Projects | Alice (Xia) Zhu

Current and Past Projects

The Vertical Distribution of Microplastics in the ETNP Oxygen Minimum Zone (2025-present)

In collaboration with a student, I am investigating the vertical distribution of plastic pollution in the water column of the North Pacific Ocean, specifically in the ENTP OMZ region, and how it relates to key physical variables (temperature, salinity, dissolved oxygen, etc.) in order to elucidate how plastic is transformed after it enters the ocean and how these variables affect its fate. Samples of the ocean water column were obtained on a UC Ship Funds Student Cruise March 9-20, 2023 at Scripps Institution of Oceanography, La Jolla, USA onboard the R/V Sally Ride.

The Impact of Plastic Pollution on the Biological Carbon Pump (2024-present)

I am sampling the "sinking pool" of microplastics in the North Atlantic Ocean and Gulf of Mexico using deep sediment traps in conjunction with colleagues from Memorial University of Newfoundland (Canada), National Oceanography Centre (UK), and the Leibniz-Institute for Baltic Sea Research (Germany). My aim is to quantify the settling flux of plastic pollution in the global ocean. In tandem, I am conducting experiments to elucidate the impact of microplastics on the biological carbon pump using a cold-water diatom, Thalassiosira gravida.

The Plastics & Climate Project (2023-2025)

I conducted a systematic review to determine the knowns and unknowns in our understanding of how plastics impact climate as part of The Plastics & Climate Project. The end products of this two-year project included a peer-reviewed journal article, summary report, and convening in Washington D.C. to help disseminate knowledge to governments and the public. This project was completed in conjunction with Monterey Bay Aquarium, World Resources Institute, Environmental Law Institute, and GRID-Arendal.

Systematic review: Zhu et al. (2025)

Plastic is part of carbon cycle, Front. Mar. Sci.: Zhu (2021)

Editorial in The Conversation: Zhu (2021)

Summary report, press release, and Washington Post article

Global Reservoirs of Plastic Pollution in the Marine Environment (2017-present)

I am quantifying major reservoirs of plastic pollution in the marine environment to help solve the puzzle of the fate of plastic pollution. Reservoirs of interest include coastlines, the ocean water column, the ocean floor, and marine animals. This project is in conjunction with colleagues from Scripps Institution of Oceanography, Sea Education Association, and Commonwealth Scientific and Industrial Research Organization.

The Global Plastic Cycle: Zhu (2021)

The ocean floor reservoir: Zhu et al. (2024)

The marine animals reservoir: Zhu et al. (2025) and The Conversation piece

Plastic Spiraling in River Networks (2021-2025)

Together with colleagues from Loyola University Chicago, the University of Toronto, and the University of New Hampshire, I am investigating how plastic is transported through watersheds and what factors (storm intensity, imperviousness) affect its movement. We have sampled microplastic and macroplastic from various habitats in three watersheds across North America (Don River, North Branch Chicago River, and Ipswich River). We found that stormflow plays a major role in mobilizing plastic in rivers and that the composition of microplastics in the water column shifts from fibre- to rubber-dominated during higher flows.

NSF Grant Start Date: 10/01/2021, Awarded Amount: $418,107

The influence of flow on riverine plastic: Haney et al. (2025)

Storms influence plastic transport: Schwenk et al. (2025)

Emissions Inventories of Plastic Pollution (2020-2024)

Akin to emissions inventories of greenhouse gases, I proposed novel a framework for measuring emissions of plastic pollution that can be applied to any city, province/state, or country around the world. This accounting tool can help make the Global Plastics Treaty more quantitative - by helping to inform effective mitigation, measure baseline emissions, set emission reduction targets, and track progress towards reaching targets. My work is currently helping to inform a national toolkit for measuring plastic emissions being developed by the United Nations Environment Programme.

Viewpoint about concept in ES&T: Zhu and Rochman (2022)

Framework and case study of Toronto in ES&T: Zhu et al. (2024)

Sources and Fate of Microplastic and Other Anthropogenic Microdebris in San Francisco Bay, California, USA (2017-2021)

I helped lead an ecosystem-wide study of plastic pollution in San Francisco Bay in collaboration with San Francisco Estuary Institute, 5 Gyres Institute, and the University of Toronto. My team and I analyzed 300+ samples of sediment, fish, and water for microplastics and reported our findings to help inform policies to mitigate microplastic inputs into the Bay. Throughout this multi-year project, numerous studies were published that helped to advance knowledge of sources and sinks, sampling and analysis protocols, and mitigation strategies in the field of plastic pollution including:

Summary paper of our findings: Zhu et al. (2021)

Raingardens mitigate microplastic inputs: Gilbreath et al. (2019)

Stormflow is a major pathway for microplastics and tire dust: Werbowski et al. (2021)

Recommendations for sampling surface water: Hung et al. (2010)

A novel microfiber identification method: Zhu et al. (2019)

Microplastics in SF Bay summary report: Sutton et al. (2019)