Tackling plastic soup

Pollution of water by plastic poses a serious threat to plants, animals and possibly human health. The ‘plastification of ocean water’ – more than 70% of our Earth’s surface and the source of food for more than half of the world’s population – is a serious problem that is now affecting the water in our cities. Deltares offers a range of possible solutions for mapping out the extent of the plastics problem and reducing the ‘plastic soup’ to the natural level: cleaner salt- and freshwater systems, and city waters that are safer and regain their appeal as locations for leisure activities.

Huge amounts of plastic

Plastic such as packaging material, water bottles, cosmetics and other objects enter the environment in all sorts of different ways. This is all the result of increasing consumption and packaging. Throughout the world, huge amounts of plastic waste drift around the oceans, seas and cities. Weathering, sunlight and waves break down the plastic, which can then no longer be seen. But of course, it is still there.
This is how microplastics are formed, particles measuring about 5 mm which, like their even smaller counterpart nanoplastics, are slowly but surely turning our water into a plastic soup. Plastics release substances into the water that are toxic for humans and the environment. In addition, a range of organisms, including even the small organisms such as zooplankton, mistake the particles for food. In that way, plastic particles and associated toxic substances enter the aquatic food chain and they may also constitute a risk for human health. This is an area that has not yet been adequately researched.
Plastic soup in the city brings the microplastics even closer to people. How long can we continue serving this soup while protecting the environment and human health? If we do not make major improvements in waste management and take additional measures, the world’s oceans will contain more plastic than fish by 2050.

Is there a solution?

Some solutions are available. Deltares experts have acquired considerable experience in recent years with research looking at pollution, and the fast and practical application of this knowledge. Deltares has been involved for some time now in modelling water flows in order to identify the sources and spread of toxic substances. This expertise has now been extended to include specific knowledge about plastic pollution in the waters of delta areas and delta cities. We are involved in international studies of plastics in water. And we are involved in discussions about measures to reduce the impact of plastics on ecosystems, human health and society as a whole.

Determining high concentrations and effects

Deltares uses model simulations to calculate where there are high concentrations of plastics and to identify the effects that plastics have on how water plants and animals function (these simulations are known as Dynamic Energy Budget modelling). That allows government authorities, policymakers and administrators to take effective measures.

Interdisciplinary approach

Plastic soup is a complex problem that requires an understanding of technology, environmental hygiene and socio-economic disciplines. We are used to working on interdisciplinary lines at Deltares. Together with our partners and the problem-owners, we look for solutions.

Much more knowledge needed

We know more and more about the behaviour and effects of plastics in the environment, but there is also still a lot that we do not know. We conduct experiments to acquire new knowledge, for example about how plastics behave in the water column, but also how to simplify the measurement of the amount of plastics in the environment. For example, Deltares has been involved in experiments for the CleanSea project using our own simulated plastic soup. Different types of plastics were exposed to UV light and mechanical stress to see how fast the materials degrade. Here also, we strive to collaborate with research organisations and universities to learn more. The transportation and accumulation of microplastics in aquatic food chains and the potential effects on human health are important issues that we will address.

We already know that plastics and microplastics can have all sorts of effects on organisms in the environment. Deltares has developed knowledge about those effects in a number of major EU projects (CleanSea, MICRO). But what is the effect on human health? So far, there is no clear answer to this question but government authorities, policymakers, market parties and NGOs need one if they are to take the right measures.
The amounts of plastic in the environment are often still measured manually and this applies to both sampling and analysis in the laboratory. Deltares is involved in a number of projects that aim to monitor plastics in innovative and more automated ways.
We have, for example, taken the first steps toward the monitoring of plastics using sensors. We are also working on protocols and analytical techniques for plastics and this work involves close collaboration with universities (Department Environment & Health of the VU University Amsterdam, Delft University of Technology and Wageningen University and Research Centre).

Spread of plastics after disasters

Extreme events such as storms, tidal waves and tsunamis are an important direct source of a lot of plastic waste on coasts and in delta waters. Deltares aims to contribute to reducing the dangers and risks of waste that is dispersed over wide areas after floods. We will be investigating this area further in collaboration with research organisations and universities.

Important health implications of plastic waste

In the environment, plastic debris is often covered with micro-organisms. Some of these organisms, such as viruses and other pathogens, can spread disease. Deltares is involved in a number of initiatives to better understand which strains of bacteria and other potential pathogens are present. One of the organisations we work with in this area is the ILVO (Belgium).

The health implications of plastic debris may mainly play a role in delta areas, where many people rely on surface water for daily use and there are regular outbreaks of infectious diseases.

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