Influence of Environmental Conditions on Contaminants Leaching From, and Sorbing To, Marine Microplastic Debris
Leaching from and sorbing to microplastics was the main focus of this study.

The Virginia Institute of Marine Science (VIMS), funded by a research grant from the NOAA Marine Debris Program, investigated how various environmental conditions can affect contaminants leaching from, and attaching (sorbing) to, marine microplastic debris.

Project Dates: September 2013 - August 2016

What is the project?
Microplastics (plastic particles less than 5 mm in their longest dimension) are found throughout our ocean. They can be composed of many different types of plastic, which can all react differently with the marine environment in ways we do not fully understand. This may be due to differences in the production process, where plastics are often modified with additives (e.g., flame retardants and plasticizers such as phthalates) to change the properties of the plastic like how strong, flexible, or flame resistant it is. These “persistent, bio-accumulative, and toxic substances,” or “PBTs,” can leach out of the plastic and into seawater when plastics end up in the ocean as marine debris. Existing PBTs in the marine environment can also attach to plastics through a process called “sorption” (a physical and chemical process by which one substance becomes attached to another).

VIMS scientists explored how four different types of plastic – polyethylene (e.g., plastic bags and bottles), polystyrene (e.g., foam take-out food containers and disposable razors), polyurethane (e.g., memory foam mattresses and insulation), and polyvinyl chloride (e.g., PVC pipes and single use medical equipment) – interact with the marine environment. The project included an investigation of how various characteristics of the environment (i.e., temperature and salinity), different levels of weathering, size of microplastics, and the concentration of PBTs in the microplastics and in the water may affect the rate and amount of PBTs leaching from and sorbing to the different types of microplastics.

Who is involved?
The investigation was conducted by Dr. Robert Hale from the Virginia Institute of Marine Science (VIMS), with funding from a NOAA Marine Debris Program research grant.

What does it accomplish?
Plastics were long believed to have no chemical impact on the marine environment, so previous research tended to focus on the interaction of large plastic debris with marine species, such as entanglements and ingestion. It has only recently been shown that plastics indeed interact chemically with the marine environment. This study built on this knowledge, enhancing our understanding of how microplastics and their additives may react in combinations of varying environmental conditions.

What is something unique about the project?
Unlike other studies of this kind, this study cross-examined the effects of microplastic characteristics (type, size, and level of weathering), characteristics of additives (type, mixture, and percentage level) and the characteristics of the environment (salinity, temperature, and dissolved organic matter), with the anticipation that the numerous crossings of variables would result in critical information on a range of microplastic-additive-environment reactions.

For more information on this project, please visit the Marine Debris Clearinghouse.