0°roofs - influence of contact time and water matrix on the release of Mecoprop from bitumen roofing membranes

In contrast to normal flat or green roofs, 0°roofs retain water and therefore offer many solutions for minimizing the consequences of climate change. However, green roof substrates are often built on bitumen roofing membranes with herbicides (Mecoprop) to protect buildings from root damage. Mecoprop (MCPP) is a water-relevant pollutant that is released in high concentrations from these bitumen roofing membranes. The aim of our research is to investigate and evaluate the influence of contact time and water matrix on the release, as these are very relevant for the release of MCPP according to the current state of knowledge. In particular, different roof structures contribute to the change in the water matrix due to the materials used. For this reason, three gravel, extensive and intensive roof structures were each constructed on a pilot scale in the experiments and tested for their MCPP release. The roofs were irrigated with 30 liters of synthetic rainwater. The roofs were left to soak for one to 12 days, then drained and the water matrix analyzed for MCPP.

The aim of the research project is to demonstrate the hypothesized correlation between contact time, water matrix and MCPP release and thus to better characterize the MCPP release potential. This information will in turn be used to develop decentralized stormwater treatment systems for the MCPP release behaviour of green roofs in order to maximize the retention of MCPP. Furthermore, it is planned to issue a recommendation for action for green roof uses.