Northern lakes are the largest natural sources of methane, a potent greenhouse gas, but it is unclear how and whether feedbacks from warming in Arctic regions will exacerbate or mitigate lake methane emissions. This proposal investigates two potential drivers of methane emissions, which are rapidly changing as the Arctic warms: (1) the composition and quantity of dissolved organic matter (DOM) transported into lakes from the land as vegetation changes and permafrost melts, and (2) the increasing quantities of windblown (aeolian) dust that is released from glacial discharge as the Greenland ice sheet melts. We hypothesize that DOM and dust are the key drivers of methane emissions. DOM is the dominant external source of carbon to lakes with the potential to fuel the methane cycle. Aeolian dust is a source of nutrients that drive microbial activity and, particularly, rare earth elements (REE) from the lanthanide group which are enzymatically-linked to methanotrophy. Understanding how such changes and interactions between DOM and dust/REE influence methane emissions requires approaches from different scientific fields. Methane cycling is powered by microbes and their interactions, but the lake conditions, trophic structure and environmental situation will modify the supply, distribution and bioavailability of elements that support the methane cycle over a variety of timescales and climatic conditions. This consortium focuses on a well-studied lake district as a living laboratory in West Greenland, and assembles experts in the microbiology of lanthanide-dependent methanotrophs, microbial and lake ecology to investigate respectively how microbial interactions and higher trophic levels of the food web modify methane production. Combining limnology and paleolimnology (sediment core analysis) with citizen scientist work will allow linkages between DOM, dust/ REE supply and methane production to be quantified at the landscape-scale and across timescales of decades to centuries as a means of evaluating their broader biogeochemical significance.

https://climet.nl/en

• dr. Wim Hoek
• dr. Charlie Beard
• prof. dr. Paul Mason
• prof. dr. Suzanne McGowan

In our “GRAIT2” project, PhD student Leon Duurkoop uses a trait-based ecohydrological approach to quantify the impact of different mountain plant species, greening trends and mechanisms and mountain hydrology. To assess trait-related effects on hydrology, he combines field research with experiments, remote sensing and modelling.

https://mountainhydrology.org/projects/grait/

• prof. dr. Walter Immerzeel
• dr. Philip Kraaijenbrink
• Leon Duurkoop MSc
• dr. Jana Eichel

We are testing the effects of elevated CO2 concentrations on the performance of ancient plant lineages such as horsetails (Equisetum). These plants have evolved under naturally high CO2 and where thriving as gigantic wetland plants during the Carboniferous. In our modern vegetation they are tiny and only around in very limited species numbers and abundances. Will these paleozoic plants make a comeback in the high CO₂ future of our planet?

We use different methods to answer this question. For example, we conduct experiments in the NPEC growth facilities of Utrecht University to test Equisetum response to CO₂: https://www.npec.nl/phenotyping-modules/module-3-multi-environment-climate-chamber/ 

Iris de Wolf is working on this question: https://www.uu.nl/medewerkers/IKdeWolf/Onderzoek