Dr. Bärbel Müller-Karulis from the Baltic Sea Science Centre, Stockholm University, Sweden, will talk about her current scientific work.
Online via Zoom on Monday 2 February 2026
15:00 cet (Rostock, Stockholm time zone);
16:00 eet (Helsinki, Tallinn time zone)
Please register via the link at the bottom (just name and e-mail address) to get the participation link.
Land-based food production: Land-use, eutrophication and impacts
Dr. Bärbel Müller-Karulis,
Baltic Sea Science Centre, Stockholm University. Her title is:
Abstract:
Approximately 70% of the current riverine nitrogen and phosphorus loads to the Baltic Sea originate from human activities within the drainage basin. Diffuse sources distributed across the landscape account for about 90% of the anthropogenic riverine nitrogen and 80% of the anthropogenic P load, with agriculture being the primary contributor. Agriculture is the dominant land use in the catchments of the Danish Straits and the Baltic Proper, while boreal forest cover much of the northern catchments.
About 20% of the total catchment area of the Baltic Sea drainage was used for agriculture in 2020, a decline from 33% since 1910. Fuelled by technological advances and access to mineral fertilizers agricultural production increased despite the decline in agricultural area. In particular the growing mineral fertilizer consumption after WWII led to increasing net anthropogenic inputs of nitrogen and phosphorus to the drainage basin. Compared to pre-WWII, these inputs had roughly tripled until the 1980s, before declining in Denmark, Sweden, and Finland. In the former East Bloc countries net inputs grew until the collapse of the Soviet Union. Between 2000-2018, net nitrogen inputs averaged 64% and phosphorus inputs 30% of 1980s levels.
Soils and inland waters temporarily store nitrogen and phosphorus inputs to the catchment, forming active legacy pools that contribute to riverine nutrient loads over longer times. A simple storage model suggests that these legacy pools delayed the response of riverine loads to changes in nitrogen and phosphorus inputs to the catchment with average response times of approximately 4 years for nitrogen and 6 – 18 years for phosphorus. If the current, low phosphorus inputs to the Baltic Sea catchment can be maintained, we expect a continued decline in riverine phosphorus loads. Nitrogen loads, on the other hand, are already in balance with current levels of inputs and will respond primarily according to future changes in nitrogen use in the catchment.
After the EU expansion in 2004, agriculture re-intensified in the former East Bloc countries. In the Baltic States, agricultural land was taken back into use, mainly for wheat production, which also increased in Sweden and Finland. The past decade also saw rising fertilizer application in many countries around the Baltic Sea. In parallel, waterborne nitrogen loads from most countries to the Baltic Proper and the Gulf of Riga started to increase again, whereas phosphorus loads continued to decline
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