The previous work done in this project 2017-2018 focused on understanding the differences in nutrient and sediment removal for two constructed wetlands. This work will be published in January 2019 and then be used to prepare a popular science summary. This work will show how different factors control the effectiveness of both wetlands. One of the important factor is management of constructed wetlands. In Nybble wetland the sediments were removed during summer of 2016 and in Bergaholm the sediments were removed during summer of 2018. Sediment removal is an important management practice to keep the wetlands operational as large amounts of sediment accumulating over a long time clog the inlet and outlet pipes, reducing the function of the wetland. However, the effect of sediment removal is both wetland and weather-specific.
In 2019 we want to answer the following specific questions:
1. Has dredging lead to similar effects on nutrient and sediment retention in both wetlands?
2. How weather and flow conditions during and immediately after the sediment removal affected the effectiveness of this practice?
3. Has extremely dry summer of 2018 affected the nutrient and sediment retention in both wetlands?
Finally, thanks to two optical sensors installed in Bergaholm wetland combined with sorption and denitrification measurements we will be able to address another question:
4. Are constructed wetland retaining nutrients and sediments due to hydrological or biogeochemical retention?