Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 114 (2013): 149-163, doi:10.1007/s10533-013-9847-z.
Description:
Mobile sources are the single largest source of nitrogen emissions to the atmosphere in
the US. It is likely that a portion of mobile-source emissions are deposited adjacent to roads and
thus not measured by traditional monitoring networks, which were designed to measure longterm
and regional trends in deposition well away from emission sources. To estimate the
magnitude of near-source nitrogen deposition, we measured concentrations of both dissolved
inorganic nitrogen (DIN) and total (inorganic + organic) dissolved nitrogen (TDN) in throughfall
(i.e., the nitrogen that comes through the forest canopy) along transects perpendicular to two
moderately trafficked roads on Cape Cod in Falmouth MA, coupled with measurements of both
DIN and TDN in bulk precipitation made in adjacent open fields at the same transect distances.
We used the TDN throughfall data to estimate total nitrogen deposition, including dry gaseous
nitrogen deposition in addition to wet deposition and dry particle deposition. There was no
difference in TDN in the bulk collectors along the transects at either site; however TDN in the
throughfall collectors was always higher closest to the road and decreased with distance. These
patterns were driven primarily by differences in the inorganic N and not the organic N. Annual throughfall deposition was 8.7 (+0.4) and 6.8 (+0.5) TDN - kg N ha-1 yr-1 at sites 10 m and 150 m
away from the road respectively. We also characterized throughfall away from a non-road edge
(power line right-of-way) to test whether the increased deposition observed near road edges was
due to deposition near emission sources or due to a physical, edge effect causing higher
deposition. The increased deposition we observed near roads was due to increases in inorganic N
especially NH4
+. This increased deposition was not the result of an edge effect; rather it is due to
near source deposition of mobile source emissions. We scaled these results to the entire
watershed and estimate that by not taking into account the effects of increased gaseous N
deposition from mobile sources we are underestimating the amount of N deposition to the
watershed by 13% - 25%.
Description:
This research was supported by Woods Hole SeaGrant (grant NA06OAR4170021), NSF
IGERT (grant DGE 0221658), an Edna Bailey Sussman Environmental Internship Award from
Cornell University, and a Mellon Foundation award though Cornell University.
Description:
2014-04-14
Keywords:
Nitrogen deposition
;
Roadside
;
Forest edges
;
Throughfall
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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