While it was recently reported that we could be ingesting a teaspoon of microplastics every week, UNSW Canberra researchers were creating new ways of tracking these harmful contaminants using smartphones.  

Dr Isabel Jalón Rojas and her oceanography students are particularly interested in the microplastics found off the NSW South Coast in Jervis Bay.

Despite Jervis Bay’s zoning as a marine protected area, researchers from the University of Tasmania found that it contains a higher level of microplastic pollution than Sydney Harbour.

“These findings were very surprising because Jervis Bay is a pristine system compared to Sydney Harbour, so we really want to understand why this is the case. What are the sources, and the fate of microplastics in Jervis Bay?” Dr Jalón Rojas said.

Microplastics are small pieces of plastic, less than 5 millimetres in length. Primary microplastics are made to be that size, and include the microbeads found in beauty products. Secondary microplastics are pieces of plastics that have broken down from larger items, such as bottles or bags.

Both types of microplastic can stay in the ocean for centuries, modifying habitats and ecosystems.

“Microplastics can absorb and transport pollutants and invasive species, affecting the biodiversity,”  Dr Jalón Rojas said.

“Microplastics are commonly mistaken for food by marine animals, so this consumption leads to physical damages. When small animals consume microplastics, they can be transferred to other animals that eat them.

“Essentially, humans can also consume microplastics, not only from seafood, but from other foods that may be contaminated by microplastics during the production process. This contamination also affects economic activities, such as fisheries, aquaculture or tourism.”

Dr Jalón Rojas said tracking microplastics allows researchers to understand and predict their distribution and behaviour in aquatic systems. This is essential for assessing environmental and economic risks, as well as for identifying the main sources of contamination.

The UNSW Canberra research team used two approaches to track microplastics in the ocean. First, they developed a numerical model to simulate the three-dimensional transport of debris and microplastics. They are also measuring the trajectories of floating debris in ocean, by placing bottles using smartphones as trackers in the ocean for several days.  

“We needed to know the real-time position of the bottles in order to recover them, or to be sure we can get the data. This can be with sophisticated GPS devices, but they are expensive, and the development can take a lot of time. So, we thought: why not put smartphones inside the bottles?”

In addition to providing a low-cost solution for tracking debris, it was also a valuable experience for oceanography students.

“The students participated in the release, real-time tracking of the devices, picking up and post processing of data,” Dr Jalón Rojas said.

“They developed observational skills and increased their confidence to discuss data in the context of a real and exciting research project.”

The next step for the team is to calibrate and validate their numerical model for Jervis Bay. They will adjust the parameters of the model in order to simulate the observed trajectories of the smartphones.

Once the model is validated, they can perform numerical simulations to understand the potential sources, trajectories and fate of microplastics in Jervis Bay.