Department of Environmental Science

Research and Publications

 


FOREST SOILS IN NORTHEASTERN NORTH AMERICA have been variably impacted by decades of acid deposition that has caused a loss of base cation nutrients 
Forest Soils Kevin Keys(calcium, magnesium, potassium) and an increase in aluminum and acidity in many affected soils. However, acid deposition levels have decreased significantly since the signing of pollution treaties in the US and Canada in the early 1990s. To see how forest soils are recovering from reduced deposition, a study is being conducted to compare old and new soil chemistry data from sites across the northeast. In Nova Scotia, a site at Kejimkujik National Park was chosen for this research. This past summer, Kevin Keys (soil scientist with Nova Scotia Natural Resources and adjunct with SMU Department of Environmental Science) teamed up with researchers at Parks Canada to re-sample soils at two sites that were first sampled back in 1995. Samples are still being analyzed, but results will be part of a report to Parks Canada as well as a planned journal submission. To the right is a picture of one of the soil pits excavated for this study. Soils in this profile show a range of colours as influenced by parent material, soil forming processes, and natural disturbance events.     


 

AN OIL SPILL DECISION MATRIX IN RESPONSE TO SURFACE SPILLS OF VARIOUS BITUMEN BLENDS
Published in Environmental Science: Processes and Impacts
Canada's production, transport, and sale of diluted bitumen (dilbit) products are expected to increase by a million barrels per day over the next decade. The anticipated growth in oil production and transport increases the risk of oil spills in aquatic areas and places greater demands on oil spill capabilities to respond to spills, which have raised stakeholder concerns. Current oil spill models only predict the transport of bitumen blends that are used in contingency plans and oil spill response strategies, rather than changes in the oil's physical properties that are relevant to spill response. We conducted weathering studies of five oil products (two conventional oils and three bitumen blends) in the Department of Fisheries and Oceans' flume tank. We also considered two initial oil slick thicknesses, 4.0 mm and 7.0 mm. We found that there is a major difference in the time evolution of oil properties (density and viscosity), raising doubts on weathering models that do not consider the thickness of oil. We also developed empirical expressions for the evolution of the density and viscosity of these oil products. The findings from the 4.0 mm results were incorporated with data from the literature to provide an update on the factors to consider during the decision making for spills of diluted bitumen products. The matrix indicated that most response options, including chemical dispersants, work much more effectively within 48 hours of the initiation of weathering. After this window of opportunity closes, natural attenuation or in situ burning is the only option remaining, but containment of oil is a limiting factor for in situ burning.

Coastal communities depend on the marine environment for their livelihoods, but the common property nature of marine resources poses major challenges for the governance of such resources. Through detailed cases and consideration of broader global trends, this volume examines how coastal communities are adapting to environmental change, and the attributes of governance that foster deliberate transformations and help to build resilience of social and ecological systems.


THE LICHEN-FORMING FUNGI IN THE HALIFAX PUBLIC GARDENS, NOVA SCOTIAPaper by Dr. David Richardson and Dr. Anwar Tumur

Fifty-three lichens species belonging to 28 genera were recorded from the Halifax Public Gardens in Nova Scotia. A brief history of the gardens and of lichen recording in the city is presented, along with a commentary on the lichens found in this study. The results of this lichen survey are of particular interest as the lichen flora has not been previously documented and it provides a baseline for monitoring future changing patterns of pollution and climate. In addition, the Halifax Public Gardens are celebrating in 2017 the 150th anniversary of the opening of the gardens.


GREEN ROOF THERMAL STORMWATER PERFORMANCE COMPARISONS BETWEEN NATIVE AND INDUSTRY-STANDARD PLANT SPECIES|
A Heim, S Appleby-Jones, J Lundholm - Cities and the Environment (CATE), 2017

There is a demand to use native species on green roofs in North America. However, research is needed to determine which native species are suitable for the green roof environment and how these species impact the ecosystem services attributed to the green roof. This study compared the thermal performance and stormwater mitigation services provided by species native to Nova Scotia, Canada, and those commonly used by the green roof industry. The study was conducted on two extensive green roofs using a vegetated mat system. The native and Sedum treatments resulted in similar substrate temperatures and stormwater retention for the majority of the study period. Additionally, the green roof treatments performed significantly better than the conventional roof treatment for the majority of the study period. However, at both study sites the Sedum treatment recorded significantly lower average substrate temperatures for the summer of 2014. Since canopy density did not play a significant role in these findings, these results are most likely due to differences in species composition. For stormwater retention, no significant differences were detected between the Sedum and native treatments for the entire study period. This is particularly interesting because the substrate cover in the native treatment was significantly lower than in the Sedum treatment for the entire study period. It is possible that, as the cover of native species increases, the water retention in these modules will also increase. This study demonstrates that these native species are a viable option for green roofs in a maritime climate.