Geochemistry and mineralization of the Archean Titan (Roaring River) intrusion, Thunder Bay, Ontario

The 2690 ± 3.2 Ma Titan intrusion is an approximately 7 by 3 km, roughly ovoid, mafic-ultramafic intrusion, located just north of the inferred boundary between the Winnipeg River and Marmion terranes. Outcrop in the area is relatively sparse, largely due to cover from pervasive glacial till and Proterozoic diabase sills associated with the Midcontinent Rift. Titan consists of a variety of lithologies, including leucogabbros, melagabbros, gabbros, and pyroxenites, which are distributed throughout the intrusion. Both mafic and felsic dikes are observed in outcrop, as are felsic breccias. Titan consists of a single magma body, with one pulse of magma which has subsequently undergone fractional crystallization within a closed system. This is supported by smooth linear trends in the major element bivariate plots, with moderate amounts of scatter, and consistent, tight primitive mantle normalized REE trends. Titan samples have a range of (La/Sm)N from 0.7 to 3.8, a range of (Gd/Yb)N from 2.3 to 7.4, and a range of Nb/Nb* values from 0.02 to 0.47. [...

Estimated discharge of microplastics via urban stormwater during individual rain events

Urban stormwater runoff is an important pathway for the introduction of microplastics and other anthropogenic pollutants into aquatic environments. Highly variable concentrations of microplastics have been reported globally in runoff, but knowledge of key factors within urban environments contributing to this variability remains limited. Furthermore, few studies to date have quantitatively assessed the release of microplastics to receiving waters via runoff. The objectives of this study were to assess the influence of different catchment characteristics on the type and amount of microplastics in runoff and to provide an estimate of the quantity of microplastics discharged during rain events. Stormwater samples were collected during both dry periods (baseflow) and rain events from 15 locations throughout the city of Calgary, Canada’s fourth largest city. These catchments ranged in size and contained different types of predominant land use. Microplastics were found in all samples, with total concentrations ranging from 0.7 to 200.4 pcs/L (mean = 31.9 pcs/L). Fibers were the most prevalent morphology identified (47.7 ± 33.0%), and the greatest percentage of microplastics were found in the 125–250 µm size range (26.6 ± 22.9%) followed by the 37–125 µm size range (24.0 ± 22.3%). Particles were predominantly black (33.5 ± 33.8%), transparent (22.6 ± 31.3%), or blue (16.0 ± 21.6%). Total concentrations, dominant morphologies, and size distributions of microplastics differed between rain events and baseflow, with smaller particles and higher concentrations being found during rain events. Concentrations did not differ significantly amongst catchments with different land use types, but concentrations were positively correlated with maximum runoff flow rate, catchment size, and the percentage of impervious surface area within a catchment. Combining microplastic concentrations with hydrograph data collected during rain events, we estimated that individual outfalls discharged between 1.9 million to 9.6 billion microplastics to receiving waters per rain event. These results provide further evidence that urban stormwater runoff is a significant pathway for the introduction of microplastics into aquatic environments and suggests that mitigation strategies for microplastic pollution should focus on larger urbanized catchments

Designing a new, inexpensive, all-in-one microplastics extraction device

Microplastics are small plastic particles, 0.1 μm–5 mm in size, and are an ill understood pollutant in Earth’s environment. Their small size makes reliable extraction from water and sediment samples difficult, and requires a variety of techniques such as filtration, peroxide digestion, and density separation to make them accessible for identification. Extractions can introduce contaminants or leave behind microplastics as the sample is transferred from the original container to subsequent glassware and filtration devices. The goal of this project is to develop a device in which the majority of the necessary extraction steps could be performed in a single chamber which would limit the introduction of contaminants or loss of microplastics. This device will be easier to use and is made from local, inexpensive materials for ease of building. The device features a series of smooth, 2” plastic tubes attached to removable ball valves so that liquids may be retained or drained as needed. The smooth interior aids in cleaning, and the fact that various parts of the device are removable allows customization depending on required extraction techniques. The device will be compared with the current extraction methods by looking at how it performs in total contamination and in recovery of samples spiked with homemade microplastic fragments, fibres, and beads. If the device can show an increase in recovery or a decrease in total contamination then it will be used in future microplastic projects working with environmental samples.   Faculty Mentor: Matthew Ross Department: Chemistry &nbsp

Estimated discharge of microplastics via urban stormwater during individual rain events

Urban stormwater runoff is an important pathway for the introduction of microplastics and other anthropogenic pollutants into aquatic environments. Highly variable concentrations of microplastics have been reported globally in runoff, but knowledge of key factors within urban environments contributing to this variability remains limited. Furthermore, few studies to date have quantitatively assessed the release of microplastics to receiving waters via runoff. The objectives of this study were to assess the influence of different catchment characteristics on the type and amount of microplastics in runoff and to provide an estimate of the quantity of microplastics discharged during rain events. Stormwater samples were collected during both dry periods (baseflow) and rain events from 15 locations throughout the city of Calgary, Canada’s fourth largest city. These catchments ranged in size and contained different types of predominant land use. Microplastics were found in all samples, with total concentrations ranging from 0.7 to 200.4 pcs/L (mean = 31.9 pcs/L). Fibers were the most prevalent morphology identified (47.7 ± 33.0%), and the greatest percentage of microplastics were found in the 125–250 µm size range (26.6 ± 22.9%) followed by the 37–125 µm size range (24.0 ± 22.3%). Particles were predominantly black (33.5 ± 33.8%), transparent (22.6 ± 31.3%), or blue (16.0 ± 21.6%). Total concentrations, dominant morphologies, and size distributions of microplastics differed between rain events and baseflow, with smaller particles and higher concentrations being found during rain events. Concentrations did not differ significantly amongst catchments with different land use types, but concentrations were positively correlated with maximum runoff flow rate, catchment size, and the percentage of impervious surface area within a catchment. Combining microplastic concentrations with hydrograph data collected during rain events, we estimated that individual outfalls discharged between 1.9 million to 9.6 billion microplastics to receiving waters per rain event. These results provide further evidence that urban stormwater runoff is a significant pathway for the introduction of microplastics into aquatic environments and suggests that mitigation strategies for microplastic pollution should focus on larger urbanized catchments.</jats:p

DataSheet1_Estimated discharge of microplastics via urban stormwater during individual rain events.pdf

Urban stormwater runoff is an important pathway for the introduction of microplastics and other anthropogenic pollutants into aquatic environments. Highly variable concentrations of microplastics have been reported globally in runoff, but knowledge of key factors within urban environments contributing to this variability remains limited. Furthermore, few studies to date have quantitatively assessed the release of microplastics to receiving waters via runoff. The objectives of this study were to assess the influence of different catchment characteristics on the type and amount of microplastics in runoff and to provide an estimate of the quantity of microplastics discharged during rain events. Stormwater samples were collected during both dry periods (baseflow) and rain events from 15 locations throughout the city of Calgary, Canada’s fourth largest city. These catchments ranged in size and contained different types of predominant land use. Microplastics were found in all samples, with total concentrations ranging from 0.7 to 200.4 pcs/L (mean = 31.9 pcs/L). Fibers were the most prevalent morphology identified (47.7 ± 33.0%), and the greatest percentage of microplastics were found in the 125–250 µm size range (26.6 ± 22.9%) followed by the 37–125 µm size range (24.0 ± 22.3%). Particles were predominantly black (33.5 ± 33.8%), transparent (22.6 ± 31.3%), or blue (16.0 ± 21.6%). Total concentrations, dominant morphologies, and size distributions of microplastics differed between rain events and baseflow, with smaller particles and higher concentrations being found during rain events. Concentrations did not differ significantly amongst catchments with different land use types, but concentrations were positively correlated with maximum runoff flow rate, catchment size, and the percentage of impervious surface area within a catchment. Combining microplastic concentrations with hydrograph data collected during rain events, we estimated that individual outfalls discharged between 1.9 million to 9.6 billion microplastics to receiving waters per rain event. These results provide further evidence that urban stormwater runoff is a significant pathway for the introduction of microplastics into aquatic environments and suggests that mitigation strategies for microplastic pollution should focus on larger urbanized catchments.</p