Press release 2017-11-27

New model important piece of the land-sea carbon cycle puzzle

Researchers at IVL Swedish Environmental Research Institute, SLU, Norwegian NIVA, English CEH and Scottish Water, have developed a method that makes it easier to estimate both the rate at which dissolved organic carbon in lake water is produced or conversely the rate at which it is consumed – this as a function of water nutritional status and turnover. Their findings have been published in the Nature Geoscience journal.

– In the context of environmental work, this means that calculations of the transport of dissolved organic carbon from land to sea and the carbon dioxide emissions associated with this, which are part of the large-scale models that describe carbon circulation in nature, can be significantly improved, says Filip Moldan at IVL Swedish Environmental Research Institute.

Water plays a significant role in the carbon cycle. The transport of dissolved organic carbon from land to sea is a dynamic ingredient in the global carbon cycle. Organic matter in lakes is converted, through both biological and photochemical processes, and carbon is transferred between land, sea and the atmosphere. However, until now the inability to carry out measurements directly in water has made it difficult to predict the rate at which dissolved organic carbon is produced or consumed. But now scientists have found a way to calculate this based on the nutritional status of the lakes and water turnover.

In the present study, the researchers have compiled data from 82 lakes in Europe and North America. They have established that the nutritional status of the lakes clearly determines whether they act as dissolved organic carbon sources or as carbon sinks, and that the rate at which carbon is produced or consumed in seawater can be predicted from water turnover in lakes. When lakes are over-nourished, they change from being carbon sinks to becoming sources of dissolved organic carbon.

– The fastest breakdown of organic carbon takes place in nutrient-poor watercourses and in lakes with a rapid water turnover and the process is largely driven by sunlight. In lakes where water is resident over long periods of time slower processes dominate and the net effect is more about the balance between organic material that is produced and that which is consumed in biological processes. This study has succeeded in finding a way to predict and quantify net effects for both carbon sources and carbon sinks, says Filip Moldan.

Read the whole article in Nature Geoscience.

If you have any questions, please contact:
Filip Moldan, filip.moldan@ivl.se +46 (0)10-788 67 81