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De Grachtwacht conducts research into urban nature and the impact of plastic on nature. With our clean-ups, we not only collect waste, but also data. In this way, we try to find out the source of the waste and turn off the tap on shore. This way, less plastic ends up in the canal!

Why our research is needed

Of all the plastic in canals and rivers, only 2% ends up in the sea. The rest, the remaining 98%, gets stuck behind water plants or sinks to the bottom for example. Unlike with plastic pollution on beaches or in the sea, little is known about plastic in freshwater. Therefor it's important to study it; and that's what we do at 'De Grachtwacht' together with Leiden University, Wageningen University and our passionate Plastic Spotters. Through citizen science, we work with more than 500 volunteers and conduct real scientific research that is published in peer-reviewed scientific journals. Research from Leiden, with an international impact. Our clean-ups have already been picked up by CNN, The Guardian and National Geographic. We not only remove plastic from the canals, we also contribute to more knowledge about plastic pollution. By tracing and tackling the source, we prevent plastic from ending up in the water. This is how we are working on structurally reducing the amount of plastic in the canal - and with success!

Terrace waste in the Leiden canals

With the canoe fleet, we investigate the impact of the terrace boats in Leiden and help cafés and restaurants to make the switch to plastic-free terraces. From biscuit packaging to coffee milk cups and honey bags; there is a sustainable alternative!

Impact of corona litter on nature

The face masks and gloves that are supposed to protect us are actually dangerous for the animals around us. The discovery of a perch entrapped in a glove in the canals of Leiden led to a worldwide inventory of animal victims.

DNA from the canal!

We are sequencing the DNA of the canal's most obscure animals. Together with our volunteers, we are building a public genetic database. This is a revolutionary way of mapping the canal's biodiversity!

Where are the plastic hotspots?

Together with Wageningen University, we are investigating plastic hotspots in the city. Where does plastic accumulate? In which places are clean-ups more necessary?

Tracing back the source of plastic

We collect not only waste, but also data. By finding out the source of the waste, we try to close the tap on shore. This is how we are working towards structurally less waste in the canal!

Where does our plastic go?

We know where they are found, and we know where they come from. So by researching menus, we are investigating how plastic moves through the canal. Where does our plastic actually flow to?


Scientific papers