Status: this preprint was under review for the journal TC but the revision was not accepted.
Increased nitrate and decreased δ15N–NO3− in the Greenland Arctic after 1940 attributed to North American oil burning
Nathan J. Chellman,Meredith G. Hastings,and Joseph R. McConnell
Abstract. Nitrogen oxides (NOx = NO + NO2) have an important impact on the atmosphere and biosphere through controls on oxidant concentrations and the formation of nitric acid (e.g. acid rain). Anthropogenic emissions from fossil fuel combustion, land use change, and agriculture have altered the global nitrogen cycle since the beginning of the Industrial Revolution but contributions from specific sources are difficult to quantify, hindering understanding of changes to the natural environment and design of effective mitigation strategies. Ice core records reveal changes in the nitrogen cycle over time in connection to climate, atmospheric chemistry, and the biosphere. Here we use a seasonally resolved ice core record of the nitrogen isotopic composition of nitrate (δ15N–NO3−), together with a broad suite of highly resolved (> 22 samples y−1) elemental and chemical tracers, to investigate sources of nitrate deposited in central Greenland from 1760 CE to present. A marked negative trend in δ15N–NO3− since ~ 1940 CE paralleled a nearly three-fold increase in nitrate concentration. Based on correlated increases in tracer concentrations, independent emission estimates of oil burning, and an isotope mixing model, North American oil combustion likely was the primary driver of recent changes in the nitrogen cycle recorded in Greenland.
How to cite. Chellman, N. J., Hastings, M. G., and McConnell, J. R.: Increased nitrate and decreased δ15N–NO3− in the Greenland Arctic after 1940 attributed to North American oil burning, The Cryosphere Discuss. [preprint], https://doi.org/10.5194/tc-2016-163, 2016.
Received: 30 Jun 2016 – Discussion started: 13 Jul 2016
This manuscript analyzes the changing sources of nitrate deposition to Greenland since 1760 CE using a dataset consisting of sub-seasonally resolved nitrogen isotopes of nitrate and source tracers. Correlations amongst ion concentration, source tracers, and the δ15N–NO3− provide evidence of the impact of biomass burning and fossil fuel combustion emissions of nitrogen oxides and suggest that oil combustion is the likely driver of increased nitrate concentration in Greenland ice since 1940 CE.
This manuscript analyzes the changing sources of nitrate deposition to Greenland since 1760 CE...