Freshwater plastics

With a significant amount of plastic pollution entering the environment in urban settings and making its way to the oceans through freshwater channels (rivers, creeks and stormwater) it is important to understand the transition from human use to pollution, and how it affects the plastics’ fate and impact on the environment.

Just like the analysis of marine environments, ESR researchers and collaborators are undertaking projects that examine plastic at different stages of the freshwater plastic pollution journey. They look at how microplastics act as a direct chemical contaminant source, absorb contaminants and make them bioavailable, and the microbial interactions involved in these processes.

Metropolitan urban

The Whau River catchment is in Auckland, Aotearoa New Zealand's largest city. The catchment includes urban and industrial areas and contains some of Auckland’s highest levels of pollution from urban stormwater, commercial/industrial site runoff, combined sewage overflows and litter.

Te Hau o te Whau(external link) (the essence of the Whau) is a pollution and waste-focused project that brings together groups working across science, community and iwi to help improve the mauri (life force) of the Whau River. Read more about the microplastics analysis and impact assessment carried out at the Whau: Plastics and Te Wai Whau, Tāmaki Makaurau-Auckland [PDF, 1 MB]

Ecotoxicology and ecological effects

Little is known about the impact of microplastics on dry land, and a PhD project by Helena Ruffell within the Aotearoa Impacts and Mitigation of Microplastics (AIM²) research programme is investigating the impacts of microplastics in productive soils. The aim of the project is to investigate the sources of microplastics to the terrestrial environment, focusing on the beneficial reuse of biowastes (effluent, biosolids, compost, vermicast) and their application on to land. A method was developed to extract microplastics from these mediums, and using this method, microplastics were extracted from samples of these different biowastes collected from all around Aotearoa. A selection of microplastics recovered from this study are pictured below. The impact of microplastic contaminated soil on plant growth was also assessed, with a pot trial of mustard and ryegrass, with oxidative stress biomarkers and nutrient uptake analysed.

Above: A selection of microplastics recovered from the productive soils study.


Other student projects are focused on the impact of microplastics at the Christchurch wastewater treatment plant, to examine the relationship between different plastics and the chemicals and microbes. This is because wastewater treatment plants represent a major source of plastics into the environment. By establishing the relationship between different plastics and the chemicals and microbes we can better understand the risks they may pose the environment.