Claire Coutris
Research Scientist
Biography
Claire is a research scientist at NIBIO, since 2013. She holds a PhD in Environmental Chemistry and Ecotoxicology from the Norwegian University of Life Sciences (Norway), and a MSc in Ecology and Ecotoxicology from the University of Toulouse (France).
Claire works with soil biology, environmental chemistry, and the fate of emerging contaminants in soils. She conducts toxicity tests on soil microorganisms, invertebrates and plants in mesocosms, with an emphasis on the impact on soil processes. She works on several Norwegian Research Council projects on recycling of waste resources (biogas digestate, sewage sludge, compost) to soils.
Abstract
Since the 1950s, the use of plastics in agriculture has helped solving many challenges related to food production, while its persistence and mismanagement has led to the plastic pollution we face today. A variety of biodegradable plastic products have thus been marketed, with the aim to solve plastic pollution through complete degradation after use. But the environmental conditions for rapid and complete degradation are not necessarily fulfilled, and the possibility that biodegradable plastics may also contribute to plastic pollution must be evaluated. A two-year field experiment with biodegradable mulches (BDMs) based on polybutylene adipate terephthalate (PBAT/starch and PBAT/polylactic acid) buried in several agricultural soils in mesh bags showed that also under colder climatic conditions does degradation occur, involving fragmentation after two months and depolymerization by hydrolysis, as shown by Fourier-transform infrared spectroscopy. The phytopathogenic fungus Rhizoctonia solani was found to be associated with BDM degradation, and the formation of biodegradable microplastics was observed throughout the experimental period. Between 52 and 93 % of the original BDM mass was recovered after two years, suggesting that accumulation is likely to happen in cold climatic regions when BDM is repeatedly used every year. Mass loss followed negative quadratic functions, implying increasing mass loss rates over time. Despite the range of climatic and edaphic factors, with various agricultural practices and vegetable productions at the study locations, the parameters that significantly favored in situ BDM degradation were higher soil organic matter content and temperatures.
Authors
Christophe Moni Eva Farkas Claire Coutris Hanna Marika Silvennoinen Anders Aas Marit Almvik Liang Wang Kathinka Lang Xingang Liu Marianne StenrødAbstract
Biochar and pesticides are likely to be increasingly used in combination in agricultural soils, yet their combined effects on climate change mitigation remain unexplored. This study presents an 8-month incubation experiment with different soil types (silt loam and sandy loam), biochars (corncob and corn stem), and pesticides (with and without a pesticide mixture), during which CO2 production from soil organic matter (SOM) and biochar mineralisation was monitored using isotopic methods. A comprehensive modelling approach, describing all mineralisation results over the entire incubation with a reduced set of parameters, was employed to isolate the effects of biochar, pesticides, and their interactions across soil types and carbon pools, and captured the dynamic effect of biochar on SOM mineralisation. Over 99.5% of biochars remained inert after 8 months, confirming the role of biochar as a carbon sequestration technology. Biochar addition showed higher SOM stabilisation potential in soil with high clay content compared to soil with low clay content. This suggests that biochar amendment should be considered carefully in clay-depleted soils, as it could result in a loss of native SOM. Corn stem biochar, characterised by high surface area and low C/N ratio, demonstrated higher SOM stabilisation potential than corncob biochar with low surface area and high C/N ratio. Pesticide application reduced SOM mineralisation by 10% regardless of soil and biochar types. Finally, the interaction between corncob biochar and pesticides further reduced SOM mineralisation by 5%, while no interactive effect was observed with corn stem biochar. These findings highlight the importance of considering biochar-pesticide interactions when evaluating the impact of biochar amendments on native SOM stability.
Abstract
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