Browsing by Author "Groeneveld, Tianna M."
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Item Estimated discharge of microplastics via urban stormwater during individual rain events(2023) Ross, Matthew S.; Loutan, Alyssa; Groeneveld, Tianna M.; Molenaar, Danielle; Kroetch, Kimberly; Bujaczek, Taylor; Kolter, Sheldon; Moon, Sarah; Huynh, Alan; Khayam, Rosita; Franczak, Brian C.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.Item Estimated discharge of microplastics via urban stormwater during individual rain events(2023) Ross, Matthew S.; Loutan, Alyssa; Groeneveld, Tianna M.; Molenaar, Danielle; Kroetch, Kimberly; Bujaczek, Taylor; Kolter, Sheldon; Moon, Sarah; Franczak, Brian C.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.Item Insight into the post-impact hydrothermal system at the Chicxulub impact structure, Mexico(2020) Walton, Erin L.; Groeneveld, Tianna M.The 66-million-year-old Chicxulub impact structure was formed by the hypervelocity impact of an asteroid into the Yucatán peninsula. Hypervelocity impacts generate hydrothermal circulation systems in the resulting craters and create long-term thermal anomalies in near-surface areas of the crust. Drill cores have sampled preserved impactites from the Chicxulub crater with the most recent core, M0077A, intersecting the peak ring. Analysis of the mineralogy, composition, and occurrence of secondary minerals in the core may be used to understand conditions in the postimpact hydrothermal environment. In this study, the secondary minerals within ten thin sections and five polished offcut tiles from drill core M0077A were investigated. The thin sections were sampled from ~750-1300 metres below sea floor (mbsf), while the tiles were constrained to a depth of ~1250-1330 mbsf. Identified secondary minerals include andradite-grossular garnet assemblages, anhydrite, Fe-oxides, calcite, Mg-Fe-Al-rich clay group minerals, sulfides, Casulphates, titanite, albite, fluorite, epidote, quartz, and halite. These minerals occur as vein- and vug-filling assemblages in the shocked granite and suevite breccia. The andradite-grossular garnet assemblages are of particular interest as they suggest that high-temperatures (300-400 C⁰) dominated the early stages of the post-impact hydrothermal system. Secondary minerals anhydrite, titanite, epidote, and Fe-oxides support the temperature range indicated by the garnets, but do not constrain the temperature as tightly. The temperature range indicated by the garnets is sufficiently hot for the hydrothermal system to persist for at least two million years, based on previous numerical modeling1,3. Calcite, Mg-Fe-Al-rich clay group minerals, sulfides, and halite formed as the hydrothermal system cooled. The secondary minerals identified attest to the depth and range of thermal and chemical modification that occurred in the Earth’s crust due to impact events, both immediately after and in the ensuing millions of years.