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Human impact on the nitrogen cycle is diverse. Agricultural and industrial nitrogen (N) inputs to the environment currently exceed inputs from natural N fixation . [ 1 ] As a consequence of anthropogenic inputs, the global nitrogen cycle (Fig. 1) has been significantly altered over the past century.
Elevated nitrate in groundwater is a concern for drinking water use because nitrate can interfere with blood-oxygen levels in infants and cause methemoglobinemia or blue-baby syndrome. [28] Where groundwater recharges stream flow, nitrate-enriched groundwater can contribute to eutrophication , a process that leads to high algal population and ...
Nitrification is the biological oxidation of ammonia to nitrate via the intermediary nitrite. Nitrification is an important step in the nitrogen cycle in soil. The process of complete nitrification may occur through separate organisms [1] or entirely within one organism, as in comammox bacteria. The transformation of ammonia to nitrite is ...
Fertilizer production is now the largest source of human-produced fixed nitrogen in the terrestrial ecosystem. Ammonia is a required precursor to fertilizers , explosives , and other products. The Haber process requires high pressures (around 200 atm) and high temperatures (at least 400 °C), which are routine conditions for industrial catalysis.
[12] [13] Complete nitrification, the conversion of ammonia to nitrate in a single step known as comammox, has an energy yield (∆G°′) of −349 kJ mol −1 NH 3, while the energy yields for the ammonia-oxidation and nitrite-oxidation steps of the observed two-step reaction are −275 kJ mol −1 NH 3, and −74 kJ mol −1 NO 2 − ...
At the same time, red meat, including beef, is categorized by the International Agency for Research on Cancer as a Group 2A carcinogen, meaning it "probably" causes cancer to humans - though the ...
Putrefying bacteria also play a role in putrefaction and fermentation of proteins in the human gastrointestinal tract. [2] Putrefying bacteria play a key role in the nitrogen cycle. Putrefying bacteria is a broad term used to define several species of bacteria involved in decomposition and fermentation.
A biogeochemical cycle, or more generally a cycle of matter, [1] is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust.