Environmental Geology & Geochemistry Seminar (EGGS)

Date
Nov 18, 2021, 12:30 pm1:30 pm
Location
Guyot 220

Speaker

Details

Event Description

Nitrogen is the most reported limiting nutrient in terrestrial ecosystems. Biological nitrogen fixation (BNF), the reduction of atmospheric dinitrogen (N2) into bioavailable ammonia, is the only biological pathway to input new nitrogen in natural ecosystems. As such, this process is critical to support primary production, and it greatly contributes to the capture of CO2 through biomass accumulation and C : N coupling.

Despite the importance of BNF, our understanding of the drivers that control its activity in natural settings remain unperfect, and our estimates of N input through BNF are experiencing significant spatial and temporal variability. These shortcomings are critical in ecosystems with large carbon storage capacity, such as high latitude ecosystems and coastal benthic sediment. Reliable estimates of new N input are necessary to accurately predict the response of these carbon-rich ecosystems to ongoing global environmental changes.

In this talk, I will illustrate how conceptual mechanistic models rooted in our understanding of organisms’ metabolism can allow simple ecological and chemical variables to identify predictable patterns of BNF activity at the scale of landscapes or even ecosystems. During this research, we notably report on the first demonstration of the contribution of the molybdenum-independent, vanadium-containing nitrogenase in boreal forests of northeastern Canada and its environmental drivers. This result calls for a re-evaluation of the importance of alternative nitrogenases in natural habitats.

Overall, this research will lead to better estimates of N input in ecosystems with high carbon density and at several spatial scales and could help better predict the effect of environmental changes in these ecosystems. It also brings new insights on the biogeochemical coupling of the cycles of micronutrient trace metals with those of major elements.