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Nitrogen Chemistry and the Environment
Kursthemen
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No Planet B
Does our planet have limits? Johan Rockström, Director of Stockholm Resilience Center, along with 28 planetary scientists tried to answer this very complex question in the report "Planetary Boundaries: Exploring the safe operating space for Humanity".
In this prologue, you will explore the concept of 'planetary boundaries' and its significance for the course.
Below you can see how planetary boundaries were changing over time. Reflect on which change surprises you most? Was there something that you expected to see, and what you never thought of before?
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Previously, you've learned about the planetary boundary "Modification of Biogeochemical Cycles". Biogeochemical cycles, or flows reflect transformation of elements between Earth's spheres. Let's explore this concept and understand fundamentals of global elements flows.
Flow of nutrients interconnects all biotic and abiotic elements in the marine, terrestrial, and atmospheric environments that support life on Earth.
Therefore, any disruptions in a nutrient cycle will have multiple impacts across the biosphere as a whole.
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In order to understand different processes related to the biogeochemicals flows, let’s first look at the nitrogen as a chemical element.
Nitrogen is all around us.
Nitrogen is an element that plays a crucial role in our daily lives, often in ways we might not immediately recognize. For instance, the air we breathe is about 78% nitrogen. What about other properties of this essential element?
An introduction to nitrogen in the environment begins with a paradox: nitrogen — existing in its inert state as N2 — is the most abundant element in the earth’s atmosphere but, in this form, is almost wholly unusable by the vast majority of living organisms. (Braun et al., 2007)
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If you need to refresh your knowledge of Lewis structures and the octet rule, check out this interactive video!
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In the previous chapter, you learned about nitrogen's capacity to exist in a wide range of oxidation states, as well as the strength of the triple bond between nitrogen atoms, which contributes to its remarkable stability and inertness in the atmosphere. Now, let’s take a closer look at the biogeochemical cycle of nitrogen, which is crucial for sustaining life on Earth. This cycle illustrates how nitrogen transitions through various chemical forms and environmental compartments, from the atmosphere to the soil, and ultimately into living organisms.
Reflect on how the processes of nitrogen fixation and biofixation play a crucial role in the nitrogen cycle, and consider how evolutionary adaptations in organisms have enabled them to overcome the challenge of utilizing atmospheric nitrogen.
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