Road trips, Caribbean islands and many, many bags of sand

By Lone Mokkenstorm – BSc student Leiden University College

If someone would have told me a project in an Environmental Science course would eventually evolve into a capstone, I wouldn’t have believed it. Now, a year later, Lucia, Froukje and me have been working in the lab for weeks, extracting plastic particles from sand samples and even preparing for capstone research overseas.

Last February, we rented a car to take sand samples along the Dutch coast. It turned into a road trip that involved two days, a boat, an island and ten beaches. We even climbed the most muddy dike in The Netherlands, looking for  mud and dressed in a wading suit! After this adventure, third year student Aiken Besley taught us the extraction procedure he used for his research. The past few weeks we have been working on the extraction of these samples from the Dutch coast. The results will hopefully give us more insights into distributions and concentrations on the national scale as well as the potential factors that influence them.

The results will be compared with the research we will be doing in The Caribbean in June. The Caribbean Netherlands Science Institute (CNSI) on St. Eustatius will host us for 5 weeks. We will take samples on this island as well as the surrounding islands Anguilla, St. Martin and St. Barthelemy.  In the institute’s lab, we will quantify the microplastic concentrations of these samples. The dynamics in an insular coastal system are of a very different kind than in the coastal system of The Netherlands and it would be certainly interesting to see how this affects microplastic distributions.

Soon we will be starting with the global samples as well. The more than 40 samples we have gotten so far from LUC students and staff are amazingly diverse, and we would like to encourage everyone to contribute to this project coming summer as well. All you need is some ziplock bags, a spoon and a (phone with a) camera. Interested? Check out the sampling instructions and the map of the destinations we have covered so far!

Although we understand everyone is eager to know how many microplastics were found in the samples  that were brought back last summer, there is a reason why we prioritized the Dutch samples: they form the basis of the research. Right now our priority is to get our methodology straight with samples we could potentially replicate if anything goes wrong. Wouldn’t want your sample from the US to be flushed down the sink, right?

If anything, we will keep you up to date on this blog with any results as well as the progress regarding the Caribbean adventures. Also, please get in touch if you would you like to contribute to our global project or if you have any questions!


Microplastics in Scheveningen

by Lone Mokkenstorm, BSc student at Leiden University College

Photo 1

One of the strengths of LUC’s educational program is that it encourages you to go out in the field and experience the theories you study in the classroom. This semester, Thijs Bosker’s Environmental Science class worked on a field project on the beaches around The Hague. The aim was to quantify the amount of plastics in the region’s coastal areas and to determine if there were any distribution patterns. The class was divided in four research teams and each was assigned coordinates of a sample site somewhere between the pier of Scheveningen and Meijendel, the water purification site.

Plastic is a very durable material and its use has increased tremendously over the past few decades. Plastics in the environment originate for example from industry, sanitary products, and waste. In our research, we distinguished between micro- and macroplastics. Macroplastics are bigger than 5 mm, and basically form the litter you can see lying around on the beaches. Microplastics, however, are trickier: they are smaller than 5 mm and are hard to distinguish from sand particles. However, exactly this small size is what makes them so hazardous for the environment — and us!

Microplastics enter the environment in several ways, for example through surface runoff, sewage systems, or macroplastics breaking down into smaller particles. They are easily consumed by coastal and aquatic organisms. Apart from the fact that they can block an organism’s digestion system, plastics often contain toxic substances (persistent organic pollutants, or POP’s). These POP’s accumulate more with every step in the food chain, and can eventually end up on our plates. Several European countries have recently issued a joint call to ban microplastics from cosmetic products in order to improve the quality of some seafood products, such as the famous Dutch mussels.

As this is a relatively new area of study, scientists have yet to identify all the sources of these plastics, as well as their exact negative health impacts. Even if we know the impacts are hazardous, more research has to be done before this can be taken into account in policies.

beach2On the beach, we sieved the sand with a 5 mm sieve to filter out all shells and driftwood. Afterwards, we let the sand dry for 48 hours and sieved it with two other sieves to distinguish small and bigger microplastics.

The results of our project confirmed this once again. We found more plastics on the sites that werefarthest away from the pier in Scheveningen — which is not exactly what you would expect to be the case, given the amount of human activity and tourism in that area. More questions arose the moment we saw the graphs: Which mechanisms could cause this? Is there another source of plastics? What are the potential impacts if any of those plastics would end up in the water purification pond in Meijendel? An ecological problem that initially seemed straightforward ended up to be more complex than we thought.

Therefore, this hands-on science experience taught us a lot. Everything that could go wrong did indeed go wrong: we tried to sieve wet sand, got lost somewhere in Meijendel, and we found the opposite of what we expected to. It proved that science is a matter of trial and error, and this is something you can’t learn in a classroom. Despite all uncertainties, I do feel that we contributed within this young area of study, concerning an issue that is to be perceived on a local level, whilst impacting health and environment globally.

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Extractions underway

The extraction of samples is underway. We are currently processing the samples which we have received. Three undergraudate students, Lone Mokkenstorm, Lucia Guaita and Froukje Lots are conducting a Research Clinic on the topic. In addition to extracting the samples, they will collect additional samples along the Dutch coast: updates to follow.

Beach sampling pictures

We have received samples from all over the world over the last, in fact from each continent except Antarctica (any takers)? Sampling locations include: Cambodia, Canada, The Caribbean, Spain, Indonesia, Norway, Island, Australia and Zanzibar. Some pictures of the collections can be found below.




St. Martin
2015-08-06 11.02.29




Our first global community project

Dear all,

As part as a research project we want to use our network to collect samples around the world: A true Citizen Science Project! As you might be aware of, plastics are a major issue in the environment. One group of plastics that we are very concerned about are microplastics. A short intro on the issues regarding microplastics can be found here.

So… what are we asking? That you visit a beach on your vacation, collect some sand, and return it to Leiden University College where we analyze the samples. We hope you can bring back 5 small bags of sand, take a picture from the beach, and use your cell phone/mobile to get the GPS coordinates…

Collection instruction can be downloaded here: Sampling Instructions

Please let us know if you have questions,

Thijs Bosker (, Martina Vijver and Paul Behrens