric lifetimes of about 2 months and about 2 weeks, respectively. They contribute to formation of ground-level ozone on a regional and continental scale. Oil and gas production and processing activities are the main source of ethane and propane. Propane can also be released to the atmosphere from storage and distribution of liquified petroleum gas.


Butanes and acetylene contribute to formation of ozone on local to regional scales. Butanes are emitted from gasoline vapors, vehicle exhaust, and oil and gas production. Vehicle exhaust is the main source of acetylene.


Pentanes are also contributors to ozone formation on local to regional scales. Pentanes are primarily emitted from gasoline vapors and oil and gas production.


Because i-pentane and n-pentane are released in different relative quantities by different sources, the i/n pentane ratio can be used to separate the influence of urban emissions from oil and gas emissions (Gilman, 2013; Thompson, 2014). An i/n pentane ratio of 0.8 - 0.9 is typical of raw oil and gas emissions, whereas a ratio from 2-4 is characteristic of vehicle and urban emissions. In recent years, Boulder’s average pentane ratio has been around 1.1 (Gilman, 2013), suggesting a mix of influences from vehicle, urban, and oil and gas emissions.


Benzene and toluene contribute to ozone formation and may be hazardous to health if breathed at high levels. Sources of toluene include paints, solvents, gasoline vapors and vehicle exhaust. Sources of benzene include gasoline vapors, vehicle exhaust, and oil and gas production activities.

All times are reported in Mountain Standard Time (MST). Data during Daylight Savings Time (March-November) will have to be corrected by adding one hour.

Click here to see graphical analyses of all monthly data since April 2017.

Nitrogen Oxides (NOx) During the Past Three Days                                                Back to Top



Nitrogen oxides (NOx = NO2 + NO) react in the atmosphere to form ozone, nitric acid, and particulate nitrate. Nitrogen oxides are formed during high temperature combustion in engines and fossil-fuel fired power plants. 

All times are reported in Mountain Standard Time (MST). Data during Daylight Savings Time (March-November) will have to be corrected by adding one hour.

Click here to see graphical analyses of all monthly data since February 2017.


Wind Speed and Direction During the Past Three Days                                          Back to Top




All times are reported in Mountain Standard Time (MST). Data during Daylight Savings Time (March-November) will have to be corrected by adding one hour. All wind data are given in meters per second, but can be converted to miles per hour by roughly doubling them (~2.2).

Click here to see graphical analyses of all monthly data since February 2017.


Project Motivation                                                                                                        Back to Top


The Colorado Front Range (CFR) has been in exceedance of the U.S. National Ambient Air Quality Standard (NAAQs) for ozone since 2004 and was designated as a moderate non-attainment area for ozone. This designation sets requirements for the State of Colorado to develop plans for curbing emissions of ozone precursors, with the goal to reduce ozone and reach attainment of the ozone standard. Despite efforts to reduce emissions, air quality has not reached target levels, raising questions about which emission sources are contributing the CFR's air quality concerns (Denver Post).

In partnership with CDPHE, the Atmospheric Research Lab at INSTAAR is providing near real-time measurements of trace gases including methane (CH4), nitrogen oxides (NOx), and volatile organic compounds (VOC) at the Boulder Reservoir. These measurements, combined with wind and other meteorological data provided by CDPHE are used to inform the public about air pollution levels, and by regulators and researchers for studying emissions sources and transport in the NCFR. The end goal is the monitoring and improving of our understanding of emissions and impacts of oil and natural gas development on air quality in Boulder County.

Ozone is a secondary pollutant, formed in the atmosphere from reactions of NOx and VOCs. More background information on ozone, its formation chemistry and health effects, can be found through the EPA. Monitored compounds include ozone (by CDPHE), nitrogen oxides, VOC, and methane, serving as a tracer for oil and natural gas emissions.

This monitoring will continue through the fall of 2018, providing a complete yearly cycle and two summer ozone season data sets, all of which will be publically accessible through this page.

Monitoring Methods                                                                                                    Back to Top


The monitoring includes 1-min time resolution measurements of NOx with a Thermal Environmental Corporation 42TL chemiluminescence analyzer. Data are averaged to 5-min intervals for display on this website.

Methane is monitored by loop injection of 10 ml samples and gas chromatography with flame ionization detection. Samples are collected at 20-min intervals.

VOC are monitored by preconcentration of 500 ml-samples onto a micro-adsorbent trap, with subsequent thermal desorption, capillary column gas chromatography separation, and flame ionization detection. Samples are collected at 2-hour intervals. Currently quantified compounds include ethane, ethene, propane, propene, i-butane, acetylene, n-butane, i-pentane, n-pentane, hexane, isoprene, benzene, toluene, ethyl-benzene, m,p-xylene, and o-xylene.

Wind speed and direction are measured by an R.M. Young propeller anemometer, 4 meters above ground level.

Contacts                                                                                                                        Back to Top

Boulder County Public Health
Attn: Pam Milmoe (pmilmoe@bouldercounty.org)

INSTAAR – CU Boulder
Attn: Detlev Helmig (detlev.helmig@colorado.edu)

CDPHE
Attn: Greg Harshfield (gregory.harshfield@state.co.us)

   
Last Updated: June, 2017 - Webmaster: Brendan Blanchard
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