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Doctoral defence of Elham Kakaei Lafdani, MSc, 22.9.2023: Biochar as a water protection tool in peatland forestry – nutrient recovery from runoff water

The doctoral dissertation in the field of Forest Sciences will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus.

What is the topic of your doctoral research? Why is it important to study the topic?

This thesis investigates the potential for adsorption-based nutrient recovery from clear-cut peatland runoff water using biochar. The quality of water is significantly affected by forest harvesting on drained peatlands, which causes a notable increase in sediment load and nutrient export to water bodies. This poses a growing challenge to water protection, particularly as approximately 700,000 hectares of peatland forests in Finland will reach regeneration age within the next decade. Furthermore, the seasonal fluctuations in nutrient concentrations in the runoff further underscore the need of efficient water protection tools in peatland forestry. To address these issues, adsorption-based water protection methods using biochar can potentially offer an effective alternative for water protection in peatland forestry.

What are the key findings or observations of your doctoral research?

The present study highlights the capacity of biochar to recover both organic and inorganic N from peatland runoff waters characterized by high levels of dissolved organic material. Furthermore, the findings indicate that the adsorption process is conditional upon the N concentration present in the water. The investigation indicated a positive association between the adsorption capacity and the initial N concentration, thereby suggesting that elevated rates of nutrient export could enhance adsorption efficacy. In addition, the results demonstrated that TN desorption rates for biochar were negligible, making biochar a viable water protection solution, especially in areas where clear-cut peatlands release substantial amounts of nutrients.

How can the results of your doctoral research be utilised in practice?

The results of this research have led to a better understanding of how biochar functions as a water protection tool for forestry. As a result of this understanding, it is possible to plan new schemes for water protection in forestry. The use of appropriate water protection methods contributes to the preservation and increase of biodiversity in the receiving water bodies by improving the quality of runoff waters. Seasonal changes in nutrient concentrations highlight the need for an effective water protection tool in peatland forestry, which is why using biochar for adsorption-based nutrient removal seems to be efficient.

What are the key research methods and materials used in your doctoral research?

This research was conducted in two small-scale and one meso-scale laboratory experiments with biochars produced from Norway spruce and Silver birch chips. The water in the experiments was taken from a ditch that drains a clear-cut peatland forest in eastern Finland. To construct a biochar reactor for water purification, the biochar's adsorption rate and capacity for the dominant chemicals in the runoff water were studied by shaking adsorption experiment. A biochar reactor was used to evaluate the recovery of different N compounds in runoff water passing through biochar filled-columns. Furthermore, the effect of N concentration on adsorption-desorption dynamics of biochars were examined in an experiment contained separate set-ups for determining TN adsorption under different TN concentrations in the water (adsorption setup) and for determining TN desorption, which possibly occurs when the TN concentration lowers after preceding adsorption (desorption setup).

The doctoral dissertation of Elham Kakaei Lafdani, MSc, entitled Biochar as a water protection tool in peatland forestry – nutrient recovery from runoff water will be examined at the Faculty of Science, Forestry and Technology, Joensuu Campus. The opponent will be Senior Research Scientist, Docent Anna-Kaisa Ronkanen, Finnish Environment Institute (Syke), and the custos will be Professor Annamari Laurén, University of Eastern Finland. Language of the public defence is English.

For more information, please contact:

Elham Kakaei Lafdani,