Mapping Methane Concentrations in Urban EnvironmentsResults from Truck Surveys in the G.T.A.

Sajjan Heerah(1), C. Arrowsmith(1), N. Pak(1), A.G. Tevlin(2), S. Gichuk(2), D. Risk(2), D.Wunch(1)

(1) University of Toronto; (2) St. Francis Xavier University

LGR

Weather Station

LGR

GMethane in the G.T.A.

Weather StationLGR

An inventory of CH4 emissions in the G.T.A. give its total emissions as 79 kt per year. According to this inventory, the G.T.A. has a mix of source types and sizes and they are unevenly located within the city.

3) Methods

LGR

2) Project GoalsIn this project we aimed to measure CH4 enhancements at known point sources in the G.T.A. Using this data, we can begin to describe the spatial and temporal patterns of emissions in the region.

During this campaign we used an LGR Ultra-porable greenhouse gas analyser to measure CH4 concentration. The LGR samples ambient air and measures the absorption of laser light at specific frequencies through it. This allows it to determine ambient concentrations of CO2 ,CH4, CO & H2O every second.

The LGR was installed in the bed of a truck during the campaign. The LGR was connected to a gas intake line at the front of the truck allowing it to sample clean air ahead of the truck’s tailpipe.

CO2 and other greenhouse gases like CH4 & N2O, trap heat, warming the earth

The Greenhouse Effect

Human activity since the Industrial Era have led to increases in greenhouse gases with signi icant impact on the climate system(IPCC, 2014).

0.8oC rise 1900-2000

Global Temperature Land-Ocean Index

Climate Change

Figure source: Department of Ecology, Washington

Figure Source: Department of Ecology, Washington

Methane: a Greenhouse Gas Methane (CH4 ) is the is the 2nd most important greenhouse gas (Myhre, 2014). Its major sources are natural gas, anaerobic respiration in waste treatment, animals and wetlands.Its short lifetime and the existence of effective emission reductions make it an attractive target for short term climate change mitigation (Saunois, 2016).

Urban MethaneCities are signi icant parts of the global CH4 cycle(2). They contain a complex mix of source types in an uneven distribution.There are gaps in our understanding of urban CH4 particularly, the magnitude, location and source sector of emissions at ine scales not resolvable with stationary

measurements (Hopkins, 2016a & Hopkins, 2016b ). These are barriers to mitigation.

Map of G.T.A. CH4 sources based on an inventory. Sources are unevenly distributed & of many types. Also shown are E.C. stationary measurement sites.

1) Context

Night Surveys, July 24th - 26th, 2017 

North Sheridan & Erindale Landfills

Near Union Gas Milton Compressor Station & Pipeline

Unknown Source South or in Keating Channel

Unknown source within Rouge Valley.

Day Surveys August 2nd -4th, 2017 2017

North Sheridan & Erindale Landfills

GE Booth Wastewater

Keating Channel & Ashbridges Wastewater

Duffin Creek Wastewater

Keele Valley Landfill

Disco Road Organics Processing

GTAA Cogen

Gerdau Steel Mill

Instrument

Gas Intake

Laser Cavity

Detector

Mobile Lab

Ram Truck with LGR mounted. Lab also included a weather station and gps unit.

Gas Intake LGR

AMR

3) MethodsSurvey Method★ 3 routes created to

target point sources in inventory.of different types.

★ Each route replicated , twice during day and once at night.

★ Make transects uo and down wind of plumes to characterise.

★ ~2700 km driven over 9 days from 24th July - 4th August

LGR Ultraportable GHG Analyser. Measures absorption of a laser by air pumped into cavity to determine concentrations of CO2, CH4, CO, & H2O.

4) Results

6) Acknowledgements 7) References

Measured Wind Direction

Measured Wind Direction

2

5) Results

Example of a CH4 Plume:August 4th Day, Du in CreekWastewater Treatment plant

1

22

2 ppm Enhancement over Background

3

Measured Wind Direction

Wastewater Digesters, 2

1

3

& Future Work

I would like to acknowledge C. Arrowsimth, N. Pak, A.G. Tevlin and S.Girchuk who participated in the surveys, D. Risk who provided the truck used in the survey and Professor Wunch for her guidance and supervision during this campaign.I would also like to acknowledge the Center for Global Change Studies at the University o Toronto who funded this internship.

IPCC, Climate Change 2014: Synthesis Report. Contribution o Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.Myhre, G., D. Shindell, F.-M. Bréonet al. Anthropogenic and Natural Radiative Forcing.In: Climate Change 2013: The Physical Science Basis. Contribution o Working Group I to the Fifth AssessmentReport of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen,J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, UnitedKingdom and New York, NY, USA.

Saunois, M., Bous uet, P., Poulter, B., Peregon, A., Ciais, et al.: The global methane budget 2000–2012, Earth System Science Data, 8(2), 697–751, doi:10.5194/essd-8-697-2016, 2016.

Hopkins, F. M., Ehleringer, J. R., Bush, S. E., Duren, R. M., Miller, C. E., Lai, C.-T., Hsu, Y.-K., Carranza, V. and Randerson, J. T.: Mitigation of methane emissions in cities: How new measurements and partnerships can contribute to emissions reduction strategies, Earths Future, 4(9), 408–425, doi:10.1002/2016ef000381, 2016.

Hopkins, F. M., Kort, E. A., Bush, S. E., Ehleringer, J. R., Lai, C.-T., Blake, D. R. and Randerson, J. T.: Spatial patterns and source attribution of urban methane in the Los Angeles Basin, Journal of Geophysical Research: Atmospheres, 121(5), 2490–2507, doi:10.1002/2015jd024429, 2016.

Inventory compiled by S. Heerah & N. Pak from various publicly available sources.

1) Large CH4 enhancements are concentrated spatially and can often be linked to known sources.

2) Unknown CH4 plumes can be localised to within a few meters.

3) Largest enhancements are from a variety of source sectors including wastewater treatment, solid waste management, natural gas transport and power generation.

4) Many enhancements seen at night appear during day but are smaller. This is due to the weaker atmospheric mixing at night.

Overall Patterns in Data2) Localising a CH4 enhancement from an unknown source to natural gas infrastructure.

Enbridge Gate Station Night Plume on 26th July

Enbridge Gate Station Day Plume on 2nd August

1.4ppm

0.3 ppm

Enhancements in River Valleys

One unexpected results was the observation of large and persistent enhancements in CH4 within river valleys. May be due to uninventoried point sources in the valleys or due to anaerobic respiration in wetlands or in wastewater run off. Further river measurements are needed.

4) Day-Night Changes in enhancements

6) Conclusions & Future Work★ Truck surveys with the LGR can provide a dataset which

resolves source scale enhancements in CH4 in the G.T.A. at both night and day.

★ The dataset characterises the extent and magnitude of many plumes well enough to be used for future emission estimates of sources using air dispersion models.

★ More campaigns in the city over a longer time period and during other seasons. This will be especially important for characterizing natural gas distribution leaks and for determining seasonal variability in emissions

Don River, 25th July Enhancement

Rouge River, 25th July Enhancement

2) Objectives The main aim of this campaign was to determine the feasibility and usefulness of truck surveys in mapping CH4 concentrations at ine scales in the G.T.A..