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Abstract:
Aerosol emissions from construction sites have a strong impact on local air quality. The chemical and physical characteristics of particles and
trace gases emitted by earthworks (excavation and loading of soil as
well as traffic on unpaved roads) and road works (asphalt sawing,
smashing, soil compacting, asphalt paving) have therefore been addressed
in this study by using a mobile set-up of numerous modern online aerosol
and trace gas instruments including a high-resolution aerosol mass
spectrometer.
Fuel-based emission factors for several variables have been determined,
showing that earthwork activities and compacting by use of a plate
compactor revealed the highest median emission factors for PM10 to 54 g
l(-1)). Construction activities were assigned to contribute about 17%
(36 000 t a(-1)) to total PM10 emissions and 3% (13 500 t a(-1)) to
total traffic-related NO emissions in Germany. In particular, calculated
PM10 emissions by earthworks are about 15 800 t a(-1) corresponding to
44% of total PM10 emissions by construction activities in Germany.
Mechanical processes such as asphalt sawing (PM1/PM10 = 18 +/- 31%),
soil compacting by a plate compactor (PM1/PM10 = 5 +/- 6%) and
earthworks (PM1/PM10 = 2 +/- 5%) emit predominantly coarse mineral dust
particles. Contrary to that, particle emissions by thermal construction
processes (asphalt paving: PM1/PM10 = 62 +/- 14%) and by the internal
combustion engines of heavy machinery (e.g. road roller PM1/PM10 = 94
+/- 9%) are mostly in the submicron range. These particles were mainly
composed of organics containing non-polar saturated and unsaturated
hydrocarbons (e.g. asphalting: O:C < 0.01, H:C = 2.01). Besides
construction activities, mineral dust is also emitted over cleared land
by wind-driven resuspension depending on wind speed. PM10 emissions by
construction activities often result in local concentrations > 100 mu g
m(-3) and can easily breach the European limit level of PM10. This study
also shows that particulate mineral dust emissions are strongly
dependent on soil moisture and can thus successfully be reduced to a
high percentage by wetting the ground (for PM10 up to 95 +/- 34%)
showing the importance of potential mitigation strategies. (C) 2015
Elsevier Ltd. All rights reserved.
