Browsing by Author "AlAmiri, Noora"

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    Atmospheric Deposition of Microplastics in South Central Appalachia in the United States
    Elnahas, Adam; Gray, Austin; Lee, Jennie; AlAmiri, Noora; Pokhrel, Nishan; Allen, Steve; Foroutan, Hosein (American Chemical Society, 2024-12-26)
    Due to the increased prevalence of plastic pollution globally, atmospheric deposition of microplastics (MPs) is a significant issue that needs to be better understood to identify potential consequences for human health. This study is the first to quantify and characterize atmospheric MP deposition in the Eastern United States. Passive sampling was conducted at two locations within the Eastern United States, specifically in remote South Central Appalachia, from March to September 2023. Each location had five sampling periods, with collections over a 21 day period. Samples were processed to remove biological material, and the presence of MPs was confirmed using Raman spectroscopy to match particles based on polymer similarity. The relative average atmospheric MP deposition in South Central Appalachia was determined to be 68 MPs m-2 d-1. Most verified MPs were fibers, and the most abundant polymer type identified was poly(ethylene terephthalate) PETE. This study's average MP deposition rate is qualitatively comparable to rates reported in other studies that employed a similar methodology in a similar landscape. Scaling up our measured deposition rate to all of South Central Appalachia, an area of over 94,000 km2 and home to five million people, suggests a yearly MP deposition of approximately 321 metric tonnes. Our study highlights the prevalence of MP deposition in the Eastern United States, providing baseline data for future work to further assess routes of MP introduction.
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    Monitoring Wind and Particle Concentrations Near Freshwater and Marine Harmful Algal Blooms (HABs)
    Bilyeu, Landon; Gonzalez-Rocha, Javier; Hanlon, Regina; AlAmiri, Noora; Foroutan, Hosein; Alading, Kun; Ross, Shane D.; Schmale, David G. III (Royal Society of Chemistry, 2023-10-05)
    Harmful algal blooms (HABs) are a threat to aquatic ecosystems worldwide. New information is needed about the environmental conditions associated with the aerosolization and transport of HAB cells and their associated toxins. This information is critical to help inform our understanding of potential exposures. We used a ground-based sensor package to monitor weather, measure airborne particles, and collect air samples on the shore of a freshwater HAB (bloom of predominantly Rhaphidiopsis, Lake Anna, Virginia) and a marine HAB (bloom of Karenia brevis, Gulf Coast, Florida). Each sensor package contained a sonic anemometer, impinger, and optical particle counter. A drone was used to measure vertical profiles of windspeed and wind direction at the shore and above the freshwater HAB. At the Florida sites, airborne particle number concentrations (cm−3) increased throughout the day and the wind direction (offshore versus onshore) was strongly associated with these particle number concentrations (cm−3). Offshore wind sources had particle number concentrations (cm−3) 3 to 4 times higher than those of onshore wind sources. A predictive model, trained on a random set of weather and particle number concentrations (cm−3) collected over the same time period, was able to predict airborne particle number concentrations (cm−3) with an R squared value of 0.581 for the freshwater HAB in Virginia and an R squared value of 0.804 for the marine HAB in Florida. The drone-based vertical profiles of the wind velocity showed differences in wind speed and direction at different altitudes, highlighting the need for wind measurements at multiple heights to capture environmental conditions driving the atmospheric transport of aerosolized HAB toxins. A surface flux equation was used to determine the rate of aerosol production at the beach sites based on the measured particle number concentrations (cm−3) and weather conditions. Additional work is needed to better understand the short-term fate and transport of aerosolized cyanobacterial cells and toxins and how this is influenced by local weather conditions.