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Abstract:
We investigated the isotopic composition of atmospheric NO3- deposition
at a moderately polluted site in Western Europe over an annual cycle
from December 2011 to November 2012. On average, we measured
load-weighted delta N-15 values of +0.1 and +3.0 parts per thousand in
wet and dry deposition, respectively. A comparison to source-specific N
emission trends and to isotope data from the 1980s reveals distinct
changes in delta N-15-NO3- values: In contrast to the increasing
relative importance of isotopically depleted natural NOx sources, we
find an increase of isotope values in comparison to historical data. We
explore the role of land-based N sources, because backward trajectories
reveal a correlation of higher delta N-15 to air mass origin from
industrialized areas. Nowadays isotopically enriched NOx of coal-fired
power plants using selective catalytic converters and land-based vehicle
emissions, which use same technology, are apparently the main driver of
rising delta N-15 values in nitrate deposition. (C) 2014 The Authors.
Published by Elsevier Ltd.
