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~ This paper not to be cited without prior reference to the author
International Council for
the Explo~ation ofthe SeaC.M. 1979/C:2
Hydrography Cttee
Ref. Marine Environmental
Quality Cttee
Investigations of Temperature, Salinity, ·Oxygen,
pH, Alkalinity and Organie Pollutants in the
Baltic Sea during BOSEX i 77
by
Gerhard Dahlmann
Horst Gaul
Günter Weichart
Deutsches:Hydrographisches Institut
Bernhard-Nocht-Strasse 78
2000 Hamburg 4Federal Republic of Germany
* BOSEX Contribution No. 25
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ABSTRACT
From 12 to 23 September 1977 the Deutsches Hydrographisches
Institut participated with the RV "Gauss" in the research
program of BOSEX'77 (Baltic Open Sea Experiment 1977). BOSEX'77
was a joint interdisciplinary experiment, that took place in
the Baltic proper in September 1977. It was arranged by ICES/
SCOR Working Group on the study of the pollution of the Baltic,
and its purpose was to joinphysical, chemical and biological
efforts.
This paper presents the results of the physical and chemical
examinations, i.e. measurements of temperature, salinity, O2
,
pH, alkalinity, and organic pollutants (chlorinated- and
petroleum hydrocarbons).
As expected, the central stations of the BOSEX area show very
similar vertical distributions, indicating a pattern of dis
crete horizontal layers, typical for the Baltic.
The pollutant measurements indicate this area as a compara
tively low polluted part of the Baltic.
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Du 12 au 23 septembre 1977, le Deutsches Hydrographisches
Institut avait partici~e, avec le navire de recherche GAUSS,
au programme BOSEX '77 (Baltic Open Sea Experiment 1977).BOSEX '77 etait une experience commune interdisciplinaire
qui ~vait ete e~~ectuee, en septembre 1977, dans la mer
Baltique proprement dite. Cette experience avait 'ete orga
nise par le groupe de travail ICES/SCOR pourles etudes de
la pollution dans la mer Baltique. Son objecti~ etait de
joindre des travaux de physique, chimie et biologie •
Cet article presente les resultats des etudes physiques et
chimiques, c'est-~-dire des mesures de la temperature, de la
'salinite, del'02' du pH, de l'alcalinite et des polluants
organiques (hydrocarbures chlorees et hydrocarbures de petrole).
Comme attendu, les stations centrales de la region de l'ex
perience BOSEX rev~lent des distributions verticales pareilles,
indiquant un mod~le de couches individuelles horizo~tales qui
sont caracteristiques pour la mer Baltique.
Les mesures de polluants montrent que, dans cette region.de
la mer Baltique, la pollution est comparativement peu importante •
, .
( ,
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METHODS
Parameters of the classical, chemical oceanography:
Water sampIes were taken by plastic Nansen bottles (Hydrobios,
Kiel) from 3 m, 10 m, 20 m, 30 m, 40 m~ 50 m, 70 m, 90 m etc.
The pH was measured by a glass eleytrode (Schott & Gen., Mainz). 0 +
at about 150. The precision (95 % confidence) was -0,01 unit.
Alkalinity was calculated from pH after addition of HGl, ac
cording toANDERSON and ROBINSON, Industr. Eng. Chem. (Anal.)
18, 767 - 773 (19 46 ). The precision (95 % confide~ce) was
!0,02 mequivalents • dm~3.
Temperature was measured with normal hydrographic reversing
thermometers.
Salinity was determined using an inductive salinometer (Beckmann
Instruments).
Pesticides and PCBs:
Sampling:
Sampling the surface layer was done with a stainless steel
funnel, that collects 1 1 water when sinking through the sea
surface. The water sampIe corresponds to a 3,5 mm layer from tIthe surface (STADLER & SCHOMAKER, Dt. hydrogr. Z. 28, 117
(1975».
Because the surface film proved to be an accumulator for
chlorinated hydrocarbons and other pollutants subsurface
sampIers have to pass through the surface in a closed po
sition in order to avoid contamination. We used two types
of sampIers, one is a 20 1 stainless steel cylinder (STADLER &
SCHOMAKER, Dt. hydrogr. Z. ~, 81 (1976», the other consists
of a 10 1 standard Duran 50 reaction vessel with a 100 mm
"
~
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wide flat ground flange fixed by ,a stainless steel protective
basket to the hydrographie wire (STADLER & SCHOMAKER, Dt. hy
drogr. Z. JQ. 20 (1977».
The glass sampIer is more appropriate for several reasons:
The smoother surface (mostly glass), the better accessibility
for cleaning proeedure (100 mm wide easydemountable flange)
and the possibility to extract directly from the sampling
vessel (minimized losses by adsorption).
All water sampIes were immediately extracted with hexane by
shaking for half an hour. When the phases had separated two
hours later the hexane phase was collected on board and stored
until further treatment in the land based laboratory.
Analyses:
The extracts were dried with sodium sulfate, concentrated to
2 ml and sprayed on thin layer plates coated with silica gel,
together with a standard for calibration purposes. The plate
was developed in acetone und hexane. According to the
standard the plate was cut in four different zones, which
were eluted separately.
These four fractions were brought to dryness on a rotary
~ evaporator rinsed with hexane and finally brought to a
volume of 0,2 ml.
From this volume aliquots were taken for gas chromatography
on paeked eolumns of different polarity (STADLER & ZIEBARTH,
Dt. hydrogr. Z. 28, 263 (1975». Calibration was done once
a day.
A compound was considered to be identified when the retention
'time on both columns was correct within 2 % and the substance
appeared in the corresponding zone of the thin layer chro
matogram.
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Because some of the values for DDT and its metabolites proved
to have been unsufficiently separated from PCBs the DDT data
are omitted.
Petroleum hydrocarbons:
Sampling:
The sampling and handling procedure aboard were exactly the
same as described for pesticide and PCB analyses except for
the investigation of the surface layer: Surface sampies were
collected with a stainless steel wire screen (STADLER & ttSCHOMAKER, Dt. hydrogr. Z. 22, 61 (1977». After collection
the sampie was extracted with 300 ml spectroquality CCl4
.All samples were stored in the dark until further treatment
in the land based laboratory.
Analyses:
The analyses were carried out according to the "guide of
operational procedures for the IGOSS pilot project", IOC,
Manuals and Guides No. 7:
The extracts were dried with sodium sulfate and evaporated
to 5 ml.
The surface samples were analysed by IR-spectroscopy, after
a "clean up" by column chromatography (column packed with
Florisil and A1 2 0 3 ) to retain "polar" material.
The subsurface sampies were analysed by UV-Fluorescence with
the extracts excited at 310 nm and measured at 360 nm.
Specific quantitative data cannot be obtained by spectros
co~c methods because of some generaldifficulties:
1) The detected material is unknown and variable in com
position.
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2) Tbe spectroscopic investigation allows to summarize mole
cular properties that are common to all hydrocarbons, but
does not allow any conclusions for a specific substance.
Thcrefore all concentrations of petroleum hydrocarbons in this
paper are given in uni ts of an arbi trari'ly, chosen Ekofisk crudei < ,,-
oil, even thoughthe detected material may in part be of bio-
genic origin.
Procedural blanks were determined by carrying all solvents
through the entire analyses •
RESULTS AND DISeUSSION'
According to the BOSEX program, the RV "Gauss" carried out
4 stations per day, situated in 7 km distance around the cen
tral station (see Fig. 1). One station was chosen f~r inter
calibration purposes with the RV "Argos". Subsequently an
additional station was darried out in the Bornholm Deep,
followed by a number of monitoring stations in the Lübecker
Bucht and Kieler Bucht.
Parameters of the classical chemical oceanography:
SampIes for salinity, O2 , pH and alkalinity were taken from
8 tu 10 different depths. All vertical profiles (see Fig. 2
and J) show no stratification to about JO m to 40 m depth.
Below the layer the temperature decreases rapidly to about
J oe to 4 oe, followed by a slight increase to 4 oe to 5 oe
in about 90 m depth. The pH decreases continuously from about
8,25 to 7,J and remains almost~constant below 80 m depth.
The concentration of oxygen decreases from about 7 cmJ/dmJ in
the surface layer to 1,5 to 2,1 cmJ/dmJ ?elow 90 m. There is
a remarkable phenomenon, which was found in all the series~,
,from the BOSEX aren. Just below the surface layer in 40 m to
50 m depth the oxygen concentration increases slightly to about
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7,5 to 8 cm3/dm3 . A probable explanation may be an exchange
(shear) o~ the sur~ace layer by the preceeding storm.
The limits of the different layers can also be seen in the
vertical profiles o~ salinity and alka\nity by slight bends
01' their curves.
These observations indicate the strong vertical stability of
the water masses in the Baltic proper even aft~r the stormy
weather conditions mentioned above.
Pesticides and PCBs:
Tab. 1 shows the results of the pesticide- and PCB-analyses.
Because the BOSEX area is remote from intense shipping and
obviously not directly influenced by industrial 01' municipal
waste waters, we have reason to assurne, that the distribution
of the pollutants is homogeneous within the different water
layers in this area.
At the surface thc concentrations of chlorinated hydrocarbons
vary considerably due to the patchiness of surface films, as
can be seen from the standard deviation.
Thc 10 m layer is much more homogeneous with standard devia
tions weIl within the range of confidence o~ the methods used.
The subsurface sampies below 60 m show a by far greater va
riability, the reason for this is not yet understood.
The concentrations in the BOSEX area are of the same magnitude
as have been observed in West~n Baltic and German Bight in
1975.
Petroleum hydrocarbons:
The results of the petroleum hydrocarbon measurements are
shown in Tab. 2. These data indicate the whole BOSEX area
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as relatively low polluted. It is therefore convenient to com
pare these data with the results from other stations in the
Baltic, especially in those areas with intense shipping.
Fig. 1 shows the con~entrations of petroleum hydrocarbons in
the surface layer determined during the BOSEX cruise and also
another cruise in the Baltic in 1978. It can clearly be seen,
that there are low concentrations in the open sea, whereas in
the bights of Kiel and Eckernförde and on the main shipping
routes (Fehmarn Belt) these concentrations are high.
Despite of the disadvantages of the methods used for petroleum
hydrocarbon analyses (no differentiation between hydrocarbons
of natural origin and oil pollution, arbitrarily chosen stan
dard etc.) the comparison of the data indicates that the
Western Baltic especially in areas with intense shipping
traffic is significantly pollutedby petroleum hydrocarbons.
Table 1
Results of' Pesticide and PCBs Analyses
Station Position }:PCB Lindane Dieldrin o<.-BHC (pg/l)
Surf'ace 7 56°09,0' N 18°43,0' E 2.5,9 3, 1 - 4,9
(0 - J mm) 9 56°00,2' N 18°43,0' E 21,7 2,4 2,2
13 56°0.5,0' N 18°36,5' E 54,9 4,0 - .10,4
34,2 3, 1 5,7 X *18, 1 0,8 4,0 +
**s -
.53 26 70 s ~
Subsurface 7 56°09,0' N 18°43,0' E 11 ,8 2,6 0,06 6,0
(10 m) 10,3 2,6 0,10 6,3 ...56°00,2' 18°43,0' 8,7 4,4
09 N E 3,3 0,07
10,6 2,3 0,06 4,8
13 56°0.5,0' N 18°36,.5' E 5,8 2,6 0,08 2,0
9,4 2,7 0,07 4,7 X
2,3 0,3 0,02 1,7 +8 -
24 11 29 36 s ~
X * = average value
s :t ** = standard deviation
Table 1 (cont.)
Results of' Pesticide and POBs Analyses
Station Position ~PCB Lindane Dieldrin ot-BHC (pg/l)
60 m 7 56°09,0' N 18°43,0' E 4,2 1,3 0,°9 4,2
85 m 7 3,1 2,5 0,°9 6,5
110 m 9 .56°00,2' N 18°43,0' E 6,3 2,6 0,17 0,5
107 m 9 18,6 2,8 0, 11 5,4
56°05,0' 18°36,5' 2,4~
95 m 13 N E 0,7 0,°3 0,8 ~
6,9 2,0 0,10 *
x * = average value+s - ** = standard deviation
6,7
97
0,°5
50
2,7
77
+s - **
Table 2
Results of the Petroleum Hydrocarbon Analyses
Subsurface (pg/l)
Station PositionSurface
SamplerDepth Sampier Depth
(pgfm2 ) (~) (m)
56°9 ' 18°43' * 85 1.047 N E 133 SET 13 1.23 SET>< 56°0.2' 18°43' * 0.80I'il (lj 9 N E 117 K 13 1.07 SET 110enG>
56°9.9' 19°2.8'O$.l 12 N E 33 K 13 1.28I:Q (lj
13 56°5 ' N 18°36.5' E 100 K 13 1.02
average values 88 1. 17 0.92
subtracted average solvent blank 75 0.08
1 54°49' N 9°50' E 633 K 6 1.90 K 16 1. 76
2 54°43 ' N 10°8' E 183 K .'8 1.53 K 18 1.56
4a 54°36' N 10°27' E 100 K 6 1. 81 K 13 1. 69
5 54°26 ' N 10°43' E 117 K 16 1. 92 ....7a 54°34.9' N 11°13.9' E 717 K 10 2.71 K ·25 3.22
/'IJ
8 54°26 ' N 11°27' E 516 K 8 1. 71 K 18 1. 31
9a 54° 15' N 11°18' E 217 K 8 1.90 K 18 2.42
10 54°7 ' N 11 0 4! E 142 K 8 1. 72 K 18 2.08
13a 54°55' N 13° E 67 K 10 1.96 K 35 1. 39
17 54°40' N 15°10' E 142 K 10 1. 88 K 56 1.99
20 54°29 ' N 9°57' E 342 K 10 2.49
25 54°27 • N 10°'6' E 158 K 7 1. 69 K 14 2.85
28 55°19.4' N 15°49.9' E 67 K 10 1.95 K 80 1. 56
29 55° N 14° E K 10 1.54 K 40 2.24
subtracted average solvent blank 183 0.17
* K*SET =stainless steel sampier = glass sampler~e
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--I:=-
mequival . dm- 3
TEMPERATURESALINITY
5 10 oe ,%0 15o
o
1
80
100m
120
1,0 1,5
ALKALINITY --t:>
pH - VALUE -~I:=-
o 7.+'O....&.-."--"'-~7_5"---'---Io.-..l'--8""'-O~.........~8-L5--1-.&..-....I-_i i\ I
20 I i:r:: 40 I II-- pH .-----. ''''. 02~50 ~~
j80 ~.
19R \120 +--r--'--r----r--r--,---r-r----r--r-
2 " 6 8 cm3'dm- 3
OXYGEN CONCENTRATION C'=
o20
:r:: 40I--
& 50Cl
Fig. 2 Depth profiles of station no. 5(17 September, 111.00 h)
•- .
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TEMFERATURE c:::=-
SALINITY c::=-
O 5 70°C, %0 150 i i I
20 i i iS! j j T
2:: 40 \ ~-------r" \th 60
\ .""'.""'. ALKALINITYCl
~80 \ \. \
\ , \
100• m120
1,0 1,5 mequival " dm- 3ALKALINITY C!-
pH-VALUE c:::-
O 70 7,5 8,0 8,5\ i
20 I iI i
40 / \~ /
.
'"0- 60 ~.. . °2~
J
80 !(100m
1200 2 4- . 6 8 cm3'dm~3
OXYGEN CONCENTRATION c:::-
F ig. J : Depth profiles 01' station no. 7(18 September, 8. 00 h)