@misc{nagel_ncycling_and_2013, 
author={Nagel, B., Emeis, K.-C., Flohr, A., Rixen, T., Schlarbaum, T., Mohrholz, V., Plas, A.van der},
title={N-cycling and balancing of the N-deficit generated in the oxygen minimum zone over the Namibian shelf - An isotope-based approach},
year={2013},
howpublished = {journal article},
doi = {https://doi.org/10.1002/jgrg.20040},
abstract = {The northern Benguela upwelling system is a nutrient-replete region with high plankton biomass production and a seasonally changing oxygen minimum zone. Nitrate:phosphate ratios in fresh upwelling water are low due to denitrification in the near-seafloor oxygen minimum zone and phosphate efflux from sediments. This makes the region a candidate for substantial dinitrogen fixation, for which evidence is scarce. Nutrient and oxygen data, N isotope data of nitrate, nitrogen isotope ratios of particulate matter, particulate organic carbon content, and suspended matter concentrations on a transect across the shelf and upper slope at 23°S illustrate N-cycling processes and are the basis for estimating the contribution of N-sources and N-sinks to the reactive nitrogen pool. It appears that N-removal due to denitrification exceeds N gain by N2 fixation and physical mixing processes by a factor of >6, although inorganic N:P ratios again increase as surface water is advected offshore. Nitrate and ammonium regeneration, nutrient assimilation with N:P < 16, shelf break mixing, atmospheric input, and N2 fixation all contribute to the restoration of inorganic N:P ratios back to Redfield conditions, but in seasonally changing proportions. The Benguela upwelling system thus is a nutrient source for the oceanic-mixed layer where N-sources and N-sinks are not in balance and Redfield conditions can only re-adjust by advection and mixing processes integrated over time.},
note = {Online available at: \url{https://doi.org/10.1002/jgrg.20040} (DOI). Nagel, B.; Emeis, K.; Flohr, A.; Rixen, T.; Schlarbaum, T.; Mohrholz, V.; Plas, A.: N-cycling and balancing of the N-deficit generated in the oxygen minimum zone over the Namibian shelf - An isotope-based approach. Journal of Geophysical Research : Biogeosciences. 2013. vol. 118, no. 1, 361-371. DOI: 10.1002/jgrg.20040}}