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| Titel |
Microphysical and chemical characteristics of near-water aerosol over White and Kara Seas |
| VerfasserIn |
S. A. Terpugova, V. V. Polkin, M. V. Panchenko, L. P. Golobokova, V. S. Kozlov, V. P. Shmargunov, V. P. Shevchenko, A. P. Lisitzin |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250029706
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| Zusammenfassung |
| The results are presented of five-year-long (2003-2007) study of the spatial - temporal
variability of the near-water aerosol in the water area of White and Kara Seas (55, 64, 71 and
80-th cruises of RV “Professor Shtockman”; 53 and 54-th cruises of RV “Akademik Mstislav
Keldysh”).
Measurements of aerosol microphysical characteristics were carried out by means of the
automated mobile aerosol complex consisting of nephelometer, photoelectric counter and
aethalometer. The aerosol disperse composition was studied with photoelectric counter in 256
size intervals from 0.4 to 10 μm. About 1500 series of measurements were carried out in
White Sea, and about 1400 series in Kara Sea.
Chemical characteristics of aerosol were determined from samples collected on aerosol
filters (92 samples were collected in White Sea and 48 in Kara Sea). The ion composition was
determined under laboratory conditions. The H+, Na+, K+, Ca2+, Mg2+, NH4+, Cl-,
NO3-, HCO3-, SO42- ions were under examination.
Comparing aerosol characteristics of two seas, one can note that the mean values of the
aerosol content parameters in Kara Sea are less than in White Sea. The ratio of the aerosol
mass concentration are from 2 (Yamal Peninsula, northern part of Novaya Zemlya) to 9 times
(Blagopoluchia Bay, Ob’ Gulf). The differences in the concentration of black carbon vary
from 3 (Yamal Peninsula) to 17 times (Blagopoluchia Bay). The differences in the aerosol
number concentration NA are not so big. The values NA near Kara Gate, Yamal
Peninsula and northern part of Novaya Zemlya are practically the same as in White Sea.
The concentration NA at Ob’ gulf is one order of magnitude less than in White
sea.
The obtained aerosol volume size distributions were approximated by the sums of two
fractions, submicron and coarse, with lognormal size distributions. The mean volume size
distribution of submicron fraction in White Sea is approximated by the distribution with the
variance of the radius logarithm Ïs=0.6 and modal radius Rs0=0.096 μm, and the total
volume concentration V s=37.6 μm3cm-3, and the distribution of coarse fraction has
the following parameters Ïc=1.19, Rc0=2.15 μm and V c=19.7 μm3cm-3. The
distribution of submicron particles in the central part of Kara sea is approximated by
lognormal function with parameters Ïs=0.443, Rs0=0.215 μm and V s=1.01 μm3cm-3,
while parameters of the coarse fraction are Ïc=0.825, Rc=2.04 μm and V c=3.29
μm3cm-3.
The main differences in the size spectra in White and Kara Seas are observed in the
submicron size range R < 1 μm. The higher values of the distribution function in this range
are explained by the fact that White Sea, on the contrary to Kara Sea, is internal sea, so
near-water aerosol undergoes the effect of continental sources, which can have anthropogenic
origin and generate great amount of submicron aerosol, which is transferred to long
distances.
Comparison of ion composition of aerosol over White and Kara Seas has shown that the
concentrations of practically all ions, on average, are greater in the region of White Sea. The
enhancement of ions of marine origin (Cl-, Na+, Mg2+) is from 1.4 to 1.7 times. This
differences in “continental” ions (Ca2+, SO42-, NO3-, NH4+) reach 2.3÷3.7 times.
The exception is the ion K+, the concentration of which in Kara Sea is 1.4 times
greater.
To estimate the contribution of continental and marine sources into formation of the
chemical composition of near-water aerosol, the technique was applied using the factors
V cont and V ocean representing the fraction of the mass concentration of ions of continental
and marine origin, respectively. Depending on the hydrometeorological conditions, V cont
varies in wide range (~ 0.1÷1), and its mean value in White Sea is 0.38 (respectively, V ocean
= 0.62). That means, the contribution of continental sources is essential, although the role of
marine sources prevails on average. The mean value of V cont in central regions of Kara Sea
is 0.3, but this factor in the regions adjacent to the continent can reach the values of
0.6÷0.8.
The obtained long-term data on the aerosol microphysical characteristics and chemical
composition are convincing evidence of the fact that significant parts of the water area of
White sea undergo anthropogenic pollution through the atmospheric channels and are under
permanent anthropogenic loading. They are coastal regions of Dvina Gulf and river
Severnaya Dvina mouth, Kandalaksha Bay (near to the river Kandalaksha mouth), as well as
coastal regions of Kola Peninsula.
The work was supported in part by the Program of basic researches of Presidium RAS
No. 17 “Basic problems of oceanology: physics, geology, biology, ecology”, the project
“Investigations of the properties and regularities of variability of atmospheric aerosol over
ocean”. |
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