Phytoplankton oxidation

Another important greenhouse gas is a product of phytoplankton oxidation of ammonium. This reaction can follow two pathways ... 

As an alternative to partial assimilatory NOs reduction by phytoplankton, oxidation of NH4+ by Bacteria and Archaea (the first step in the 2-step process of nitrification) can produce N02 as an intermediate product. Nitrifying bacteria were first isolated from the marine environment by Watson (1965) and are now known to be ubiquitous in the global ocean. Wada and Hattori (1971) used a sensitive chemical assay to measure changes in N02 in incubated samples, to conclude that NH4+ was the major source of N02 in the PNM in the central North Pacific Ocean. Miyazaki et al. (1973, 1975), using a N tracer method, found that, in Sagami Bay and in the western North Pacific, NH4+ and NOs were both important sources ofN02. ... 

Climate is often viewed as the aggregate of all of the elements of weather, with quantitative definitions being purely physical. However, because of couplings of carbon dioxide and many other atmospheric species to both physical climate and to the biosphere, the stability of the climate system depends in principle on the nature of feedbacks involving the biosphere. For example, the notion that sulfate particles originating from the oxidation of dimethylsulfide emitted by marine phytoplankton can affect the albedo (reflectivity) of clouds (Charlson et ai, 1987). At this point these feedbacks are mostly unidentified, and poorly quantified. 

CH3SCH3 20-200 pptv Oceanic phytoplankton and algae Oxidation to SO2... 

The vast majority of sulfur at any given time is in the lithosphere. The atmosphere, hydrosphere, and biosphere, on the other hand, are where most transfer of sulfur takes place. The role of the biosphere often involves reactions that result in the movement of sulfur from one reservoir to another. The burning of coal by humans (which oxidizes fossilized sulfur to SO2 gas) and the reduction of seawater sulfate by phytoplankton which can lead to the creation of another gas, dimethyl sulfide (CH3SCH3), are examples of such processes. 

Kuma, K. and Matsunaga, K. (1995). Availability of colloidal ferric oxides to coastal marine phytoplankton, Mar. Biol., 122, 1-11. 

The ocean plays an important role in determining atmospheric composition because it is net source of some gases and a net sink of others. As described later, most of the gases that undergo net degassing are produced by phytoplankton, bacteria, or the photochemically mediated oxidation of DOM. Many of the gases for which the ocean... 

CH3I Oxidation capacity Phytoplankton Photochemistry 0.13 to 0.36Tg ... 

If ammonium concentrations in seawater are low, phytoplankton will assimilate nitrate and nitrite using chemical-specific permeases. Once inside the cell, these DIN species are transformed into ammonium via redox reactions in which nitrogen is reduced to the -III oxidation state ... 

This process is commonly referred to as assimilatory nitrogen (nitrate or nitrite) reduction. The electrons for these reductions are supplied by half-cell oxidations involving NADPH/NADP" and NADH/NAD" (Table 7.11). All of these reactions and membrane transport processes are mediated by enzymes that are specific to the DIN species. Considerable variation exists among the phytoplankton species in their ability to produce the necessary enzymes. Since marine phytoplankton are often nitrogen limited, the quantity and type of DIN available in the water column can greatly influence overall phytoplankton abundance and species diversity. 

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