Refractory black carbon at Crawford Point, Greenland: Implications for mitigation policy
Thesis
Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in
the Graduate School of The Ohio State University
By
Demie Huffman, B.A.
Graduate Program in Environmental Sciences
The Ohio State University
2018
Thesis Committee
Joel Barker, Advisor
Cinnamon Carlarne
Ellen Mosley-Thompson
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Copyrighted by
Demie Huffman
2018
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Abstract
Refractory black carbon (rBC) particles are naturally and anthropogenically emitted as a by-product of the incomplete combustion of carbonaceous materials. As a strong absorber of incoming solar radiation, rBC warms whichever part of the atmosphere in which the particle is suspended and decreases the albedo of any ice- or snow-covered surface onto which it has been deposited. This makes the Arctic particularly vulnerable to rBC deposition, as atmospheric pollutants concentrate there and deposited rBC will accelerate glacier melt and make the immediate area more susceptible to warming. Within the past 15 years, global attention has turned to targeting rBC emissions in mitigation strategies in an attempt to slow the rate of near-term climate change, as rBC particles only have an atmospheric residence time of 7-10 days, which provides mitigation efforts with more immediate results. This research utilizes a firn core collected from Crawford Point (CP), Greenland in the summer of 2007 by the Program for Arctic Regional Climate Assessment (PARCA) to quantify and characterize the deposition of rBC and other absorbing materials, such as dissolved organic matter
(DOM), onto the Greenland ice sheet (GrIS) from 1980-2007. Median rBC concentration throughout the CP firn core is 0.86 μg/L and ranges from 0.02-19.93 μg/L. The declining trends observed in anthropogenic rBC emissions and deposition to CP suggest that the implemented mitigation efforts may be successful. However, Canadian forest fires can
ii lead to high deposition events at CP, which will only get worse as climate change impacts continue to worsen.
This research also aims to determine emission and source of rBC particles in three circumpolar countries – the Russian Federation, Canada, and the United States of
America – and one regional economic integration organization – the European Union – and their mitigation efforts to decrease air pollution as it relates to rBC. The two largest sources of anthropogenic rBC emissions globally are residential combustion (for heating) and diesel engines (for on- and off-road transportation). Future rBC mitigation efforts should focus on these sectors and use a variety of intergovernmental economic incentives, information dissemination and regulatory tactics. Future policy work should also focus on establishing comparable BC emission inventories by reaching a global consensus on (1) the definition of BC, (2) how to define various BC emission sectors, (3) and which quantification techniques to use when creating emission inventories.
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Dedication
To my family and friends, whose unconditional support has meant everything.
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Acknowledgments
I would first like to thank Dr. Joel Barker for his support, guidance and aid throughout my Master’s degree and in my development as a scientist.
Thank you to Dr. Ellen Mosley-Thompson for her mentorship throughout this process, and for providing the firn core used for this project, as well as the density data from the Crawford Point drill site.
Thank you to Professor Cinnamon Carlarne for her time and mentorship this past year, and for our meaningful conversations both in and out of the classroom.
Thank you to Donald Kenny at BPCRC for analyzing the major ions in our firn core samples.
To my lab mates George Grant and Carissa Hipsher, thank you for helping me maintain my sanity over the past two years. I am incredibly grateful for your friendship.
To Miriam Handler, thank you for your help with the experimental design and coding for the HYSPLIT model. I am extremely glad we both took Climate Change Law.
Lastly, this work would not have been possible without the PARCA team or the funding sources provided by NSF, NASA, and NOAA for the various PARCA projects.
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Vita
June 2012...... Granville High School, Granville, OH
May 2016...... B.A. Chemistry with Creative Writing, Goucher College, Baltimore, MD
August 2016 to present...... Graduate Teaching/Administrative Associate, Environmental Science Graduate Program, The Ohio State University, Columbus, OH
Fields of Study
Major Field: Environmental Science Specialization: Climate Change Science and Policy
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Table of Contents
Abstract ...... ii Dedication ...... iv Acknowledgments...... v Vita...... vi List of Tables ...... ix List of Figures ...... x Chapter 1. Introduction ...... 1 Chapter 2. Background ...... 4 2.1. The Arctic Air Mass and Aerosol Emissions ...... 4 2.2. Black Carbon ...... 5 2.2.1. Formation and Atmospheric Removal of rBC ...... 6 2.2.2. Incorporation of rBC into GrIS ice mass ...... 7 2.2.3. Global Historic rBC Emissions and rBC Deposition onto the GrIS ...... 8 2.3. Addressing Atmospheric Pollution through Policy ...... 9 2.3.1. Intergovernmental Climate Change and Air Pollution Action ...... 10 2.3.2. Targeting rBC for Near-Term Climate Change Mitigation ...... 14 Chapter 3. Methods ...... 16 3.1. Drill Site Location and Sample Collection ...... 16 3.2. Sample Preparation ...... 16 3.3. Contamination Testing ...... 17 3.4. Refractory Black Carbon Quantification ...... 18 3.5. Cation and Anion Quantification ...... 20 3.6. Dissolved Organic Matter Characterization and Absorbance Quantification ...... 21 3.7. Back-Trajectory Analysis ...... 23 3.8. Policy and Profiles of Key States...... 24 Chapter 4. Results and Discussion ...... 25 4.2. Firn Core Dating with Ion Analysis Results ...... 25 4.3. Quantification of rBC within Crawford Point Firn Core ...... 26 vii
4.4. Dissolved Organic Matter Characterization and Absorbance ...... 28 4.5. Post-depositional transportation through glacier ice mass...... 29 4.5.1. Post-Deposition Transportation Analyses Results ...... 30 4.6. Determining rBC Emission Sources ...... 32 4.6.1. Back-Trajectory Analyses ...... 32 4.6.2 Using Non-Sea Salt Sulfate to Understand rBC Emission Source ...... 33 Chapter 5. Policy Results and Discussion: ...... 35 5.1. Framing the Importance of Economic and Legal Developments ...... 35 5.2. Overview of rBC Emissions Inventories ...... 35 5.3. The Arctic Council ...... 36 5.4. Profile of the United States of America ...... 37 5.4.1. Overview of rBC Emissions ...... 37 5.4.2. Legal and Economic Developments and rBC Mitigation ...... 38 5.5. Profile of Canada ...... 41 5.5.1. Overview of rBC Emissions ...... 41 5.5.2. Legal and Economic Developments and rBC Mitigation ...... 42 5.6. Profile of USSR and Russian Federation (Russia) ...... 44 5.6.1. Overview of rBC Emissions ...... 44 5.6.2 Legal and Economic Developments and rBC mitigation ...... 45 5.7. Profile of the European Union (EU) ...... 47 5.7.1. Overview of rBC Emissions ...... 47 5.7.2. Legal and Economic Developments and rBC Mitigation ...... 48 6.1. rBC Deposition at Crawford Point ...... 50 6.2. Relating Policy and Economic Trends to rBC Deposition at Crawford Point ...... 51 6.3. Possible Post-Depositional Redistribution of rBC ...... 52 6.4. Potential Radiative Role of DOM in the CP Firn Core ...... 53 Chapter 7. Conclusions ...... 55 Appendix: Figures and Tables ...... 58 References ...... 83
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List of Tables
Table 1: Contamination testing rBC and major ion results...... 78
Table 2: Results of replication testing for major ions ...... 79
Table 3: Average rBC concentrations in Greenland ice cores ...... 80
Table 4: Mean loading values for PARAFAC model components...... 81
Table 5: HYSPLIT back-trajectory frequencies ...... 82
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List of Figures
Figure 1: Map of the Greenland Ice Sheet ...... 58
Figure 2: Duplicate rBC analyses ...... 59
Figure 3: Dated major ion concentrations ...... 60
Figure 4: Dated rBC deposition record ...... 62
Figure 5: Annual medians of rBC ...... 63
Figure 6: Regression of annual rBC mean concentrations...... 64
Figure 7: PARAFAC components ...... 65
Figure 8: PARAFAC component loadings, alongside the rBC record and absorbance ... 66
Figure 9: Dated rBC deposition record and location of refreeze layers ...... 67
Figure 10: Dated rBC concentrations and Mg2+/Na+ ratio ...... 68
Figure 11: rBC concentration vs. density ...... 69
Figure 12: Mean clusters of frequency plots for HYSPLIT back-trajectory analyses ...... 70
Figure 13: rBC concentration vs. nss-S concentration at Crawford Point ...... 74
Figure 14: Comparison of BC emission inventories for Russia, the United States, Nordic
European countries and Canada ...... 75
Figure 15: Black carbon emissions invententories for the United States, Russia, the
United Kingdom, France, and Germany ...... 76
Figure 16: Number of fires and area burned in Canada from 1970-2014 ...... 77
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Chapter 1. Introduction
Natural archives, such as marine sediments, speleothems, and ice cores, often preserve records of past climatic conditions. These archives are indirect indicators, or proxies, that paleoclimatologists use to study Earth’s past climates on both geologic and more recent time scales (Bradley, 2015, among others). Specifically, ice core records provide information on variations in temperature, precipitation patterns, the atmospheric composition of gases, and the deposition of aerosols and particulate matter (PM; Bradley,
2015). A historical record of atmospheric aerosol deposition can provide information about the rate and amount of change in its emission. These changes may be a result of the promulgation of legislation, such as the Clean Air Act (1970), or as a result of shifting energy generation sources, such as changing from coal burning to natural gas or cleaner energy sources. These trends in particulate emission, brought about by the implementation of laws, will ultimately influence the quantity of the particulate that is deposited within, and ultimately recorded by, natural archives. One such observable atmospheric aerosol is black carbon (BC).
BC forms as a byproduct of the incomplete combustion of fossil fuels and biomass (Bond et al., 2004). It is a strong absorber of incoming solar radiation, absorbing more radiation than it reflects, both while in the atmosphere and once it has been deposited onto glacier surfaces (IPCC, 2014). BC accelerates glacial melt, heating the surface and reducing the reflectivity (albedo) of snow, disproportionally affecting the
Polar Regions compared to other, non-snow-covered regions of the planet (Jacobson, 1
2004; Koch and Hansen, 2005; McConnell et al., 2007). BC has a radiative forcing (RF) of +1.1 W m-2 (+0.17 to +2.1 W m-2 uncertainty range; Ramanthan and Carmichael,
2008; Bond et al., 2013). This RF value is second only after carbon dioxide (CO2; RF of
+1.6 W m-2 (+1.33 to +2.03 W m-2 uncertainty range); IPCC, 2014). Therefore, BC is an important component of Earth’s radiation budget that merits further study.
Although BC has a short atmospheric residence time (7-10 days) and high regional variability relative to many other atmospheric aerosols, it can still be transported globally depending on its source location and the prevalent atmospheric circulation
(Flanner et al., 2009; Bond et al., 2013). As a result of this short atmospheric lifetime, changes in emission source or the quantity of emissions can drastically alter both regional and global atmospheric BC concentrations. Further, BC is often co-emitted with other atmospheric pollutants, such as sulfates, or within carcinogenic diesel exhaust, which have a history of being regulated as their emissions reduce air quality and public health
(California Environmental Protection Agency, 2017; Environment and Climate Change
Canada, 2017). This makes BC a target for short-term mitigation strategies, as reducing
BC emissions can improve public health and air quality, decrease the emissions of other co-pollutants, and mitigate climate warming (Bond and Sun, 2005; Bond et al., 2013;
Hienola et al., 2013; IPCC 2014).
Ice cores can be used to document historical deposition of BC that is specific to the region from which the ice cores are derived (Bisiaux et al., 2012). This record provides an historical record of BC emissions in response to various factors (e.g., industrialization, air quality legislation). However, the reliability of this record may be affected by possible post-depositional transportation (such as percolating melt water) of
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BC on, and within glaciers. Accurate historical documentation is essential when evaluating the effectiveness of the implementation of various regulatory legislation and incentive-based policies that are aimed at mitigating BC emissions, because the natural archives can provide observable evidence that speaks to the timing of the legislations’ results. Trends in BC deposition over the Greenland Ice Sheet (GrIS) could correlate to mitigation policies and BC emission sources in countries whose emissions reach the
Arctic. By identifying these countries and their emission sources, specific sectors could be targeted for regulation to mitigate BC deposition on the GrIS.
By using a firn core collected from Crawford Point on the GrIS, this research examines BC emission and subsequent deposition on glacial surfaces by quantifying its concentration throughout the firn core, evaluating regulatory and mitigation policies, and studying post-depositional processes that may be occurring. Specifically, the objectives of this research are to:
1. Quantify BC in the Crawford Point firn core;
2. Examine the potential effect of post-depositional processes on the BC firn core
record;
3. Determine emission concentrations and regional sources of BC to Crawford Point;
and
4. Evaluate the effect of regulatory measures on mitigating the delivery of BC to the
GrIS.
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Chapter 2. Background
2.1. The Arctic Air Mass and Aerosol Emissions
The Arctic, and the GrIS, specifically, is a collection point for Northern
Hemisphere pollution (Iversen, 1984; Barrie, 1986; Wolff, 1990; Gogoi et al., 2016). The
Arctic air mass is distinctive in that (1) for much of the year it has a sub-zero temperature, (2) there is little precipitation, and most falls during the warmer half of the year, (3) strong vertical mixing is prevented by stable stratification, and (4) there are low levels of solar radiation, particularly in the winter (Barrie, 1986). Arctic circulation is characterized by a frontal system that separates air masses of different temperatures
(Iversen, 1984). Within the frontal zone of the Arctic, vertical movement of an air parcel will be dependent on the humidity. The air parcels moving adiabatically will ascend, and those that contain enough humidity will further ascend as latent heat is released, and a significant portion of the air parcels’ pollution is removed via wet deposition (Iversen,
1984). Continental air is dry compared to maritime air, and pollution from these drier sources are able to reach high altitudes (Iversen, 1984).
During the winter, when aerosol concentrations are highest in the Arctic (Arctic haze particles are 20 – 40 times more abundant than in the summer, which is mostly comprised of wind-blown dust and sea salt; Iversen, 1984; Barrie, 1986; Gogoi et al.,
2016), the northernmost regions of Eurasia have a similar atmospheric temperature structure to the Arctic, which allows this region to contribute to ground level Arctic pollution in a way pollution originating from North America cannot (although North
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American pollution can be associated high-altitude Arctic pollution; Iversen, 1984). The predominant pathway for winter North American atmospheric pollution to the Arctic is over the Atlantic Ocean, whereas Eurasian air pollution travels over snow-covered land- ice areas (Barrie, 1986), and represents the most important pathway for atmospheric pollutionfrom the mid-latitudes to the Arctic (Rahn and Heidam, 1981). Causes for these seasonal observations may include planetary waves, which enhance the meridional transport of air along certain latitudes, such as those of northernmost Eurasia and Nordic countries, when atmospheric temperatures of the Arctic and these regions are similar
(Iversen, 1984). Increased cloud and fog frequency (greater abundance of stratus clouds in the lower troposphere; Barrie, 1986) and precipitation in the summer months can also contribute to seasonal variations in air mass sources (Iversen, 1984; Gogoi et al., 2016).
Therefore, it is the aerosol emissions from Eurasia and North America that will likely have the strongest signals within Arctic glacier ice masses (Heidam, 1984; Barrie, 1986).
2.2. Black Carbon
Formally, BC is defined as “an ideally light-absorbing substance composed of carbon” (Petzold et al., 2013). Historically, however, the term “black carbon” has also been regularly utilized synonymously with “soot”, “elemental carbon (EC)”, and
“refractory black carbon” (rBC; Petzold et al., 2013). EC is a carbonaceous fraction of
PM of pure carbon (rather than being chemically bonded with hydrogen or oxygen), stable in an inert atmosphere, and can take either a crystalline structure or be amorphous
(Ogren and Charlson, 1983). Soot is a colloquial term for EC, but refers to the collective black and organic carbon emissions from combustion (Petzold et al., 2013). BC, produced via combustion, is an impure form of EC with a graphite-like microstructure 5
(Novakov, 1984), which, while mostly containing carbon (over 60%), also includes hydrogen, oxygen, nitrogen, and sulfur (Petzold et al., 2013). BC (1) strongly absorbs radiation across the visible wavelength spectrum, (2) is refractory and retains its basic form across a broad temperature range, and (3) is insoluble in water (Bond et al., 2013). rBC, meanwhile, is defined as the carbonaceous fraction of PM that is insoluble and vaporizes near temperatures of 4000 K (Schwarz et al., 2010; Petzold et al., 2013). While the scientific literature has begun to denote these differences in terminology, intergovernmental policies continue to refer to rBC as BC (referred to as rBC hereafter).
2.2.1. Formation and Atmospheric Removal of rBC
rBC is emitted from a variety of natural and anthropogenic sources, including biomass burning, internal combustion engines (particularly diesel engines; Reff et al.,
2009; Carbon Limits AS, 2016; California Environmental Protection Agency, 2017), and industrial processes, such as petrochemical flaring and coke-making (Bond et al., 2013). rBC also affects a number of Earth systems. rBC and other aerosols, such as sea salt or ammonium sulfate (Kojima et al., 2005), indirectly influence cloud properties by acting as cloud condensation and ice nuclei. Clouds with increased aerosol concentrations will be less likely to precipitate, as they will have a greater number of smaller water droplets that will grow at a slower rate (Croft et al., 2005). Further, rBC will also diminish the reflectivity of snow and ice, which, in turn, exacerbates melting (Flanner et al., 2007;
Bond et al., 2013; Flanner, 2013).
Atmospherically, rBC particles undergo ‘ageing’ processes, including oxidation, condensation, and coagulation of particles, which act to change its solubility (Croft et al.,
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2005). Atmospheric rBC, therefore, exists in one of two states: insoluble particles or in soluble mixtures. When in a soluble mixture, rBC is more efficiently removed via wet and dry deposition, leading to a shorter atmospheric residence time. Generally, wet deposition accounts for 70-90% of atmospheric rBC removal (Croft et al., 2005). This process, from emission to deposition, takes approximately 7-10 days (Flanner et al.,
2009; Bond et al., 2013).
2.2.2. Incorporation of rBC into GrIS ice mass
Once deposited onto a glacier surface, rBC decreases snow albedo, thereby absorbing more incoming solar radiation (Flanner et al., 2007; Hadley et al., 2010). Near- surface katabatic winds on the GrIS which result from local boundary layer processes, such as the surface temperature inversion that is strongest in the winter, can horizontally redistribute snow, in which aerosol particulates are embedded (van As et al., 2014).
Horizontal redistribution may also be occurring as rBC is carried across the GrIS through melt water streams. Once deposition has occurred, rBC may also be redistributed vertically through the snowpack as melt water percolates downward from the surface to older snow layers until it refreezes. rBC can also be incorporated into the glacier ice mass during firnification of snow into glacier ice (Bisiaux et al., 2012). As surface snow and deposited rBC persist through a melt season and are buried by subsequent snowfall, successive layers representing annual accumulation build up, and the deeper layers are subjected to higher pressure and increasing density. With subsequent snow accumulation, density continues to increase as the volume of air-filled pores is reduced via plastic deformation and mechanical packing. Firn becomes glacier ice when the interconnecting
7 air passages between the grains are sealed off from the atmosphere above and form individual air bubbles (Herron and Langway, 1980). It is in this way that many glaciers provide a high-resolution annual record of aerosol deposition onto the glacier surface (in the absence of internal melting and/or internal deformation that interfere with annual layer stratigraphy (Meese et al., 1997; Cuffey and Paterson, 2010)) and that ice cores drilled vertically from the glacier surface are used to document atmospheric composition with time (Thompson et al., 1993; Bradley, 2015).
2.2.3. Global Historic rBC Emissions and rBC Deposition onto the GrIS
Since industrialization in the mid 19th century, global rBC emissions have fluctuated largely as a result of trends in industrial production, economic growth and decline, technological advancements, and environmental mitigation policies (McConnell et al., 2007; Junker and Liousse, 2008; Lamarque et al., 2010). Prior to 1850, rBC emissions varied significantly interannually and were highly seasonal, globally, with low rBC deposition over the GrIS in the winters, and high deposition in the summers in response to forest fires involving coniferous vegetation in Canada (McConnell et al.,
2007). This suggests that forest fires were the major source of rBC on the GrIS prior to large-scale industrialization in Europe and North America. Post-industrialization, rBC emissions increased from 1860 and peaked in 1910 based on evidence retrieved from
GrIS ice core records (D4 and D5 drill sites, McConnell et al., 2007) and global rBC emissions calculations based on fuel consumption data and industrial technology (Junker and Liousse, 2008). The decline in global rBC emissions after 1910 is associated with both technological advancements in efficiency and the economic depression of the 1920s
8 and 1930s (Junker and Liousse, 2008). This decline continued until the 1950s, when post- war emissions rose with increased industrialization, peaking in the 1980s and decreasing thereafter, coinciding with the widespread implementation of global environmental policy and improvements in technology efficiency (Junker and Liousse, 2008). Despite the post
180s decrease, global rBC emissions were 4-5 times greater at the end of the 20th century than they were in the mid 19th century (Junker and Liousse, 2008; Lamarque et al., 2010).
2.3. Addressing Atmospheric Pollution through Policy
By the mid-17th century, it was widely accepted that air pollution (as a result of burning coal for industrial and domestic coal burning) was directly responsible for the increased mortality rates that were observed in urban centers compared to those in the rural settings (Brimblecombe, 1977). Further, air pollution was blamed for a lack of plant diversity in London by the 18th century (Brimblecombe, 1977). One of the more obvious indicators for poor air quality was the discoloration of the air and decreased visibility due to particulate matter aerosols that were dominant in urban areas in the United Kingdom in the 17th century (Brimblecombe, 1977). In 1952, atmospheric sulfur dioxide emissions in
London, the result of coal burning both industrially and residentially, were chemically converted into particulate sulfate via gas-phase oxidation or aqueous reactions, facilitated by nitrogen dioxide in the atmosphere (which was also emitted during coal combustion;
Zhang et al., 2015; Wang et al., 2016). A toxic fog enveloped London for several days that led to the deaths of approximately 4,000 people, which spurred the passage of legislation to improve air quality (e.g., the United Kingdom’s Clean Air Act of 1956;
Zhang et al., 2015).
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Domestic environmentally-oriented legislation, particularly that which addressed reducing air pollution in an effort to protect public health, has been widespread since the
1960s through the end of the century. For example, the United States (U.S.) passed the
Air Pollution Control Act of 1955, the Clean Air Act of 1963, the Air Quality Act in
1967, and the Clean Air Act (CAA) of 1970 (which was later amended in 1977 and 1990;
Federal Environmental Laws, 2011). Further, the U.S. Congress also created the
Environmental Protection Agency (EPA) under the 1970 National Environmental Policy
Act, in order to help implement the new environmental laws it was passing. China passed an Environmental Protection Law in 1980, which, while addressing a number of environmental concerns, also addressed the problem of declining air quality as a result of atmospheric pollution (Florig et al., 1995). The Convention of Long Range
Transboundary Air Pollution, which regulates the emission of a number of atmospheric pollutants such as sulfur dioxide, ground-level ozone, and carbon monoxide, was passed in 1999 as an international agreement between the European Union (EU) and the U.S.
(Environment and Climate Change Canada, 1991; U.S. EPA, 2015). This multinational agreement is the primary framework for domestic law within EU member countries.
2.3.1. Intergovernmental Climate Change and Air Pollution Action
Between the 1960s and 1980s, scientific consensus on the threat of climate change, as a result of atmospheric pollution, was emerging, and the global community recognized that concerted action was necessary (Ghaleigh, 2016). As such, international negotiations began in order to create a framework treaty and protocol that would “define the parameters of a global response” (Carlarne et al., 2016). Following joint decisions by
10 the World Meteorological Organization (WMO) and the United Nations Environment
Programme (UNEP) in 1987, the Intergovernmental Panel on Climate Change (IPCC) was formed the following year and tasked to “assess on a comprehensive, objective, open, and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change”
(Ghaleigh, 2016). The IPCC released its First Assessment Report (FAR) in 1990 in which it confirmed the existing scientific evidence for global climate change largely attributed to the increased emissions of greenhouse gases (GHGs), with the caveat that much uncertainty existed, and called for the need for further research into these uncertainties
(Freestone, 2016). FAR predicted that under Business-as-Usual scenarios, in which mitigation action was not taken, global mean temperature would likely rise about 0.3°C per decade over the next century, and that an increased severity in storms and other extreme weather events, adverse impacts on ecosystems and biodiversity, and sea level rise would result from climate change (IPCC, 1990a; Freestone, 2016). It also concluded that any responses to climate change undertaken would need to account for the “great diversity of different countries’ situations and responsibilities,” (IPCC, 1990b). New datasets and analyses became available which led to a more complete understanding of climate change science with each subsequent IPCC assessment report (IPCC, 1995; 2001;
2007; 2014). It was not until the Third Assessment Report (TAR) that changes in Earth systems (e.g., negative effects on biodiversity, increased storm severity) were occurring, and not until the Fourth Assessment Report (AR4) that they were the result anthropogenic activities (Freestone, 2016).
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In 1992, the United Nations Framework Convention on Climate Change
(UNFCCC) was adopted to establish a platform for intergovernmental work to respond to climate change. Largely based on a precautionary principle, the UNFCCC advocated for action in the face of scientific uncertainty when the risk to human health was high
(Freestone, 2016). The UNFCCC was concerned with the stabilization of atmospheric
GHGs at a level which would prevent “dangerous anthropogenic interference with the climate system,” (United Nations, 1992). It also introduced the concept of “common but differentiated responsibility,” (United Nations, 1992), which is the idea that the largest historical and current shares of emissions belonged to developed countries, and that those nations, therefore, should take the lead on combatting the adverse effects of climate change. The Conference of the Parties (COP), is an annual meeting where member states of the UNFCCC can review the implementation of the Convention as well as review the national communications and emission inventories submitted by Parties, assessing the progress made to combat climate change.
The Kyoto Protocol was negotiated in 1997. The mandate of the Protocol was to return the CO2 emissions of developed (Annex I) countries to 5% below 1990 levels
(United Nations, 1998). The Kyoto Protocol introduced three flexibility mechanisms
(FMs) to aid parties to achieve their emissions reduction goal by creating more opportunities, Joint Implementation (JI), Clean Development Mechanism (CDM), and
Emissions Trading (ET). The JI mechanism enables Annex I parties to finance emission reduction projects in another Annex I country. Once the project is completed, the emission reduction credits obtained from that project are transferred from the country in which the project took place to the financing country. CDM projects are similar to JI
12 projects in that an Annex I country finances a project in another country to receive emission reduction credits. However, CDMs take place in developing (non-Annex I) countries and the projects are specifically designed to promote sustainable development and GHG emission reduction. ET enabled countries to purchase reduction credits from other countries who had surpassed their own reduction targets and count them towards their reduction targets, but only if it was ‘supplemental to ongoing domestic action’
(United Nations, 1998; Freestone, 2016). An example of ET being implemented is the cap and trade program that was established by the European Union (EU), the EU
Emissions Trading System (EU ETS), which operates in 31 countries (all 28 EU member countries, plus Iceland, Liechtenstein and Norway). These FMs were the first legal international legal instrument that proposed a market-based solution to a global environmental problem (Freestone, 2016).
Although adopted in 1997, the Kyoto Protocol did not enter into force until 2005 when it was ratified by Russia. In accordance with Article 23 of the convention, at least
55 Parties of the Convention needed to ratify the Protocol, and were required to account for at least 55% of the total carbon dioxide emissions for 1990 of Annex I Parties.
Notably, the United States (U.S.) did not ratify the Kyoto Protocol. In 1997, through the
Byrd-Hagel Resolution, the U.S. Congress unanimously declared that the U.S. should not be a signatory to any protocol to, or other agreement regarding, the UNFCCC negotiations in Kyoto in December 1997 or after which would either (1) mandate new commitments to limit or reduce GHG emissions from Annex I Parties unless others had to do the same or (2) result in serious harm to the U.S. economy (105th Congress, 1997).
Although this resolution was not legally binding, it signaled domestic resistance to any
13 agreement that may put the U.S. at a disadvantage to its key trading partners, particularly
China, or otherwise result in domestic economic hardship. The U.S. decision to not ratify the Protocol led to a gap in climate action and leadership from 1997 to 2005, as it was at the time the largest historic and current GHG emitter. Further, between 1997 and 2006,
GHG emissions were growing in rapidly developing economies, such as China and India, though under Kyoto, neither country would have been required to mitigate their emissions. Also notable is that Canada officially withdrew from the Kyoto Protocol in
2011, before the first phase ended in 2012, as the country had not met its reduction targets.
2.3.2. Targeting rBC for Near-Term Climate Change Mitigation
The Kyoto Protocol only applied to six GHGs: CO2, CH4, nitrous oxide (N2O), hydofluorocarbons (HFCs) perfluorocarbons (PFCs) and sulfur hexafluoride (SF6; United
Nations, 1998). Since the Protocol was adopted and ratified, other climate-forcing pollutants have been targeted to mitigate climate change, particularly those with shorter atmospheric lifetimes compared to that of CO2. The short atmospheric lifetime of rBC has made it, along with other short-lived climate pollutants (SLCPs) such as methane or tropospheric ozone (with atmospheric lifetimes of 12.4 years and one month, respectively; IPCC, 2007), a target for mitigation strategies around the globe (European
Investment Bank, 2016; Environment and Climate Change Canada, 2017). One reason that SLCPs are good targets for mitigation is because there is a more immediate effect following reduction measures due to their shorter lifetimes. It is also politically easier to
14 focus on regulating pollutants that have short-term effects, as these results will be noticeable more quickly, helping politicians win re-election.
Globally, diesel engines (20%), industrial coal (9%), residential solid fuel combustion (25%) and open biomass burning (40%), accounted for 94% of global rBC emissions in 2000 (Bond et al., 2013). Developing countries and economies-in-transition in Africa and Asia are dominated by residential coal and biomass fuels (60-80% of rBC emissions), while 70% of rBC emissions in developed countries in North America,
Europe, and Latin America are the result of diesel engines, industry, residential solid fuel, and open biomass burning (Bond et al., 2013). Mitigation efforts such as stringent regulations on diesel fuel consumption, or informational initiatives to educate people on the benefits of burning dry wood over wet wood, have already reduced rBC emissions globally (Carbon Limits AS, 2016; Environment and Climate Change Canada, 2017).
Although only 10-20% of global rBC emissions reach the Arctic (Gogoi et al., 2016), rBC regulations already in place in 2011 had the potential to reduce Arctic warming on the order of 0.7ºC by 2040 compared to projected estimates without those measures in place (United Nations Environment Programme, 2011). The effect of these mitigation efforts, specifically related to rBC, may be reflected in the rBC record in GrIS ice cores.
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Chapter 3. Methods
3.1. Drill Site Location and Sample Collection
This project uses the GrIS as an area that captures atmospheric rBC composition for circumpolar, Annex I countries within the Northern Hemisphere. We use a shallow firn core, which differs from an ice core in that firn is the intermediate metamorphic stage between snow and glacier ice, that was collected from Crawford Point on the GrIS by the
Program for Arctic Regional Climate Assessment (PARCA; Mosley-Thompson et al.,
2001; 2005) to document rBC deposition from 1980 to 2007. The firn core was retrieved in June of 2007, at the Crawford Point drill site (69°52’26.9” N, 46°58’03.2” W), at 2090 m elevation on the western side of the GrIS (Fig. 1). The core was drilled using an electromechanical drill, without the presence of drilling fluids. Once drilled, the core was wrapped in polyethylene and transported frozen to the Byrd Polar Climate and Research
Center (BPCRC) at The Ohio State University and stored at a minimum temperature of -
23°C. The Crawford Point (CP) firn core (core number F07) is 20.41 m long and comprises firn with intermittent ice lenses throughout its length.
3.2. Sample Preparation
All firn core sections were visually inspected to identify the presence and depth of changes in firn grain characteristics, dust layers, and ice lenses. Core sections were then cut at 3 cm increments (629 samples total) using a band saw that was housed in a cold room (-5C). The outer surfaces of the cut samples were scraped with a clean chisel to
16 remove possible contamination from the band saw blade and ice core barrel. Samples were separated into thirds and placed in individual Ziploc bags and stored frozen (-35°C) prior to analysis.
3.3. Contamination Testing
The band saw used here was also used to prepare an ice core from the Guliya
Glacier, Tibet. This is notable as Tibet potentially has 10 times the rBC deposition than
Greenland (Bauer et al., 2013). To assess the potential for cross contamination between the two cores during sample preparation, we conducted contamination testing on three previously uncut firn core samples from a firn core drilled in 1998 (core A) at the Dye 2
(66°28’52” N, 46°16’59” W) drill site on the GrIS Using a clean chisel, 10 cm of the core was removed and divided into two 5 cm sections. One of the sections was split down the middle, creating a completely uncontaminated cross-section with the chisel, while the other section was processed normally with the band saw. Samples were then analyzed for rBC and major ion concentrations (Table 1).
Two of the three samples (2 and 3) processed using the band saw have higher concentrations of BC with percent differences of 31.4% and 19.3%, respectively, than when prepared using the clean chisel, whereas one sample (1) when prepared with the chisel has a percent difference of 53.4% greater that of the sample prepared with the band saw (Table 1). The results of the ion analysis were similar. In two species (chloride and sulfate) the band saw resulted in higher concentrations two-thirds of the time (with a range of percent differences between 0.7 – 106.2%). Other ions (fluoride, nitrate, potassium, magnesium, sodium and calcium) had higher concentrations in two of the three samples prepared with the clean chisel (percent differences between 10.9 – 17
107.3%). The only ions that were consistent were for MSA and ammonium, where no
MSA was detected in any of the six samples, and the samples prepared with the band saw had lower concentrations of ammonium than the samples prepared without it (20.6 –
173.5 % difference). The individual ion and BC results showed that there was not often a consistent trend in whether the preparation with the band saw or clean chisel resulted in higher concentrations (the exception being ammonium). This indicates that there was no systematic contamination of the CP firn core resulting from the band saw.
Another observation of the contamination testing results is that there can be high intersample variability among the core sections tested. An example of this can be observed in the results for sodium. In sample 1, the sodium concentration was only 0.7% higher in the sample prepared with the chisel, showing low intersample variability.
However, in another core section (section 2), the sample prepared with the chisel had
84.3% greater concentration of sodium than when the band saw was used, indicating high intersample variability.
3.4. Refractory Black Carbon Quantification
rBC particles were quantified using a Single Particle Soot Photometer (SP2;
Droplet Measurement Technologies, Longmont, CO) located in a Class 100 clean room at
BPCRC. Assuming rBC density is 1.8 g/cm3 (Schwarz et al., 2012), the SP2 particle detection range was from 0.07 - 2 μm. The SP2 measures rBC concentration by particle incandescence using a Nd:YAG laser source under a known airflow. Introduced liquid samples are first nebulized, then reach a laser chamber when rBC particles are heated to their boiling point, at which time they emit incandescent light. The peak intensity of this emitted incandescence is linearly proportional to the rBC particles’ size and mass 18
(Schwarz et al., 2006; Slowik et al., 2007). To constrain the composition of the incandescing particle, the ratio between the broadband and narrowband incandescent signals can be used, as this ratio is related to the boiling point of the incandescent particle
(Schwarz et al., 2006; Schwarz et al., 2010; Menking, 2013). In this way, rBC is detected as particle incandescence in the absence of false-positive results from organic carbon combustion (Moteki and Kondo, 2007). Another advantage is that the SP2 methodology does not require sample tier filtration, allowing samples to be analyzed with less volume than is required by other methods, such as thermal-optical analyses (Menking, 2013).
The SP2 was calibrated using Aquadag standards ranging from 0-12 µg/L each day prior to analysis. Frozen firn core samples were melted at room temperature, transferred to 50 ml polyethylene tubes, and sonicated for 20 minutes immediately prior to analysis to minimize the effect of rBC particle adherence onto the tubes (Kaspari et al.,
2011). During measurement, samples were stirred with a magnetic stir bar to encourage the particles to remain in solution rather than adhering to the tubes. A peristaltic pump introduced the liquid sample to a Cetac Marin-5 pneumatic nebulizer and then to the SP2 at a flow rate of 0.3 g/min, using a carbon-free carrier gas (Wendl et al., 2014). A
Nd:YAG laser with 5V power was used to heat the rBC particles to the point of incandescence. As incandescence is empirically related to the mass of rBC, the SP2 can quantitatively measure the mass of BC particles individually and exclusively, independent of light-scattering material coatings (Slowik et al., 2007; Kaspari et al.,
2011). The data output from the SP2 was processed using the PSI toolbox (Droplet
Measurement Technologies, Longmont, CO) on the Igor Pro V.7 software platform.
19
To determine the reproducibility of the rBC analysis, twelve samples were recut and re-analyzed for rBC concentration on a second day. These samples were prepared using the same methods described above. The results of both the first and second analyses were compared. By calculating the R2 value for the line of best fit, which had a slope of 0.85, was 0.83 (Fig. 2A). Compared alongside one another, five of the duplicated samples (1-3, 9, 11) showed high reproducibility, falling within 10% of each other (Fig.
2B). Two samples (4 and 10) fell within 20% of their respective duplicates. Five samples
(5-8, 12) were over 20% of their duplicate values, showing lower reproducibility.
Whether using the original samples or the replicates, the interpretation of the dataset would not change, with the exception of the Sample 7, where in the original dataset, it is a slight decrease from Sample 6 (2.3 to 2.2 µg/L), but it increases from 4.6 to 6 µg/L in the replicate testing. Together, these indicate that while there is slight intersample variability within the core, the repeated samples were not significantly different from the original samples. This intersample variability may be due to ice lenses, or partial refreeze layers that did not run through the entire horizontal cross section. Only two samples (5 and 7) did not contain any kind of refreeze layer or ice lense.
3.5. Cation and Anion Quantification
Major ion analysis was conducted to enable firn core dating and possible rBC source allocation, as ion concentrations can vary seasonally (Rasmussen et al., 2006).
Anion and cation analyses were conducted in the Class 100 clean room at BPCRC by ion chromatography (Dionex ICS 3000; Dionex Corp., Sunnyvale, CA). Ions analyzed
2- - - included sulfate (SO4 ), methanesulfonic acid (MSA), chloride (Cl ), fluoride (F ), nitrate
- + 2+ + 2+ (NO3 ), sodium (Na ), calcium (Ca ), potassium (K ), magnesium (Mg ), and 20
+ ammonium (NH4 ). Samples were melted at room temperature immediately prior to analysis.
For the anions, a Dionex IonPac AG11 guard column (4 X 50 mm I.D.) and AS11 analytical column (4 X 250 mm I.D.) were used. Three eluents of varying concentrations of NaOH (3.8 x10-4 M, 0.01 M, 0.5 M) were used throughout sample analysis over a gradient. Cations were analyzed using a Dionex IonPac CG12A guard column (4 X 50 mm I.D.) and a CS12A analytical column (4 X 250 mm I.D.). The eluent was an isocratic
1 M H2SO4 solution.
- - - 2- + + 2+ + 2+ Replicates of standards for F , Cl , NO3 , SO4 , Na , NH4 , Ca , K , and Mg were analyzed twice daily over the course of the experiment in order to quantify the
2- possible error within the measurements (Table 2). SO4 had the largest standard deviation
2+ + + - among samples, at 11.73% the average. Ca , K , Na , and NO3 had standard deviations
2+ - + - of 11.18, 8.22, 7.55 and 7.22%, respectively. Mg , Cl , NH4 , and F had standard deviation values of 2.64, 1.96, 0.64, and 0.55%, respectively.
The ion analyses performed for this study were missing samples from 5-5.5 m depth, due to sample volume limitation. Further, samples from 16.3-17.3 m depth were not analyzed for major ion concentrations, as the core during sample pre-processing.
3.6. Dissolved Organic Matter Characterization and Absorbance Quantification
The dissolved organic matter (DOM; which is comprised of biomolecules from both living and decaying organisms) within the CP firn core was examined to deterime whether the rBC emissions source originate from biomass or fossil fuel combustion.
Similar to rBC, DOM also absorbs in the ultraviolet (UV) and visible part of the electromagnetic spectrum, and has an impact on the radiative budget (Morris et al., 21
1995). Both fluorescence and absorbance were characterized using an Aqualog spectrofluorometer (Aqualog; HORIBA Scientific, Edison, NJ).
Depth intervals sampled of the core were from 0-2.8 m, 5-6m, 13.3-15.3m, and
16.4-20.4 m to determine if there were changes in deposition at the bottom, middle, and top of the core. Core sections were melted at room temperature immediately prior to analysis. Samples (284 total) were placed in a quartz cuvette with a 1 cm pathlength and analyzed for total fluorescence, with excitation wavelengths ranging from 400-240 nm in
3 nm increments, and emission ranging from 621.24-211.85 nm in 3.28 nm increments, at a 10 s integration time. The sum of the slit widths was set to 10 nm, and first and second order Rayleigh scattering were masked as a part of post-processing. Fluorescence emission was normalized to a quinine sulfate standard (Starna Scientific Ltd., Atascadero,
CA).
Parallel factor analysis (PARAFAC) was used to identify individual fluorescing components (fluorophores) that were responsible for variance in the total fluorescence spectra dataset (excitation-emissions matrices or “EEMs”; 237 of the total samples were used, as some EEMs were removed from the model due as outliers). PARAFAC is a multi-way chemometric method that decomposes data to identify components that produce the variability in an ensemble of matrices (Bro, 1997). Post-processing to the
EEM data included incorporating a non-negativity constraint and removing Raman and
Rayleigh-Tyndall scattering using SOLO (Eigenvector Research Incorporated, Manson,
WA). The resultant 3-component model explained 97.52% variance within the EEM dataset. It had a core consistency of 90% and a half-split value of 96%. Both core consistency and half-split results can be used to “evaluate the appropriateness” of a
22
PARAFAC model (Murphy et al., 2013). Core consistency values decrease when too many components are selected for the model (for this research, the core consistency went from 90 with a 3-component model to 70 when a 4-component model was attempted;
Murphy et al., 2013). Half-split analyses divide the dataset into two halves and create a
PARAFAC model on both halves, individually. A high half-split value, near 100%, indicates that the same model was created for both halves of the dataset, and that the correct number of components was selected for the model (Harshman and Lundy, 1994;
Bro, 1997).
3.7. Back-Trajectory Analysis
Back-trajectory analyses were conducted using the National Oceanic and
Atmospheric Administration’s (NOAA) Hybrid Single-Particle Lagrangian Integrated
Trajectory model (HYSPLIT; Stein et al., 2015) to determine the origin of air masses that passed over CP, and thus the catchment region for atmospheric aerosols that accumulate at the CP site. To understand the origin of the air masses reaching CP originated during winter and summer seasons, daily analyses were conducted for January and July from
1980-2007 (each year recorded within the firn core) at 6 hour intervals. Meteorological data were obtained from the National Center for Atmospheric Research and the National
Center for Environmental Protection (NCAR/NCEP) 2.5-deg global reanalysis archive from NOAA’s Air Resources Laboratory (ARL) server. Trajectories extended back 168 hours (one week), to account for the atmospheric lifetime of BC, and the elevation of the starting location was set to 10 m above ground level. Post-processing was conducted in
MATLAB (MathWorks, Natick, MA) to convert back-trajectory results into frequency
23 plots to visualize the frequency distribution of atmospheric aerosols over the Arctic and determine the source regions of BC particles that were deposited at the CP site.
3.8. Policy and Profiles of Key States
The legal and economic developments and the primary BC emission sources of four key states were examined for this research: Canada, the Union of Soviet Socialist
Republics (USSR) and the Russian Federation (collectively referred to as Russia), the
U.S., and the Nordic European countries that are member states of the EU: Denmark,
Finland, and Sweden. These countries were selected as a result of the HYSPLIT analyses that indicate that BC originating within these countries could reach the CP site within the atmospheric residence time of BC. Literature reviews were conducted to reconstruct a history of economic, legal, and environmental developments within these countries throughout the twentieth century by examining sources from government documents, academic journal articles, and reviews of enacted laws.
24
Chapter 4. Results and Discussion
4.2. Firn Core Dating with Ion Analysis Results
- + - 2+ 2- Concentrations of MSA, Cl , Na , NO3 , Ca , and SO4 measured throughout the core were used to identify annual layers in the CP firn core (Fig. 3A and 3B). These ions were selected as they typically have clear annual signals. Annual signals of Ca2+ occur in the spring as a result of high mineral dust, which is derived from the chemical and physical weathering of crustal materials and the subsequent formation and transport of dust (Fischer et al., 2007). Spring dust storms occur annually throughout Asia, and it is through these storms that dust can reach high enough elevations to be transported to the
Arctic in the spring (Fischer et al., 2007; Quinn et al., 2007; Kuramoto et al., 2011). This contributes to the springtime Arctic haze phenomenon, which is an annual event where high concentrations of anthropogenic aerosols from Europe and northern Asia reach the
Arctic and decrease visibility (Zou and Zhai, 2004; Frossard et al., 2011). Arctic haze
2- also contains sulfate aerosols, which allow us to use peaks in SO4 concentrations to identify spring and summer deposition in the CP firn core, although this signal is noisy
- (Rasmussen et al., 2006; Frossard et al., 2011). NO3 has observable peaks in both the summer and the winter-to-early-spring on the GrIS (Kuramoto et al., 2011). Summer
- NO3 likely originates from natural biomass burning, biogenic soils, and lightning, whereas winter emissions are anthropogenic (Hastings et al., 2004; Kuramoto et al.,
2011). MSA, an oxidation product from dimethylsulfide (DMS), is mainly produced via the photochemical activity of phytoplankton (Legrand and Mayewski, 1997). In the
25 winter, when sea ice expands in the Arctic, phytoplankton remain largely inactive.
However, as sea ice melts in the spring and summer, Arctic water is exposed and photosynthesis occurs more abundantly, resulting in an [MSA] peak in the summer
(Rasmussen et al., 2006; Kuramoto et al., 2011). [Na+] and [Cl-] will often peak in late winter or early spring in Greenland, originating from sea-salt aerosols, which derive from the open ocean as sea ice melts and sea surface spray evaporates (Steffensen, 1988;
Kuramoto et al., 2011; Lewandowska and Falkowska, 2013).
The results from these ions within the CP firn core were used to identify annual layers within the core. The core was drilled in the summer of 2007, which corresponds to the top of the core. Annual winter peaks in ion concentrations were counted backwards from 2007, and showed that the firn core spanned from 1980-2007 (Fig. 3A). However, due to the missing ion data for depths from 16.3-17.3 m and 5-5.5 m, there may be missing annual layers. Based on annual firn accumulation at CP (Porter and Mosley-
Thompson, 2014) around 2001 (5-5.5 m depth) there may be one missing annual layer, and there may be two layers missing around 1986 (16.3-17.3 m depth). Further, as ion concentration data for CP is noisy, there may have been up to two layers that were added or missed. Dating for the CP firn core is therefore likely accurate to ±5 years after 1986.
4.3. Quantification of rBC within Crawford Point Firn Core
rBC concentrations throughout the core ranges between 0.02-19.93 μg/L (Fig. 4).
The median rBC concentration is 0.862 μg/L, and 75% of rBC concentrations are below
1.43 μg/L. Fifty percent of rBC measurements are between 0.56-1.43 μg/L, and only 10% of samples had BC concentrations greater than 2.36 μg/L. These values are comparable to rBC concentrations reported from different locations across the GrIS from similar time 26 periods (Table 3). The two highest peaks in rBC concentration both occur in 2002, while the third and fourth largest peaks occurred in 1989. The single lowest concentration of rBC also occurred in 1989. However, trends in these data can be more readily observed when noise is minimized plotting the median of rBC concentration with time (Fig. 5)
The annual median removes much of the noise within the data and indicates that
2002 had the highest median concentration in rBC deposition (6.00 μg/L), followed by
1985 (1.86 μg/L). The lowest value for the rBC concentration yearly median was found in 2004 (0.5 μg/L). There is a detectable declining trend in rBC deposition to the GrIS, with the exception of 2002, wherein the median deposition of rBC did not exceed 0.8
μg/L after 1997, whereas from 1980-1990, the concentration did not fall below this same value. 64% of years recorded in the CP firn core had annual peaks in rBC concentration occurring in the summer.
These trends (Fig. 5 and Fig. 6) show that 1989 had peaks in rBC concentrations at a time when BC deposition at the CP site was generally higher than it was at the beginning of the 21st century (1980-1990 vs 1998-2007). The plots also show that the high rBC deposition in 2002 was anomalous compared to lower emissions trend at that time, suggesting a short lived increase against a longer term trend. A regression was conducted for the annual mean rBC concentration data to determine if there was a statistically significant declining trend in rBC deposition (Fig. 6). The data from 2002 had to be removed from the regression, for when it was included the anomalously high concentration made the regression slope erroneously positive. The slope of the regression was -0.02 [R2 = 0.23, p < 0.01].
27
4.4. Dissolved Organic Matter Characterization and Absorbance
As described in Section 3.6, a PARAFAC model was created to identify fluorophores that are responsible for variation in the fluorescence properties in DOM in the CP firn core. Component 1 (C1; representing 44.6% of the model) has a primary peak at an Ex/Em wavelength of 241/348 nm, and a secondary peak at 289/348 nm, which is characteristic of protein-like material (Coble, 2014; Fig. 7A). Component 2 (C2; representing 40.2% of the model) has a peak at Ex/Em wavelength 244/322 nm and is associated with simple lignin phenols, which are terrestrial in origin and can be transported into natural waters (Coble, 2014; D’Andrilli et al., 2017; Fig. 7B).
Component 3 (C3; representing 15.2% of the model) has a primary peak at 271/325 nm, and a secondary peak at 271/306 nm (Fig. 7C). This component has been associated with humic-like material, which is derived from soils and vegetation (Coble, 1996; D’Andrilli et al., 2017). Together, the presence of C2 and C3 suggest that organic matter (OM) found within the CP firn core is associated with allochthonous sources, derived from soils and lignin-containing plants before being transported to the GrIS. C1 may be autochthonous and produced in situ by microbes (Uhlig et al., 2015).
The abundance of protein- and humic-like components (C1 and C3) are similar at the beginning (2007) and end (1980) of the firn core, with mean values of 0.40 versus
0.54 and 0.42 versus 0.31, respectively, indicating that their abundance may not have been considerably different in the 1980s and the 2000s. The values of the simple lignin phenol-like (C2) loadings, however, do change throughout the core, and are 1.33 in 2007, and 0.15 in 1980 (Table 4). There are peaks in 1986 of all three components that nearly coincide with a peak in rBC concentration (Fig. 8). This may suggest that this particular
28 peak in BC is the result of biomass burning, as C2 and C3, which are likely aromatic, may be transported via wind after a forest fire event.
As previously stated, DOM behaves radiatively, thus the aromaticity of the DOM was measured using specific ultraviolet adsorption (SUVA). Defined as the UV absorbance of a water sample at a given wavelength normalized for the dissolved organic carbon (DOC) concentration, and for this the absorbance at 254 nm is commonly used
(Hansen et al., 2016). Although DOC concentration was not measured, the absorbance of the samples at 253 nm should provide some information as to the aromaticity of the organic matter between samples, assuming DOC concentration is roughly constant
(Peacock et al., 2014). As C2 and C3 are likely aromatic, and if a correlation exists between their values and the absorbance at 253 nm, it would indicate that aromaticity is driving the trends in absorbance. If no correlation exists between the datasets, then DOC concentrations are likely driving absorbance trends, resulting in more radiative forcing from the DOM found within the CP firn core. Spearman rank correlations were performed for both C2 and C3 with absorbance at 253 nm. The Spearman Rho for C2 was 0.37 [n = 274, p < 0.01] and the Rho for C3 was 0.35 [n = 274, p < 0.01]. Both results indicate weak positive correlations between the aromatic components and absorbance at 253 nm. This weak correlation suggests it is more likely that DOC concentration is driving the absorbance. Greater concentrations of DOC would lead to more radiative behavior within the CP core.
4.5. Post-depositional transportation through glacier ice mass
To determine if post depositional redistribution of rBC occurs at the CP site, three separate analyses were conducted. The first analysis examined where visible 29 refreeze layers in the firn core occurred, and what the concentration of rBC was in corresponding samples. These visible refreeze layers of bubble-free ice indicate summer melt of surface snow that has percolated downward into the glacier before refreezing. If rBC was mobilized by melt water within the snowpack, then these refreeze layers should be enriched in rBC. Second, the ratio of Mg2+/Na+ was used as an indicator of melt having occurred within a sample. If rBC has been mobilized by melt percolation, then rBC concentrations should be low at depths where melting has occurred. Third, snowpit density measurements were compared to rBC concentration. Snowpack density from three pit walls at the CP drill site were measured when the core was retrieved (Mosley-
Thompson et al., 2001; 2005). These snowpit depths overlapped with the firn core depths over a 1 meter interval, and were used as a proxy for the firn core density. Within near- surface firn and the snowpack, the main control of changes in density comes from the refreezing of meltwater, which increases the density (Braithwaite et al., 1994). Surface katabatic winds in Greenland will also increase the density of surface snow as the snow is compacted from the exerted force (Fausto et al., 2018). These results were used as a proxy for the density of the core to see if it correlated to rBC concentrations.
4.5.1. Post-Deposition Transportation Analyses Results
Before samples were prepared for analysis and cut, each core section was visually characterized for refreeze layers as indicated by ice lenses. These depths were compared to the rBC record (Fig. 9). Of the 28 years documented in the CP firn core, 17 (61%) of the annual peaks in rBC concentration coincide with the presence of a refreeze layer. It is also noteworthy that the two largest peaks in rBC concentrations, both of which fall in
30
2002, do not contain refreeze layers, although the peaks in 1989 (the third and fourth largest peaks) do contain refreeze layers. Of the 165 samples that contained refreeze layers, 114 (69%) are associated with lower concentrations of rBC.
The ratio of Mg2+/Na+ in a sample can be used as an indicator of melting for three reasons. The two ions have the same source (sea-salt), do not have sharp peaks in wet snow, and are flushed through the snowpack during thawing events: with Mg2+ moving at a faster rate than Na+, ultimately reducing Mg2+ in a sample that has experienced melt
(Iizuka et al., 2002). A ratio of Mg2+/Na+ between 0.01-0.05 is indicative of flushing by meltwater due to snowpack melting while ratios greater than 0.13 indicate the refreezing of percolated melt water (Iizuka et al., 2002). rBC was compared to a smoothed (5-point running mean) ratio of Mg2+/Na+ (Fig. 10). 12 of the 22 peaks (54.5%) for the Mg2+/Na+ ratio (peaks 1-2, 4, 6-8, 10-11, 13-14, 16, and 19) that were greater than 0.13 coincided with peaks in the rBC concentration.
Finally, rBC concentration for the first meter of the CP firn core was compared to the density measurements of the first meter of snow from the CP drill site (Fig. 11), and a
Spearman Rank test was performed. The Spearman Rho value was -0.26 [n = 30, p >
0.15], which suggests a weak negative correlation. However, the p-value was not significant at 90% confidence level. These results are not what would be expected if rBC was being transported into refreeze layers, because those layers would have higher density than the surrounding firn.
31
4.6. Determining rBC Emission Sources
4.6.1. Back-Trajectory Analyses
Back-trajectory analyses were conducted using NOAA’s HYSPLIT model for
January and July from 1980-2007. January and July were selected to represent winter and summer circulation, respectively. During January, there was a high frequency of trajectories that originated in Canada, Europe, and the Russian Arctic (Table 5).
Approximately 10% of January trajectories originated over the European continent, 26% over Canada, 0.6% over both the Russian Arctic and the U.S., and 55% of trajectories originated over the GrIS itself (Fig. 12). In July, the frequency of trajectories that originated over Russia and Europe declined, with approximately 0.3% of trajectories originated in Europe (Table 5).
Five years (1986, 1989, 1994, 2002, and 2005) were also chosen for closer examination of the trajectories in their respective winters and summers, again using the months of January and July to capture the trajectories in these seasons. These years were selected because they either had peaks in rBC concentration (1989 and 2002), or aid in showing the declining trend in emissions observed from the running medians over the timespan of the firn core (1986, 1994, and 2005; Table 5). For all 5 years, July showed 7- day back-trajectories originating from North America, the GrIS, or in the middle of the
Atlantic Ocean. January had more variability. In 1986, all 7 day back-trajectories originated over the GrIS. In 1989 and 1994, 9% and 4% of back-trajectories, respectively, originated over Canada, whereas the rest were over Greenland. In January of 2002, 17% of trajectories originated over Canada, 10% originated over the EU, 5% over the Arctic
32
Ocean, and 63% over Greenland. In 2005, 23% of January back-trajectories originated in
Canada, 9% over Europe, and the rest over Greenland.
These results show that Canadian emissions, both in the winter and summer months, reach CP, though there is an increasing trend in the frequency of winter emissions reaching the GrIS. Since the turn of the century, European winter emissions also reached CP. U.S. emissions, particularly in the North East, also had the ability to reach the drill site. Although trajectories during these five years did not originate in the
Russian Arctic, as the frequency plots show, trajectories do occasionally originate from that region (0.6% if January trajectories from 1980-2007), though less frequently than others (Table 5).
4.6.2 Using Non-Sea Salt Sulfate to Understand rBC Emission Source
Two major sources of atmospheric sulfate are biogenic production over the oceans (Charlson et al., 1987) and sulfate that is anthropogenically emitted over land mass from fossil fuel combustion, particularly in the Northern Hemisphere (Langner et al., 1992; Gao et al., 1996). Non-sea-salt sulfate (nss-S; sulfate resulting from sources other than marine sources) was calculated to determine if anthropogenically produced sulfate was being deposited onto the GrIS at CP using:
2- + [nss-S] = [SO4 ] – (0.25*[Na ]). (1)
The use of the constant 0.25 was derived from the sulfate:sodium ratio in seawater. The results of this calculation were then correlated to the nss-S to rBC concentrations to determine if nss-S was the only source of rBC, or if there were other, non-fossil fuel based sources (Fig.13). A Spearman Rank test, which measures the strength and direction
33 of association between the two ranked variables, was then conducted. Spearman’s Rank test is a nonparametric version of the Pearson Correlation, and this test is appropriate as the data used are not normally distributed. The Spearman R constant for nss-S and BC is
0.3 [n = 629, p > 0.01], indicating a weak positive correlation, and that there is at least one additional, non-marine source of sulfate.
34
Chapter 5. Policy Results and Discussion:
5.1. Framing the Importance of Economic and Legal Developments
Throughout the 20th century the terms ‘economic development’ and
‘industrialization’ were nearly synonymous. To be considered a developed country with a thriving economy, a country needed to increase production and industry (United Nations,
2014). Understanding this relationship is important when considering general trends in the dichotomy between economic development and environmental legislation.
Historically, emissions of greenhouse gases (GHGs), aerosol particles, and other atmospheric pollutants have risen at the same time as gross domestic product (GDP;
Klyza and Sousa, 2013; Fridley et al., 2017). The legal developments described in section
2.3, such as the creation of new agencies and laws to regulate GHGs and other pollutants, and the creation of the UNFCCC, provided a platform to address global climate change and intergovernmental actions, such as air pollution regulations. For these reasons, understanding when such legal and economic developments occurred can provide context for trends in emissions for individual countries.
5.2. Overview of rBC Emissions Inventories
Although rBC was not explicitly regulated in the 20th century (although it was indirectly regulated through controls on PM, soot, and co-pollutants such as SO2), as the scientific community has reached consensus on the important role that rBC plays in the climate system, and the global community has recognized its potential as a target for
35 mitigating the adverse effects of short term climate change. To mitigate rBC’s emissions, however, emissions inventories of the sources of anthropogenic rBC need to be developed for each country. Most inventories are based on estimates of the EC and organic carbon (OC) content of PM2.5 (particulate matter that is under 2.5 μm in diameter) rather than a direct measurement of rBC. These inventories assume that rBC and EC (the light-absorbing, and refractory constituents of carbonaceous aerosols, respectively; Singh et al., 2014) emissions are identical (Arctic Contaminants Action
Program, 2014). However, while similar, there are differences in the emission concentration of rBC and EC that are derived from the same source (Singh et al., 2014).
To obtain rBC emission concentrations, a single emissions factor for a specific technology is multiplied by the fuel consumption (Arctic Contaminants Action Program,
2014). However, differences in how sources are grouped, how data are collected, and which emissions factors are used can lead to uncertainty and make comparing inventories difficult. With this potential uncertainty in mind, a comparison of various emission inventories shows that the U.S. and Russia emit more rBC annually than Canada or the
Nordic European countries (Fig. 14).
5.3. The Arctic Council
The Arctic Council, whose members include Canada, Denmark, Finland, Iceland,
Norway, Russia, Sweden, the U.S., and six organizations representing Arctic indigenous peoples, is the leading intergovernmental forum which promotes working relationships between Arctic States and Arctic indigenous communities for Arctic issues, such as sustainable development and Arctic protection (Arctic Council, 2018). The work of the
Arctic Council is primarily carried out within six working groups, two of which are 36 important for rBC emissions: the Arctic Contaminants Action Program and the Arctic
Monitoring and Assessment Program. In the 2010s the Arctic Council has fostered a number of intergovernmental projects, particularly in the Russian Arctic (described in more detail in Section 5.6.2).
5.4. Profile of the United States of America
5.4.1. Overview of rBC Emissions
A rBC Emissions Inventory concluded that diesel engines were the largest source of anthropogenic rBC in the U.S., followed by biomass burning and residential combustion (Reff et al., 2009). Open biomass burning and mobile sources (that is, emission sources that are able to move from one location to another) accounted for 82-
87% of the rBC emissions in the United States. Energy generation, industry, residential burning and other sources accounted for approximately 7%, 1%, 4%, and 1% of emissions, respectively (Carbon Limits AS, 2016; California EPA, 2017). It is important to note that wildfires were not included in the biomass burning calculations, as they are not anthropogenic emissions. rBC emissions in the U.S. peaked around 1910 and a little before 1980, and by the beginning of the 21st century, started to increase, again (Fig. 15;
Junker and Liousse, 2008). This second peak before 1980, and subsequent decline in emission, could be related to improvements in industrial and vehicle efficiency and tail- pipe emissions standards, and related to the implementation and strengthening of the PM,
SO2, and NO2 National Ambient Air Quality Standards (NAAQS) as required by the
CAA (discussed in more detail in Section 5.4.2). In 1979, the U.S. became a signatory of the United Nations Convention on Long-Range Transboundary Air Pollutants
37
(CLRTAP), which was the first international treaty to address transboundary air pollution on a regional basis, and may have also led to declines in rBC emission after 1980
(discussed in more detail in Section 5.7.2).
5.4.2. Legal and Economic Developments and rBC Mitigation
Comprehensive environmental protection legislation was not enacted at the federal level until 1964. The U.S. Congress signed the National Environmental Protection
Act in 1970, which notably established the Environmental Protection Agency (EPA).
Between 1964 and 1980, the U.S. Congress passed 22 stringent and robust environmentally-centered laws, covering issues including air and water pollution, endangered species, and hazardous waste (Federal Environmental Laws, 2011; Klyza and
Sousa, 2013). Although no federal laws in the U.S. address rBC explicitly, the Clean Air
Act (CAA; 1970) lists atmospheric PM (both PM2.5 and PM10, PM under 10 μm in diameter) as a criteria pollutant, setting NAAQS for their atmospheric concentrations
(Federal Environmental Laws, 2011). In 1971, PM (using total suspended particles as an indicator) had a primary standard (set to protect public health) of an annual geometric mean of 75 µg/m3, which was not to exceed 260 µg/m3 more than once per year.
Secondary standards (to protect public welfare, such as visibility) were annual geometric means of 60 µg/m3, and concentrations were not to exceed 150 µg/m3 more than once per year (EPA, 2018). Since the NAAQS for PM were established, they have been strengthened four times. Currently, PM2.5 has a primary standard of an annual arithmetic mean, averaged over 3 years, of 12.0 µg/m3, and an annual secondary standard of 15
3 3 µg/m . In a given 24-hour period, PM2.5 concentrations are not to exceed 35 µg/m . PM10
38
(particulate matter that is less than 10 micrometers in diameter) is not to exceed 150
µg/m3 within a 24-hour period more than once a year (U.S. EPA, 2018). By strengthening standards over time, polluting industries are able to become gradually more efficient, and national standards make it possible for businesses to comply with regulations without unduly negatively impacting themselves financially.
In an effort to combat potentially costly regulations in the 1980s, regulated industries claimed legislation put an ‘undue burden’ on them. As these businesses began heavily financing the campaigns of congressional representatives who would oppose environmental legislation and support their interests, hence Congress became gridlocked on environmental issues by the 1990s (Klyza and Sousa, 2013). As such, no major environmental law was passed federally since the CAA Amendments of 1992 until the
Toxic Substances Control Act was reformed in 2016 (Federal Environmental Laws, 2011;
114th Congress, 2016). This gridlock has led state and local governments to take the initiative on environmental regulation. In particular, States such as California have imposed air pollution standards, primarily through clean energy initiatives, that are lower than the federal NAAQS (Klyza and Sousa, 2013). It is in this vein that it has been possible to test a number of mitigation initiatives, such as cap and trade programs, on smaller scales, before federal adoption of those measures occur.
The emission of rBC has been targeted indirectly at all levels of government within the U.S. through a mixture of regulatory, economic initiatives and information dissemination tactics (Carbon Limits AS, 2016). Economic incentives to mitigate rBC- related emissions include discounted prices to change-out wood stoves and supplementing other environmental or mitigation-centered projects. These methods,
39 particularly those aimed at replacing older fleets with newer models, have effectively mitigated rBC emissions from the transportation and residential combustion sectors
(Carbon Limits AS, 2016). The federal government has sponsored information campaigns like Burn Wise Program, which educates people on different ways to improve air quality and save money using wood-burning appliances, replacing or retrofitting old units, and has distributed health and safety awareness kits in relation to rBC. There were also voluntary retrofit programs, such as the Clean Diesel Campaign, the objective of which was to replace or upgrade older technologies with newer engines (Carbon Limits AS,
2016).
Promulgation of the CAA has also led to a reduction in rBC emissions in multiple ways. For example, because the law lists particulate matter as a criteria pollutant, both
PM2.5 and PM10 are regulated at the federal level through standards for new on- and off- road engines and new wood burning stoves. Retrofit programs for legacy mobile diesel engines have also been in place, such as the 2008 Clean Diesel Campaign and the
SmartWay Transport Partnership (Carbon Limits AS, 2016). rBC emission is also indirectly reduced through the regulation of co-pollutants such as sulfates and nitrogen oxides. For example, scrubbers are used in smokestacks to mitigate SO2 emissions to prevent acid rain, but scrubbers also remove rBC and other atmospheric pollutants from being emitted into the atmosphere.
Some states have adopted more stringent regulations than are required federally.
For instance, rBC emissions in California have been reduced by over 90% since the
1960s, and it is estimated that existing regulation in California will lead to reduction of
75% of mobile source rBC emissions between 2000 and 2020. Such reductions are the
40 result of reducing on-road vehicle diesel particulate matter emissions in an effort to reduce carcinogenic emissions and improve air quality. To further reduce emissions,
California set a goal to reduce 50% of all anthropogenic rBC from 2013 levels by 2030
(California EPA, 2017). Other actions taken by states are being led by the U.S. Climate
Alliance, a bipartisan coalition of 17 governors from California, Colorado, Connecticut,
Delaware, Hawaii, Maryland, Massachusetts, Minnesota, New Jersey, New York, North
Carolina, Oregon, Puerto Rico, Rhode Island, Vermont, Virginia and Washington. The
U.S. Climate Alliance announced in June of 2018 a commitment to reducing SLCPs, including rBC (United States Climate Alliance, 2018).
rBC mitigation action in the U.S. is dominated by setting industrial and vehicular transportation emissions standards, and retrofitting or replacing older generations of engines and wood-burning appliances for newer technologies. These formats of regulatory initiatives are beneficial in that they set industry-wide standards that enable industrial plants to adhere to the new standards without being placed at an economic disadvantage compared to their competitors. A drawback of these methods is that there is no inherent incentive for regulated industry to reduce emissions beyond federal standards
(Klyza and Sousa, 2013).
5.5. Profile of Canada
5.5.1. Overview of rBC Emissions
In 2014, both on- and off-road diesel engines were the largest source of anthropogenic rBC in Canada, accounting for over 40% of its emissions (ECCC, 2017).
Residential wood burning, at 28%, was the second largest source, followed by rail and
41 marine transportation at 12.3%. Although the sources are grouped differently be sector, this inventory is similar to a 2006 inventory, when on and off-road diesel accounted for
60% of emissions, followed by residential wood burning at 14%, then shipping and energy/industrial production, each accounting for 10% of rBC emissions (Arctic
Contaminants Action Program, 2014; ECCC, 2017). In 2015, approximately 80% of
Canadian energy production came from either coal or natural gas (National Energy Board
Canada, 2017). From 2013 to 2016, Canadian rBC emissions have decreased by 18%
(ECCC, 2018). This recent decrease in emissions may be a result of the incentives in place to encourage the replacement of residential wood burning appliances and diesel engines for newer, cleaner technologies (discussed in more detail in Section 5.5.2).
5.5.2. Legal and Economic Developments and rBC Mitigation
Under the Canadian Constitution, the protection and promotion of the environment is a responsibility that is shared between the Canadian government and the provinces and territories. Environment and Climate Change Canada (ECCC) is the primary federal department for a large variety of environmental issues, working closely with the Canadian Environmental Assessment Agency and Parks Canada. To aid local efforts to regulate PM emissions and air quality, the federal government has released a number of guidance documents and non-binding protocols. Several Canadian provinces and municipalities including British Columbia, Yukon territory, and the city of Montreal have economic incentives in place to promote citizens to replace wood stoves in favor of less-polluting technology (Arctic Contaminants Action Program, 2014; ECCC, 2017).
42
In 1999, the Parliament of Canada passed the Canadian Environmental Protection
Act (CEPA), the goal of which was to prevent pollution from a variety of wide range of sources and to protect the environment and human health while contributing to the country’s sustainable development (CEPA, 1999). CEPA regulates air pollution through controlling the quality of fuels used in transportation, sharing the responsibility of on- road vehicular emissions with Transport Canada and incorporating off-road vehicular emissions into regulations. CEPA includes a provision that allows the Minister of ECCC to address sources of atmospheric pollution that my pollute the air in another country or where that pollution violates Canadian international agreements (CEPA, 1999).
Three federal departments – Natural Resources Canada, Environment Canada, and Health Canada – worked together to create the Burn it Smart Programme from 2002-
2007. In the Programme, educational workshops led by scientists, local fire brigades, and non-governmental organizations, were held throughout the country to encourage people to update their wood-burning appliances and learn about the important impact wood moisture has on rBC and other PM emissions. In a follow-up survey, 73% reported the workshop positively changed how they burned wood, 34% of responders updated their wood-burning appliances (90% of which were EPA-approved products), and 41% intended to change out appliances for cleaner technology (Arctic Contaminants Action
Program, 2014).
There is currently an agreement between the Canadian and United States governments that requires ships sailing within 200 nautical miles of Canadian or
American coastlines, excluding Arctic waters, to burn fuel with a sulfur content less than
0.1%. This agreement, which is referred to as the North American Emission Control
43
Area, is expected to reduce PM2.5 emissions 74% by 2020 throughout North America
(U.S. EPA, 2010).
Recently updated regulations for new diesel vehicles and engines have been enacted at the federal level (Carbon Limits AS, 2016). Other near- and long-term approaches taken to mitigating the major sources of Canadian rBC emissions include regulating new and existing stationary diesel sources and regulating both new and existing wood-burning appliances. ECCC is currently working to propose new regulations for new stationary diesel engines (ECCC, 2017).
5.6. Profile of USSR and Russian Federation (Russia)
5.6.1. Overview of rBC Emissions
Preliminary results of the National Emissions Inventory in 2016 showed that 52% of all rBC in the Russian Arctic originated from off-road diesel sources, such as agriculture, railways, mining, and construction. It was also reported that 70% of on-road diesel emissions were sourced from heavy-duty trucks, while cars only accounted for 4% of on-road diesel emission sources (Arctic Council, 2016; 2017). Flaring and residential biomass burning are also significant sources of rBC in the Arctic and in Russia (Carbon
Limits AS, 2016; Arctic Council, 2017). There currently is not enough information available to assess the success of the Russian rBC mitigation actions to decrease rBC emissions.
44
5.6.2 Legal and Economic Developments and rBC mitigation
There is little information available on Russian legislative or national action on environmental controls in the 20th century, prior to the collapse of the Soviet Union
(USSR). This is partly due to the secretive nature of Soviet leadership, poor relations with major world leaders, and a willful attempt to suppress government information, particularly immediately after the fall of the USSR in 1991 (Tsypkin, 1991; Gibbs, 1995).
When Stalin took power in 1924, he placed a heavy emphasis on industrialization and the collectivization of agriculture in an effort to improve the USSR’s economy, which also increased the country’s industrial emissions (Smirnov, 2015). In the mid-1980s,
Gorbachev rose to power and heralded massive economic and political reforms to combat the economic stagnation that the country had been experiencing, leading to further increases in the emissions of both GHGs and PM.
With the collapse of Soviet Russia in 1991 came the collapse of the Russian economy and a drastic decrease in economic activity, and, thus, industrial emissions. The
Kyoto Protocol was negotiated, the emissions baseline at 1990 levels, thus setting the baseline before the collapse of the USSR, when Russian emissions were relatively high.
As a result, even as a party to the Kyoto Protocol, Russia was able to increase its emissions for a time while staying below their emission ‘reduction’ target. While other countries worked to reduce their emissions, Russia was able to focus on rebuilding its economy by revitalizing its industry (Korppoo et al., 2016). Even with this industrial revitalization, a number of countries had accumulated a large number of unused pollution credits which threatened to destabilize the carbon marketplace as the 2012 deadline of the
45 first phase of the Kyoto Protocol approached, particularly if Eastern European countries were able to ‘bank’ or sell their excess units.
As a member state of the Arctic Council, Russia has been involved in a number of agreements and actions intended to govern the Arctic. Between 2011-2016, Russia partnered with the U.S. and Canada in the Arctic Black Carbon Initiative to reduce rBC emissions in the Russian Arctic (Arctic Council, 2010). One major project undertaken in the name of this partnership was the Black Carbon Diesel Initiative, which set goals to create an inventory of primary rBC emissions in Russia, develop baseline inventories for the country’s diesel sources, implement specifically-targeted projects to actively reduce diesel rBC emissions, and recommend national policy based on the results of the previous three goals (Arctic Council, 2016). One resultant policy occurred in 2013, when the
Russian government restricted vehicle emissions and put municipal air quality controls in place (Carbon Limits AS, 2016).
Another ongoing mitigation project to address rBC emissions in Russia focuses on mapping its emissions, specifically in the oil and gas sector. The goal of the project, which was approved in 2016, is to create a basis upon which concrete mitigation measures and improvement policies can be developed. This three-year project works to create an emissions inventory of rBC source points, mitigate emissions from natural gas flare sites, develop policies and regulations, and to build mitigation capacity and disseminate that information (Arctic Council, 2016).
46
5.7. Profile of the European Union (EU)
5.7.1. Overview of rBC Emissions
EU countries have begun to voluntarily submit their rBC emission inventories under CLRTAP to provide a clearer understanding of current rBC emissions throughout
Europe. Diesel combustion in the transportation sector and residential combustion emissions, together, account for 84% of the EU’s current rBC emissions (von
Schneidemesser et al., 2017). Residential combustion, for the purposes of heating, typically comes from burning biomass, though in Eastern Europe residential coal combustion is common. It is expected that the percentage contribution of emissions from residential combustion will rise as emissions from other sectors are decreased. By 2030 nearly 70% of rBC emissions in the EU will be a result of domestic heating (von
Schneidemesser et al., 2017). Possible efforts to mitigate rBC from this sector could include replacing standard wood combustion units with devices with exhaust-control technologies, that are based on wood-gasification technology, or appliances with effective particle separators (von Schneidemesser et al., 2017). Since 2000, European rBC emissions have decreased by approximately 100 kilotonnes (kT) as of 2016 (Centre on Emission Inventories and Projections, 2018). This declining trend may correlate with the implementation of CLRTAP and the adoption of the Gothenburg Protocol in 1999, which targeted the reduction of rBC co-pollutants. This could suggest that international treaties have been effective in regulating industrial rBC emissions.
47
5.7.2. Legal and Economic Developments and rBC Mitigation
The precursor to the EU, the European Economic Community (EEC), was cooperative agreement that was initially established after World War II in 1957 to create trade allies with neighboring countries, in an effort to prevent further war from breaking out (European Union, 2017). As the number of member States began to grow, the EEC began to function beyond the capacity of trade partners. In the 1970s, the EEC adopted laws that protected the environment, and introduced the “polluter pays” concept. One international agreement into which the EEC entered was the 1979 Convention of Long-
Range Transboundary Air Pollution (CLRTAP), along with the U.S. and Canada, which was adopted to protect human health and the natural environment from air pollution
(European Investment Bank, 2016). A specific goal of CLRTAP was to reduce either sulfur emissions or transboundary fluxes by at least 30% by 1993 from 1980 levels
(United Nations Economic Commission for Europe, 1979). Although initially a response to acid rain, the reduction of sulfuric emissions has had the co-benefit of reducing rBC and other PM aerosols. In 1993, the Maastricht Treaty on European Union created the
Single Marketplace, officially forming the EU (European Union, 2017).
In 1999, the Gothenburg Protocol to Abate Acidification, Eutrophication, and
Ground-Level Ozone was adopted under CLRTAP. It was a multi-pollutant protocol that originally set emissions ceilings for sulfur dioxide (SO2), nitrous oxides (NOx), volatile organic compounds (VOCs) and ammonia. The Gothenburg Protocol was amended in
2012 to include emission reduction commitments for PM2.5 aerosols (Reis, 2012;
European Investment Bank, 2016).
48
The EU issues Directives that set emission targets for member states, but allow the individual EU countries flexibility in how they meet their respective goals. In 2008, the Ambient Air Quality Directive set emissions regulations on particulate matter. A target value of 25 μg/m3 was set for EU countries, which entered into force in January
2015 (Official Journal of the European Union, 2008). In a 2010 directive, limits were set for fine particulate matter emissions from industrial plants, although it made no distinction between PM10 and PM2.5 (Official Journal of the European Union, 2010).
In 2001, the first and EU Directive set National Emission Ceilings (NECs), providing the maximum amount of four pollutants (NOx, SO2, NH3, and VOCs) that each
Member State was able to emit. In 2016, there was another NEC Directive issued that that required Member States to prioritize rBC in their emissions reductions plans for particulate matter in their National Air Pollution Control Programmes (NAPCPs; Official
Journal of the European Union, 2016). As these standards are phased-in, rBC from on- road transportation will likely be further reduced, and it is expected that off-road sources of rBC emissions will dominate in the future (von Schneidemesser et al., 2017).
Therefore, creating more stringent regulations on this emission source will be needed.
49
Chapter 6. Discussion
6.1. rBC Deposition at Crawford Point
There were two years in the firn core, 1989 and 2002, where large rBC deposition events are observed. The 1989 events occur in the summer, and according to the
HYSPLIT back-trajectory analyses for July of that year, 15% of trajectories originated over Canada (Table 5). Further, when rBC and nss-S concentrations were compared (Fig.
13), there were three points that had low concentrations of nss-S (between 0-50 ppb) and high concentrations of rBC (between 10-15 μg/L; Fig.13). These specific rBC particles fall within the deposition that occurred in 1989. Because of the low concentrations of nss-
S that are associated with these specific rBC particles, it is unlikely that they originated from fossil fuel combustion. Indeed, 1989 had the largest number of forest fires in
Canada and the greatest total burned area of any other year from 1970 to 2014 (Fig. 16).
Together, this information suggests that the high deposition of rBC in 1989 was the result of forest fire events in Canada.
The anomalously high deposition events in 2002 show that the largest and second largest rBC peaks occur in the late winter. The HYSPLIT back-trajectory analysis results show that the winter peaks likely originate from the EU (10%) and Canada (17%). The first peak (19.9 μg/L of rBC) is associated with low nss-S concentrations (between 0-50 ppb), whereas the second peak (18.6 μg/L) has a nss-S concentration of almost 250 ppb.
The first rBC deposition event may have been the result of residential combustion, as both Canada and the EU have listed residential biomass burning as one of their largest
50 sources of rBC emission in their respective inventories. The secondary peak in rBC deposition, which is strongly correlated to nss-S concentrations within the sample, possibly suggest that fossil fuel combustion was its source. Diesel transportation is the largest source of fossil fuel-related rBC emissions in both the EU and Canada, and may well be the source of these deposition events at the CP site.
The rBC measurements from the CP firn core are comparable, although slightly lower than the mean rBC concentrations found across the GrIS from other studies from similar time periods (specifically the 1980s and “mid-late 20th century”; Table 3). This may be because rBC deposition was greater throughout the 1980s than it was from 1998-
2007 (Fig. 5), and the mean value for this study period also includes the former time period, whereas the other studies that were conducted in the 1980s and 1990s, could not account for 21st century rBC deposition. It would therefore be reasonable to conclude that the rBC measurements from the CP site is representative of a larger region of rBC deposition over the GrIS.
6.2. Relating Policy and Economic Trends to rBC Deposition at Crawford Point
Arctic Council member states make up only 10% of global rBC emissions, however, their emissions make up approximately 30% of the rBC that reaches the Arctic and Greenland (Arctic Council, 2017). Therefore, these are countries whose emissions are likely overrepresented in the Arctic, and mitigating their emissions could have a significant impact on Arctic rBC deposition. The HYSPLIT back-trajectory results suggest that Canadian emissions may be particularly important for deposition at CP (Fig.
12; Table 5).
51
rBC deposition at CP increased from 1980 to the mid-to-late 1980s, when deposition peaked. rBC concentrations declined until 1991, when there was an anomalous peak in 1994, only to continue to decline once again (Fig. 5). In the early 1980s, when rBC deposition was increasing, rBC emissions in the U.S. and EU were significantly declining, likely as a result of improved technological efficiency and environment regulations (Junker and Liousse, 2008; Fig. 15). Russian emissions at that time, however, increased markedly. This corresponds to a time when the USSR was undergoing massive economic reform (Smirnov, 2015), and indicates that Russian emissions likely contributed more to rBC deposition at CP than the back-trajectory analyses indicated.
Two possible explanations for this are that (1) even though Russian air masses reaching
CP are minor, their potential load of rBC is greater, or (2) that Russian air reaches CP more frequently in other winter months than it does in January. The overall declining trend in rBC deposition from the 1980s to 2007, suggests that mitigation efforts have been successful in decreasing emissions that reach the GrIS. However, it is important to note that these mitigation actions did not specifically target rBC, and that did not become common practice until after the CP firn core was drilled.
6.3. Possible Post-Depositional Redistribution of rBC
The results from three analyses – refreeze layer location, and the ratio of
Mg2+/Na+, and density in relation to rBC concentration throughout the core gave ambiguous results in determining if rBC was being transported vertically via percolating melt water and thus accumulating within refreeze layers (Fig. 10). Of the 629 samples analyzed for rBC, only 165 (26%) contained refreeze layers. Of the 28 years represented in the CP firn core (1980-2007), 17 (61%) of the annual peaks in rBC concentration 52 occurred in samples that were associated with refreeze layers. These results suggest that rBC accumulates in refreeze layers within firn intermittently, but somewhat more frequently than not. When the Mg2+/Na+ ratio was analyzed, 12 of the 22 (54.5%) peaks in the ratio were greater than 0.13, and therefore indicative of a location of a refreeze layer, also coincided with annual peaks in rBC concentration (Fig. 10). These results suggest that there may be some vertical redistribution of rBC particles, though it is not conclusive. The correlation results between pit wall density and the rBC concentration within the firn core indicated a weak negative correlation (Spearman Rho = 0.26 [n = 30, p > 0.15]. These results were unexpected, as increased density within glacier firn is largely controlled by melt water refreezing in deeper parts of the snowpack. If rBC was being transported with this percolating melt water, a positive correlation between its concentration and density would be the anticipated result. From these three analyses, it appears that while there is evidence to suggest that rBC accumulates in refreeze layers and may be carried throughout the glacier firn via melt water, it is not conclusive that rBC is being consistently transported post depositionally. It does, however, merit further study as these results are ambiguous.
6.4. Potential Radiative Role of DOM in the CP Firn Core
The results of the absorbance and DOM analyses indicate that the DOM within the CP core behaves radiatively and drives the absorbance of UV-Visible light. As the concentration of DOM increases, so too will the amount of solar radiation absorption
(Avagyan et al., 2014). The likely sources of DOM found within the CP firn core are microbial communities at the CP site and terrestrial organic materials that have to be transported to the GrIS. Forest fire emissions may be facilitating this transportation of 53 organic materials to Greenland. If they are, such events are projected to occur more frequently and become more intense as the consequences of climate change worsen (York et al., 2017), and more DOM would have the potential to reach the Arctic and the GrIS.
The increased concentrations of DOM on glacier surfaces could further decrease their albedo (as rBC also diminishes the reflective properties of snow- and ice-covered surfaces). Therefore, future work should focus on quantifying the DOM concentrations found within the core to establish a record of deposition, as well as defining its sources, and determining if and how DOM and rBC interact with one another, as the deposition of these aerosols could have implications for the radiative behavior of glacier surfaces.
54
Chapter 7. Conclusions
rBC concentrations throughout the core from 1980-2007 range between 0.02-
19.93 μg/L, with a median concentration of 1.43 μg/L. rBC deposition at CP peaked in the mid-to-late 1980s. rBC concentration throughout the core declined until it began to rise again in 1991, peaking in 1994. After this, median deposition decreased until the core was drilled in 2007. There were two years in particular, 1989 and 2002, that had anomalously high concentrations of rBC. Based on the correlation between nss-S and rBC concentrations throughout the core, HYSPLIT back-trajectory results, and data from the Canadian National Fire Database, these deposition events are likely a result of
Canadian forest fires, residential biomass burning, and diesel transportation. The back- trajectory analyses also suggested that the Russian Arctic, the U.S., Canada and countries in the EU were likely sources of rBC aerosols that were deposited at CP. While the implemented policies by these counties appear to be mitigating anthropogenic rBC emissions and deposition to CP, forest fires, particularly in Canada, may be sources of high rBC deposition events, which will only be further exacerbated by climate change.
The DOM found within the CP firn core was comprised of protein-like (C1), simple lignin phenol-like (C2), and humic-like (C3) materials, which are terrestrial (C2 and C3) and microbial (C1) in origin. The abundance of the protein- and humic-like components did not significantly change between the top and bottom of the firn core, although the simple lignin phenol-like component was more heavily loaded at the top of
55 the core than the bottom. As there were only weak correlations between the aromatic components of the PARAFAC model, DOM concentrations likely drive the absorbance.
It was hypothesized that rBC was being transported post-deposition through the glacier ice mass. While the analysis of visible refreeze layers did suggest that higher BC concentrations were overrepresented in sections of the core that contained refreeze layers, results from the Mg2+/Na+ indicator only mildly supported that finding, and the density analysis did not support it. Although some BC may move throughout the CP firn core, our results do not suggest that BC is being consistently transported via that percolation of melt water.
The major sources of anthropogenic rBC in the Arctic come from diesel-derived transportation and residential biomass combustion. For this reason, many Arctic countries have focused their mitigation efforts on addressing these sectors. Initiatives taken to this end have included a mix of economic, regulatory, and informational approaches at all levels of government, both domestically and internationally. These actions have successfully decreased rBC emissions and continue to do so. An individual country’s mitigation actions will be dependent on its political structure, politics, and precedent. For example, in the U.S., it will likely be easier, more effective, and faster to set regulations at the state level than at the federal, with states like California taking the lead and experimenting with different strategies. In Canada, there has been success with the federal government providing guidelines and suggestions to aid provinces and territories in regulating mobile emissions, and such efforts could continue to work in other sectors.
In the EU, directives can be enacted that set regulatory goals for member states while still providing flexibility as to how countries choose to meet those goals. Russian action has
56 recently been enacted as a result of Arctic Council agreements, and includes partnerships with other countries.
Each country will have different incentives to and reasons to engage in rBC mitigation actions, and should be explored individually. Focus should be given to the co- benefits of rBC mitigation actions other than the climate benefits when endorsing regulations that address rBC emissions. Examples include the improvements to air quality, the health benefits of mitigating rBC, the economic incentives of increased efficiency standards, and the reduction of other co-polluted aerosols and greenhouse gases.
Moving forward, an international consensus should be reached on the definition of rBC emission sectors, their emission factors, and inventory methodology for rBC emission inventories. At the moment, there are substantial discrepancies among rBC emissions inventories as a result of differences in data collection, source categorization, and the inclusion or exclusion of wildfires in biomass combustion estimates. Resolving these problems will provide a clearer image of a country’s rBC sources, make international comparisons more direct, and better inform policymakers and regulators.
57
Appendix: Figures and Tables
Figure 1: Location of the Crawford Point, Dye 2, Dye 3, Dye 4, and Camp Century drill sites on the GrIS (adapted from Hamilton and Whillans, 2002).
58
y = 0.8513x - 0.237 2 (A) R = 0.83953
p < 0.04
(B)
Figure 2: Duplicate analyses of rBC concentrations of twelve Crawford Point samples were conducted to test the repeatability of results. (A) Shows the duplicate and original measurements are plotted alongside one another and (B) shows the original and duplicate samples plotted against one another.
59
(A)
Figure 3: Concentrations of (A) four major ions (ppb) throughout the Crawford Point core versus core depth (m) with annual peaks labeled with years and (B) major ions (ppb) with annual years depicted by alternating grey and white background.
60
Figure 3 continued.
(B)
61
Figure 4: rBC concentration in the Crawford Point firn core.
62
7
6
5
4
μg/L) 3 (
2 1.46 rBC concentration rBC concentration μg/L
1
0
Years
Figure 5: Annual medians of rBC (μg/L) for the Crawford Point firn core.
63
Figure 6: Regression of annual rBC mean concentrations, excluding the anomalous data from the year 2002.
64
A) B)
C)
Figure 7: Components identified by the PARAFAC model (A) protein-like material, (B) lignin phenol-like, and (C) humic-like material.
65
Figure 8: Loadings for the three components from the PARAFAC model alongside the dated rBC record and the measured absorbance for samples.
66
Figure 9: Dated rBC deposition record overlain with marked location of sample containing visible refreeze layers, delineated by stars.
67
Figure 10: Dated rBC concentrations with a 3-point running mean of Mg2+/Na+ ratio. Peaks with ratios above 0.13 are numbered, as they indicate a refrozen layer within the sample.
68
Figure 11: rBC concentration from the first meter of the Crawford Point core versus one meter of pit wall density at the Crawford Point drill site.
69
(A)
Figure 12: Mean clusters of daily HYSPLIT back-trajectory analyses for January from (A) 2000-2007, (B) 1990-1999, and (C) 1980-1989, and July trajectories for (D) 2000- 2007, (E) 1990-1999, and (F) 1980-1989.
70
Figure 12 continued
(B)
(C)
71
Figure 12 continued
(D)
(E)
72
Figure 12 continued
(F)
73
Figure 13: rBC concentration vs. nss-S concentration for samples from the Crawford Point firn core, with samples from the 1989 high deposition event marked.
74
Bond et al., 2007 AMAP, 2011 AMAP, 2015
Fu et al., 2015 Lamarque et al., 2010 CLRTAP, 2015
Figure 14: Comparison of rBC emission inventories (in kilotonnes of rBC) for Russia, the United States, Nordic European countries and Canada (Carbon Limits AS, 2016).
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Figure 15: rBC emissions for the period spanning 1860 to 1997 by country on the basis of fuel production (Etemad et al., 1991; black symbols) and of United Nations Statistical Commission (grey symbols; Junker and Liousse, 2008).
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Figure 16: Number of fires and area burned in Canada from 1970-2014 (Natural Resources Canada, 2015).
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Table 1: Results of the ion and rBC contamination testing of the Dye 2 core.
Core rBC F - MSA Cl- NO3- SO42- Na+ NH4+ K+ Mg2+ Ca2+ sample C/BS (ug/L) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) Dye2.1 C 7.42 0.90 0.00 60.73 884.47 97.99 82.55 9.80 81.23 11.74 1135.04 Dye2.1 BS 4.29 0.00 0.00 68.21 492.13 64.68 81.96 6.25 72.82 8.19 342.57 Percent Difference 53.4% - - 11.6% 57% 41% 0.7% 44.2% 10.9% 35.6% 107.3% Dye2.2 C 1.14 0.00 0.00 19.57 320.64 47.12 36.73 156.06 48.31 6.57 202.46 Dye2.2 BS 0.83 0.76 0.00 63.91 577.59 78.16 90.24 11.07 84.13 8.57 549.80 Percent Difference 31.5% - - 106.2% 57.2% 49.6% 84.3% 173.5% 54.1% 26.4% 92.3% Dye2.3 C 1.59 0.58 0.00 65.43 476.41 129.27 51.95 22.61 51.00 7.88 420.09 Dye2.3 BS 1.93 0.00 0.00 41.85 341.52 161.44 46.20 18.38 29.52 6.04 250.91 Percent Difference 19.3% - - 44% 33% 22.1% 11.7% 20.6% 53.4% 26.4% 50.4%
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Table 2: Results of replicate testing of ion concentrations and the relative standard deviation among samples analyzed. All measurements are in ppb.
Date Sample Fl- Cl- NO3- SO42- Na+ NH4+ K+ Mg2+ Ca2+ 1/10/18 1a 7.913 11.715 28.081 60.801 21.448 18.191 10.639 18.098 95.78 1b 6.665 14.155 27.534 77.33 20.86 17.703 15.448 22.714 104.141 1/25/18 2a 7.98 17.102 29.679 50.962 24.154 18.175 11.645 18.156 98.139 2b 7.146 14.818 28.666 54.362 25.407 17.068 17.002 24.502 123.389 2/20/18 3a 7.251 11.264 11.264 40.025 21.452 19.171 9.903 17.789 93.829 3b 6.572 10.721 10.721 45.084 45.808 18.068 33.257 22.4 122.99 2/21/18 4a 8.179 27.758 27.758 51.437 21.782 17.532 9.621 19.936 112.39 4b 7.775 27.322 27.322 47.356 21.07 17.323 10.006 24.918 119.493 3/22/18 5a 7.699 27.82 27.82 50.541 23.204 18.348 4.778 19.441 101.417 5b 7.549 27.289 27.289 71.618 22.204 18.725 4.568 21.028 105.238 Mean 7.47 19 24.61 54.95 24.74 18.03 12.69 20.9 107.69 Standard Deviation 0.52 7.2 6.84 11.13 7.16 0.61 7.79 2.51 10.61
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Table 3: Comparison of average rBC concentration in the Crawford Point core to other ice core and snow samples from different GrIS locations.
Site Name Location Time rBC Average Source Lat; Long: Elevation Period Concentration Crawford 69°52’26.9” N; 1980-2007 1.3 μg/L This work Point Ice 46°58’03.2” W: Core 2090 m Dye-3 Snow 65.2°N; ~1985 < 3.5 μg/L Clark and 43.8°W: Noone, 1985 2480 m Camp 77.2° N; ~1987 2.4 μg/L Chylek et al., Century 61.1° W: 1987 Snow 2000 m D4 Ice Core 71.4° N; Mid-late 2.3 ng/g McConnell et 44° W: 20th century al., 2007 2766 m
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Table 4: Means of loading values for the three resultant PARAFAC components and absorbance at the first and last three meters of the Crawford Point firn core.
PARAFAC Top of core (first Bottom of core Component 3 m) loading (last 3 m) loading value value C1 – protein-like 0.4 0.54 C2 – simple phenol 1.33 0.15 lignin-like C3 – humic-like 0.42 0.31 Absorbance at 253 nm 0.031 0.028
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Table 5: Results of HYSPLIT back-trajectory analyses by month (January vs July), for the timespan of the entire Crawford Point core and specifically for 1986, 1989, 1994, 2002, and 2005 by the region from which trajectories originated. Regions include the EU, Russia, the U.S., Canada, the Greenland Ice Sheet, and other, where trajectories originated over water rather than a land mass.
Total Core (1980- 1986 1989 1994 2002 2005 2007) January July January July January July January July January July January July EU 10% 0.3% 0% 0% 0% 0% 0% 0% 10% 0% 9% 0% Russia 0.6% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% U.S. 0.6% 0.6% 0% 20% 0% 0% 0% 0% 0% 0% 0% 0% Canada 26% 12.3% 0% 45% 9% 15% 4% 0% 17% 6% 23% 19% Greenland 55% 77% 100% 35% 91% 67% 96% 95% 63% 83% 68% 78% Other 7% 5.3% 0% 0% 0% 19% 0% 5% 5% 11% 0% 3% Total 99.20% 95.50% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
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