Cycling of carbon and nutrients

Like CO2 and CH4, nitrous oxide has both natural and anthropogenic sources. The largest sources of N2O are associated with nitrogen cycling in natural and agricultural ecos)7stems (Section 2.4.2, Cycling of Carbon and Nutrients) nitrification and denitrification both release N2O (Haynes, 1986). N2O is abo formed as a b rproduct of fuel combustion. Human activities are estimated to have increased the release of N2O by 40-50% over... 

The cycles of carbon and the other main plant nutrients are coupled in a fundamental way by the involvement of these elements in photosynthetic assimilation and plant growth. Redfield (1934) and several others have shown that there are approximately constant proportions of C, N, S, and P in marine plankton and land plants ("Redfield ratios") see Chapter 10. This implies that the exchange flux of one of these elements between the biota reservoir and the atmosphere - or ocean - must be strongly influenced by the flux of the others. 

Enzyme assays are simple and serve as excellent indicators of microbial activities. They have also been used as indicators to evaluate nutrient/contaminant impacts in wetlands. However, there are several limitations to their use in quantitative evaluation of carbon and nutrient cycling in wetlands (Sinsabaugh et al., 1991). Some of the limitations are... 

High-nutrient wetland systems are characterized by rapid turnover of carbon and nutrients, and by open elemental cycling, where the nutrient inputs often exceed the demand (Figure 17.2). These systems are low stress systems and contain varying degrees of internal cycling. In response. 

Mineralisation As used in organic geochemistry, and studies of carbon and nutrient cycling, the term implies breakdown of organic matter to simple dissolved carbon, nitrogen, etc. species (e.g., CO2, NOs ", NH3, etc.). 

In many freshwater aquatic systems, dissolved organic material (DOM) represents a major pool of organic material. Processes that produce, consume, and transform DOM are important in the overall cycling of carbon, energy, and nutrients in these aquatic ecosystems. Current research has... 

Role of arbuscular mycorrhizal fungi in carbon and nutrient cycling in grassland... 

Ratios between O2 consumption and inorganic carbon and nutrients regeneration, called the remineralization ratios, provide useful insights into biogeochemical cycles in the oceans (e.g., export of material to the deep sea and depth-dependent preferential regeneration, if any, of one constituent over the others). For the Indian Ocean, these ratios have been derived from observed variations in concentrations of O2, nutrients and inorganic carbon. Utilizing linear relationships between NOs and... 

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