Chemistry Reference
In-Depth Information
100
30
Concentration
Temperature
90
25
80
20
70
15
60
50
10
40
5
30
0
20
-5
10
0
-10
Fig. 12 Weekly air concentration (gas + particle phase) of the summed seven ICES PCB
congeners and ambient air temperature from April 2005 to 2006 in the semi-rural area of Ispra,
northern Italy [
80
]
ambient air temperatures for a semi-rural site in northern Italy is shown in Fig.
12
[
80
]. Summertime concentrations are about twice as high as wintertime
concentrations, due to the influence of temperature (e.g. ambient air PCB
concentrations increase with increasing temperature due to volatilization from
soil or water). On the other hand, PAHs in the same site show much higher
concentrations in cold than in warmer periods (Fig.
13
), which is likely due to
increases of biomass combustion emissions for domestic heating and litter removal
in fields and gardens [
81
].
Reports of the European Environmental Agency (e.g. [
7
]) have shown several
national emission inventories and have described the temporal trend of POP
emissions between 1990 and 2009 (Fig.
14
). During this period, the reported POP
emissions have decreased considerably to levels that in 2009 were less than half of
those in 1990. In the case of PAH, the mean reduction was 61%, and this was due to
the decreased residential use of coal for domestic heating, to the improvement in the
technologies for metal refining and smelting and to regulations on emissions for
road transport. Since 2003, the emissions of these compounds do not show
variations. The average HCB emissions decreased 98% in Europe as consequence
of regulations in the chemical industry, although the secondary aluminium industry
is responsible for a relative increase of HCB emissions. HCH emissions decreased
80% by changes in agriculture uses. PCB emissions decreased about 75% due to
changes in electronic equipment, while there was a relative emission increase as
consequence of industrial waste incineration.
POP concentrations in the European atmosphere can be estimated from these
national emission inventories by using model calculations, such as the MSCE-POP
model. This is a three-dimensional Eulerian multi-compartment model operating
within the geographical scope of EMEP regionwith a spatial resolution of 50 km
50
