Phosphorus Fluxes in the Baltic Sea Region

Abstract

Phosphorus (P) budgets and flows in particular regions or countries are assessed and suitable strategies discussed to identify and improve the P use efficiency in these countries. These strategies will help to reduce P losses, close the P cycles and protect vulnerable waters, such as the Baltic Sea, from further eutrophication. The P budgets and flow analyses show that in most of the Baltic Sea Region (BSR) countries P inputs exceed outputs, and a high amount of P that entered the system is retained, especially within the soils of the agricultural production sector. The continuous accumulation of P in the soil results in excessive P surpluses and increases the risk of P losses and eutrophication in the long run. Various suitable measures to help to minimize these P losses are proposed, including more stringent recycling of wastewater P (communal sewage sludges and their ashes; struvite and related precipitation products from wastewater treatment), biodegradable solid wastes (biowaste compost) and incinerated slaughter residues. However, the commercial implementation depends on the overcoming of considerable obstacles which include the development and implementation of adequate technology, the adjustment of existing and creation of new governmental regulations and promoting social acceptance of the necessary changes. Furthermore, the monitoring of P fluxes needs improvement in order to generate more consistent and comparable results. It is recommended that fluxes are modelled not only on a national but also on a regional scale in order to be able to account for the specific geographical condition of each country. Also, the P status of agricultural soils with its changes over time and some key soil characteristics need to be considered on a sub-national/regional scale to assess the actual risk of P loss via erosion/run-off/leaching from a particular area/region. Finally, P flow analyses should comprise several years to monitor long-term developments and trends in P flows.