POLYCYCLIC AROMATIC HYDROCARBON (PAH) CONTAMINATION IN SNOW DUMP SITE SEDIMENTS A pilot study to assess and characterize PAH species retained in snow dump site sediments LAHTI UNIVERSITY OF APPLIED SCIENCE S Climate Change and Urban Sustainabilit y Master’s Degree Programme in Environmental Technology December 2016 John A. Allen Lahti University of Applied Sciences Master’s Degree Programme in Environmental Technology ALLEN, JOHN: POLYCYCLIC AROMATIC HYDROCARBON (PAH) CONTAMINATION IN SNOW DUMP SITE SEDIMENTS A pilot study to assess and characterize PAH species retained in snow dump site sediments Master's thesis in Environmental Technology, 45 pages, 14 pages of appendices Autumn 2016 ABSTRACT Polycyclic aromatic hydrocarbons (PAHs) are a ubiquitous class of environmental micropollutants produced by combustion processes. They are commonly produced in urban areas by vehicles and from road dust. The United States Environmental Protection Agency (EPA) has included 16 PAHs (PAH16) on their list of Priority Pollutants. During the winter in northern climates PAHs may be entrained with urban snow and removed to snow disposal sites or snow dumps. The fate of PAHs in snow dumps is not well understood. This study attempts to determine if PAH16 species are retained within snow dump site soils. Four snow dump sites and four control sites were selected in the Lahti region of South Central Finland. Soil samples were collected from each site and tested by GC-MS to determine which PAH16 species were present and their concentrations. All 16 PAHs were detected in the dump sites. Statistically significant differences were found between the dump and control sites in the observed concentrations of 13 of PAH16 species. Keywords: PAHs, urban, snow, snow dumps, pollution, polycyclic aromatic hydrocarbons 2 Contents 1 INTRODUCTION 3 2 FRAMEWORK OF THE STUDY 8 3 MATERIALS AND METHODS 12 3.1 Characteristics and climate of the study locality 12 3.1.1 Snow dump sites 16 3.1.2 Sampling 17 3.1.3 Reagents and equipment 18 3.1.4 Sample preparation and analysis 18 4 RESULTS 23 5 DISCUSSION 26 5.1 Results from GC-MS analyses 26 5.2 Statistical analyses and results 32 5.2.1 Occurance of individual PAHs 33 6 CONCLUSIONS 41 SOURCES 42 ACKNOWLEDGMENTS 46 APPENDICES 47 Appendix 1. Site layout maps 47 Appendix 2. Data tables 51 Appendix 3. Mean concentrations of individual PAH species 55 3 1 INTRODUCTION Modern cities rely on an open and safe network of roadways, pedestrian and cycle paths to transport goods, provide services and conduct daily business. The winter season in temperate and higher latitudes may bring weather conditions that hamper the use of urban transportation networks. Below freezing temperatures and precipitation in the forms of freezing rain, sleet and snow may cause significant disruptions to traffic, especially in areas which do not historically experience or are ill equipped to handle such conditions. A quick internet search for phrases such as ”snow causes chaos” , ”snow causes pile up” or ”snow causes problems” will yield thousands of results, mostly news stories about traffic accidents, many sadly, involving multiple fatalities. Snow falling in urban areas presents problems for residents and city managers. How cities have dealt with snow is an interesting subject and has even been included in a video game, Cities:Skylines Snowfall (Paradox Interactive, 2016), a simulation game in which players must manage the wintertime needs of their city, such as providing heating to residents and keeping roadways clear of snow. The history of snow handling in the US is the subject of the book Snow in the Cities: A History of America's Urban Response by Blake McKelvey (1995) in which he writes: The snowstorm experiences and responses of American cities Supply fruitful material for environmental as well as urban historians. As with most historical subjects the topic is multi- dimensional. Not only was the natural environment pulsating and unpredictable, buffeting selected cities at different times and with varied frequency and intensity, but the impact of similar storms also changed radically as the cities grew in size and technological complexity. And as the man-made urban environment developed, it's response expanded to include, in addition to private and cooperative adjustments, concerted efforts by agencies of commerce and communication to 4 maintain their services; in time it also inspired municipal regulations that led finally to active civic programs for snow plowing and snow removal. Automotive traffic became the primary mode of transport in cities beginning the early 20th century, and also marks the beginning of modern snow removal practices, which center on plowing snow and accumulated ice from roads and pedestrian paths, and spreading sand and salt to improve traction and melt the remaining ice. As occasionally happens, this solution has led to a set of new problems. Firstly, snow plowing and removal is expensive. New York City has spent an average of $55.3 million annually from 2003 to 2014 to clear their streets. In Finland, Helsinki has budgeted 21 - 22 million euros for snow clearing work in 2016 (Särkkä, 2016). Helsinki removed 320 000 dump trucks of snow in 2012 (approximately 3.2 to 4.5 million cubic meters of snow) (Keskinen, 2012). The city of Lahti, in South Central Finland 3 removed over 500 000 m of snow from their streets during the 2012-2013 snow season (Figure 1), while the city of Heinola, a smaller city within the 3 Lahti area, removed about 10 000 m . The Lahti region is the focus of this study. Snow removal and deicing programs also present environmental problems, which began to be widely recognized in the mid 20th century. Initially, scientists and environmental experts and the public began to notice that salt used in deicing operations on roadways was causing automotive body corrosion, damaging roadside plant life, polluting fresh surface and ground waters, and causing fish kills (Cheshire, 2016). Additionally, the sand or grit applied to roadways may cause significant problems in stormwater collection systems and receiving waters by filling sediment traps, blocking drainage pipes and smothering benthic plants and animals. 5 600000 500000 400000 3 m 300000 200000 100000 0 Rälssi Vanhatie Hakapelto Figure 1: Volume of snow removed to Lahti area snow dumps Figure 2: Plowed snow stored in a park in Hyvinkää, Finland. Additionally, research has shown that snow is a very effective trap for air pollutants (Nazarenko et al., 2016). Even snow which falls as far away from urban areas as Antarctica (Na et al., 2011) may contain detectable quantities of anthropogenic pollutants. Snows which accumulate in urban areas may then, unsurprisingly, contain high concentrations of pollutants other than salt, sediment and litter. Recent studies from Canada, Finland, Sweden and other countries with significant annual snowfall have shown that urban snow may contain high concentrations of pollutants such as heavy metals, oils, nutrients, nanosized soot particles, as well as 6 polycyclic aromatic hydrocarbons (PAHs), which are the focus of this study. More information about PAHs will be given in the next section. Figure 3: Plowed snow stored on the roadside, Hyvinkää, Finland. Plowed snow and ice accumulates in piles and ridges along roadways, in on-street parking spaces and in parks and other urban green spaces over the course of the winter (Figures 2 and 3). Eventually the accumulation becomes too great, and the material must be removed from the city. This is typically done by using frontend loaders to fill dump trucks which then deliver the snow, ice and entrained litter, pollutants and debris to a disposal site. The final disposal of the snow maybe accomplished in one of several different ways: By dumping into a nearby water body, such as a river, lake, harbor or sea; By melting using large snow melting devices; Or by stockpiling in snow dumps or other wasteland sites where it is allowed to passively melt over the course of the following spring and summer months. Melt water from the sites is typically allowed to infiltrate into the ground, or collects in shallow basins where it may stage up and discharge to surface waters. Snow dumps are the focus of this work 7 While, as previously mentioned, many studies have examined the contaminates present in urban snows, and many have looked at PAHs, relatively little, if any, work has been done to determine if PAH species are retained in the soil at snow dump sites after the accumulated snow has melted away. This study aims to address this lack of information This research is important because it looks at snow dumping sites that have been in use for many decades in areas that have historically received significant annual snow fall. Current climate models predict that as climate change progresses, and weather patterns shift, areas which do not currently received significant amounts of snow could begin to experience heavy annual snowfalls. By studying the quality of soils in current snow dump sites I hope to provide valuable information about the long term impacts of this handling option. The original idea for this research project came from my interest in urban stormwater and pollution prevention, and was originally going to examine bacterial loadings from urban snow melt. However, due to impracticalities of analysing bacterial samples and through discussions with my thesis advisors at LAMK and with professors and researchers at the University of Helsinki’s Department of Environmental Ecology, my focus shifted to looking at chemical contamination in snow dump sites. At the suggestion of Dr. Anna-Lea Rantalainen and examination of PAHs was selected as the subject of my project since some work had recently been done at the University of Helsinki on these compounds, and so knowledge, equipment and supplies were available for my use. 8 2 FRAMEWORK OF THE STUDY Polycyclic aromatic hydrocarbons (PAHs) are a group of organic chemical compounds formed from the fusion of two or more benzene rings. PAHs containing up to four benzene rings are known as light PAHs, while those containing more than four rings are called heavy PAHs (Wenzl et al., 2006). In solid form they are typically colorless, white or yellowish, with their individual characteristics determined by the arrangement of the benzene rings, with hundreds of different known combinations. PAHs range in molecular weight from 128.16 g (Naphthalene) to 300.36 g (Coronene), with lighter compounds being more volitile than heavier compounds. It has been shown that some PAHs can be carcinogenic and mutagenic (Kim et al., 2013, Nisbet & LaGoy, 1992) and are also potent immune-suppressants. The Environmental Protection Agency (EPA) of the United States has included 16 individual PAHs (Figure 4) in its list of 126 Priority Pollutants, and it is this group of PAHs that are examined in this study. Some PAHs occur naturally as the result of forest and brush fires, but they are typically of anthropogenic origin, being created and released to the atmosphere during the incomplete combustion of garbage, wood, biomass, and hydrocarbon fuels (gasoline, diesel and other fuel oils, and coal) (EPA, 2008). Due to their structure, PAHs commonly bind to organic matter in the environment, maybe highly hydrophobic, and resistant to biological degradation. Lighter compounds may unbind more easily from organic matter and re-volatilize to the atmosphere while heavier compounds tend to remain attached and accumulate in sediments and soils. PAHs are common urban pollutants and many studies have shown that PAHs may occur in urban surface and storm waters and sediments (Honkonen & Rantalainen, 2013 & 2016; Ngabe et al., 2000, Paul & Meyer, 2001; etc..), in the urban atmosphere (Halsall, et al., 1994; Menichini, 1992; Tang, N. et al., 2005; etc..) and in the soils of urban and industrial areas (Gan et al., 2009; Tang, L. et al., 2005; Trapido, 1999; Teaf et al., 2008, etc..). 9 Figure 4: PAHs included in the EPA's list of Priority Pollutants and their molecular structures (Mugica, et al. 2010) If released during cold weather, these compounds are less volatile, and may be entrained and deposited during snow showers. Recent work by Nazarenko et al. (2016) has demonstrated that snow acts as an efficient scavenger of pollutants, including PAHs, from vehicle exhaust. Studies have also shown that PAHs of anthropogenic origin occur in areas far removed from urban and industrial centers (Aamot et al., 1996; Garban et al., 2002; Mazzera et al., 1999; etc..), indicating that these compounds are easily transported in the atmosphere, deposited with snow fall, and that they have a long life in the environment. Indeed, PAHs are ubiquitous in the modern environment (Abdel-Shafy & Mansour, 2016).