Half a Century of Measures Has Reduced Phosphorus Inputs to Lake Vomb, but Challenges Remain
New research shows that phosphorus inputs to Lake Vomb have decreased as a result of improved wastewater treatment and measures implemented across the catchment area. However, challenges related to internal phosphorus loading remain.
– In this study, we used long-term monitoring data collected within the Kävlinge River catchment, where the eutrophic Lake Vomb is located. This enabled us to analyse long-term trends in phosphorus entering and leaving the lake and gain a better understanding of how the lake has responded to several decades of mitigation measures throughout the catchment,” says Anna Söderman, industrial PhD student at Sweden Water Research and lead author of the article published in the journal Hydrobiologia.
The results show that external phosphorus loading declined throughout the study period. The largest reductions can be linked to improvements in wastewater treatment. Agricultural measures and wetland restoration have also contributed to lower phosphorus loads, although their effects have been more gradual.
In contrast, reductions in phosphorus concentrations and phosphorus transport at the lake’s outlet have been less evident. After 2015, the researchers also observed signs of increasing internal phosphorus loading, including rising phosphorus concentrations and greater phosphorus transport from the lake.
Reducing nutrient inputs from the catchment alone is not sufficient. To achieve good ecological status in Lake Vomb, restoration strategies must also address the lake’s internal processes. The study further highlights the considerable value of long-term monitoring programmes. Without several decades of data, it would not have been possible to understand the relationships between implemented measures and the lake’s development over time.
The article was authored by Anna Söderman in collaboration with Christian Alsterberg, Magnus Larson, Kenneth M. Persson and Magnus Persson.