Predicting and monitoring the effects of large-scale ocean iron fertilization on marine trace gas emissions

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 364:283-288 (2008) - DOI: https://doi.org/10.3354/meps07549 Contribution to the Theme Section ‘Implications of large-scale iron fertilization of the oceans’ Predicting and monitoring the effects of large-scale ocean iron fertilization on marine trace gas emissions C. S. Law* National Institute of Water and Atmospheric Research (NIWA), Evans Bay Parade, Private Bag 14-901, Kilbirnie, Wellington 6241, New Zealand *Email: c.law@niwa.co.nz ABSTRACT: Large-scale (>40000 km2, >1 yr) ocean iron fertilization (OIF) is being considered as an option for mitigating the increase in atmospheric CO2 concentrations. However OIF will influence trace gas production and atmospheric emissions, with consequences over broad temporal and spatial scales. To illustrate this, the response of nitrous oxide (N2O) and dimethylsulphide (DMS) in the mesoscale iron addition experiments (FeAXs) and model scenarios of large-scale OIF are examined. FeAXs have shown negligible to minor increases in N2O production, whereas models of long-term OIF suggest significant N2O production with the potential to offset the benefit gained by iron-mediated increases in CO2 uptake. N2O production and emission will be influenced by the magnitude and rate of vertical particle export, and along-isopycnal N2O transport will necessitate monitoring over large spatial scales. The N2O–O2 relationship provides a monitoring option using oxygen as a proxy, with spatial coverage by Argo and glider-mounted oxygen optodes. Although the initial FeAXs exhibited similar increases (1.5- to 1.6-fold) in DMS, a subsequent sub-arctic Pacific experiment observed DMS consumption relative to unfertilized waters, highlighting regional variability as a complicating factor when predicting the effects of large-scale OIF. DMS cycling and its influence on atmospheric composition may be studied using naturally occurring blooms and be constrained prior to OIF by pre-fertilization spatial mapping and aerial sampling using new technologies. As trace gases may have positive or negative synergistic effects on atmospheric chemistry and climate forcing, the net effect of altered trace gas emissions needs to be considered in both models and monitoring of large-scale OIF. KEY WORDS: Iron fertilization · Trace gases · Nitrous oxide · Dimethlysulphide · Remineralization Full text in pdf format PreviousNextCite this article as: Law CS (2008) Predicting and monitoring the effects of large-scale ocean iron fertilization on marine trace gas emissions. Mar Ecol Prog Ser 364:283-288. https://doi.org/10.3354/meps07549Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 364. Online publication date: July 29, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.