Anoxic environments, characteristics

Denitrification takes place in anoxic environments where nitrate and nitrite act as electron acceptors (oxidizers) and nitrification reactions then reverse NOf => NO2 => NO. The processes of denitrification (H2) on land are important channels for nitrogen to get into the atmosphere. The intensity of these processes depends on temperature, humidity, pollution of soils with poisonous chemicals, and pH. The quantitative and functional characteristics of these dependences have been well studied. The global model need only take into account temperature and humidity ... 

None of the Marine Silks display significant inorganic content, but they are encrusted with both inorganic and organic deposits that reflect the anoxic environment established within the trunk. All of the infrared absorbance peaks characteristic of fibroin were identified in the Reference, Historic, and Marine Silks and no new peaks were identified in either the Historic or the Marine... 

In the sediments of the Nansha Islands waters, compositional characteristics of nalkanes, isoprenoid alkanes, alkanes, steranes, and hopanes indicate that they come from marine planktons. Lower Pr/Ph ratios show that the depositing environment is anoxic. With increasing burial depth, the relationship of diagenetic transformation between hopenes and hopanes and that between hopane isomers are found (Duan et al., 1996). 

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