Kovacs, A., Honti, M., Zessner, M., Eder, A., Clement, A. and Blöschl, G. 2012. Identification of phosphorus emission hotspots in agricultural catchments. Science of the Total Environment, 433, 74–88.
Doctoral Programme on Water Resource Systems
Karlsplatz 13/222, A-1040 Vienna, Austria
Searching out phosphorous emission hotspots
Phosphorous is essential for growing food, but it can also seriously damage water ecology. With the PhosFate model hotspots for water management solutions could be identified.
While essential for growing the food we eat, phosphorous can also be a pollutant, and can seriously damage the ecology of rivers, lakes, estuaries and even oceans. One of the major challenges in managing the use of phosphorous in agriculture is predicting and controlling how phosphorous applied to a field will reach a stream or river. This knowledge is essential to identify exactly where phosphorous applications are causing the greatest harm and should be controlled. Adam Kovacs and his co-authors addressed this challenge using a model to identify the location of emission hotspots in two agricultural catchments in Austria and Hungary. Because phosphorous usually moves around attached to particles of soil they applied an improved version of the PhosFate model to explore how suspended sediment travels around the catchments. Through the application of the model, recently published in Science of the Total Environment, the researchers were able to show that approximately one third of the catchment area provides the source for the majority of phosphorus emissions. These source areas would be ideal places to implement management practices to reduce phosphorus losses from the soil.
Management strategies on just small selected areas result in improved water quality
Very interestingly, only a very small percentage of these source areas actually contribute to transporting phosphorous to the catchment outlet (transmission areas). These transmission areas would be perfect sites for management interventions that could directly reduce the transfer of phosphorous to the river and so raise river water quality. The improved PhosFate model enables the researchers to identify source and transmission areas in the catchment, and estimate the effect of management strategies on phosphorus movement around the catchment and its concentration in the rivers. They found that by applying management strategies on just one to three percent of the catchment areas a remarkable improvement in water quality could be seen.
Future work will look at how the model can be applied to test how phosphorous concentrations in the catchment change if specific management strategies, such as conservation tillage, afforestation or creating agriculture free buffer zones directly beside the river banks are applied.