Nitrogen cycle component

What chemical reactions are included in these two important components of the nitrogen cycle (see also Fig. 24-1) ... 

The inventory of NH in the ocean is approximately three orders of magnitude smaller than that ofNO. Nevertheless, the cycHng ofNH in the ocean is a cmcial component of the upper ocean nitrogen cycle. In fact, the chemical distinction of NO3 versus NH permits oceanographers to investigate the sources and fate of nitrogen in the upper ocean in a much more detailed way than it would be possible if nitrogen existed just in one major chemical form, such as is the case for PO, for example. 

Nitric oxide (NO), nitrous oxide (N2O), dinitrogen (N2), and ammonia (NH3) are constituents of the Earth s atmosphere. They play important roles in the chemistry and climate of the present-day Earth. Moreover, they are intermediates of the oceanic nitrogen cycle. In contrast to most of the other components of the oceanic nitrogen cycle, they exist as dissolved gaseous molecules. Being gases they can be transferred across the seasurface-troposphere interface. 

The purpose of this chapter is to emphasise the role of the microbial loop in the oceanic nitrogen cycle. It begins by briefly introducing classical concepts of microbial loop function, then shifts to the increase in our knowledge that has occurred in the past three decades. It then introduces the components of the microbial loop that... 

By the end of the nineteenth century, humans had discovered nitrogen and the essential components of the nitrogen cycle. In other words, they then knew that some microorganisms convert N2 to NH4, other microorganisms convert NH4 to NOJ, and yet a third class of microorganisms convert NOJ back to N2, thus completing the cycle. 

For the most part, nitrogen cycles within the ocean have the same microbial processes as in the soil (Figure 1). BNF is the dominant source of new nitrogen to the ocean, with other smaller contributions coming from atmospheric deposition and riverine runoff. Ammonification, nitrification, uptake, and decomposition are all critical components. There are two primary removal mechanisms—denitrification and burial in marine... 

Nitrogen is an essential component of many substances that make up living organisms. It is a key element in protein molecules, nucleic acids, and ATP. Like other elements, the supply of nitrogen on Earth is fixed. It must be recycled, as shown in Figure 26-20. Follow the diagram as you read about the nitrogen cycle. 

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