ALBERT

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Colson, B. C., & Michel, A. P. M. Flow-through quantification of microplastics using impedance spectroscopy. ACS Sensors, 6(1), (2021): 238–244, doi:10.1021/acssensors.0c02223.

Description: Understanding the sources, impacts, and fate of microplastics in the environment is critical for assessing the potential risks of these anthropogenic particles. However, our ability to quantify and identify microplastics in aquatic ecosystems is limited by the lack of rapid techniques that do not require visual sorting or preprocessing. Here, we demonstrate the use of impedance spectroscopy for high-throughput flow-through microplastic quantification, with the goal of rapid measurement of microplastic concentration and size. Impedance spectroscopy characterizes the electrical properties of individual particles directly in the flow of water, allowing for simultaneous sizing and material identification. To demonstrate the technique, spike and recovery experiments were conducted in tap water with 212–1000 μm polyethylene beads in six size ranges and a variety of similarly sized biological materials. Microplastics were reliably detected, sized, and differentiated from biological materials via their electrical properties at an average flow rate of 103 ± 8 mL/min. The recovery rate was ≥90% for microplastics in the 300–1000 μm size range, and the false positive rate for the misidentification of the biological material as plastic was 1%. Impedance spectroscopy allowed for the identification of microplastics directly in water without visual sorting or filtration, demonstrating its use for flow-through sensing.

Description: The authors thank the Richard Saltonstall Charitable Foundation and the National Academies Keck Futures Initiative (NAKFI DBS13) for their funding support.

Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Walsh, A. N., Reddy, C. M., Niles, S. F., McKenna, A. M., Hansel, C. M., & Ward, C. P. Plastic formulation is an emerging control of its photochemical fate in the ocean. Environmental Science & Technology, 55(18), (2021): 12383–12392, https://doi.org/10.1021/acs.est.1c02272.

Description: Sunlight exposure is a control of long-term plastic fate in the environment that converts plastic into oxygenated products spanning the polymer, dissolved, and gas phases. However, our understanding of how plastic formulation influences the amount and composition of these photoproducts remains incomplete. Here, we characterized the initial formulations and resulting dissolved photoproducts of four single-use consumer polyethylene (PE) bags from major retailers and one pure PE film. Consumer PE bags contained 15–36% inorganic additives, primarily calcium carbonate (13–34%) and titanium dioxide (TiO2; 1–2%). Sunlight exposure consistently increased production of dissolved organic carbon (DOC) relative to leaching in the dark (3- to 80-fold). All consumer PE bags produced more DOC during sunlight exposure than the pure PE (1.2- to 2.0-fold). The DOC leached after sunlight exposure increasingly reflected the 13C and 14C isotopic composition of the plastic. Ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry revealed that sunlight exposure substantially increased the number of DOC formulas detected (1.1- to 50-fold). TiO2-containing bags photochemically degraded into the most compositionally similar DOC, with 68–94% of photoproduced formulas in common with at least one other TiO2-containing bag. Conversely, only 28% of photoproduced formulas from the pure PE were detected in photoproduced DOC from the consumer PE. Overall, these findings suggest that plastic formulation, especially TiO2, plays a determining role in the amount and composition of DOC generated by sunlight. Consequently, studies on pure, unweathered polymers may not accurately represent the fates and impacts of the plastics entering the ocean.

Description: Funding was provided by the Seaver Institute, the Gerstner Family Foundation, Woods Hole Oceanographic Institution, and the National Science Foundation Graduate Research Fellowship Program (A.N.W.). The Ion Cyclotron Resonance user facility at the National High Magnetic Field Laboratory is supported by the National Science Foundation Division of Chemistry and Division of Materials Research through DMR-1644779 and the State of Florida.

Description: Submitted in partial fulfillment of the requirements for the degree of Master of Science in Aeronautics and Astronautics at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2021.

Description: Global temperature rise and increased atmospheric carbon dioxide (CO2) levels have affected the health of the world’s ocean and water ecosystems, impacting the balances of natural carbon cycling and causing ocean acidification. Additionally, as global temperatures rise, thawing permafrost has stimulated increased release of methane (CH4), a gas with a shorter lifetime in the atmosphere but with even more heat trapping ability than CO2. In situ analysis of dissolved gas content in surface waters is currently performed with large, expensive instruments, such as spectrometers, which are coupled with gas equilibration systems, which extract dissolved gas from water and feed it to the sensor. Accurate, low cost, and portable sensors are needed to measure the dissolved CH4 and CO2 concentration in water systems to quantify their release and understand their relationship to the global carbon budget. At the same time, while greenhouse gases are well established threats to water ecosystems, the ubiquity and potential consequences of microplastics in aqueous environments are just beginning to be recognized by the environmental research community. Microplastics (MPs) are small particles of polymer debris, commonly defined as being between 1 μm and 1000 μm. Despite the pervasiveness of MPs, our ability to characterize MPs in the environment is limited by the lack of technologies for rapidly and accurately identifying and quantifying MPs. This thesis is concerned with the engineering challenges prompted by the need for high quality and quantity environmental data to better study and the impact, cycling, and prevalence of these pollutants in aqueous environments. Three distinct investigations are presented here. First, the design of the Low-Cost Gas Extraction and Measurement System (LC-GEMS) for dissolved CO2 is presented. At just under $600 dollar to build, the LC-GEMS is an ultra-portable, toolbox-sized instrument for dissolved gas sensing in near-surface waters. The LCGEMS was characterized in the lab and demonstrated linear relationships with dissolved CO2 as well as temperature. Lab calibrations and subsequent field testing in the Little Sippewissett Marsh, in Falmouth, Massachusetts showed that the LCGEMS captures both diurnal and minute-time scale trends in dissolved CO2. Second, this thesis presents the novel design of three simple and low-cost planar nanophotonic and plasmonic structures as optical transducers for measuring dissolved CH4. Through simulations, the sensitivity of the structures are evaluated and found to exhibit superior performance in the reflectance intensity readout mode to that of the standard surface-plasmon-polariton-mode Spreeta sensor. A practical, small, and low-cost implementation of this chip with a simple intensity-based measurement scheme is proposed. This design is novel in the space of dissolved gas monitoring because it shows potential to measure directly in the water phase while being robust and low-cost to implement. Finally, this thesis presents a literature review and perspective to motivate the development of field-deployable microplastic sensing techniques. A framework for field-deployable microplastic sensing is presented and seeks to inform the MP community of the potential in both traditional MP analysis techniques and unconventional methods for creating rapid and automated MP sensors. The field-deployabilty framework addresses a full scope of practical/technological trade-offs to be considered for portable MP detection.

Description: Committed to inspire & empower Indian youth to embrace entrepreneurship, self-leadership & environmental stewardship to become exemplary world leaders, EnviroVision2050 and its community of Explorers continuously seek ways to build awareness and take action towards a sustainable planet.

Description: Challenge 9: Skills, knowledge and technology for all; Challenge 10: Change humanity’s relationship with the ocean.

Description: Published

Description: Not Known