Unformatted text preview: Biological’
phosphorus Figure 1 | Depiction of the global nitrogen cycle on land and in the
ocean. Major processes that transform molecular nitrogen into reactive
nitrogen, and back, are shown. Also shown is the tight coupling between
the nitrogen cycles on land and in the ocean with those of carbon and 25 Burial ‘Biological’
phosphorus phosphorus. Blue fluxes denote ‘natural’ (unperturbed) fluxes; orange
fluxes denote anthropogenic perturbation. The numbers (in Tg N per year)
are values for the 1990s (refs 13, 21). Few of these flux estimates are known
to better than ±20%, and many have uncertainties of ±50% and larger13,21. 294 Gruber & Galloway, Nature, 2008 Nitrogen Sources to soils • Important atmospheric phases (NH4+, NO3- , NOx, N2O, N2) • Main sources: – N- ﬁxa:on of atmos. N2 (human or microbial) – Decomposi:on of organic maSer releases N (NH4+; NO3- ) Losses to rivers – Par:culate N (minor) • Organic N – Dissolved N (major) • Organic N • Inorganic N – Major: nitrate ion (NO3- ) » mobile anion easily l...
View Full Document
This note was uploaded on 01/30/2014 for the course ESCI 271 taught by Professor Lisakellman during the Fall '12 term at St. Francis Xavier, Antigonish.
- Fall '12