Microplastics in freshwater sediments : an investigation of stream sediments downstream of artificial football turfs

Due to climate conditions and a high demand of playing time there has been a rapid increase in the number of artificial football turfs in Norway in the last two decades. A rising concern linked to these turfs is the use of rubber granulate particles as infill and their possible emission to the environment. Estimations from Norway and Sweden indicate that the spreading of these particles potentially is one of the largest sources to microplastic emissions in the two countries. Presently there is little knowledge about the fate and abundance of these particles in the environment, and it is unclear to which extent granulate particles from artificial football turfs are spread to adjacent streams and rivers. In this thesis, sediment samples from seven streams in Oslo, Asker and Bærum municipalities were examined, to investigate whether granulate particles from artificial football turfs are released to adjacent watercourses. Sediment samples were taken both upstream and downstream the turfs. 117 sediment samples were analysed, taken from four upstream and 28 downstream sampling stations. Each sediment sample represented a volume of 0,14 litre and was taken from the upper five cm of the sediment. Except three turfs, all the investigated turfs were used during winter time. In addition, they were all connected to watercourses either through drainage pipes or by surface runoff. To extract granulate particles, a combination of sieving and visual identification was used. In total, granulate particles were found in 85,4% of the downstream sediment samples. The amount of granulate particles varied greatly between the streams and ranged from 0,0008 to 6,67g per sample (equals to 0,006 to 47,3 g/litre). The number of granulate particles ranged from 1 to 1672 particles/sample (equals to 1 to 11830 particles/litre). Generally, there were found more granulate particles at stations located closest to the turfs, compared with those further downstream. However, granulate particles also were found at all upstream stations, as well as up to 4.3 km downstream, indicating that granulate particles have the ability to spread far and “randomly”, i.e. not only downstream along waterways. In addition, it appears that the location of the turfs, winter operations and the placement of snow during winter time is crucial in terms of the amount of granulate particles that are released to adjacent waterways. The results from this study show that spreading of rubber granulate from artificial football turfs to adjacent waterways is a major problem, and measures must be implemented to prevent further spreading in the future.