Atlantic Geoscience Society 2004 Colloquium & Annual General Meeting: Abstracts

2004 Atlantic geology  
Acid rock drainage is a well-known problem associated with the Meguma Supergroup in the Halifax region of Nova Scotia, Canada. Finding the ideal site for waste rock disposal is not always easy, and it has been proposed that dumping waste acid generating materials into salt water of the Bedford Basin is a possible solution. This study focuses on the survival and geomicrobiological interactions of Acidithiobacillus ferrooxidans, and the behaviour of the Halifax slates and the Goldenville-Halifax
more » ... oldenville-Halifax transition zone (GHT) in fresh and saline waters. Samples collected from both the Halifax slates and GHT were crushed and divided into <0.5 mm, 1 mm, and 4.75 mm size fractions. Five grams of each size fraction from the Halifax slates, and 5 grams of each size sample from the GHT, were covered by 50 ml of fresh water. An additional set of samples of both Halifax slates and the GHT were covered by 50 ml salt water from the Bedford Basin. Data collected over a period of 5 weeks indicate that for all size fractions, and for both the fresh and salt water samples, an initial dramatic drop of pH is followed by a levelling off in pH, producing an exponential curve of pH vs. time. This trend is evident for the Halifax slates with an initial average fresh water pH of 5.6 (range 5.3-6.1), and an average fi nal pH of 3.2 (range 3.1-3.5). The salt water samples of Halifax slates have an average initial pH of 6.71 (range 6.3-7.0), and an average fi nal pH of 4.03 (range 3.6-5.5). The trend of the GHT data is similar; however, the salt water pH drop is not as dramatic as the drop in pH of the fresh water. The average initial pH of GHT fresh water samples is 7.1 (range 6.9-7.4), and an average fi nal pH of 4.7 (range 3.8-5.5). The GHT salt water average initial pH is 7.23 (range 7.1-7.4), and the average fi nal pH is 6.31 (range 5.4-7.0). Implications from this study show that although the pH change is somewhat less in salt water, the drop is not insignifi cant, and indicates the continuing oxidization of sulphide minerals. Care should be taken when disposing of waste acid rock in any aquatic environment. Petrological studies of mafi c pegmatites in the Jurassic North Mountain Basalt, Nova Scotia: a record of extreme fractionation in the late-stage evolution of continental tholeiite The Morton Environmental Centre, Heckmans Island, is a 40 ha fi eld research station located near Lunenburg, Nova Scotia, that has 1.6 kilometres of coastline that can be characterized as a shallow marine environment. The effects of climate variability, in particular ocean water temperature fl uctuations, rising sea levels, and the impacts of increased storminess (all proposed future climate scenarios) are not well known for shallow marine environments. This study evaluates the sensitivity of the shallow marine environment at the Morton Centre to various climate scenarios. Physical characteristics of the nearshore marine environment were surveyed to determine: relative temperature, current activity, bathymetry, bottom substrate fl ora and sedimentology. The intertidal zone was characterized using longitudinal surveys to determine slope, percolation, and sediment type. Preliminary results of this survey indicate much variability in substrate composition and biological communities, that together infl uence sediment cohesion and susceptibility to movement. The complex nature of sediment distribution may be infl uenced by storm activity and seiche length, but is also infl uenced by tidal currents which were found to be quite strong at select sites. The intertidal zone is also variable with zones of intense erosion and deposition located in close proximity. Future climate change scenarios predict increased and anomalous storm activity and rising sea level which, given survey results, could dramatically alter intertidal and nearshore morphology, sediment distribution and type in both of these zones. This in turn is projected to have a signifi cant impact on ecology in this environment. The sensitivity model developed in this study will be used to develop management strategies for the site and has the potential to be transportable to other similar environments. Learning from our legacy: high soil lead levels in St. John's, Newfoundland
doi:10.4138/730 fatcat:xeeitwhlrvbunjgiex4mrdqmgm